JPH1178156A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance print quality while reducing noise by disposing a butter member for absorbing vibration of a thermal head occurring in the press contact direction of a thermal head and a platen at a position on the inside of a printer where a load is applied when the thermal head is brought into press contact with the platen through a recording sheet. SOLUTION: A thermal head 19 comprises a head body 26, a head holder 28 for holding a head body 26 while oscillating freely round a shaft 27, and a spring 29 for urging the head holder 28 to oscillate clockwise to a retracting position. A cam mechanism 30 for oscillating the head holder 28 counterclockwise to a thermal recording position is fixed above the head holder 28. The head body 26 is provided, on the lower surface thereof, with a heating element array 32 comprising multiple heating elements arranged in line in the direction perpendicular to the carrying direction of a color thermal recording sheet 3. A buffer member, i.e., a rubber plate 34, for absorbing vibration generated in the head body 26 is interposed between the head body 26 and the head holder 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer, and more particularly, to a thermal printer improved to prevent thermal head vibration.

[0002]

2. Description of the Related Art On a support, at least three types of thermosensitive coloring layers, for example, a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer,
2. Description of the Related Art A color thermal printer that prints a full-color image using a color thermal recording paper in which yellow thermal coloring layers are sequentially formed is known. In this color thermal printer, when printing, the thermal head is pressed against the color thermosensitive recording paper, the yellow image is thermally recorded line by line on the yellow thermal coloring layer having the highest thermal sensitivity, and immediately thereafter, the yellow thermal coloring layer is irradiated with ultraviolet rays. To settle. Next, a magenta image is thermally recorded on the magenta thermosensitive coloring layer, and then fixed by irradiating ultraviolet rays. Finally, a cyan image is thermally recorded on the cyan thermosensitive coloring layer to obtain a full-color image.

FIG. 4 schematically shows a printing section of a reciprocating color thermal printer. In the printer section 2, a transport roller pair 4 including a capstan roller and a nip roller is used to transport the color thermosensitive recording paper 3. The transport roller pair 4 alternately transports the color thermosensitive recording paper 3 in a forward direction in which the recording paper 3 is nipped and transported from the paper supply side to the paper discharge side, and a reverse direction in which the paper is transported from the paper discharge side to the paper supply side. .
At the time of transport in the forward direction, the color thermosensitive recording paper 3 is pressed and heated between the platen roller 5 and the thermal head 6 to sequentially record three colors of yellow, magenta, and cyan.
When the paper is transported in the reverse direction, the yellow fixing device 7 and the magenta fixing device 8 are turned on to fix the yellow thermosensitive coloring layer and the magenta thermosensitive coloring layer.

As shown in FIG. 5, a color thermal printer 10 in which the print unit 2 is incorporated has the print unit 2 mounted on a chassis, and the upper part thereof is covered by an outer case 12. Also, in order to prevent vibrations from outside the color thermal printer 10 from being transmitted to the thermal head 6 to cause deterioration in print image quality such as misregistration or uneven density, leg portions formed of rubber or the like are provided on the lower surface of the chassis 11. 13 is attached, and a plate-like anti-vibration rubber 14 is interposed between the chassis 11 and the print unit 2 to absorb vibration.

[0005]

However, vibration of the thermal head 6 may be generated by the thermal head 6 itself in addition to the vibration applied from outside the printer 10. The vibration of the thermal head 6 is caused by the vibration isolating rubber 1 described above.
No. 4 cannot absorb light, causing problems such as deterioration of print image quality such as registration deviation and density unevenness, and noise during printing due to resonance of a frame holding the thermal head 6 and the platen roller 5 and the like.

The vibration of the thermal head 6 itself is
It is generated by a protective layer provided on the color thermosensitive recording paper 3. As shown in FIG. 6A, the color thermosensitive recording paper 3 is
On the cyan thermosensitive coloring layer 3b, magenta thermosensitive coloring layer 3c, and yellow thermosensitive coloring layer 3d provided on the support 3a,
Further, a transparent protective layer 3e is provided. This protective layer 3
e is solidified at normal temperature, but softens when heated, and the heating element 6a of the press-contacted thermal head 6 is heated.
However, as shown in FIG. 3B, the protective layer 3e enters the protective layer 3e. When the color thermosensitive recording paper 3 moves in this state, the heating element 6a of the thermal head 6 moves from the state where it enters the protective layer 3e to the smooth surface of the protective layer 3e, so that the thermal head 6 is impacted. And this protective layer 3
Since the softening of e is caused by the heating of the thermal head 6 by the heating element 6a, the energization of the thermal head 6 and the vibration of the thermal head 6 are synchronized as shown in FIGS. .

