JPH09278232A - Thermal transfer printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect a position of a clamper without using a plurality of expensive sensors by installing no reflection type sensor in a complicated mechanism part for detecting this part. SOLUTION: The substantial circumference length of a pair of timing belts 3 wound between the first pulley 2 and the second pulley 4, which are arranged in both ends of a platen roller 1 coaxially and separately rotationally, is integral multiplies of the substantial outer circumference length of the second pulley 4. In an optional one point on the circumference of a clamper 9 arranged between the timing belts 3, a reference position sensor detecting a reference position of the clamper 9 is arranged. A slit 25b in a light shielding plate 25a connected to the second pulley 4 is detected by means of an optical sensor 25c, and a motor 21 driving the second pulley 4 is controlled so that a position detected by the optical sensor 25c after a specified times of detection after the first detection is detemined as a stopping position for the clamper 9 on the basis of the detection by the reference position sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a recording sheet feeding mechanism of a thermal transfer printer which holds a sheet by a sheet clamper installed between belts on both sides and conveys the sheet.

[0002]

2. Description of the Related Art FIG. 9 shows, for example, JP-A-2-219661.
FIG. 7 is a cross-sectional view of a main part of a conventional thermal transfer printer shown in Japanese Patent Publication No. In the figure, 1 is a platen roller, and this platen roller 1 is rotated by a first motor (not shown). 2 are platen rollers 1 on both sides of the platen roller 1
And a pair of first pulleys 3 which are coaxially rotatably provided separately from each other, 3 a pair of timing belts hung on the first pulley 2, 4 a second pulley for stretching the timing belt 3, and 5 a torque Timing belt 3 via limiter 6
Is a second motor for driving the vehicle. The platen roller 1 and the timing belt 3 are rotated by different driving sources, and the traveling speed of the timing belt 3 is slightly higher than the peripheral speed of the platen roller 1.

Reference numeral 7 is an ink sheet, and 8 is a platen roller 1.
A thermal head 9 which is contacted and separated from the ink sheet 7 to form an image by thermal transfer printing of the ink of the ink sheet 7 on the paper 10, is installed on the timing belt 3, holds one end of the paper 10 and conveys it in the direction of arrow B. It is a clamper. 1
Reference numeral 1 is a paper detection sensor, 12 is a clamper opening mechanism, 13 is a clamper closing mechanism, and 14 is a paper feeding mechanism. The clamper opening mechanism 12 and the clamper closing mechanism 13 are provided with optical sensors for detecting the arrival of the clamper 9. ing.

A reflection type photo sensor is used as the optical sensor, and the light of the built-in light emitting diode is reflected to a reflector (mark seal) attached to a clamper 9 mounted on a timing belt 3 which is a movable object. It is a type of irradiating and detecting with a built-in phototransistor the presence or absence of the reflected light from the reflector at that time. The same optical sensor is used as the paper detection sensor 11.

Next, the operation of the conventional thermal transfer printer will be described. In color printing, three or four color inks are printed on the same pixel. First, before the printing operation is started, the clamper 9 is located above the clamper closing mechanism 13, the paper 10 is fed from the paper feeding mechanism 14, and the leading end thereof is inserted between the claws of the clamper 9. Then, the clamper closing mechanism 13 operates to grip the sheet 10, and the platen roller 1 starts rotating in the direction of arrow A.
At this time, the thermal head 8 is separated from the platen roller 1, and the clamper 9 is conveyed to the position of the sheet detection sensor 11 through this gap. When the paper detection sensor 11 detects the leading edge of the paper 10, the second motor 5 is stopped to stop the conveyance of the clamper 9 at a predetermined position, and the thermal head 8 sandwiches the ink sheet 7 and the paper 10 and the platen roller 1 Abut. As a result, the platen roller 1 and the clamper 9 start to rotate and the printing of the first color is started. When the timing belt 3 is rotated along with the printing operation and the clamper 9 reaches the position of the clamper closing mechanism 13, the thermal head 8 is separated from the platen roller 1, the ink sheet 7 is set up for the next color, and the clamper 9 is conveyed. To do. When the sheet detection sensor 11 detects the leading edge of the sheet 10 again, the thermal head 8 is moved to the platen roller 1.
And the second color is printed. Similarly, when printing of the third or fourth color is completed and the clamper 9 reaches the position of the clamper opening mechanism 12, the clamper 9 releases the paper 10 and discharges the paper 10 on which the printing is completed.

