DE3504029A1 - Image-generating device - Google Patents

Abstract

An image-generating device is described, for generating an image on a sheet of paper by transporting an inking ribbon (44) which is impregnated in certain sections with printing ink of different colours, from one spool (or winding shaft) (96) to another spool (98) and by transferring the printing inks from the inking ribbon (44) to the sheet of paper. Two couplings (136, 138) which have armatures or rotors (144, 146) and can be rotated by motors (132, 134) are connected to the spools (96, 98). The rotors (144, 146) can be removed or locked by means of a braking unit (160) so that the spools (96, 98) are prevented from rotating. <IMAGE>

Description

The present invention relates to an image forming apparatus for forming an image by transferring colorants or printing inks from a ribbon, as

Transfer element, onto a latent image formed on a sheet of paper.

Various image forming apparatus of this type are known. Underneath is a thermal transfer printer that prints an image by heating a ribbon impregnated with colorants or printing inks. This printer is comparatively small, inexpensive and quiet in operation, and it can ^{print out 1} ^ on normal paper. He is therefore at

electronic calculators, word processors and photocopiers.

The ribbon is partly wound onto a spool (winding axis) and partly onto another spool. During the printing process, one of these spools is rotated by a motor. In the non-printing state (waiting state), both spools can be rotated. Therefore if the printer im not printing state, i.e. in the waiting state, oscillates, both spools can rotate a little and thus turn on Loosening and wrinkling of the ribbon. If you continue to take up the ribbon If the spool is suddenly stopped, the ribbon supply spool may continue to rotate a little. thereby producing the same effect. When inserting a ribbon cassette into the machine (after the Removing a used cartridge) may also cause the same phenomenon because both Winding axles or coils are rotatable.

The object of the invention is to provide an image forming apparatus in which a loosening or

Wrinkling (wrinkling) of an ink ribbon

prevents, when the machine vibrates in a waiting state, an ink ribbon take-up shaft is suddenly stopped or a ribbon cassette is inserted into the machine.

This task is performed in an image forming apparatus which forms an image by moving a transfer member from one spool (or winding shaft) to another and by transferring a colorant from the transfer element generated on a sheet of paper, according to the invention solved by latching means for engaging both coils, by a drive unit for driving both coils via the latching means and for Transporting the sheet of paper and through a braking unit to slow down or inhibit the two reels. 20th

The following is a preferred embodiment of the Invention explained in more detail with reference to the drawing. Show it:

² ^ Fig. 1 is a perspective view of a

Thermal or thermal printer as an embodiment of the image forming device according to the invention,

Fig. 2 is a partially cut-away perspective Representation of the device according to Fig. 1,

3 shows a vertical section through the device according to an enlarged scale Fig. 1,

Fig. 4 is a perspective view of an ink ribbon and a sheet of paper for illustration the way in which the 5th

Device according to Fig. 1 on the sheet of paper a

Creates expression,

Fig. 5 is a plan view of a (s) ink ribbon (ab-

section) to show its impregnation

^ tion with printing inks of different colors,

FIGS. 6 to 9 are sectional views to illustrate the mode of operation of the device according to FIG. 1,

¹ ^ Fig. 10 is a block diagram of a control circuit

of the device according to Fig. 1,

11 is a vertical section, on an enlarged scale, through a main part ² ^ of the printer;

12 is a perspective view of the main part schematically illustrating a holder unit;
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13 shows a perspective partial view of the holder unit,

14 shows a perspective illustration of the holder unit with a drive unit for

their drive,

Fig. 15 is a side view of the holder unit and

a brake unit,
35

Fig. 16 is a perspective view of the brake unit and an ink ribbon cassette for

illustration of the engagement connection the cassette with the braking unit and

17 is an illustration for explaining the operation of the brake unit.

