JPH1076694A - Serial type thermal head and cooling device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a serial type thermal head excellent in radiation characteristics. SOLUTION: In a serial type thermal head wherein a large number of heating elements 3... arranged in one direction, a supply electrode 4 for supplying a drive current to the arbitrary heating elements 3, a return electrode 5 and a folded electrode 6 are formed on the partial glaze part 2a of a glaze layer 2, a metal tape 21 as a cooling layer is fixed to the upper positions of the supply electrode 4, the return electrode 5 and the folded electrode through a protective layer 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a serial type thermal head and a cooling device for the serial type thermal head.

[0002]

2. Description of the Related Art Conventionally, a thermal type serial head in which a plurality of heating elements are arranged in a line in a vertical direction (recording paper feeding direction) is scanned by scanning in a horizontal direction (main scanning direction) of the recording paper. 2. Description of the Related Art A printing apparatus that prints a recording line and prints an image on a recording sheet by repeating the printing of the scanning recording line is known.

FIG. 7 is an enlarged perspective view showing a conventional serial type thermal head. Alumina substrate 101
A glaze layer 102 is formed thereon, and the glaze portion 10 of the glaze layer 102 which is raised in a mountain shape is formed.
A plurality of heating elements 103 are formed at a predetermined interval on 2a. A common electrode 104 is connected to one end of each heating element 103, and this common electrode 104 is connected to a power supply unit (not shown) through the side of the endmost heating element 103 on the near side in the drawing. Each of the other ends of each heating element 103 is connected to an individual electrode 105.
The individual electrodes 105 are connected to a heating element drive circuit (not shown).

FIG. 8 is an enlarged perspective view showing another conventional serial type thermal head. Alumina substrate 1
A plurality of heating elements 103 are formed at predetermined intervals on a partial glaze portion 102a of the glaze layer 102 which is raised in a mountain shape. Adjacent heating elements 103, 103
Are electrically connected to each other by a folded electrode 106, and these two adjacent heating elements 103, 1
03 corresponds to one printing dot.
Then, these two adjacent heating elements 103, 103
The supply electrode 107 is connected to one of the other ends, and the return electrode 108 is connected to the other end.
In this type of thermal head, there is no problem such as a voltage drop at the common electrode 104 in the type of thermal head of FIG.

[0005]

However, in the above-mentioned conventional serial type thermal head, if the scanning speed of the serial head is increased in order to increase the printing speed, heat storage tends to occur in the central portion of the serial head. In the print density of the print portion corresponding to the portion from the upper end to the lower end of the serial head (the portion from the upper end to the lower end in one scan recording line), the density at both ends is the density at the center. A phenomenon occurs in which it is lower than that of. Therefore, in an image printed by such a serial head, the density between the scanning recording lines is reduced, and "streaks" are generated in the portions between the lines, and the printing quality is degraded.

Such a problem does not occur so remarkably in the thermal head shown in FIG. 7 because each of the heating elements 103 is thermally connected by the common electrode 104. This is particularly likely to occur in the thermal head because the heating elements 103 are not of a structure that is thermally connected.

Incidentally, Japanese Patent Laid-Open No. 6-15922 (IP
CB41J 29/377) discloses an apparatus capable of cooling a thermal head, but has a drawback that the structure is complicated because the apparatus uses a fan.

In view of the above circumstances, an object of the present invention is to provide a serial type thermal head and a cooling device for the serial type thermal head which have a simple structure and excellent heat radiation characteristics.

[0009]

SUMMARY OF THE INVENTION A serial type thermal head according to the present invention comprises a plurality of heating elements arranged in one direction, and an electrode for supplying a drive current to an arbitrary heating element. In the head, a cooling layer is formed at a position above the electrode via a protective layer.

With the above configuration, since heat is taken by the cooling layer, the heat accumulation of the thermal head can be suppressed and the temperature distribution in the thermal head can be made uniform.

It is preferable that the cooling layer is formed so as to correspond to a central heating element of the heating elements. According to this, the heat storage at the central portion of the thermal head where heat storage is likely to occur is suppressed, so that the temperature distribution in the thermal head can be further uniformed.

