CA2366292A1 - Method for controlling the heating elements of a thermal print head - Google Patents
Method for controlling the heating elements of a thermal print head Download PDFInfo
- Publication number
- CA2366292A1 CA2366292A1 CA002366292A CA2366292A CA2366292A1 CA 2366292 A1 CA2366292 A1 CA 2366292A1 CA 002366292 A CA002366292 A CA 002366292A CA 2366292 A CA2366292 A CA 2366292A CA 2366292 A1 CA2366292 A1 CA 2366292A1
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- Prior art keywords
- heating elements
- temperature
- pulse
- recording
- pulse train
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
- B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
- B41J2/35—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads providing current or voltage to the thermal head
- B41J2/355—Control circuits for heating-element selection
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
- B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
- B41J2/38—Preheating, i.e. heating to a temperature insufficient to cause printing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2202/00—Embodiments of or processes related to ink-jet or thermal heads
- B41J2202/30—Embodiments of or processes related to thermal heads
Abstract
The invention relates to the recording and deleting of data on a reversibly writable thermal recording material (5) using a thermal print head (2). An energy pulse (W) is delivered to the heating elements (8) of the thermal print head for recording, said energy pulse causing the recording material to heat up to a temperature (T1) at which it becomes coloured and/or opaque. For deleting following the recording pulse (W), the heating elements (8) are subjected to an energy pulse strain (E1).
Description
Method for controlling the heating elements of a thermal print head This invention relates to a method for controlling the heating elements of a thermal print head for recording and erasing dots with a reversibly writable thermal recording ma-terial.
A reversibly writable thermal recording material is char-acterized in that its transparency and/or color can change reversibly from a transparent and/or colorless state to an opaque and/or colored state and vice versa in dependence on temperature.
The reversibly wri~able thermal recording material is supplied step-by-step to the thermal print head having a row of individually drivable resistance heating elements extend-ing over the total printing width transversely to the trans-port direction of the thermal recording material. In each step one can thus record a line of dots corresponding to the row of heating elements if the heating elements are heated to a temperature leading to the colored/opaque state of the thermal recording material.
Erasure of the colored/opaque dots can be effected by a second thermal print head whose heating elements are heated to a temperature at which the reversibly writable thermal re-cording material changes back to the colorless/transparent state. One can also use a single thermal print head which erases when the recording material is moved along it in one direction, and records, i.e. writes dots, upon subsequent movement of the recording material in the reverse direction (DE 41 30 539 A1).
DE 42 10 379 C2 discloses first applying an energy pulse train to drive the heating elements that are to record a dot and then applying another energy pulse train to the heating elements that are to perform dot-by-dot erasure, in each transport cycle.
A reversibly writable thermal recording material is char-acterized in that its transparency and/or color can change reversibly from a transparent and/or colorless state to an opaque and/or colored state and vice versa in dependence on temperature.
The reversibly wri~able thermal recording material is supplied step-by-step to the thermal print head having a row of individually drivable resistance heating elements extend-ing over the total printing width transversely to the trans-port direction of the thermal recording material. In each step one can thus record a line of dots corresponding to the row of heating elements if the heating elements are heated to a temperature leading to the colored/opaque state of the thermal recording material.
Erasure of the colored/opaque dots can be effected by a second thermal print head whose heating elements are heated to a temperature at which the reversibly writable thermal re-cording material changes back to the colorless/transparent state. One can also use a single thermal print head which erases when the recording material is moved along it in one direction, and records, i.e. writes dots, upon subsequent movement of the recording material in the reverse direction (DE 41 30 539 A1).
DE 42 10 379 C2 discloses first applying an energy pulse train to drive the heating elements that are to record a dot and then applying another energy pulse train to the heating elements that are to perform dot-by-dot erasure, in each transport cycle.
In known reversible recording methods, however, the re-cording speed leaves something to be desired.
The problem of the invention is to substantially increase the recording and erase speed in thermal printing of a re-versibly writable recording material.
This is obtained according to the invention by the method characterized in claim 1. The subclaims render advantageous embodiments of the inventive method.
