US3810192A

US3810192A - Thermosensitive line printer

Info

Publication number: US3810192A
Application number: US00372109A
Authority: US
Inventors: K Okabe
Original assignee: Nidec Copal Corp
Current assignee: Nidec Copal Corp
Priority date: 1972-06-29
Filing date: 1973-06-21
Publication date: 1974-05-07
Anticipated expiration: 1991-05-07
Also published as: IT986608B; JPS5216673Y2; JPS4936835U

Abstract

The thermosensitive line printer has a printing head provided with a thermally activated dot-matrix capable of printing a line of letters on a thermosensitive recording sheet upon receipt of a signal from the printer, a head receiving pad and a sheet feeding mechanism provided with a ratchet. In order to operate in succession the printing head for moving the same toward the pad for the printing operation and moving away from the pad for feeding the sheet and the sheet feeding mechanism for feeding the sheet intermittently while the printing head is held apart from the pad, a single electromagnet is operatively connected to a driving lever for reciprocal movement thereof each time the electromagnet is energized which lever is in turn operatively connected to a head supporting lever, a ratchet driving lever and a hook lever so that, upon application of a signal to the electromagnet, the driving lever is actuated to drive the head supporting lever, the ratchet driving lever and the hook lever in timed relation so that the printing operation is effected during the head is urged against the pad and, after the head is moved apart from the pad and temporarily held in that position by the hook lever, and, after the deenergization of the electromagnet, the driving lever is returned to its initial position so that the ratchet is driven by the ratchet driving lever to feed the sheet while the head is held apart from the pad and, at the end of the return movement of the driving lever, the hook lever is released to free the head supporting lever to urge the head against the pad so as to be ready for the next line printing.

Description

Unite Okabe States Patent [451 May 7,1974

[ THERMOSENSITIVE LINE PRINTER [75] Inventor: Katsuhiko Okabe, Tokorozawa,

Japan [73] Assignee: Kabushikikaisha Copal, Tokyo,

Japanv [22] Filed: June21,1973

[211 A l- -F .7 r .1

[30] Foreigi Application l riority llata r qgg n Japan ..T.;.;;';47 itse [52] US. Cl. 346/79, 101/93 C, 197/133 R, 346/76 R, 346/136 [51] Int. Cl. G0ld 15/24 [58] Field of Search 346/76 R, 79, 136, 141', 197/133 R, l R; 101/93 C [56] References Cited UNITED STATES PATENTS 1,124,820 1/1915 Simonsson 346/79 X 2,944,867 7/1960 Gregory 3,754,278 8/1973 Borden 346/76 R Primary Examiner-Joseph W. Hartary Attorney, Agent, or Firm-Hans Berman [57] ABSTRACT The thermosensitive line printer has a printing head provided with a thermally activated dot-matrix capable of printing a line of letters on a thermosensitive recording sheet upon receipt of a signal from the printer, a head receiving pad and a sheet feeding mechanism provided with a ratchet. In order to operate in succession the printing head for moving the same toward the pad for the printing operation and moving away from the pad for feeding the sheet and the sheet feeding mechanism for feeding the sheet intermittently while the printing head is held apart from the pad, a single electromagnet is operatively connected to a driving lever for reciprocal movement thereof each time the electromagnet is energized which lever is in turn operatively connected to a head supporting lever, a ratchet driving lever and a hook lever so that, upon application of a signal to the electromagnet, the driving lever is actuated to drive the head supporting lever, the ratchet driving lever and the hook lever in timed relation so that the printing operation is effected during the head is urged against the pad and, after the head is moved apart from the pad and temporarily held in that position by the hook I lever, and, after the deenergization of the electromagnet, the driving lever is returned to its initial position so that the ratchet is driven by the ratchet driving lever to feed the sheet while the head is held apart from the pad and, at the end of thereturn movement of the driving lever, the hook lever is released to free the head supporting lever to urge the head against the l pad so as to be ready for the next line printing.

4 re P ar efliser 1 THERMOSENSITIVE LINE PRINTER BACKGROUND OF THE INVENTION The present invention relates to a thermosensitive line printer and, more particularly, to improvements in a thermosensitive line printer having a thermal printing head provided with a thermally activated matrix for printing a line of letters or symbols on a thermosensitive recording sheet upon receipt of a signal from the printer.