Figures 1 and 2 illustrate a thermal or thermal head printer as an example

¹ ^ for an image forming apparatus according to the invention. The printer 10 comprises a housing 12 with an original carrier 14 arranged on its upper side, on which an original to be copied can be placed and which is made of a transparent material, for example glass, and is provided with a cover 15. A scanning unit 16 for scanning the original lying on the original carrier 14 is located in the housing 12 directly below the original carrier 14. The scanning unit 16 contains an optical exposure system 18 which can be moved in the direction of the arrow N for scanning the original (by means of light) and for receiving the light reflected from the original. The light received by the system 18, ie the optical information, is converted into electrical signals.

in the middle area of the housing 12 is located an image generation unit 20 which - as will be described in more detail below - for generation of an image on a sheet of paper in accordance with the electrical signals supplied by the scanning unit 16 is designed.

A compartment 22 for receiving the finished copies is attached to the top of the housing 12. In the front of the housing 12, a paper cassette 24 is removably inserted, the paper sheets receive which can be transferred individually to the device. At the front of the case

12, a control panel 32 is provided directly above the cassette 24, which has a start button 26, a Keypad with decimal keys 28, a display 30 for displaying a warning, e.g. "paper jam", for the Notification of the operator and a button 31 has. When the start button 26 is pressed, the device is put into operation. A ribbon cassette can be ejected by pressing button 31

the.

A flap or door 36 attached to the housing 12 closes one formed in this side of the housing Opening. The door 36 is opened to a ribbon cassette 34 through the opening in the housing to use or to take from it. The door 36 has a lock or bolt mechanism (not shown) on, which locks the door 36 in response to signals generated by pressing some of the Decimal keys 28 are entered in a prescribed order.

In the following, the image generation unit 20 is described in detail with reference to FIG. 3, which is equipped with a Holder 42 for holding an ink ribbon cassette 34 inserted into the housing 12 and a heat or heat exchanger. Thermal (print) head 4 6 for heating the outside accessible portion of the ribbon 44 for the purpose of transferring ink from the ribbon to a sheet of paper P is provided. The thermal head 46 includes a number of heating elements selectively driven by the exposure system 18 supplied electrical signals can be controlled to the ribbon accordingly heat and from this to transfer the printing ink to the paper sheet P. The image generation unit 20 further includes a thermal head 46 facing with an ink ribbon 44 therebetween

Pressure roller 48 which is displaceable in order to press the paper sheet P and the ink ribbon 44 against the thermal head 46. At the back of the thermal head there is 46 5

a heat radiating plate 50 for radiating the heat generated by the thermal head 46 is arranged.

When a roller 52 disposed at the front end of the paper cassette 24 is replaced by an unillustrated one The drive is set in rotation, a sheet of paper P is discharged from the cassette 24. Right next to the roller 52 are two guide plates 54 for guiding the paper sheet P from the roller 52 as well two alignment rollers 56 for aligning (i.e. straightening) the leading edge of the through the guide plates 54 guided sheet of paper P. On opposite sides of the pressure roller 48 are support or pressure rollers 58 arranged, the fed from the aligning rollers 56 in cooperation with the pressure roller 48 Grasp the paper sheet P and guide it around the pressure roller 48 in order to make it contact pressure with the latter to keep.

The compartment 22 adjoining the image generation unit 20 comprises a plate 60, a first guide plate 62 and a third (second) guide plate 64. These plates 60, 62 and 64 are made of the same material. The plate 60 serves as a shelf for receiving the printed sheets or the finished copies. the Guide plates 62 and 64 are used to guide the sheets so that they are during the imaging process can be temporarily stored. At the inner end of the plate 60 are two discharge or Output rollers 66 for transporting the individual printed sheets or copies from the image forming unit 20 onto the plate 60. The output rollers 66 are connected to the tray 22 so that they come together

can be pulled out of the housing 12 with the compartment 22.