According to the invention the heating elements are driven for writing with a single energy pulse leading to a temperature at which the reversibly writable thermal re-cording material assumes a first, high temperature leading to the colored/opaque state.
The heating elements which are to perform erasure are then subjected to an energy pulse train when the maximum tem-perature has been reached after the recording pulse. This permits the processing, i.e. recording and erasure of the in-dividual dots of a printed line, to be reduced to 3 millisec-onds or less and an accordingly high recording and erase speed to be reached.
According to the invention one uses a reversibly writable thermal recording material that becomes colored and/or opaque at the first, high temperature, retains the colored/opaque state upon rapid cooling but loses it upon slow cooling, but whose colored/opaque state is also lost if constant heating to a second lower temperature takes place.
The first high temperature that makes the thermal re-cording material become colored or opaque, i.e. milky, may be 150°C or more for example. The second lower temperature to be held constant leading to erasure is preferably at least 20°C
lower.
Therefore, the heating elements can be subjected to the energy pulse train for erasure in two variants according to the invention.
According to one variant, all heating elements are first driven with the recording energy pulse and subsequent to the recording energy pulse an energy pulse train is supplied that slows down the cooling of those heating elements which are to bring about erasure such that the recording material assumes its colorless/transparent state. In this variant, all heating elements are thus in each cycle first heated to the tempera-ture necessary for coloring the recording material and the heating elements that are to erase dot-by-dot are then sub-jected to the pulse train in order to cool more slowly than the other heating elements. It is obvious that one need not necessarily drive all heating elements of the thermal print head in this fashion, but only those which correspond to the desired printing width. It is also clear that the colorless/
transparent state might also have a different color from the one appearing upon coloring of the thermal recording mate-rial.
According to the other variant, the heating elements for recording are subjected to the recording energy pulse and the heating elements for erasure, directly subsequent to the re-cording energy pulse, to an energy pulse train which heats the heating elements to a second temperature to be held con-stant at which the thermal recording material assumes a transparent/colorless state, the second temperature being be-low the temperature producing the colored/opaque state.
In the second variant, however, the second temperature must in general be held for a certain time of at least 1 mil-lisecond for erasure. It is therefore in general somewhat slower than the first variant. That is, the pulse duration for the recording pulse is approximately 1 to 2 milliseconds.
Whereas the duration of the pulse train supplied during cool-ing in the first variant is approximately 1 to 2 millisec-onds, the duration of the pulse train for erasure in the sec-ond variant is approximately 2 to 3 milliseconds in order to hold the temperature for at least approximately 1 millisecond at the second temperature at which the thermal recording ma-terial assumes the transparent/colorless state.
The problem of the invention is to substantially increase the recording and erase speed in thermal printing of a re-versibly writable recording material.
This is obtained according to the invention by the method characterized in claim 1. The subclaims render advantageous embodiments of the inventive method.
According to the invention the heating elements are driven for writing with a single energy pulse leading to a temperature at which the reversibly writable thermal re-cording material assumes a first, high temperature leading to the colored/opaque state.
The heating elements which are to perform erasure are then subjected to an energy pulse train when the maximum tem-perature has been reached after the recording pulse. This permits the processing, i.e. recording and erasure of the in-dividual dots of a printed line, to be reduced to 3 millisec-onds or less and an accordingly high recording and erase speed to be reached.
According to the invention one uses a reversibly writable thermal recording material that becomes colored and/or opaque at the first, high temperature, retains the colored/opaque state upon rapid cooling but loses it upon slow cooling, but whose colored/opaque state is also lost if constant heating to a second lower temperature takes place.
The first high temperature that makes the thermal re-cording material become colored or opaque, i.e. milky, may be 150°C or more for example. The second lower temperature to be held constant leading to erasure is preferably at least 20°C
lower.
Therefore, the heating elements can be subjected to the energy pulse train for erasure in two variants according to the invention.