[0012] The cooling layer may be made of a metal tape. Further, the configuration may be such that a part of the metal tape is provided apart from the serial head main body.

The cooling device for a serial-type thermal head according to the present invention is characterized in that one scanning head is provided at a position on the plate-shaped platen formed in the scanning direction of the serial-type thermal head that is long in the scanning direction on the end side in the scanning direction. It is characterized in that it has a cooling layer that contacts the thermal head on which the recording line has been formed without interposing the recording paper and absorbs the heat.

The non-uniformity of the temperature distribution of the thermal head increases as the formation of the scanning recording lines is repeated. However, with the above configuration, each time the formation of one scanning recording line is completed, the thermal head becomes nonuniform. Heat can be quickly absorbed, and the influence of the non-uniformity of the temperature distribution caused by the formation of the preceding scan recording line in the formation of the next scan recording line can be reduced.

It is preferable that the cooling layer is formed at a position corresponding to the center of the thermal head. According to this, a large amount of heat can be absorbed in the central portion of the thermal head in which heat is easily generated.

[0016] The cooling layer may be made of a metal tape. Further, a part of the metal tape may be provided apart from a plate-shaped platen.

Further, in the cooling device for a serial type thermal head according to the present invention, at least the terminal end side in the scanning direction of the plate-shaped platen formed long in the scanning direction of the serial type thermal head is made of silicone rubber. The thermal head comes into contact with the silicone rubber portion on the side of the terminal end without interposing the recording paper. The entire platen platen may be made of silicone rubber.

Conventional plate-like platens have used NBR (nitrile butadiene rubber) or the like. However, the above silicone rubber has a higher thermal conductivity than NBR, and when the thermal head comes into contact, the heat is quickly released. Can be absorbed. Therefore, even in the above configuration, the heat can be rapidly absorbed from the thermal head every time the formation of one scan recording line is completed, and in the formation of the next scan recording line, the formation of the previous scan recording line can be performed. Can reduce the influence of the non-uniformity of the temperature distribution.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a recording paper transport system and a printing mechanism of the printing apparatus. The printing apparatus includes a transport roller 11 for transporting a recording paper (not shown), a plate-like platen 12 disposed near the transport roller 11, and a motor (not shown) that rotates a predetermined angle in response to a pulse. )When,
A gear group 13 for transmitting the rotational force of the motor to the transport roller 11 and a serial type thermal head 14 for printing on a recording sheet (because it is located on the back side of the head support member 15, a virtual line ), A carriage 19 having the head support member 15 and the ink ribbon cassette accommodating portion, and a shaft 1 for guiding the carriage 19 in the lateral direction of the recording paper.
7 and a paper feed tray 18.

FIG. 2 is an enlarged perspective view showing the arrangement structure of the plate-like platen 12. As shown in FIG. Plate-shaped platen 1
2 is supported by a platen base 25. Further, a recording paper sensor 26 is provided in a portion of the platen base 25 which is a position close to the plate-shaped platen 12 and on a position (not shown) on the recording paper conveyance direction side.

FIG. 3 is an explanatory view showing the printing mechanism. The recording paper 10 is located between the thermal head 14 and the platen platen 12. And this recording paper 10
Between the ink ribbon cassette 1 and the thermal head 14
No. 6 ink ribbon 16a is interposed. The thermal head 14 and the ink ribbon cassette 16 move to the left (the carriage scanning direction) in the figure, and
6a is unwound from the supply roll 16b and is wound by the wind roll 16c. When one line (one scanning recording line) is printed, the transport roller 11 is driven, and the recording paper 10 is moved by the line feed width.

The thermal head 14 is provided with a drive electronic circuit (not shown) for driving the heating elements. A head flexible cable 20 is drawn out of the driving electronic circuit, and the head flexible cable 20 is connected to a printing data generating unit (not shown). A metal (for example, Cu) tape 21 is provided along the head flexible cable 20. The metal tape 21 passes above the electrodes 4 and 5 (see FIG. 4) of the thermal head 14 and reaches the vicinity of the heating elements 3... (See FIG. 4).