A first distribution guide or switch 68 is between the alignment rollers 56 and the pressure roller 58 articulated so that they the transport path of the sheets able to change during the image formation process in order to allow the alignment rollers 56 to be used Sheets fed to the platen 48 are selectively guided onto the first guide plate 62. A second distribution guide or switch 70 is pivotably mounted between the output rollers 66 and the pressure roller 48, to selectively guide the sheets transferred onto the second guide plate 64. According to FIG. 3 is still a bypass guide 7 2 is provided, which is used to guide the paper sheets when they are through the operator can be manually entered into the device one at a time.

The printing ink (as colorant) 74 with which the

Ribbon 44 is impregnated, is through the thermal

head 46 heated and melted and thus on the

in the manner shown in Fig. 4 on a sheet of paper P over-

wear. Move during this ink transfer

the ink ribbon 44 and the paper sheet P move simultaneously in the direction of arrows S and T.

According to FIG. 5, the ink ribbon 44 comprises length units or sections A, each consisting of an area 76 for yellow printing ink, an area 78 for magenta printing ink and an area 80 for cyan printing ink. Optionally, the ribbon 44 may comprise units of length or sections B, each consisting of the aforementioned printing ink areas 76, 78 and 80 and an area 82 of black printing ink exist. At the Printing process is first of all printing ink from one of the

Transfer areas of printing ink onto the sheet of paper P. The latter is then returned to the starting position, wherein ink from a different ink area on the same portion of sheet P is transmitted. This process is repeated to transfer the other printing inks to the paper sheet P. As a result, the different colored printing inks are produced to produce a multicolor printout superimposed on each other. In general, a black image can be printed out on the paper sheet P, when the inks for yellow, magenta and cyan are transferred to the same portion of the sheet P, respectively will. An image of deeper blackening becomes however, by transferring the ink from the area 82 of black ink to sheet P obtain.

The operation of the image forming unit 20 is described below i ^m 6 to 9 with reference to FIGS.. When the feed roller 52 rotates in the direction of arrow C in FIG. 6, a sheet of paper P is fed out of the cassette 24. The guide plates 54 guide the paper sheet to the alignment rollers 56, which in turn align the paper sheet P so that its leading edge is parallel to the pressure roller 48. Then, the paper sheet P is transferred to the platen 48. Since the pressure roller 48 rotates in the direction of the arrow D, the paper sheet P moves until it reaches the thermal (printing) head 46 with the interposition of the ink ribbon 44 in opposition. The latter then heats part of the ink ribbon 44 in accordance with the signals supplied by the exposure system 18 for the purpose of transferring the first printing ink from the ink ribbon 44 to the sheet P.

Then, according to FIG. 7, the second switch 70 is swiveled up. She then does that with the first

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Ink-printed paper sheet P to the guide plate 64 on which the paper sheet P is temporarily placed.
5

According to FIG. 8, the paper sheet P is then transferred from the top of the second guide plate 64 to the top of the first guide plate 62. This means that the paper sheet P is returned to the guide plate 62 for printing with the second printing ink and is deposited thereon. The pressure roller 48 rotates counterclockwise or in the direction of arrow E, so that the paper sheet P is displaced along the first guide plate 62. The first ¹ ^ switch 68 is pivoted downwards at this point in time.

When the paper sheet P has been transferred onto the first guide plate 62, the platen 48 rotates

² ^ as shown in FIG. 9 in the direction of arrow D, so that it brings the paper sheet P in the opposite position to the thermal head 46. Here, the second printing color is transferred from the ink ribbon 44 onto the paper sheet P. Then, similar printing operations are repeated to transfer the third and fourth printing colors to the sheet P to form a multicolor image. The second diverter 70 is (then) swung up, so that the paper sheet P discharged from the image forming unit 20 and the plate _au f 60 of the compartment 22 output.