[0006]

In the conventional thermal transfer printer as described above, the paper detection sensor 11, the clamper opening mechanism 12 and the clamper closing mechanism 13 have sensors (not shown) for detecting the arrival position of the clamper 9, respectively. It is provided. Further, in order to position the clamper 9 at the printing start position, the printing end position, the clamper opening position and the clamper closing position, it is necessary to provide an optical sensor at each position, and in particular, an optical sensor is not provided near the thermal head. However, there is a problem in that it is difficult to attach the sheet because the pinch roller or the like that attaches the sheet to the platen roller becomes an obstacle.

Further, in order to detect the moving clamper 9 with high accuracy, it is necessary to use an expensive reflection type photo sensor for each, and there is a problem that the manufacturing cost becomes high.

Further, since the reflector (mark seal) is attached to the clamper 9 mounted on the timing belt 12, the reflector (mark seal) is displaced and peeled off.
There is also a problem that detection is not possible or detection accuracy is deteriorated due to dirt and the inclination of the reflecting surface.

The present invention has been made in order to solve the above-mentioned problems, and a sensor is provided at a position where there is a spatial margin, not near the thermal head, and the stop position of the clamper near the thermal head is detected. It is also an object of the present invention to provide a thermal transfer printer capable of accurately detecting the position of the clamper without using a plurality of expensive sensors and performing highly reliable positioning.

[0010]

According to a first aspect of the present invention, there is provided a thermal transfer printer in which a platen roller and a first platen roller are provided at both ends of the platen roller so as to be rotatable coaxially with the platen roller and separately. A pulley, a second pulley, and a pair of timing belts suspended between the first pulley and the second pulley and having a substantial peripheral length which is an integral multiple of the substantial peripheral length of the second pulley, A clamper that is installed between the timing belts and that holds the end of the sheet of paper and pulls and runs the paper, and a reference position that is provided at an arbitrary position on the circumference of the clamper and that detects the reference position of the clamper. A sensor, a thermal head that presses against the platen roller by sandwiching a print medium sheet and an ink sheet when performing thermal transfer printing, and the timing pulley connected to the second pulley. A motor for driving and driving the belt, a light-shielding means having a slit, which is connected to the second pulley, an optical sensor for detecting the slit of the light-shielding means, and a detection of the reference position sensor. And a control unit for controlling the motor so that the slit detection of the optical sensor for a specified number of times after the slit detection is set to the stop position of the clamper.

According to a second aspect of the present invention, the thermal transfer printer has a plurality of designated positions after the first slit detection of the optical sensor and a plurality of stop positions of the clamper.

According to a third aspect of the present invention, in the thermal transfer printer, the mounting relative angle between the second pulley and the slit of the light shielding means can be changed so that the stop position of the clamper can be adjusted. is there.

In a thermal transfer printer according to a fourth aspect of the present invention, the light shielding means comprises a plurality of light shielding plates having fan-shaped notches and slits, and the plurality of light shielding plates form a plurality of slits. The relative mounting angles of the plurality of light shielding plates are made variable so that the plurality of slit intervals can be changed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. FIG. 1 is a perspective view showing a main part of a thermal transfer printer according to an embodiment of the present invention. In this figure, 1 is a platen roller, 2 is a pair of first pulleys provided coaxially on both sides of the platen roller 1 so as to be able to rotate separately from the platen roller 1, and 3 is hooked on a first pulley 2. A pair of timing belts, 4 is a second pulley that extends the timing belt 3, and 8 is a platen roller 1.
Ink sheet (not shown) that is contacted with and separated from by an electric signal
A thermal head 9 for forming an image by thermal transfer printing of the ink of FIG.
The clamper grips one end of the sheet 10 and conveys it in the direction of arrow D.

Reference numeral 21 is a DC motor, and the second pulley 4
Is rotationally driven to generate a traveling driving force of the clamper 9 via the timing belt 3. 22 is a speed reduction mechanism
The torque is directly transmitted to the drive shaft 4a of the pulley 4. 23
Is a roller provided on the drive shaft 4a, and 24 is a bearing, which holds the drive shaft 4a and the shaft of the platen roller 1 in a frame (not shown) of the apparatus main body.

Reference numeral 25 denotes an encoder which is directly connected to the drive shaft 4a and detects the rotation of the second pulley 4. The encoder 25 has a disc-shaped light shield plate 25a as a light shield means attached to the drive shaft 4a. It is composed of an optical sensor 25c for detecting a slit 25b provided in the light shielding plate 25a.