As a device for absorbing the vibration of the thermal head itself, there is a thermal printer described in Japanese Utility Model Publication No. 2-19238. In this invention, the thermal head is held by a leaf spring and a rubber plate, and the vibration generated by the thermal head is absorbed so as not to be transmitted to a frame or the like. However, the vibration of the thermal head absorbed by the present invention is the vibration in the recording paper conveyance direction generated by the rotation of the platen roller, so that the vibration in the direction in which the thermal head is pressed against the platen roller cannot be absorbed. Nazu,
Conversely, the vibration increases. Further, there is a problem that the positioning of the thermal head in the sub-scanning direction becomes unstable, and registration deviation and density unevenness occur.

Further, the invention described in Japanese Patent Application Laid-Open No. 8-282059 discloses that thermal play between a thermal head and a support shaft for swingably supporting the thermal head causes vibration of the thermal head. The mounting of the head on the support shaft has been strengthened. However, since the vibration of the thermal head is transmitted directly to the chassis of the printer, there is a problem in that noise during printing becomes severe.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to prevent a thermal head from vibrating, thereby improving print quality and reducing noise.

[0010]

In order to solve the above-mentioned problems, a thermal printer according to the present invention includes a thermal head at a position inside the printer where a load is applied when a thermal head is pressed against a platen via recording paper. A buffer member is provided for absorbing the vibration of the thermal head generated in the pressure contact direction between the head and the platen. The buffer member is provided between the thermal head and a head holder that holds the thermal head, between a platen holding member that holds a platen, and a printer chassis to which the platen holding member is attached.

[0011]

FIG. 2 schematically shows a color thermal printer according to the present invention. In this color thermal printer, the color thermal recording paper 3 is inserted from an insertion port 16 provided on the right side in the figure. The color thermosensitive recording paper 3 performs thermal recording and fixing of a full-color image while being reciprocated in the forward direction, which is the insertion direction, and in the reverse direction. The color thermal recording paper 3 on which the thermal recording has been completed is discharged from a discharge port 17 provided on the left side in the figure. In order to reduce the size of the printer, the distance from the insertion port 16 to the discharge port 17 must be equal to the color thermal recording paper 3.
Is smaller than the length of the color thermosensitive recording paper 3 during the reciprocating movement.
A part is always projected from 7.

A thermal head 19 is located behind the insertion slot 16.
And a platen roller 20 are arranged opposite to each other. Further, a reflection type photosensor 21 for detecting the leading edge of the color thermosensitive recording paper 3 and a transport roller pair 22 are arranged further behind.

As shown in FIG. 1, the thermal head 19
Is a head body 26, a head holder 28 that holds the head body 26 and is swingable about a shaft 27, and biases the head holder 28 to a retracted position clockwise in FIG. And a spring 29 for swinging. Further, a cam mechanism 30 for swinging the head holder 28 to a thermal recording position in a counterclockwise direction in the figure is attached to an upper portion of the head holder 28.

The head main body 26 is provided with a heating element array 32 on its lower surface in which a number of heating elements are arranged in a line in a direction perpendicular to the direction of transport of the color thermosensitive recording paper 3. Heat sink 3 for cooling
3 is attached. The heating element array 32 generates heat energy suitable for the thermosensitive coloring layer to be printed. The head main body 26 is attached to a lower portion of a head holder 28 having a shape that does not interfere with the heat sink 33, for example, a U-shape. Between the head main body 26 and the head holder 28, a rubber plate 34 which is a buffer member for absorbing vibration generated in the head main body 26 is sandwiched.

The cam mechanism 30 is provided with a pressing plate 37 slidably mounted on two shafts 36 erected on the upper surface of the head holder 28 in a vertical direction, and between the pressing plate 37 and the head holder 28. A spring 38 attached so as to be sandwiched, and a cam 3 for pressing the pressing plate 37 downward.
9 and a cam motor 41 for rotating the cam 39 via a reduction gear 40.