The apparatus control arrangement or circuit shown in Fig. 10 comprises a color changing unit 79 and a storage unit 81. The storage unit 81 is between the scanning unit 18 and the image generation unit (Heat transfer unit) 20 turned on. The color change unit 79 is attached to the

Probe unit 18 connected, in turn, data corresponding to the positions of the components of the original multi-color image as well as the colors of these image components, 5

ie green, yellow, cyan and black, provides indicative signals. The color changing unit 79 receives the position data and the color signals from the scanning unit 18 and converts the signals for green, yellow, cyan and black into signals which designate the printing colors for yellow, magenta, cyan and black, respectively. The positional data and the color signals are stored in the storage unit 81. In order to print out the multicolor image on a sheet of paper P, the positional data and the color signals are read out from the storage unit 81 and supplied to the image forming unit (heat transfer unit) 20. The latter transmits the respective ink colors from the ink ribbon 44 in accordance with the color signals and the position data on the paper sheet P. In this manner, a multi-color image is printed ^Δ ^. An AND gate 85 is connected between the scanning unit 18 and the image generating unit 20, which generates a signal for black color when it receives the signals for magenta, yellow and

Receiving cyan ink.
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The scanning unit 18, the imaging / heat transfer unit 20, the color change unit 79 and the storage unit 81 are connected to a central unit (CPU) 83 connected. The latter controls the signal generation cycles or times (timings) of the units 18, 20, 79 and 81. It also controls the operation of these units.

Referring to Fig. 11, the image forming apparatus is provided with a (ribbon cassette) holder unit 86 which a holder 42 and two support elements 89 and 91. The holder 42 consists of an injection-molded metal part or from a plastic molding. He owns

a substantially C-shaped cross-section which ensures a sufficiently high level of strength. if

an ink ribbon cassette 34 placed on the holder 42 5

is, he holds the latter firmly, grasping a part of the ribbon cassette 34 and this relative to Thermal head 46 and to the platen 48 aligns properly. When the ribbon cassette 34 on the holder 42 is placed, the support elements 89 and 91 are located in the vicinity of the exposed to the outside Section of the ribbon 44, supporting and guiding the inner surface of the ribbon cassette 34. The support elements 89 and 91 extend from the upper and lower sections of the holder unit 86, respectively both parallel to the pressure roller 48. The holder 42 has one between the support elements 89 and 91 arranged carrier 88, which serves to support and guide the thermal head 46.

^ The ribbon cassette 34 includes a housing 100 as well Spools (or winding axles) 96 and 98. In the ribbon cassette 34 is one end portion of the ribbon 44 on the spool 96, its other end portion rolled up on the spool 98. Both coils are dated

² ^ housing 100 enclosed. The front half of the ribbon cassette 34 is made of a thinner plate material than the rear half, in which the greater part of each spool is arranged and from which the remaining part of each spool protrudes. the

^The front half of the housing is therefore mechanically weak, and it is supported by the support elements 89 and 91 when the ribbon cassette 34 has been pushed into the holder 42.

The thermal head 46 includes a heating plate 90 with plumb aligned heating elements. The heat generated by the heating elements is dissipated by the heat radiation

plate 50 blasted. The thermal head 46 is coupled to a thermal head shift mechanism 94 and thereby between a position (shown in solid lines) in which he has printing ink able to transfer from the ink ribbon 44 to the paper sheet P, and one (shown in dash-dotted lines) Movable position in which the printing ink transfer is not possible.

According to FIG. 12, the thermal head 46 is attached to the holder 42 by means of a slide or slide mechanism 101 attached, which has two profile-shaped struts 102 and 104. The holder 42 has a frame block 108 on. From the ends of the frame block 108 are two bearing parts 110 and 114, each with a are provided at a right angle to the pressure roller 48 extending bore. Likewise, the Strut 102 and 104 each have two bores in their end sections, which are also below a right Angle to the pressure roller 48 run. In the bores of the strut 102 and the bore in the bearing part 110 a bolt 106 is inserted, by means of which the strut 102 is slidably connected to the bearing part 110.

Similarly, a bolt 112 is in the bores of the strut 104 and the bore of the bearing part 114 used to connect the strut 104 slidably to the bearing part 114. In each bearing part 110 and 114 a linear bearing (not shown) is embedded in each case. The thermal head 4 6 is thus in can be moved smoothly in both directions (arrow M).