According to one variant, all heating elements are first driven with the recording energy pulse and subsequent to the recording energy pulse an energy pulse train is supplied that slows down the cooling of those heating elements which are to bring about erasure such that the recording material assumes its colorless/transparent state. In this variant, all heating elements are thus in each cycle first heated to the tempera-ture necessary for coloring the recording material and the heating elements that are to erase dot-by-dot are then sub-jected to the pulse train in order to cool more slowly than the other heating elements. It is obvious that one need not necessarily drive all heating elements of the thermal print head in this fashion, but only those which correspond to the desired printing width. It is also clear that the colorless/
transparent state might also have a different color from the one appearing upon coloring of the thermal recording mate-rial.
According to the other variant, the heating elements for recording are subjected to the recording energy pulse and the heating elements for erasure, directly subsequent to the re-cording energy pulse, to an energy pulse train which heats the heating elements to a second temperature to be held con-stant at which the thermal recording material assumes a transparent/colorless state, the second temperature being be-low the temperature producing the colored/opaque state.
In the second variant, however, the second temperature must in general be held for a certain time of at least 1 mil-lisecond for erasure. It is therefore in general somewhat slower than the first variant. That is, the pulse duration for the recording pulse is approximately 1 to 2 milliseconds.
Whereas the duration of the pulse train supplied during cool-ing in the first variant is approximately 1 to 2 millisec-onds, the duration of the pulse train for erasure in the sec-ond variant is approximately 2 to 3 milliseconds in order to hold the temperature for at least approximately 1 millisecond at the second temperature at which the thermal recording ma-terial assumes the transparent/colorless state.
The reversibly writable thermal recording material that can be used according to the invention may be any known re-versibly writable thermal recording material (compare DE 41 30 539 A1, DE 42 10 379 C2 and 42 00 474 C2). However, one preferably uses a recording material available on the market that consists of a mixture of a leuco dye and a developer.
The leuco dye may be a xanthene derivative. Preferably, the xanthene has a dialkylamine residue at the 3 position and at its 9 position a phenyl residue is bound with a carboxyl acid group at the ortho position so that, as in fluorescein, a lactone ring forms with the 9 position in the leuco form, said ring being open in the colored state through re-formation of the carboxyl group. As a developer one can use an acid amide of carboxylic acid with a para-aminophenol and/or a urea derivative substituted with a para-hydroxyphenyl residue on an amino group and with an alkyl residue on the other amino group.
The energy supply for erasure in the form of a pulse train obtains fine temperature control according to the in-vention. For this purpose the pulse train has pulses with the same period of preferably less than 100 microseconds, in par-ticular less as 50 microseconds. The pulse/pause ratio per period is preferably at most 1:1, in particular approximately 1:2. That is, at a period of e.g. 30 microseconds the pulse duration is 10 microseconds and the pause 20 microseconds for example.
Preferably, the heating elements of the thermal print head are preheated before processing, i.e. recording and era-sure, to a temperature that is preferably at least 30°C below the second, i.e. erase, temperature. If the erase temperature is 120°C for example, the preheating temperature can be ap-proximately 60°C for example.
Such preheating in thermal printing is indicated for ex-ample by DE 30 33 746 A1. Preheating lowers the temperature difference until recording or erasure, i.e. reduces the heat-ing capacity necessary for printing, thereby achieving a higher printing speed due to the faster heating of the resis-tance heating elements. Moreover, the erase quality is clearly improved.
While according to DE 38 33 746 A1 the clock frequency during preheating should be no more than the quadruple of the pulse duration for recording and the pulse width during pre-heating should be constant, according to the invention the period of the single pulses of the pulse train for preheating is less than 100 microseconds, in particular less than 50 mi-croseconds, i.e. less than one tenth, preferably less than one twentieth, of the pulse duration at a pulse duration for the recording pulse of 1 to 2 milliseconds.
In order to permit the desired preheating temperature to be adjusted as exactly as possible, the pulse/pause ratio per period is furthermore preferably reduced with increasing tem-perature of the thermal print head. Thus, at a constant pe-riod of the single pulses, the pulse duration can be for ex-ample 10~ or less of the period at the beginning of preheat-ing, and for example 3~ or less at the end of the preheating process or for holding the preheating temperature. That is, at a period of for example 30 microseconds per single pulse, the pulse duration can be for example 2 microseconds at the beginning of preheating and for example 0.5 microseconds at the end of preheating and for holding the preheating tempera-ture.