The platen roller 20 is rotatably held by, for example, L-shaped bearing members 44 and 45 mounted on a chassis 43 serving as a base of the color thermal printer. It rotates in conjunction with. Although not shown in detail, a frame that holds the shaft 27 of the head holder 28 in a rotatable manner and that holds the transport roller pair 22 is attached to the chassis 43.

In the thermal head 19, the cam 39 presses the pressing plate 37 by the rotation of the cam motor 41, and the pressing plate 37 presses the head holder 28 via the spring 38, so that the spring 29 is urged. It rotates to the counterclockwise heat recording position in the drawing. Thereby, the head body 2
As shown in FIG. 2, the heating element array 32 of No. 6 is pressed against the color thermosensitive recording paper 3. The cam 3 of the cam mechanism 30
When the pressing member 9 releases the pressing of the pressing plate 37, the spring 29 swings the head holder 28 to the retracted position in the clockwise direction, and the pressure contact between the heating element array 32 and the color thermosensitive recording paper 3 is released.

The conveying roller pair 22 has a capstan roller 48 which is rotated in both directions by a motor 47, and a pinch which has a smaller diameter than the capstan roller 48 and is rotatable and which is pressed against the capstan roller 48 by a spring (not shown). And a roller 49. Transport roller pair 22
Nips the color thermal recording paper 3 inserted from the insertion slot 16 and conveys the color thermal recording paper 3 in the forward direction and the reverse direction.

As shown in FIG. 6A, a color thermosensitive recording paper 3 is formed on a support 3a by a cyan thermosensitive coloring layer 3b, a magenta thermosensitive coloring layer 3c, a yellow thermosensitive coloring layer 3d, and a protective layer 3.
e are sequentially layered. The yellow thermosensitive coloring layer 3d, which is the uppermost layer in the thermosensitive coloring layer, has the highest thermal sensitivity and develops yellow with small heat energy. The lowermost cyan thermosensitive coloring layer 3b has the lowest thermal sensitivity and develops cyan with large thermal energy. The yellow thermosensitive coloring layer d has a thickness of 420 n.
When near ultraviolet rays of m are irradiated, the coloring ability disappears.
The magenta thermosensitive coloring layer c develops magenta color with a thermal energy intermediate between the yellow thermosensitive coloring layer d and the cyan thermosensitive coloring layer b, and loses its coloring ability when irradiated with 365 nm ultraviolet rays. The color thermosensitive recording paper 3 may be provided with, for example, a black thermosensitive coloring layer to form a four-layer structure. Further, the positions of the thermosensitive coloring layers may be exchanged.

On the downstream side of the transport roller pair 22 in the forward direction,
A yellow fixing device 51 and a magenta fixing device 52 are arranged. The yellow fixing device 51 includes a rod-shaped ultraviolet lamp 53 that emits near-ultraviolet light of 420 nm, and a reflector 54 that covers the ultraviolet lamp 53 above and on both sides. The yellow thermosensitive coloring layer 3d after recording is fixed. The magenta fixing device 52 includes an ultraviolet lamp 56 that emits ultraviolet light of 365 nm, and a reflector 57 that covers the ultraviolet lamp 56 above and on both sides. Magenta fixing device 52
Irradiates ultraviolet light to the color thermosensitive recording paper 3 to fix the magenta thermosensitive coloring layer 3c after the thermal recording.

Next, the operation of the above embodiment will be described. The color thermal printer shown in FIG. 2 is connected to, for example, a personal computer. If you have an image you want to print while using a personal computer,
A print start is instructed by a keyboard or the like of a personal computer. As a result, the print data is sent from the personal computer to the color thermal printer.
The color thermal printer temporarily stores print data sent from a personal computer in a built-in memory.

After the print start operation, for example, a message indicating that the print preparation is completed and a message indicating that the color thermal recording paper 3 is to be inserted into the insertion slot 16 of the color thermal printer are displayed on a monitor of a personal computer, for example.

According to the message, the color thermosensitive recording paper 3
Into the insertion slot 16. When not in use, the cam 39 of the cam mechanism 30 shown in FIG.
7 and has been moved to a retracted position where it does not press against the platen roller 20. Therefore, the color thermosensitive recording paper 3 inserted from the insertion opening 16 passes between the thermal head 19 and the platen roller 20, and the conveying roller pair 22
At the tip. On the way, color thermal recording paper 3
Is detected by the reflection type photo sensor 21.