Heretofore, thermosensitive printers have been developed in which a single letter or symbol is printed on a thermosensitive recording sheet by a thermal printing head which is pressed against a head receiving pad with the recording sheet nipped therebetween each time a signal is applied to the printing head. In those printers, however, the movement of the printing head toward and away from the pad for printing operation and the feeding of the recording sheet are effected by separate driving mechanisms, thereby resulting in complicated construction of the printer and inaccurate operation of the printer. Further, the printing efficiency is very low,

because only a single letter or symbol is printed each time the signal is supplied to the printing head.

On the other hand, a thermosensitive line printer has been developed which enables printing ofline of letters or symbols simultaneously upon application of a printing signal to the printing head. However, the printer heretofore developed was very complicated in construction and inaccurate in operation.

The present invention aims at avoiding the disadvantages of the prior art thermosensitive printer as described above and providing improvements in a thermosensitive line printer which enable simple construction and accurate operation of the printer.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel and useful thermosensitive line printer which avoids the above described disadvantages of the prior art thermosensitive printers.

Another object of the present invention is to provide a novel and useful thermosensitive line printer of the type described above which utlizes only a single electromagnet for effecting both the operation of the printing head and the feeding of the recording sheet in timed relation.

A further object of the present invention is to provide a novel and useful thermosensitive line printer of the type described above in which the feeding of the recording sheet is effected during thetime the printing head is moved apart from the pad thereby positively preventing the wear of the printing head and providing accurate and exact printing operation.

The above object is achieved in accordance with the present invention by the provision of a thermosensitive line printer having a thermal printing head provided with a thermally activated matrix for printing a line of letters or symbols on a thermosensitive recording sheet upon receipt of a signal from the printer, a stationary pad for bearing against the printing head when the same is moved thereagainst for the printing operation, a sheet feeding mechanism for intermittently feeding the recording sheet through between the printing head and the pad each time the printing operation of the printing head is terminated, a ratchet being provided in the mechanism for driving the same, the printer being characterized by a single electromagnet having a plunger and actuated by a signal supplied thereto from the printer so as to operate the plunger, a swingable driving lever pivoted to the body of the printer and connected to the plunger so as to be actuated thereby, the driving lever having a release bar, a swingable head supporting lever pivoted at its intermediate portion to the body of the printer and having the printing head secured at its one end for cooperation with the pad and with its other end operatively coupled with the driving lever so that the printing head is moved toward and away from the pad by the actuation of the electromagnet, a sheet feeding lever pivoted at its one end to the release bar and having a ratchet driving pawl operatively coupled with the ratchet, and a hook lever pivoted to the body of the printer and operatively coupled with the release bar, thereby permitting in sucession the printing operation of the printing head, the movement of the printing head away from the pad, the feeding operation of the sheet by the sheet feeding lever through the driving pawl and the ratchet while the printing head is held apart from the pad, and the movement of the printing head toward the pad after the sheet has been fed for the next printing operation each time a signal is supplied to the electromagnet from the printer.

In accordance with a feature of the present invention, the head supporting lever is normally urged against the pad by means ofa spring with the recording sheet sandwiched therebetween and, upon actuation of the electromagnet caused by a signal issued after the printing operation has been completed, the electromagnet actuates the head supporting lever through the driving lever so that the printing head is moved apart from the pad and the head supporting lever is held temporarily in the position and, when the electromagnet is deenergized, the sheet feeding mechanism is actuated by the returning movement of the driving lever caused by a spring connected thereto so that the sheet is fed while the printing head is held apart from the pad, and, at the end of the returning movement of the driving lever, the head supporting lever is released and returned to the initial position by the spring thereby urging the printing head against the pad to be ready for the next printing operation.