FIG. 4 is a vertical sectional side view showing the thermal head 14 in an enlarged manner. This thermal head 14
Is a folded electrode type (see FIG. 8), in which a glaze layer 2 is formed on an alumina substrate 1, and a plurality of heat generations are formed on a glaze portion 2 a of the glaze layer 2 which is raised in a mountain shape. The elements 3 are formed at predetermined intervals. One end sides of the adjacent heating elements 3, 3 are electrically connected to each other by the folded electrode 6, and these two adjacent heating elements 3, 3 correspond to one printing dot. A supply electrode 4 is connected to one end of the two adjacent heating elements 3, 3, and a return electrode 5 is connected to the other end.

Then, above the electrodes 4 and 5,
The above-described metal tape 21 is adhered via the protective layer 7. The metal tape 21 forms a cooling layer (hereinafter, also referred to as a cooling layer with reference numeral 21). Further, a cooling layer 21 is formed above the folded electrode 6 and above a position protruding to the side opposite to the element via the protective layer 7.

According to the above configuration, the cooling layer 21 formed above the electrodes 4 and 5 via the protective layer 7 absorbs the heat of the thermal head 14 and suppresses the heat accumulation. The temperature distribution at 14 can be made uniform. In particular, in this embodiment, the cooling layer is made of the metal tape 21 and a part of the metal tape 21 is provided separately from the thermal head main body. And moves away from the thermal head 14, and the effect of suppressing the heat storage of the thermal head 14 is further enhanced.

The cooling layer 21 is formed by the heating elements 3.
Of the electrodes 4 connected to the central heating elements 3.
It is preferable that the protective layer 7 is formed above the layer 5. According to this, since the heat storage at the central portion of the thermal head 14 where the heat storage tends to occur is suppressed, the temperature distribution in the thermal head 14 can be further uniformed.

Further, in this embodiment, the folded electrode type is shown, but the common electrode type can also be constructed using the present invention. Further, the cooling layer 21 is, of course, not limited to a part of which is separated from the thermal head 14.
It may be formed by vapor deposition or the like.

(Embodiment 2) Next, another embodiment of the present invention will be described.

FIG. 5 is a side view showing a thermal head cooling device according to this embodiment. The cooling device is located at a position on the terminal end side in the scanning direction of the plate-shaped platen 12 formed long in the scanning direction of the thermal head 31,
A cooling layer that absorbs heat from the thermal head 31 after forming one scanning recording line is provided in a portion where the thermal head 31 can be brought into contact without interposing the recording paper 10 (hereinafter, this portion is referred to as a heat absorption region). Made of metal (for example,
It is formed by fixing a tape 32 (such as Cu). As the metal tape 32, a tape longer than the heat absorbing region is used, and a part thereof is separated from the plate-like platen 12 and is brought into contact with, for example, a metal portion of the platen base 25 (see FIG. 2). I have.

Here, the non-uniformity of the temperature distribution of the thermal head 31 increases as the number of scan recording lines formed increases. However, according to the structure of the second embodiment,
Each time one scan recording line is formed, the thermal head 31 is positioned above the heat absorbing area, and heat is quickly absorbed by the metal tape 32 in this heat absorbing area. Therefore, in the formation of the next scan recording line, the influence of the non-uniform temperature distribution of the thermal head 31 caused by the formation of the previous scan print line can be reduced.

In particular, in this embodiment, the cooling layer is made of a metal tape 32, and a part of the metal tape 32 is located away from the platen platen 12, so that the heat of the thermal head 31 is 32 and away from the platen platen 12, the thermal head 31
Therefore, heat can be more efficiently absorbed and the cooling effect can be enhanced.

As the metal tape 32, a tape corresponding to the width of the platen platen 12 or a tape corresponding to the printing width of the thermal head 31 can be used. It is preferable that a portion of the metal tape 32 serving as the cooling layer, which is located on the heat absorbing region, be formed at a position corresponding to the central portion of the thermal head 31. According to this, the heat can be absorbed at the central portion of the thermal head 31 where heat storage is likely to occur.

FIG. 6 shows a modification of this embodiment. In the thermal head cooling device according to this modification, the entire plate-shaped platen 12 ′ formed long in the scanning direction of the serial type thermal head 31 is made of silicone rubber, and the plate-shaped platen 12 ′ in the scanning direction is formed. The thermal head 3 is located at the end portion side.
1 is configured to come into contact with the recording paper without the intervention of the recording paper.