On the thermal head 4 6 are two ribbon guides 116 and 118 formed, which can be seen when moving or shifting the thermal head 46 (with move this with). When the thermal head 46 as shown in FIG. 13 over a distance X from the ink transfer position in the direction of the pressure roller 48

is shifted, the ribbon guides 116 and 118 also move the same distance. When the ribbon cassette 34 is or is inserted into the holder 42, both ribbon guides and the thermal head 46 are at a distance of <3 ^from the pressure roller 48

relieved.
10

14, a ribbon drive mechanism 123 is provided on one side of the holder 42, the is used to transport the ribbon 44. It comprises a plate attached to one end of the holder 42 120 and a further plate 122 (parallel to it). It also includes a stepper motor 124, a drive pulley 126, a belt 128 and a driven pulley 130, the parts 124, 128 and 130 all are mounted or stored on the plate 122.

₆ Di drive pulley 126 mounted on the shaft of the motor 124, while the driven pulley 130 is fixed to a coupled with the platen roller 4 8 shaft. The belt 128 is wrapped around the drive pulley 124 and the driven pulley 130. Therefore, when the motor 126 rotates clockwise or counterclockwise, the platen 48 rotates in the same direction. The ribbon drive mechanism 123 further includes two motors 132 and 134 and two clutches 136 and 138 which connect the motors 132 and 134 to the spools 96 and 98 of the ribbon cassette 34, respectively. The motors 132, 134 and the clutches 136, 138 are mounted on the plate 122. 15 and 16, the coupling 136 comprises a shaft 140, a runner or rotor 144 seated thereon, a latching element 156 connected to one end of the shaft 140, and one wound around the shaft 140 and between each other

Coiled spring 148 extending between rotor 144 and latch member 156. Clutch 138 also includes a shaft 142, a rotor 5 or rotor 146 seated thereon, and one attached to one end of the shaft 142 Latching element 158 and one wrapped around shaft 142 and between rotor 146 and the Latching element 148 extending (tensioned) helical spring 150. Latching elements 156 and 158 are capable of snap into recesses 152 and 154 in the end portions of the coils 96 and 98, respectively. It is still on A motor 157 for moving the thermal head 46 is mounted on the platen 122.

Close to the rotors 144 and 146 is a brake unit 160, which the coils 96 and 98 is able to decelerate or inhibit and thus prevent the ribbon 44 from becoming loose. According to Fig. 17, the brake unit 160 comprises in particular an electromagnet 162, a handlebar 164 and the latter spring 166 biasing away from electromagnet 162. When electromagnet 162 is energized, the handlebar 164 shifts against the force of the spring 166 against the electromagnet 162. The handlebar 162 has two legs with rubber pads 168 and 170 provided at their ends. The upholstery 168 and 170 are each on the circumferential surface of the Rotors 144 or 146 to brake or inhibit the relevant rotor 144 or 146. The driver 164 has an elongated hole 169 extending in its longitudinal direction. One attached to plate 122 Guide pin 171 engages in elongated hole 169 and is used to guide link 164.

14, the motors 132 and 134 are electrically connected to a driver circuit 172, and they are controlled by this circuit. The circuit 172 is connected to a drive mechanism control

circuit 174 connected. The brake unit 160 is electrically connected to a circuit 176 and to the (for the) electromagnet 162 connected. The circuit 176 is to the drive mechanism control circuit 174 and controls the electromagnet 162.

The drive mechanism 123 with the brake unit 160 works
as follows: When the ribbon 44 is not
is to be transported, the pads 168 and 170 abut the rotors 144 and 146, respectively, and prevent rotation of the spools 96 and 98, respectively. As a result, the ribbon 44 does not experience any looseness or slack even if the imaging device is subjected to vibrations is or when a force acts on the ribbon 44 which it tries to move. This means that after the ribbon cassette 34 has been inserted into the holder 42, none of the reels (or winding axles) can rotate, so that the ribbon 44 could become loose.