In accordance with another feature of the present invention, the printing head is normally held apart from the pad by the operative connection of the head supporting lever to the driving lever, the driving lever being urged by a spring connected thereto in the direction opposite to that in which the driving lever is moved by the actuation of the electromagnet so as to urge the head supporting lever in the direction to move the printing head apart from the pad against the action of a spring connected to the head supporting lever urging the same to move the printing head against the pad which spring is weaker than the spring connected to the driving lever so that the spring of the head supporting lever is overcome by the spring of the drawing lever. When a signal indicative of the commencement of the printing operation is supplied to the electromagnet from the printer, the driving lever is actuated to release the head supporting lever so as to move'the printing head against the pad by the action of the spring connected thereto for the printing operation while the sheet feeding mechanism is conditioned to be ready for feeding the sheet, and, after the printing operation has been completed and the electromagnet is deenergized to release the driving lever, the head supporting lever is urged by the driving lever so as to move the printing head apart from the pad and, at the end of the movement of the drivinglever, the sheet feeding mechanism is actuated by the return movement of the driving lever to feed the recording sheet while the printing head is held apart from the pad.

It is, therefore, apparent that the present invention provides a thermosensitive line printer in which the recording sheet is fed during the time the printing head is held apart from the pad while the printing operation is effected upon receipt of the signal indicative either of the commencement or the termination of the printing operation by virtue of the provision of a single electromagnet thereby permitting the printer to be made compact and simple in construction while wear of the pinter is minimized.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view with parts broken away showing a preferred embodiment of the thermosensitive line printer constructed in accordance with the present invention; and

FIG. 2 is a side view showing a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 showing the first embodiment of the present invention, the thermosensitive recording sheet 1 is nipped between sheet feeding rollers 4, 4' so as to be fed intermittently as described later. The termal head 2 having thermally actuated matrix such as a dot printing matrix is attached to one end of an L-shaped head supporting lever 3 pivoted at intermediate portion thereof to the body of the printer by a shaft 3a. The matrix is connected to a plurality oflead wire L loading to the control circuit (not shown) of the printer so asto'be supplied with electric current in accordance with the desired output informations therefrom so that a line of letters or symbols is simultaneously printed on the thermo sensitive recording sheet upon energization of the matrix. 1

As shown in FIG. 1, the thermosensitive recording sheet 1 is passed through between the thermal printing head 2 and a head receiving backing pad made of an elastic material such as silicone rubber, and the printing operation is effected when the sheet 1 is stationarily and the thermal head 2 is pressed against the pad 15.

The head supporting lever 3'is normally urged in the direction so as to urge the head 2 against the pad 15 by the action of a spring 11 connected at its one end to the lever 3 and at its other end to the body of the printer.

The other-end of the head supporting lever 3 has a shaft 3b secured thereto, and the shaft 3b is operatively coupled .with one end 50 of a driving lever 5 pivoted to the body of the printer by a shaft 5a. The driving lever 5 is coupled. with an electromagnet 6 secured to the body of the printer through a plunger shaped armature 6a while the end 50 is connected one end of a spring 12 the other end of which is secured to the body of the printer so that the driving lever 5 is normally urged by the spring 12 in the clockwise direction as seen in FIG.

1 thereby permitting the head supporting lever 3 to be swung in the anti-clockwise direction as seen in FIG. 1 by the action of the spring 11 to urge the head 2 against the pad 15. However, when the electromagnet 6 is energized, the driving lever 5 is swung in the direction shown by the arrow, i.e., in the anticlockwise direction through the plunger 6a, so that the head supporting lever 3 is swung in the clockwise direction against the action of the spring 11 by the engagement of the end 5c of the driving lever 5 with the shaft 3b secured to the lever 3 thereby moving the head 2 apart from the pad 15. During the time the head 2 is held apart from the pad 15, the recording sheet 1 is advanced as described later.

The above described other end of the head supporting lever 3 is formed with a laterally extending lug 3a. A hook-shaped latch or lever 9 is pivoted at its intermediate portion to the body-of the printer by a shaft 9a. The hook lever 9 is normally urged in the anticlockwise direction as seen in FIG. 1 by a spring 14 connected between the lever 9 andthe body of the printer. Thelever 9 is formed with a shoulder 9b.