When the reflection type photo sensor 21 detects the leading edge of the color thermosensitive recording paper 3, the motor 47 for the conveying roller pair 22 starts to drive in response to the detection signal, and the capstan roller 48 is moved in the opposite direction in the figure. Rotate clockwise. As a result, the pinch roller 48 pressed against the capstan roller 48 rotates clockwise to nip the leading edge of the color thermosensitive recording paper 3.

At the same time as the nip of the color thermosensitive recording paper 3 by the transport roller pair 22, the cam motor starts to drive and rotates the cam 39 to press the pressing plate 37. The pressing plate descends along the axis 35 and presses the head holder 28 via the spring 38 at that time. As a result, the thermal head 19 swings about the shaft 27 and moves to the thermal recording position, and the heating element array 32 presses the color thermal recording paper 3 on the platen roller 20.

The color thermosensitive recording paper 3 is transported by a pair of conveying rollers 22.
Is conveyed in the forward direction by the forward rotation of. The platen roller 20 rotates counterclockwise following the transfer of the color thermosensitive recording paper 3. When the leading edge of the recording area reaches the heating element array 32 while the color thermosensitive recording paper 3 is being conveyed,
Each heating element generates thermal energy corresponding to each pixel of the yellow image, and thermally records the yellow image line by line on the yellow thermosensitive coloring layer 3d. The color thermosensitive recording paper 3 on which the thermal recording of the yellow image has been performed passes below the yellow fixing device 51 and the magenta fixing device 52, and the leading end protrudes from the discharge port 17.

At the time of thermal recording on the yellow thermosensitive coloring layer 3d, the heating element array 32 generates heat by energizing the thermal head 19 to heat the color thermosensitive recording paper 3. This softens the protective layer 3e, so that the heating element array 32 enters the protective layer 3e as shown in FIG. 6B. When the color thermosensitive recording paper 3 is conveyed from this state, the heating element array 32 moves from the state in which the heating element array 32 enters the protective layer 3e to the smooth surface of the protective layer 3e. However, since this vibration is absorbed by the rubber plate 34 serving as a cushioning member, deterioration in print image quality such as registration deviation and density unevenness does not occur. In addition, since vibration is not transmitted to the head holder 28 by the rubber plate 34, noise due to resonance of a frame or the like holding the head holder 28 does not occur.

When the thermal recording on the yellow thermosensitive coloring layer 3d of the color thermosensitive recording paper 16 is completed, the power supply to the heating element array 32 is stopped, and the cam motor 41 rotates in the reverse direction to push the pressing plate 37 by the cam 39. Is released. As a result, the thermal head 19 swings to the retracted position by the bias of the spring 29. Immediately after this, the ultraviolet lamp 53 of the yellow fixing device 51 is turned on, and the conveying roller pair 22 starts to rotate in the reverse direction, so that the color thermosensitive recording paper 3 is conveyed from the rear edge toward the insertion slot 16.

When the color thermosensitive recording paper 3 is conveyed in the reverse direction, near-ultraviolet light of 420 nm emitted from the ultraviolet lamp 54 irradiates the color thermosensitive recording paper 3 to perform thermal recording on the next magenta thermosensitive coloring layer 3c. Occasionally, yellow is fixed so as not to develop color.

When the leading edge of the recording area of the color thermosensitive recording paper 3 is conveyed to the position of the heating element array 32 again,
The conveying roller pair 22 stops once, and the ultraviolet lamp 54
Turns off. Then, the thermal head 19 returns to the thermal recording position again, and the transport roller pair 22 rotates forward to transport the color thermal recording paper 3 in the forward direction. The thermal head 19 performs thermal recording by applying thermal energy according to the magenta image to the magenta thermosensitive coloring layer 3c.

During thermal recording on the magenta thermosensitive coloring layer 3c, the thermal head 19 also vibrates due to the softening of the protective layer 3e, but the vibration is absorbed by the rubber plate 34 as in the thermal recording of the yellow image. Also, there is no deterioration in print image quality such as misregistration or uneven density. In addition, since vibration is not transmitted to the head holder 28 by the rubber plate 34, noise due to resonance of a frame or the like holding the head holder 28 does not occur.