On the other hand, when the start button 26 (Fig. 1) is pressed, the control circuit 174 controls the driver circuit 176 for energizing the electromagnet 162. The latter then pulls the handlebar 164 against the force of the spring 166 in the direction of arrow b (Fig. 17), so that the rubber pads 168, 170 separate from the rotors 144 and 145 and their deceleration or inhibition is thereby canceled. Simultaneously the circuit 174 gives the driver circuit 172 a command for the motor 132 to be switched on or 134, so that the ribbon 44 is transported by the relevant motor.

When a stop button, not shown, is pressed, the control circuit 174 leaves the circuit 172 stop the motor 132 or 134. At the same time, the control circuit 174 gives the driver circuit 176 a command to de-energize the electrical

magnets 162 a. The handlebar 164 is then moved by the force of the spring 166 in the direction of the arrow a, until the cushions 168 and 170 lie against the rotors 144 and 146, respectively, and thereby the coils 96 or 98 are blocked.

As described, the bobbins 96, 98 are when the stop button is pressed to end the transport of the ribbon 44 braked or blocked, and they remain in this blocked state until the start button 2 6 is actuated to initiate the transport of the ribbon 44. When the ribbon 44 does not advance there is no looseness in him,

* ° even if the ribbon cassette inserted in the holder 42 34 is subject to vibration or a force tending to move the ribbon 44 is, acts. Since each time the ribbon 44 is stopped on this automatically one If a certain tension is exerted, the paper sheet P can become stuck in the event of a paper jam of the sheet) can easily be separated from the ribbon 44. The same reason is the installation of the ribbon cassette 34 in the holder and taking it out of it easy.

It goes without saying that the invention is in no way limited to the embodiment shown and described above limited, but accessible to various changes and modifications. For example The rubber pads 168 and 170 can be replaced by a rubber washer that attaches to both rotors 144 and 146 and thus able to decelerate or inhibit the coils 96, 98 at the same time. Optional A separate brake unit can be provided for each rotor 168 and 170. Furthermore can

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the brake unit 160 can be replaced by a brake unit that directly acts on the reels (or winding axles) 96, 98 or acts on the shafts of the motors 132, 134.

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Claims (7)

Claims 1. An image forming apparatus that generates an image by moving a transfer member off a spool (or Winding axis) to another and by transferring a colorant from the transfer element to one A sheet of paper characterized by latching means (136, 138) for engaging both spools (96, 98), by a drive unit (123) for driving both reels via the latching means and for transporting the paper sheet (P) and through a braking unit (160) for braking or Inhibiting the two coils. 2. Device according to claim 1, characterized in that that the braking unit (160) has a spring (166), through γ. the spring (16 6) to move in one direction * to slow down or inhibit the bobbins (96, 98) forward * ■ loaded braking elements (168, 170) and an electromagnet (162) for moving the braking elements (168, 170) in a direction opposite to the direction of action of the spring (166) to rotate the To allow coils (96, 98). 3. Apparatus according to claim 2, characterized in that the braking elements (168, 17 0) made of a material a high coefficient of friction are made. 4. Apparatus according to claim 4, characterized in that the material is rubber (or rubber). 5. Apparatus according to claim 1, characterized in that that the transmission element (44) each partially is wound onto one and the other spool (96 or 98) and that the brake unit (160) on the two coils (96, 98) at the same time 5 having decelerating or inhibiting braking element (164). 6. Apparatus according to claim 5, characterized in that the braking element (164) has two legs for braking or jamming the coils (96,98). 7. Apparatus according to claim 1, characterized in that the latching means (136, 138) each have one Coupling (136, 138 or 156, 158) that can be converted into a ¹ ^ recess in one end section of the coil (96, 98) in question is able to enter, and comprise a rotor or rotor (144, 146) connected to the clutch (136, 138 or 156, 158) and that the brake unit (160) with the rotors (144, 146) can be brought into frictional engagement.