A pulse motor 26 drives the platen roller 1 to rotate, and its torque is the DC motor 21.
The torque is much stronger than the torque of. Reference numeral 31 is a voltage control device for controlling the operation of the DC motor 21, and has a control unit 32 including a microcomputer.

FIG. 2 is a block diagram showing the details of the clamper positioning mechanism of the thermal transfer printer shown in FIG. 1, and FIG. 3 is the second of FIG.
3 is an enlarged perspective view showing a state in which the timing belt 3 is installed on the pulley of FIG. In these drawings, reference numeral 35 is a reference position sensor for detecting the reference position of the clamper 9, which is composed of a switch 35a and a lever 35b, and is attached to a position on the circumference of the clamper 9 where there is a sufficient space. There is.

Further, as shown in FIG. 3, the second pulley 4
A gear 4a is formed on the outer peripheral portion of the. A tooth groove 3 a that is driven by meshing with the gear 4 a is formed on the inner peripheral portion of the timing belt 3. The number of teeth of the second pulley 4 and the number of teeth of the timing belt 3 are configured to be an integral multiple, and in the first embodiment, they are set to 1 to 6. Therefore, the second pulley 4 and the timing belt 3 always have the same teeth at a ratio of 1/6.

In the thermal transfer printer thus constructed, the DC motor 21 (shown in FIG. 2) drives the second pulley 4 in the arrow E direction, the timing belt 3 runs in the arrow F direction, and the clamper 9 is moved. Is also conveyed in the F direction. P1 to P6 are positions of the clamper 9 when the optical sensor 25c detects the slit 25b. FIG. 4 shows the operation of stopping the clamper 9 by designating the position requiring the stop of the clamper 9 from the positions P1 to P6 of the clamper 9.
This will be described with reference to the flowchart shown in FIG.

First, when the clamper 9 is conveyed and the lever 35b of the reference position sensor 35 is operated, the switch 35a is turned on and a signal is sent to the control unit 32. From this point, the rotating disk 25a coaxially connected to the second pulley 4 rotates in the direction of arrow E, and the optical sensor 25c starts to move to the slit 2
When 5b is detected, "1" is stored in the counter in the control unit 32, and the position of the clamper 9 at that moment is set to "P".
The reference position of the clamper 9 is set to "1" (steps S40 and S41).

Next, when the clamper 9 is further conveyed and the optical sensor 25c detects the slit 25b for the third time, the clamper 9 stops at the position P3, the clamper 9 closes, and the sheet 10 (not shown). And the paper feeding operation is completed (steps S42 and S43).

When the clamper 9 which has completed the paper feeding operation is further conveyed and the optical sensor 25c detects the fifth slit 25b, the clamper 9 is stopped at the position P5 and the thermal head 8 is separated from the platen roller 1 ( Steps S44 to S46).

The clamper 9 is conveyed under the separated thermal head 8, and the optical sensor 25c causes the sixth slit 25 to move.
When b is detected, the clamper 9 stops at the position P6, and the thermal head 8 descends as shown by the alternate long and short dash line to come into contact with the platen roller 1 with the ink sheet (not shown) and the paper 10 sandwiched therebetween to prepare for printing. Is completed (step S47-
S49).

In the printing operation, printing is performed by printing three or four color ink sheets (not shown) in one printing (steps S50 and S51).

In the above, the fact that the second and fourth optical sensors 25c detect the slit 25b is ignored in the control sequence, and the stop positions P2 and P4 of the clamper 9 are ignored.
Is not used in the first embodiment, but can be used as a stop position if necessary.

After the printing is completed, the clamper 9 is conveyed and the reference position P1 is set again. Then, the optical sensor 25c detects the stop position P3, the clamper 9 is opened, and the paper 10 on which the printing is completed is released and discharged. Thus, the series of operations is completed (steps S53 to S56).

According to the first embodiment, in the conventional device in the orbit of the clamper 9, 1/6 of the circumferential length of the timing belt 3 is based on the stop position of the clamper 9 where the optical sensor is most difficult to attach in the conventional device. A reference position sensor 35 for engaging the clamper 9 to set a reference position at a distance interval;
By providing and controlling the encoder 25 connected to the pulley 4 of the above, it is possible to perform the clamper stop positioning at a plurality of positions with one optical sensor, the structure is simple, and the positioning can be performed at low cost and with high accuracy. is there. In addition, the optical sensor 25
It is possible to count the number of times the slit 25b is detected by c, select the stop position of the clamper 9 using the number of times as a key, and stop the paper 10 at a position suitable for the purpose such as feeding, printing, and discharging.