When the thermal recording of the magenta image is performed up to the rear end of the color thermal recording paper 3 in the forward direction, the thermal head 19
Moves again to the retracted position to release the pressing on the color thermosensitive recording paper 3, and the transport roller pair 22 is stopped once. Immediately after this, the conveying roller pair 22 starts to rotate in the reverse direction, similarly to the case of yellow, and at the same time, the ultraviolet lamp 57 of the magenta fixing device 52 is turned on. The magenta fixing device 52 irradiates the color thermosensitive recording paper 3 with ultraviolet light having a wavelength of about 365 nm to fix the color so that magenta does not develop color during the subsequent thermal recording of the cyan thermosensitive coloring layer 3b.

When the leading edge of the recording area of the color thermosensitive recording paper 3 is conveyed to the position of the heating element array 32, the thermal head 19 returns to the thermal recording position as described above. At the same time, the conveying roller pair 22 rotates forward to convey the color thermosensitive recording paper 3 in the forward direction. During this transport, the thermal head 19 thermally records a cyan image on the cyan thermosensitive coloring layer 3b.

At the time of thermal recording on the cyan thermosensitive coloring layer 3b,
Although the thermal head 19 vibrates due to the softening of the protective layer 3e, the vibration is absorbed by the rubber plate 34 as in the thermal recording of the yellow and magenta images. Does not occur. Also,
Since vibration is not transmitted to the head holder 28 by the rubber plate 34, noise due to resonance of the frame or the like holding the head holder 28 does not occur.

When the thermal recording on all the thermosensitive coloring layers is completed, the transport roller pair 22 discharges the color thermosensitive recording paper 3 from the discharge port 17 as it is. The cyan thermosensitive coloring layer 3b
Is a value that does not cause coloring in a normal storage state, so that the fixing property is not given, and the fixing units 51 and 52 do not operate.

In the above embodiment, the rubber plate 34 is interposed between the head main body 26 of the thermal head 19 and the head holder 28. However, as shown in FIG. 3, a bearing member 44 for holding the platen roller 20 is provided. The same operation and effect can be obtained even if rubber plates 47 and 48 are interposed between the chassis 43 and the chassis 43.

Although a rubber plate was used as the cushioning member,
Other plate-like elastic materials or viscous materials, air dampers, magnetic dampers, oil dampers using silicon oil, or the like may be used.

Further, although a color thermal printer has been described, the present invention can also be applied to a monochrome thermal printer.
Further, it can be used for a thermal transfer printer using an ink ribbon. Furthermore, a printer that reciprocates a recording sheet using a pair of conveying rollers has been described. However, a thermal printer that winds a recording sheet around an outer periphery of a large-diameter platen drum and performs thermal recording with a thermal head disposed around the outer periphery is also applicable. Can be applied.

[0039]

As described above, according to the thermal printer of the present invention, the vibration of the thermal head can be effectively absorbed by the buffer member. In addition, noise during printing can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a partial configuration of a printing unit of a color thermal printer embodying the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of a color thermal printer embodying the present invention.

FIG. 3 is a perspective view showing a partial configuration of a printing unit of a color thermal printer according to another embodiment of the present invention.

FIG. 4 is a schematic diagram showing a configuration of a printing unit of a conventional color thermal printer.

FIG. 5 is a sectional view of a main part of a conventional color thermal printer.

FIG. 6 is an explanatory diagram showing a state of a color thermosensitive recording paper during thermal recording.

FIG. 7 is a graph showing a relationship between energization of the thermal head and vibration of the thermal head.

[Explanation of symbols]

 3 Color Thermal Recording Paper 19 Thermal Head 20 Platen Roller 26 Head Body 28 Head Holder 34, 47, 48 Rubber Plate

Claims (3)

[Claims] 1. A thermal printer in which recording paper is sandwiched between a thermal head and a platen to perform thermal recording, wherein a thermal load is applied to a position inside the printer where a load is applied when the thermal head is pressed against the platen via the recording paper. A thermal printer, comprising: a buffer member for absorbing vibration of a thermal head generated in a pressure contact direction between a head and a platen. 2. The thermal printer according to claim 1, wherein the buffer member is provided between the thermal head and a head holder that holds the thermal head. 3. The thermal printer according to claim 1, wherein the buffer member is provided between a platen holding member that holds the platen and a chassis of the printer to which the platen holding member is attached.