The pulse duration during preheating can be controlled for example by the temperature of the thermal print head, which can be measured with a temperature sensor, for example a temperature-dependent resistor with a negative temperature coefficient.
Under these circumstances, the preheating temperature of the heating elements can be adjusted to for example t 2°C or even more exactly. The thermal print head is thus minimally stressed thermally and its life essentially increased. As ex-periments indicate, this even makes the life longer than without preheating since the thermal print head is subject to smaller temperature jumps during recording. The period of the single pulses of the pulse train during preheating preferably corresponds to the period of the single pulses of the pulse train for erasure, being for example 30 microseconds in both cases.
In the following, the invention will be explained in more detail by way of example with reference to the drawings, in which:
Figure 1 shows a diagram representing the change in color density of a reversible heat-sensitive recording material for use in the inventive method in dependence on temperature;
Figure 2 shows schematically a thermal printer for re-versible printing of entitlement cards;
Figure 3 shows a block diagram for driving the thermal print head; and Figures 4 and 5 show diagrams for illustrating the first and second variants of the inventive method.
According to Figure 1, the reversible thermal recording material exists at TO in a transparent and/or colorless state, i.e. with low color density. TO may be room tempera-ture or lower, or be a preheating temperature. Heating from TO to T1 (e. g. 160°C) causes the color density to increase according to the dashed line, in particular after melting point TM of the reversible thermal dye has been exceeded.
While the colored and/or opaque state is retained when rapid cooling takes place from Tl according to the unbroken line, the colorless and/or transparent state is assumed again when the thermal recording material is cooled down slowly from temperature T1 according to the dashed line, or when it is heated constantly to erase temperature T2.
According to Figure 2, thermal printer 1 has thermal print head 2 between two pairs of feed rollers 3, 4. En~itle-ment cards 5 are supplied according to arrow 6, moved step-by-step with feed rollers 3, 4 along thermal print head 2 for processing and outputted via output slit 7.
_ 7 -On its edge facing card 5, print head 2 has individually drivable resistance heating elements 8 that form on card 5 a row extending transversely to transport direction 6. Heating elements 8 are driven between two consecutive transport steps and thereby heated. Simultaneously, counterpressure roller 9 is pressed against card 5. Thus, according to the invention all heating elements 8 are first subjected to an energy pulse which causes the recording material to assume a colored/
opaque state along the line. Directly thereafter, heating elements 8 are driven with an energy pulse train at the dots of the recording material or card 5 where erasure is to take place.
According to Figure 3, shift register 10 for example re-ceives data 11 from a data source not shown for the informa-tion to be represented on card 5. Discriminator l2 distin-guishes whether a colored/opaque dot or a color-less/transparent dot is to be formed on the card by relevant heating element 8 for the information recording in the par-ticular transport step. Processing section 13 defines the data in order to generate the recording energy pulse and erase energy pulse train. The pulse data are decoded by de-coder 14 into a total pulse train for driving heating ele-ments 8 for processing the relevant line of card 5 and this total pulse train fed to driver 15.
Figure 4 shows for the first variant of the inventive method in (a) the pulse train for driving heating elements 8 and in (b) the temperature of the thermal recording material upon reception of the pulse train.
Thus, all heating elements 8 are driven for preheating or for holding temperature TO of for example 60°C with pulse train P having a period of e.g. 30 microseconds and a pulse duration per period of e.g. 2 to 0.3 microseconds, depending on how great the difference is between the temperature meas-ured by the temperature sensor (not shown) and given preheat-ing temperature T0.
For processing a line, all heating elements 8 are sub-jected at t1 to recording pulse W of e.g. 1 to 2 millisec-onds, causing the temperature of thermal recording material to rise at the end of the recording pulse at t2 to tempera-ture T1 of e.g. 160°C, i.e. a temperature above the tempera-ture at which the reversible heat-sensitive recording mate-rial assumes a colored and/or opaque state.