Embodiment 2 FIG. 5 is a configuration diagram showing details of the clamper positioning mechanism of the thermal transfer printer according to the second embodiment of the present invention. In this figure, the position of the slit 25b formed in the light shielding plate 25a of the encoder 25 and the relational position with the second pulley 4 are set at an arbitrary angle θ from the position shown in the first embodiment, a set screw (not shown), etc. The attachment / detachment allows relative movement in the rotation direction.
The movement angle θ may be in the opposite rotation direction.

According to the second embodiment, the first embodiment
When it is desired to adjust the stop position of the clamper 9 defined by, the relative angle between the second pulley 4 and the light blocking plate 25a, which is the light blocking plate, can be adjusted by moving the relative angle to the distance to be adjusted. .

Embodiment 3 6 is an exploded perspective view of a light shielding plate according to a third embodiment of the present invention, and FIG. 7 is a diagram showing a relationship of mounting angles of the light shielding plate. In these figures, 25d
Is a fan-shaped notch formed in the light-shielding plate 25a, and 25e is a second light-shielding portion between the notch 25d and the slit 25b. 26 is a second light shielding plate, 26a is a light shielding portion, and 26b
Is a fan-shaped cutout. The light blocking plate 25a and the second light blocking plate 26 are coaxially attached to the drive shaft 4a of the second pulley 4. These can be fixed at an arbitrary relative angle by a set screw (not shown).

By changing the fixed relative angle,
A case where the stop position of the clamper 9 at the designated position is finely adjusted will be described with reference to FIG. The optical sensor 25c controls the DC motor 21 by detecting the moment when the light is shielded and the light is transmitted, that is, the output level of the optical sensor 25c rises from "low (L)" to "high (H)". By doing so, the clamper 9 is stopped. In FIG. 8A, P is a reference position located at a position separated from the position where the switch 35a is turned on by a distance that is an integral multiple of the substantial outer peripheral length of the second pulley 4. After the DC motor 21 rotates the angle Θ1 from the reference position P, the fan-shaped notch 26b causes the output level of the optical sensor 25c to rise to "H", and the second light shield 25e temporarily sets the optical sensor 25c to "L". After the movement of the angle Θ2, the slit 25b again causes the optical sensor 25
"H" of the output level of c is detected. Therefore, stop control at two locations is possible. When the relative mounting angles of the light shield plate 25a and the second light shield plate 26 are changed to Θ3 and Θ4 in FIG. 8B so that the positions where the output level of the optical sensor 25c becomes “H” are different, The stop position of the clamper 9 from the reference position P can be adjusted freely.

In the control sequence in the case where there are two slits, the slit is detected twice by one rotation of the second pulley 4. Therefore, by setting the counter to an odd number, the number of times the slit is detected is designated to stop. , Θ2 or Θ4 can be designated by specifying an even number of Θ1 or Θ3. Therefore, even if the divergence position of the thermal head 8 and the paper feed position are not at intervals of an integral multiple of the substantial circumference of the second pulley 4, the specified number of slit detections of the optical sensor 25c is an odd number or an even number corresponding to that position. And choosing
Fine adjustment can be performed by changing the relative mounting angle of the light shielding plate 25a and the second light shielding plate 26. This makes it possible to set the stop position of the clamper 9 to an optimum position.

[0034]

Since the present invention is constructed as described above, it has the following effects.

A thermal transfer printer according to claim 1 of the present invention includes a platen roller, a first pulley provided at both ends of the platen roller coaxially with the platen roller and separately rotatable, and a second pulley. And a pair of timing belts suspended between the first pulley and the second pulley and having a substantial circumference length that is an integral multiple of the substantial circumference length of the second pulley, and is installed between the timing belts. , A clamper for gripping an end portion of a sheet of paper and pulling and running the paper, a reference position sensor provided at an arbitrary position on the circumference of the clamper for detecting a reference position of the clamper, and a thermal transfer printing image. When performing, a thermal head that presses against the platen roller by sandwiching a printing medium sheet and an ink sheet, and the second pulley is connected to drive the timing belt. A motor for driving, a light-shielding means having a slit, which is connected to the second pulley, an optical sensor for detecting the slit of the light-shielding means, and the detection of the reference position sensor first and thereafter the detection of the slit of the optical sensor. And a control means for controlling the motor so that the slit detection of the optical sensor for the designated number of times is set to the stop position of the clamper, and therefore the clamper is connected to the second pulley for driving the timing belt. An optical sensor for detecting the slit of the light shielding means having a slit,
With the control unit that controls the DC motor based on the signal from the optical sensor, it is possible to position the clamper stop positions at a plurality of positions, the structure is simple, and the positioning can be performed inexpensively and accurately.