The position of the shoulder 9b is so determined that the shoulder 9b arrests the lug 3a of the head supporting lever 3'when the lever 3 is moved in the clockwise direction and the hook lever 9 is swung in the anticlockwise direction thereby preventingthe head supporting lever 3 from being rotated in the anticlockwise direction so as to arrest the thermal head 2 in the position held apart from the pad 15. When the hook lever 9 is swung in the clockwise direction, the lug 3a is disengaged from the shoulder 91;- thereby permitting the anticlockwise rotation of the head supporting lever 3 by the action of the spring 11 so as to urge the head 2 against the pad 15.

In order to effect the desengagement of the shoulder 9b from the lug 3a, a latch-operating or release bar 5b is secured to the upper end of the driving lever 5 so as to extend adjacent to the upper portion of the hook lever 9at the rear side thereof as seen in FIG. 1. The position of the release bar 5b is so determined that the bar 5b abuts against the lever 9 at the end of the return movement of the driving lever 5 after it has been actuated by the electromagnet 6 and, thereafter, the electromagnet 6 is deenergized to cause the return movement of the driving lever 5 by the action of the spring 12, so that the lever 9 is moved in the clockwise direction against the action of the spring 14 so as to disengage the shoulder 9b from the lug 3a and maintain the lever 9 in this position.

The shaft 4a of the sheet feeding roller 4 is extended as shown in FIG. land a sheet feeding ratchet 10 is fixedly secured to the extended end of the shaft 4a.

A sheet feeding lever 7 is pivoted to the release bar 5b at its proximal end and the lever 7 has a bifurcated portion 7a at its free end. The bifurcated portion 7a is loosely engaged with the shaft 4a of the roller 4 so as to be supported thereby. A ratchet driving pawl 8 having a bent lug 8a is pivoted on the sheet feeding lever 7 and the bent lug extends so as to engage with the sheet feeding ratchet 10. In order to effect the engagement of the lug 8a with the ratchet 10, a spring 13 is connected at its one end to the proximal end of the lever 7 while the other end is connected to a projecting lug of the pawl 8.

As shown in FIG. 1, a resilient claw made of a leaf spring is engaged with the ratchet 10 so as to prevent the reverse rotation of the ratchet.

Thus, when the electromagnet 6 is energized to actuate the driving lever 5 together with the release bar 512, the lever 7 is moved in the direction indicated by the arrow in FIG. 1 and the lug 8a of the pawl 8 slides along the periphery of the ratchet in the direction opposite to that in which the ratchet 10 is driven by the lug 8a. When the electromagnet 6 is deenergized to cause the return movement of the driving lever 5 by the action of the spring 12, the sheet feeding lever 7 is moved in the direction opposite to that shown by the arrow thereby driving the ratchet 10 in the anticlockwise direction by the lug 8a so as to effect the feeding of the recording sheet 1 by the sheet feeding rollers 4, 4'.

The operation of the printer of the present invention as described above is as follows.

When the electromagnet 6 is energized to turn the driving lever 5 in the anticlockwise direction together with the latch operating bar 5b against the action of the spring 12 the head supporting lever 3 is turned clockwise against the action the action of the spring 11 to retract the printing head 2 from the pad while the latch 9 is moved anticlockwise by the spring 14 so as to engage the lug 3'a of the lever 3 thereby temporarily arresting the head supporting lever 3 in the retracted position of the head 2. The sheet feeding lever 7 is moved in the direction indicated by the arrow in FIG. 1 by the latch operating bar 5b so that the lug 8a slides idly over the teeth of the ratchet 10.

When the electromagnet 6 is deenergized, the driving lever 5 is returned to its initial position by the spring 12 together with the sheet feeding lever 7 thereby permitting the lug 8a to drive the sheet feeding ratchet l0 and the sheet feeding rollers 4, 4, while the head 2 is kept retracted by the engagment of the lug 3'0: with the shoulder 9b of the latch 9.

At the end of the return movement of the driving lever 5,-the bar 5b abuts against the latch 9 after the feeding of the sheet has been terminated thereby permitting the lug 3a to be disengaged from the latch 9 so that the head 2 is moved into the printing position by the spring 11.