Heating elements 8 at the dots of the line which are to be erased are driven directly after pulse W with pulse train E1. It consists for example of single pulses with a period of 30 microseconds, whereby the pulse duration may be e.g. 10 microseconds and the pause duration for example 20 microsec-onds per period.
V~hile the temperature of relevant heating element 8 decreases from T1 exponentially, i.e. rapidly, according to curve F
without pulse train E1, a more linear, slower cooling takes place to preheating or starting temperature TO according to dashed sawtooth curve S under the action of pulse train E1.
In Fig. 4, L1 represents the time period for processing, i.e. printing and erasing, the first line, and L2 for proc-essing the second line.
While according to the diagram of Figure 1 the colored/
opaque state is retained through the rapid cooling according to curve F, erasure of the particular colored/opaque dot takes place through the slower, more uniform cooling accord-ing to curve S.
The embodiment according to Figure 5 differs from that according to Figure 4 substantially in that directly after pulse F heating elements 8 are subjected, at the dots of the line where erasure is to be effected, to pulse train E2 which raises the temperature of relevant heating element 8 accord-ing to curve C to temperature T2 which is below temperature T1 according to the diagram of Figure 1. In Figure 5, (a) represents the pulse train supplied to the heating elements for recording, and (c) the pulse train which drives the heat-ing elements for erasure, while (b) and (d) represent the _ g _ temperature/time diagram upon reception of pulse trains (a) and (c) .
The leuco dye may be a xanthene derivative. Preferably, the xanthene has a dialkylamine residue at the 3 position and at its 9 position a phenyl residue is bound with a carboxyl acid group at the ortho position so that, as in fluorescein, a lactone ring forms with the 9 position in the leuco form, said ring being open in the colored state through re-formation of the carboxyl group. As a developer one can use an acid amide of carboxylic acid with a para-aminophenol and/or a urea derivative substituted with a para-hydroxyphenyl residue on an amino group and with an alkyl residue on the other amino group.
The energy supply for erasure in the form of a pulse train obtains fine temperature control according to the in-vention. For this purpose the pulse train has pulses with the same period of preferably less than 100 microseconds, in par-ticular less as 50 microseconds. The pulse/pause ratio per period is preferably at most 1:1, in particular approximately 1:2. That is, at a period of e.g. 30 microseconds the pulse duration is 10 microseconds and the pause 20 microseconds for example.
Preferably, the heating elements of the thermal print head are preheated before processing, i.e. recording and era-sure, to a temperature that is preferably at least 30°C below the second, i.e. erase, temperature. If the erase temperature is 120°C for example, the preheating temperature can be ap-proximately 60°C for example.
Such preheating in thermal printing is indicated for ex-ample by DE 30 33 746 A1. Preheating lowers the temperature difference until recording or erasure, i.e. reduces the heat-ing capacity necessary for printing, thereby achieving a higher printing speed due to the faster heating of the resis-tance heating elements. Moreover, the erase quality is clearly improved.
While according to DE 38 33 746 A1 the clock frequency during preheating should be no more than the quadruple of the pulse duration for recording and the pulse width during pre-heating should be constant, according to the invention the period of the single pulses of the pulse train for preheating is less than 100 microseconds, in particular less than 50 mi-croseconds, i.e. less than one tenth, preferably less than one twentieth, of the pulse duration at a pulse duration for the recording pulse of 1 to 2 milliseconds.
In order to permit the desired preheating temperature to be adjusted as exactly as possible, the pulse/pause ratio per period is furthermore preferably reduced with increasing tem-perature of the thermal print head. Thus, at a constant pe-riod of the single pulses, the pulse duration can be for ex-ample 10~ or less of the period at the beginning of preheat-ing, and for example 3~ or less at the end of the preheating process or for holding the preheating temperature. That is, at a period of for example 30 microseconds per single pulse, the pulse duration can be for example 2 microseconds at the beginning of preheating and for example 0.5 microseconds at the end of preheating and for holding the preheating tempera-ture.
The pulse duration during preheating can be controlled for example by the temperature of the thermal print head, which can be measured with a temperature sensor, for example a temperature-dependent resistor with a negative temperature coefficient.