According to the thermal transfer printer of the second aspect of the present invention, the control unit that counts the number of slits detected by the optical sensor, selects the stop position of the clamper, and determines the paper feeding, printing and paper ejecting positions. By providing the, the clamper can be stopped at a position suitable for the purpose.

According to the thermal transfer printer of the third aspect of the present invention, the mounting relative angle between the second pulley and the slit of the light shielding means can be changed, and the stop position of the clamper can be adjusted. Therefore, the stop position of the clamper can be easily changed by moving the relative angle between the second pulley and the light shielding means to an arbitrary position.

In the thermal transfer printer according to the fourth aspect of the present invention, the light shielding means is composed of a plurality of light shielding plates having fan-shaped notches and slits, and the plurality of light shielding plates form a plurality of slits. Since the plurality of slit intervals can be changed by changing the relative mounting angles of the plurality of light shielding plates, it is possible to easily stop the clamper by detecting the sensor output by selecting one of the plurality of slits. Can be adjusted.

[Brief description of drawings]

FIG. 1 is a perspective view showing a thermal transfer printer according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing details of a clamper positioning mechanism of the thermal transfer printer of the present invention.

FIG. 3 is an enlarged perspective view showing a state in which a timing belt is installed around the second pulley of FIG.

FIG. 4 is a flowchart showing the operation of the thermal transfer printer of the present invention.

FIG. 5 is a configuration diagram showing details of a clamper positioning mechanism of the thermal transfer printer according to the second embodiment of the present invention.

FIG. 6 is an exploded perspective view of a light shielding plate according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a relationship of mounting angles of the light shielding plate according to the third embodiment of the present invention.

FIG. 8 is a diagram showing a relationship between sensor outputs according to a third embodiment of the present invention.

FIG. 9 is a cross-sectional view of essential parts showing a conventional thermal transfer printer.

[Explanation of reference numerals] 1 platen roller, 2 first pulley, 3 timing belt, 4 second pulley, 8 thermal head, 9
Clamper, 10 sheets, 21 DC motor, 25 encoder, 25a light shielding plate (light shielding means), 25b slit, 25c optical sensor, 25d fan-shaped notch, 25e
2nd light shielding part, 26 2nd light shielding plate, 26a light shielding part, 26b fan-shaped notch, 31 voltage control device, 32
Control unit, 35 reference position sensor.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location B65H 5/08 B41J 3/20 117C (72) Inventor Toshio Komori 2-2 Marunouchi, Chiyoda-ku, Tokyo No. 3 Sanryo Electric Co., Ltd.

Claims (4)

[Claims] 1. A platen roller, a first pulley provided at both ends of the platen roller so as to be rotatable coaxially with the platen roller and separately, a second pulley, and the first pulley. A pair of timing belts suspended between the second pulleys and having a substantial peripheral length that is an integral multiple of the substantial peripheral length of the second pulley, and a pair of timing belts that are installed between the timing belts and grip the end portions of the sheet-shaped paper. Clamper for pulling and traveling the paper, a reference position sensor provided at an arbitrary position on the circumference of the clamper for detecting a reference position of the clamper, and a paper and an ink sheet of a printing medium when performing thermal transfer printing. A thermal head that presses against the platen roller with a pinch interposed therebetween; a motor that is connected to the second pulley to drive and drive the timing belt; and a second pulley. A light-shielding unit that is connected and has a slit, an optical sensor that detects the slit of the light-shielding unit, and a slit detection of the optical sensor for a designated number of times after the detection of the reference position sensor first and the detection of the slit of the optical sensor. And a control means for controlling the motor so that the clamper is at the stop position. 2. The thermal transfer printer according to claim 1, wherein a plurality of designated times after the first detection of the slit of the optical sensor are set to a plurality of stop positions of the clamper. 3. The mounting position of the second pulley and the slit of the light shielding means can be changed so that the stop position of the clamper can be adjusted. The thermal transfer printer described. 4. The light blocking means comprises a plurality of light blocking plates each having a fan-shaped notch and slits. The plurality of light blocking plates form a plurality of slits, and the relative mounting angles of the plurality of light blocking plates are variable. The thermal transfer printer according to claim 1 or 2, wherein the plurality of slit intervals are changeable.