FIG. 2 shows a second embodiment of the present invention in which the printing head 2 is normally held apart from the pad and, upon receipt of a signal for initiating the printing operation, the electromagnet is energized to move'the printing head against the pad so as to effect the printing operation and, after the deenergization of the electromagnet, the printing head is moved apart from the pad and the feeding of the sheet is effected.

The general arrangement of the embodiment of FIG. 2 is substantially similar to that shown in FIG. 1 except that the driving lever 5' is operatively coupled with the head supporting lever 3 so that the lever 3 is normally held against the action of the spring 11 in the position in which the printing head 2 is held apart from the pad 15 by virtue of the fact that the spring 11' for urging the lever 3 so as to move the printing head 2 toward the pad 15 is weaker than the spring 12 connected to the driving lever 5 so that the lever 3 is urged in the position shown in FIG. 2 by the action of the spring 12 so as to move the head 2 apart from the pad 15. A second driving lever 5" is pivoted to the shaft 5a to which the lever 5 is also pivoted and one end of a spring 5"c is connected to the lever 5" while the other end is connected to the body of the printer so as to urge the lever 5" in the clockwise direction in FIG. 2. A pin 5'b is secured to the lever 5 which abuts against the side of the lever 5" so that the lever 5 and 5" are moved together with each other.

The sheet feeding lever 7 is pivoted to the free end of the driving lever 5" by a shaft 5"b.

The sheet feeding lever 7 is formed with a bent lug 7b at the proximal end of the lever 7 which is adapted to be engaged with a shoulder 9b formed in the hook lever 9' pivoted to the shaft 9a. The hook lever 9 is urged in the clockwise direction by a spring 14 connected at its one end to the lever 9' and at its other end to the body of the printer. As shown in FIG. 2, the hook lever 9 is formed with a laterally extending portion which is adapted to engage with the pin 5b of the driving lever 5' so that the hook lever 9 is swung in the anticlockwise direction so as to disengage the lug 7b from the shoulder 9b of the hook 9 when the driving lever 5' is swung in the clockwise direction.

The relative position of the hook lever 9 and the driving lever 5 are so determined that the hook lever 9' is engaged with the pin Sb when the return movement of the driving lever 5' caused by the deenergization of the electromagnet 6 is about terminated.

During operation of the apparatus shown in FIG. 2, the electromagnet 6, when energized, turns the driving lever 5 together with the driving lever 5" against the action of the spring 12 so that the head supporting lever 3 is released by the driving lever 5' for clockwise movement under the action of the spring 11' so as to urge the printing head 2 against the pad 15 for the printing operation.

At the same time, the driving lever 5" moves the sheet feeding lever 7 toward the left as seen in FIG. 2 until the lug 7b of the lever 7 is engaged the shoulder 9b of the latch 9 while the lug 8a idly slides along the teeth of the ratchet '10.

When the electromagnet 6 is deenergized the driving lever 5' is moved clockwise by the spring 12 so that the printing head 2 is retracted from the pad 15 while the sheet feeding lever 7 isheld by the latch 9' together with the driving lever 5". At the end of the return movement of the driving lever 5', the pin 5'!) pivots the latch 9' in the anticlockwise direction so that the sheet feeding lever 7 is released permitting the lug 8a to drive the ratchet 10 for advancing the sheet I.

In the above description, the sheet feeding lever 7 is shown as being mounted on the driving lever 5", however, the driving lever 5" may be deleted and the lever 7 may be directly mounted on the driving lever 5'. In this case, the timing relationship between the engagement of the ratchet 10 with the ratchet driving pawl 8 and the actuation of the head supporting lever 3 must be appropriately adjusted for proper operation of the device.