Under these circumstances, the preheating temperature of the heating elements can be adjusted to for example t 2°C or even more exactly. The thermal print head is thus minimally stressed thermally and its life essentially increased. As ex-periments indicate, this even makes the life longer than without preheating since the thermal print head is subject to smaller temperature jumps during recording. The period of the single pulses of the pulse train during preheating preferably corresponds to the period of the single pulses of the pulse train for erasure, being for example 30 microseconds in both cases.
In the following, the invention will be explained in more detail by way of example with reference to the drawings, in which:
Figure 1 shows a diagram representing the change in color density of a reversible heat-sensitive recording material for use in the inventive method in dependence on temperature;
Figure 2 shows schematically a thermal printer for re-versible printing of entitlement cards;
Figure 3 shows a block diagram for driving the thermal print head; and Figures 4 and 5 show diagrams for illustrating the first and second variants of the inventive method.
According to Figure 1, the reversible thermal recording material exists at TO in a transparent and/or colorless state, i.e. with low color density. TO may be room tempera-ture or lower, or be a preheating temperature. Heating from TO to T1 (e. g. 160°C) causes the color density to increase according to the dashed line, in particular after melting point TM of the reversible thermal dye has been exceeded.
While the colored and/or opaque state is retained when rapid cooling takes place from Tl according to the unbroken line, the colorless and/or transparent state is assumed again when the thermal recording material is cooled down slowly from temperature T1 according to the dashed line, or when it is heated constantly to erase temperature T2.
According to Figure 2, thermal printer 1 has thermal print head 2 between two pairs of feed rollers 3, 4. En~itle-ment cards 5 are supplied according to arrow 6, moved step-by-step with feed rollers 3, 4 along thermal print head 2 for processing and outputted via output slit 7.
_ 7 -On its edge facing card 5, print head 2 has individually drivable resistance heating elements 8 that form on card 5 a row extending transversely to transport direction 6. Heating elements 8 are driven between two consecutive transport steps and thereby heated. Simultaneously, counterpressure roller 9 is pressed against card 5. Thus, according to the invention all heating elements 8 are first subjected to an energy pulse which causes the recording material to assume a colored/
opaque state along the line. Directly thereafter, heating elements 8 are driven with an energy pulse train at the dots of the recording material or card 5 where erasure is to take place.
According to Figure 3, shift register 10 for example re-ceives data 11 from a data source not shown for the informa-tion to be represented on card 5. Discriminator l2 distin-guishes whether a colored/opaque dot or a color-less/transparent dot is to be formed on the card by relevant heating element 8 for the information recording in the par-ticular transport step. Processing section 13 defines the data in order to generate the recording energy pulse and erase energy pulse train. The pulse data are decoded by de-coder 14 into a total pulse train for driving heating ele-ments 8 for processing the relevant line of card 5 and this total pulse train fed to driver 15.
Figure 4 shows for the first variant of the inventive method in (a) the pulse train for driving heating elements 8 and in (b) the temperature of the thermal recording material upon reception of the pulse train.
Thus, all heating elements 8 are driven for preheating or for holding temperature TO of for example 60°C with pulse train P having a period of e.g. 30 microseconds and a pulse duration per period of e.g. 2 to 0.3 microseconds, depending on how great the difference is between the temperature meas-ured by the temperature sensor (not shown) and given preheat-ing temperature T0.
For processing a line, all heating elements 8 are sub-jected at t1 to recording pulse W of e.g. 1 to 2 millisec-onds, causing the temperature of thermal recording material to rise at the end of the recording pulse at t2 to tempera-ture T1 of e.g. 160°C, i.e. a temperature above the tempera-ture at which the reversible heat-sensitive recording mate-rial assumes a colored and/or opaque state.
Heating elements 8 at the dots of the line which are to be erased are driven directly after pulse W with pulse train E1. It consists for example of single pulses with a period of 30 microseconds, whereby the pulse duration may be e.g. 10 microseconds and the pause duration for example 20 microsec-onds per period.