The conventional plate-shaped platen is made of NBR (nitrile butadiene rubber), but the silicone rubber constituting the plate-shaped platen 12 'is NBR.
In this case, the thermal conductivity is higher than that of the thermal head 31 and the heat can be quickly absorbed when the thermal head 31 comes into contact with the thermal head 31. Therefore, in the configuration of FIG. 6 as well, the heat can be rapidly absorbed from the thermal head 31 each time one scan recording line is formed, and in the formation of the next scan recording line, the scanning of the previous row is performed. It is possible to reduce the influence of non-uniform temperature distribution caused by the formation of the recording line.

In the configuration shown in FIG. 6, the entire plate-shaped platen 12 'is made of silicone rubber. However, the present invention is not limited to this, and at least the end of the plate-shaped platen 12' in the scanning direction is provided. It may be made of silicone rubber.

In the second embodiment described above, the time during which the thermal head 31 is located on the heat absorbing area, or when the thermal head 31 contacts the plate-like platen 12 'without the recording paper 10 interposed therebetween. The longer the time, the more desirable it is. In the control system of the drive system of the serial head 31, control for increasing the time may be performed.

[0038]

As described above, according to the present invention, the thermal storage of the thermal head is suppressed, the temperature distribution thereof is made uniform, and the density drop between the scanning recording lines in the printed image is reduced. This has the effect of suppressing and improving the printing quality.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a recording paper transport system and a printing mechanism of a printing apparatus.

FIG. 2 is an enlarged perspective view showing an arrangement structure portion of a plate-like platen.

FIG. 3 is an explanatory view showing a printing mechanism.

FIG. 4 is a vertical sectional side view showing the serial type thermal head according to the first embodiment of the present invention;

FIG. 5 is a side view showing a cooling device for a thermal head according to a second embodiment of the present invention.

FIG. 6 is a side view showing a modification of the cooling device for a thermal head according to the second embodiment of the present invention.

FIG. 7 is a perspective view showing a conventional common electrode type serial type thermal head.

FIG. 8 is a perspective view showing a conventional folded electrode type serial type thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Alumina substrate 2 Glaze layer 2a Partial glaze part 3 Heating element 4 Supply electrode 5 Return electrode 7 Protective layer 12 Plate-shaped platen 12 'Plate-shaped platen (made of silicone rubber) 14 Serial head 20 Head flexible cable 21 Metal tape (cooling layer) ) 31 Serial head 32 Metal tape (cooling layer)

Claims (9)

[Claims] 1. A serial type thermal head comprising a plurality of heating elements arranged in one direction and electrodes for supplying a drive current to an arbitrary heating element.
A serial type thermal head, wherein a cooling layer is formed above the electrode via a protective layer. 2. The serial type thermal head according to claim 1, wherein said cooling layer is formed corresponding to a central heating element of said heating elements. 3. The serial type thermal head according to claim 1, wherein the cooling layer is made of a metal tape. 4. The serial type thermal head according to claim 3, wherein a part of the metal tape is provided apart from the serial head main body. 5. A recording paper is formed on the thermal head after forming one scanning recording line at a position on the terminal end side in the scanning direction of a plate-shaped platen formed long in the scanning direction of a serial type thermal head. A cooling device for a serial-type thermal head, comprising: a cooling layer that absorbs the heat by contacting without passing through. 6. The cooling device according to claim 5, wherein the cooling layer is formed at a position corresponding to a central portion of the thermal head. 7. The cooling device for a serial type thermal head according to claim 5, wherein the cooling layer is made of a metal tape. 8. The apparatus according to claim 7, wherein a part of said metal tape is provided apart from a plate-like platen.
2. A cooling device for a serial type thermal head according to item 1. 9. A serial plate type thermal head having a plate-shaped platen formed to be long in the scanning direction, at least an end portion in the scanning direction is made of silicone rubber, and the thermal head is attached to the silicone rubber portion on the end portion side. A serial-type thermal head cooling device, wherein the device is brought into contact without interposing a recording paper.