I claim:

1. A printing apparatus comprising, in combination:

a. a pivotally mounted supporting lever;

b. a backing pad;

c. a printing head mounted on said lever for movement between a printing position adjacent said pad and a retracted position remote from said pad when said lever is pivoted;

d. an electromagnet equipped with an armature and a pivotally mounted driving lever operatively connected .to said armature and to'said supporting lever for pivotal movement of said driving lever between two angularly offset positions during movement of said armature between said positions thereof and for transmitting the movement of said armature to said supporting lever and for thereby moving said printing head between said printing position and said retracted position;

. sheet feeding means for advancing a sheet to be printed upon between said pad and said head while said, printing head is in the retracted position thereof, said sheet feeding means including 1. a feeding member operatively connected to said driving lever for movement thereby during the pivotal movement of said driving lever,

2. a pawl mounted on said member for movement therewith,

3. a ratchet wheel engaged by said pawl and rotated by said pawl when said member moves in one direction during said movement of said driving lever, and

4. sheet engaging means drivingly connected to said ratchet wheel for advancing said sheet in response to rotation of said ratchet wheel;

g. latch means mounted for movement between a locking position in which said latch means engages one of said levers and thereby prevents movement of said printing head from said retracted position, and a releasing position in which said latch means releases said one lever; and

h. latch operating means responsive to said movement of said driving lever for moving said latch means between said locking and releasing positions, said latch operating means moving said latch meansinto said releasing position when said driving lever approaches one of said positions thereof after having moved away from the other position.

2. An apparatus as set forth in claim 1, futher comprising yieldably resilient means biasing said printing head toward said retracted position, biasing said feeding member to move in said one direction, and biasing said latch means toward said locking position, said electromagnet being operatively connected to said printing head and said feeding member for moving said printing head and said feeding member against the restraint of said yieldably resilient means when said electromagnet is energized.

3. An apparatus as set forth in claim 1, further comprising first yieldably resilient means biasing said driving lever to move into one of said angularly offset positions, said electromagnet when energized causing said driving lever to move away from said one angular position against the restraint of said resilient means, second yieldably resilient means biasing said printing head toward said printing position, said driving lever engaging said supporting lever under a sufficient force of said first resilient means to move said printing head into the retracted position against the restraint of said second resilient means when said electromagnet is deenergized, third resilient means biasing said feeding member to move in said one direction, said one lever being said driving lever, said feeding member being mounted on said driving lever.

4. An apparatus as set forth in claim 3, wherein said driving lever has two pivotally connected portions, one of said portions transmitting the movement of said armature to said supporting lever, said feeding member being mounted on the other portion of said driving lever.

Claims

1. A printing apparatus comprising, in combination: a. a pivotally mounted supporting lever; b. a backing pad; c. a printing head mounted on said lever for movement between a printing position adjacent said pad and a retracted position remote from said pad when said lever is pivoted; d. an electromagnet equipped with an armature and moving said armature between a first position and a second position when said electromagnet is energized; e. a pivotally mounted driving lever operatively connected to said armature and to said supporting lever for pivotal movement of said driving lever between two angularly offset positions during movement of said armature between said positions thereof and for transmitting the movement of said armature to said supporting lever and for thereby moving said printing head between said printing position and said retracted position; f. sheet feeding means for advancing a sheet to be printed upon between said pad and said head while said printing head is in the retracted position thereof, said sheet feeding means including 1. a feeding member operatively connected to said driving lever for movement thereby during the pivotal movement of said driving lever, 2. a pawl mounted on said member for movement therewith, 3. a ratchet wheel engaged by said pawl and rotated by said pawl when said member moves in one direction during said movement of said driving lever, and 4. sheet engaging means drivingly connected to said ratchet wheel for advancing said sheet in response to rotation of said ratchet wheel; g. latch means mounted for movement between a locking position in which said latch means engages one of said levers and thereby prevents movement of said printing head from said retracted position, and a releasing position in which said latch means releases said one lever; and h. latch operating means responsive to said movement of said driving lever for moving said latch means between said locking and releasing positions, said latch operating means moving said latch means into said releasing position when said driving lever approaches one of said positions thereof after having moved away from the other position.

2. a pawl mounted on said member for movement therewith,

4. sheet engaging means drivingly connected to said ratchet wheel for advancing said sheet in response to rotation of said ratchet wheel; g. latch means mounted for movement between a locking position in which said latch means engages one of said levers and thereby prevents movement of said printing head from said retracted position, and a releasing position in which said latch means releases said one lever; and h. latch operating means responsive to said movement of said driving lever for moving said latch means between said locking and releasing positions, said latch operating means moving said latch means into said releasing position when said driving lever approaches one of said positions thereof after having moved away from the other position.