V~hile the temperature of relevant heating element 8 decreases from T1 exponentially, i.e. rapidly, according to curve F
without pulse train E1, a more linear, slower cooling takes place to preheating or starting temperature TO according to dashed sawtooth curve S under the action of pulse train E1.
In Fig. 4, L1 represents the time period for processing, i.e. printing and erasing, the first line, and L2 for proc-essing the second line.
While according to the diagram of Figure 1 the colored/
opaque state is retained through the rapid cooling according to curve F, erasure of the particular colored/opaque dot takes place through the slower, more uniform cooling accord-ing to curve S.
The embodiment according to Figure 5 differs from that according to Figure 4 substantially in that directly after pulse F heating elements 8 are subjected, at the dots of the line where erasure is to be effected, to pulse train E2 which raises the temperature of relevant heating element 8 accord-ing to curve C to temperature T2 which is below temperature T1 according to the diagram of Figure 1. In Figure 5, (a) represents the pulse train supplied to the heating elements for recording, and (c) the pulse train which drives the heat-ing elements for erasure, while (b) and (d) represent the _ g _ temperature/time diagram upon reception of pulse trains (a) and (c) .
Claims (9)
1. A method for controlling the heating elements of a thermal print head for recording and erasing data on a re-versibly writable thermal recording material, characterized in that the heating elements for recording are subjected to an energy pulse which causes the recording material to be heated to a temperature (T1) at which it assumes a colored or opaque state, and the heating elements for erasure are sub-jected to an energy pulse train subsequent to the recording pulse.
2. A method according to claim 1, characterized in that the heating elements for erasure are subjected, subsequent to the recording pulse, to a pulse train which delays the cool-ing of the heating elements such that the recording material assumes a colorless or transparent state.
3. A method according to claim 1, characterized in that the heating elements for erasure are subjected, subsequent to the recording pulse, to a pulse train which heats them to a second temperature (T2) at which the thermal recording mate-rial assumes a colorless or transparent state, the second temperature (T2) being below the first temperature (T1) at which the thermal recording material assumes the colored or opaque state.
4. A method according to claim 3, characterized in that the pulse train brings about the second temperature (T2) for at least 1 millisecond.
5. A method according to any of the above claims, charac-terized in that the heating elements are preheated for re-cording and erasure to a predetermined temperature (T0) by an energy pulse train.
6. A method according to any of the above claims, charac-terized in that the pulse train for erasure and/or for pre-heating consists of pulses with the same period.
7. A method according to claim 6, characterized in that the period of the single pulses of the pulse train is at most 100 microseconds.
8. A method according to claim 6, characterized in that the pulse/pause ratio of the pulse train for erasure per pe-riod is at most 1:1.
9. A method according to claim 6, characterized in that the pulse/pause ratio of the pulse train for preheating per period is reduced with increasing temperature of the thermal print head.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE10012360.0 | 2000-03-14 | ||
| DE10012360A DE10012360C2 (en) | 2000-03-14 | 2000-03-14 | Method for controlling the heating elements of a thermal print head |
| PCT/EP2001/002568 WO2001068370A1 (en) | 2000-03-14 | 2001-03-07 | Method for controlling the heating elements of a thermal print head |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2366292A1 true CA2366292A1 (en) | 2001-09-20 |
Family
ID=7634657
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002366292A Abandoned CA2366292A1 (en) | 2000-03-14 | 2001-03-07 | Method for controlling the heating elements of a thermal print head |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US6731318B2 (en) |
| EP (1) | EP1233866B1 (en) |
| JP (1) | JP4342759B2 (en) |
| KR (1) | KR20020008169A (en) |
| AT (1) | ATE252983T1 (en) |
| CA (1) | CA2366292A1 (en) |
| DE (2) | DE10012360C2 (en) |
| NO (1) | NO20015201D0 (en) |
| WO (1) | WO2001068370A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1866161B1 (en) | 2005-04-06 | 2014-10-22 | Zink Imaging, Inc. | Multicolor thermal imaging method and thermal printer |
| US20080158708A1 (en) * | 2006-12-29 | 2008-07-03 | Maulion Frederick A | Preparing for servo write |
| GB2582179B (en) * | 2019-03-15 | 2022-04-20 | Magicard Ltd | Method and apparatus for printing |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2729375B2 (en) * | 1987-03-02 | 1998-03-18 | キヤノン株式会社 | Driving method of recording head |
| DE3833746A1 (en) * | 1988-09-30 | 1990-04-05 | Siemens Ag | Thermal printing with pre-heating resistor elements - energised by actual data and by clock pulse of variable width and height |
| EP0461606B1 (en) * | 1990-06-14 | 1997-12-10 | Mitsubishi Denki Kabushiki Kaisha | Rewriteable recording/display apparatus and method of erasing record |
| JP2700234B2 (en) * | 1990-09-14 | 1998-01-19 | 株式会社リコー | Reversible thermosensitive recording material |
| DE4130539A1 (en) * | 1990-09-14 | 1992-03-19 | Ricoh Kk | Reversible heat-sensitive image-recording material - comprises reversible heat-sensitive- and protective-resin layers on support, for rapid recording and deletion |
| JP3032263B2 (en) * | 1990-10-04 | 2000-04-10 | 株式会社東芝 | Recording device |
| JP3100450B2 (en) | 1991-01-11 | 2000-10-16 | 株式会社リコー | Image recording method and apparatus used therefor |
| JP3017828B2 (en) * | 1991-03-29 | 2000-03-13 | 株式会社東芝 | Recording device |
| JPH05262013A (en) | 1992-03-24 | 1993-10-12 | Toshiba Corp | Recording device |
| US5424764A (en) | 1992-08-24 | 1995-06-13 | Kabushiki Kaisha Toshiba | Thermal recording apparatus for recording and erasing an image on and from a recording medium |
| US5572528A (en) * | 1995-03-20 | 1996-11-05 | Novell, Inc. | Mobile networking method and apparatus |
| US5982807A (en) * | 1997-03-17 | 1999-11-09 | Harris Corporation | High data rate spread spectrum transceiver and associated methods |
| US5987033A (en) * | 1997-09-08 | 1999-11-16 | Lucent Technologies, Inc. | Wireless lan with enhanced capture provision |
| US6254225B1 (en) * | 1997-10-17 | 2001-07-03 | Eastman Kodak Company | Continuous ink jet printer with asymmetric heating drop deflection |
-
2000
- 2000-03-14 DE DE10012360A patent/DE10012360C2/en not_active Expired - Fee Related
-
2001
- 2001-03-07 KR KR1020017013944A patent/KR20020008169A/en not_active Application Discontinuation
- 2001-03-07 US US10/030,006 patent/US6731318B2/en not_active Expired - Lifetime
- 2001-03-07 AT AT01911748T patent/ATE252983T1/en active
- 2001-03-07 JP JP2001566903A patent/JP4342759B2/en not_active Expired - Fee Related
- 2001-03-07 CA CA002366292A patent/CA2366292A1/en not_active Abandoned
- 2001-03-07 WO PCT/EP2001/002568 patent/WO2001068370A1/en active IP Right Grant
- 2001-03-07 EP EP01911748A patent/EP1233866B1/en not_active Expired - Lifetime
- 2001-03-07 DE DE50100868T patent/DE50100868D1/en not_active Expired - Lifetime
- 2001-10-24 NO NO20015201A patent/NO20015201D0/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| EP1233866A1 (en) | 2002-08-28 |
| KR20020008169A (en) | 2002-01-29 |
| JP4342759B2 (en) | 2009-10-14 |
| ATE252983T1 (en) | 2003-11-15 |
| NO20015201L (en) | 2001-10-24 |
| NO20015201D0 (en) | 2001-10-24 |
| DE50100868D1 (en) | 2003-12-04 |
| US6731318B2 (en) | 2004-05-04 |
| JP2003526549A (en) | 2003-09-09 |
| EP1233866B1 (en) | 2003-10-29 |
| US20030007059A1 (en) | 2003-01-09 |
| DE10012360C2 (en) | 2002-01-31 |
| WO2001068370A1 (en) | 2001-09-20 |
| DE10012360A1 (en) | 2001-09-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |