JP2006021349A - Recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively mount a temperature sensor for measuring a temperature in the vicinity of a heating element. <P>SOLUTION: At a rear face front end part of an element substrate 31 of a thermal head 17 of a color thermal printer 2, a plurality of the temperature sensors 40 for measuring the temperature in the vicinity of the heating element 36 are arranged at equal intervals, and a wiring pattern 41 which connects with the temperature sensors 40 is formed. The temperature sensors 40 are set at points where a distance d from immediately below the heating element 36 is within 10 mm with respect to a subscanning direction. A flexible printed board 46 for electrically connecting the wiring pattern 41 extended from the temperature sensors 40 and a circuit pattern of a control circuit with each other is mounted between the element substrate 31 and a circuit board 32. For preventing the temperature sensors 40 and the flexible printed board 46 from contacting, escape recesses 33 and 34 are formed at parts at a heat sink 30 against which the temperature sensors 40 and the flexible printed board 46 abut. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides an element substrate having a plurality of heating elements arranged on the surface, a circuit board on which a control circuit is mounted, and either the element substrate or the circuit board for selectively driving the heating elements. The present invention relates to a recording head including a driver IC and a heat radiating plate that is fixed to the back surface of the element substrate and the circuit board and dissipates heat stored by the heat generated by the heat generating elements.

  As a printer that records images on recording materials using a recording head, a color thermal printer that obtains a full-color print using color thermal recording paper in which a thermal color-developing layer that develops colors cyan, magenta, and yellow is formed on a support in order. It has been known. In this color thermal printer, while color thermal recording paper is conveyed in the sub-scanning direction, thermal recording is performed by a thermal head in which a plurality of heating elements are arranged in a line in the main scanning direction.

  The thermal head is mounted on either the element substrate on which the plurality of heating elements are arranged, the circuit board on which the control circuit is mounted, or the element substrate or the circuit board, for selectively driving the heating elements. The driver IC is fixed to the element substrate and the back surface of the circuit board, and includes a heat radiating plate that radiates heat stored by the heat generated by the heat generating element to the outside. In a conventional color thermal printer, the temperature in the vicinity of the heating element is measured with a temperature sensor, and the amount of heat received by the color thermal recording paper from the heating element is constant according to the temperature measurement result of this temperature sensor (however, the same Image data (for example, when a gray image is solid-printed) and the driving energy applied to the heating element is controlled to prevent the occurrence of uneven density in the image (see Patent Documents 1 to 3).

  In the thermal printer described in Patent Document 1, a thermistor as a temperature sensor is disposed on the back surface of a ceramic substrate that is an element substrate. In the thermal head described in Patent Document 2, the thermistor is arranged in the driver IC row portion of the ceramic substrate. Furthermore, in the thermal head described in Patent Document 3, the thermistor and the driver IC are embedded in a recess formed in the ceramic substrate.

JP-A-62-170366 Japanese Patent Publication No. 4-17798 Japanese Patent No. 3338919

  However, in the thermal printer described in Patent Document 1, it is described that the thermistor is disposed on the back surface of the ceramic substrate. However, a specific wiring method is not mentioned, and it is a practical method. Is hard to say.

  Further, the thermal head described in Patent Document 2 has a problem of interference with the platen roller, and there is a drawback that a thermistor cannot be attached in the vicinity of the heating element. In addition, when a plurality of thermistors are attached in the main scanning direction, a space for attaching to the driver IC row portion must be secured, and there is a problem that the size of the head in the main scanning direction becomes larger than necessary.

  Furthermore, in the thermal head described in Patent Document 3, the problem of interference with the platen roller in Patent Document 2 can be overcome, but the recess in which the thermistor and the driver IC are embedded is made into an element substrate that is difficult to process. The production cost is increased by the amount of formation. Moreover, the problem regarding the head dimension in the case of Patent Document 2 cannot be solved.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a recording head capable of mounting a temperature sensor for measuring the temperature in the vicinity of a heating element at a low cost.

  To achieve the above object, the present invention provides an element substrate having a plurality of heating elements arranged on the surface, a circuit board on which a control circuit is mounted, and either the element substrate or the circuit board. In the recording head, comprising: a driver IC for selectively driving an element; and a heat radiating plate fixed to the back surface of the element substrate and the circuit board and dissipating heat stored by the heat generation element to the outside. A plurality of temperature sensors for measuring the temperature in the vicinity of the heating element are arranged on the back surface of the substrate, wiring patterns connected to these temperature sensors are formed, and circuit patterns of the control circuit are formed on both surfaces of the circuit substrate. In addition, a connecting means for electrically connecting the wiring pattern and the circuit pattern is attached between the element substrate and the circuit board.

  The connecting means is preferably a flexible printed board.

  Further, it is preferable that a relief portion is formed at a portion of the heat radiating plate where the temperature sensor and the connecting means abut so that the temperature sensor and the connecting means do not contact the heat radiating plate.

  Furthermore, it is preferable that the temperature sensor is attached to a location whose distance from directly below the heating element is within 10 mm in a direction orthogonal to the direction in which the heating elements are arranged.

  According to the recording head of the present invention, a plurality of temperature sensors for measuring the temperature in the vicinity of the heating element are arranged on the back surface of the element substrate, wiring patterns connected to these temperature sensors are formed, and both sides of the circuit board are formed. Since the circuit pattern of the control circuit is formed and connecting means for electrically connecting the wiring pattern and the circuit pattern is attached between the element substrate and the circuit board, the temperature sensor can be mounted at low cost.

  In FIG. 1, a color thermal printer 2 to which the present invention is applied uses a long color thermal recording paper (hereinafter simply referred to as recording paper) 10 as a recording material. The recording paper 10 is set in the color thermal printer 2 in the form of a recording paper roll 11 wound in a roll shape.

  As is well known, the recording paper 10 has a structure in which a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer, a yellow thermosensitive coloring layer, and a protective layer are sequentially formed on a support. The yellow thermosensitive coloring layer, which is the uppermost layer, has the highest thermal sensitivity and develops yellow with a small amount of heat energy. The cyan thermosensitive coloring layer, which is the lowermost layer, has the lowest thermal sensitivity and develops cyan with large heat energy.

  The yellow thermosensitive coloring layer loses its coloring ability when irradiated with near ultraviolet rays of 420 to 450 nm. The magenta thermosensitive coloring layer develops magenta with intermediate heat energy between the yellow thermosensitive coloring layer and the cyan thermosensitive coloring layer, and loses the coloring ability when irradiated with ultraviolet rays of 365 to 390 nm. For example, a recording paper having a four-layer structure provided with a black thermosensitive coloring layer may be used.

  A paper feed roller 13 rotated by the transport motor 12 is in contact with the outer peripheral surface of the recording paper roll 11. The carry motor 12 is a stepping motor and is driven by drive pulses input from the motor driver 14. When the paper feed roller 13 rotates counterclockwise in the figure, the recording paper roll 11 rotates clockwise in the figure, and the recording paper 10 is sent out from the recording paper roll 11. When the paper supply roller 13 rotates clockwise in the figure, the recording paper roll 11 rotates counterclockwise in the figure, and the recording paper 10 is rewound onto the recording paper roll 11.

  The recording paper 10 sent out from the recording paper roll 11 is sent into a conveyance path arranged in the horizontal direction. In this transport path, a transport roller pair 15 and a paper discharge roller pair 16 are disposed that sandwich and transport the recording paper 10. The conveyance roller pair 15 and the paper discharge roller pair 16 are composed of capstan rollers 15a and 16a rotated by the conveyance motor 12 and pinch rollers 15b and 16b pressed against the capstan rollers 15a and 16a. In the figure, the sheet is reciprocated in the A direction (paper feeding direction) and the B direction (rewinding direction).

  A thermal head 17 and a platen roller 18 disposed below the transport path so as to face the thermal head 17 are provided between the paper feed roller 13 and the transport roller pair 15. On the surface of the thermal head 17 facing the recording paper 10 of the element substrate 31 (see FIGS. 2 and 3), the direction (main scanning direction M) is perpendicular to the conveyance direction (sub-scanning direction S) of the recording paper 10. 2 and FIG. 3), a heating element array 19 is provided in which a plurality of heating elements 36 (see FIGS. 2 and 3) are arranged in a line. The heating element array 19 generates heat based on the drive data input from the system controller 20 to the head driver 21, and colors each thermosensitive coloring layer of the recording paper 10.

  The platen roller 18 is driven and rotated in accordance with the conveyance of the recording paper 10 to stabilize the contact state between the recording paper 10 and the heating element array 19. Further, the platen roller 18 is movable in the vertical direction and is urged in a direction in which it is pressed against the heating element array 19 by a spring (not shown). When the recording paper 10 is fed and discharged, the platen roller 18 is lowered by a shift mechanism (not shown) including a cam and a solenoid, and the nipping of the recording paper 10 with the thermal head 17 is released.

  As shown in FIGS. 2 and 3, the thermal head 17 includes a heat radiating plate 30, an element substrate 31, and a circuit substrate 32. The heat radiating plate 30 is made of a heat radiating material such as aluminum, and radiates heat stored by the heat generated by the heat generating element 36 to the outside. The heat radiating plate 30 is fixed to the back surfaces of the substrates 31 and 32 with an adhesive or a double-sided tape so as to straddle the element substrate 31 and the circuit substrate 32.

  The heat sink 30 is formed with concave relief portions 33 and 34 at portions where the temperature sensor 40 and the flexible printed circuit board 46 are in contact with each other so that the temperature sensor 40 and the flexible printed circuit board 46 described later do not contact each other. The shape of the escape portion is not limited to a concave shape, and may be a half moon shape.

  The element substrate 31 is made of, for example, ceramic, alumina, alumina ceramic, or the like. A printing protrusion 35 having a semicircular cross section is formed at the front end portion of the element substrate 31. The printing protrusion 35 is provided with a plurality of heating elements 36 constituting the heating element array 19. A driver IC 37 for driving each heat generating element 36 is mounted on the rear end portion of the surface of the element substrate 31. The driver IC 37 and the heating element 36 are connected by a conductive layer 38 formed on the element substrate 31 and a jumper line 39. The driver IC 37 may be mounted on the circuit board 32 instead of the element substrate 31.

  A plurality of temperature sensors 40 for measuring the temperature in the vicinity of the heating element 36 are arranged at equal intervals at the front end of the back surface of the element substrate 31. In addition, wiring patterns 41 connected to these temperature sensors 40 are formed. The temperature sensor 40 is attached to a location where the distance d from directly below the heating element 36 is within 10 mm in the sub-scanning direction.

  An insulating film 42 such as a resist is applied to a portion of the back surface of the element substrate 31 that is in contact with the heat sink 30. This prevents the wiring pattern 41 from coming into contact with the heat dissipation plate 30 and short-circuiting.

  A control circuit (not shown) for the thermal head 17 is formed on both sides of the circuit board 32, and is arranged behind the element substrate 31. The driver IC 37 of the element substrate 31 and the circuit board 32 are connected by a jumper line 43. An insulating film 44 is applied to a portion of the back surface of the circuit board 32 that is in contact with the heat sink 30, similarly to the insulating film 42 of the element substrate 31. The driver IC 37 and the jumper wires 39 and 43 are covered with a transparent protective resin 45 so that the jumper wires 39 and 43 are not disconnected.

  Between the element substrate 31 and the circuit board 32, a flexible printed circuit board 46 for electrically connecting the wiring pattern 41 extending from the temperature sensor 40 and the circuit pattern of the control circuit is attached.

  At the time of image recording, each temperature sensor 40 sequentially transmits the measurement result to the system controller 20. The system controller 20 controls the driving of the heating element 36 via the head driver 21 so that the density unevenness of the image does not occur according to the measurement result transmitted from each temperature sensor 40.

  In FIG. 1, a fixing device 22 is disposed on the downstream side of the conveyance roller pair 15 in the A direction so as to face the recording surface of the recording paper 10. A cutter 23 for cutting the recording paper 10 into a predetermined print size is disposed between the fixing device 22 and the paper discharge roller pair 16. Further, on the downstream side in the A direction of the paper discharge roller pair 16, a paper discharge port 24 for discharging the recording paper 10 on which the image has been recorded to the outside is provided.

  The fixing unit 22 emits near ultraviolet rays having an emission peak wavelength of 420 to 450 nm to fix the yellow thermosensitive coloring layer, and fixes the yellow thermosensitive coloring layer. The fixing device 22 emits ultraviolet rays having an emission peak wavelength of 365 to 390 nm and emits magenta thermosensitive coloring layer. A magenta fixing light source 22b for fixing the light, and a reflector 22c for reflecting light from the light sources 22a and 22b toward the recording paper 10. Each light source 22a, 22b is driven by a lamp driver 25.

  Next, the operation of the color thermal printer 2 having the above configuration will be described. When the image recording start operation is executed, the feed roller 13 is rotated counterclockwise by the forward rotation of the transport motor 12, and the recording paper 10 is sent out from the recording paper roll 11 in the A direction. The leading edge of the recording paper 10 moves in the conveyance path, is nipped by the conveyance roller pair 15, and is further conveyed downstream in the A direction.

  When the recording paper 10 reaches the image recording start position, the rotation of the transport motor 12 is temporarily stopped. Next, the platen roller 18 is raised by the shift mechanism, and the recording paper 10 is sandwiched between the heating element array 19. In this state, the conveyance motor 12 is driven again, and the yellow thermosensitive coloring layer of the recording paper 10 is generated by the heating element array 19 that generates heat based on the drive data input to the head driver 21 while the recording paper 10 is conveyed in the A direction. A yellow image is recorded in

  When the recording of the yellow image is completed, the trailing end of the recorded image is conveyed to a position facing the yellow fixing light source 22a of the fixing device 22, and the rotation of the conveying motor 12 is stopped. At this time, the platen roller 18 is lowered by the shift mechanism, and the holding of the recording paper 10 by the thermal head 17 is released. Next, the yellow fixing light source 22a is turned on by the lamp driver 25, the conveyance motor 12 is rotated in the reverse direction, and the recording paper 10 is rewound in the B direction.

  After fixing the yellow thermosensitive coloring layer, the recorded image is conveyed to the position where the leading edge of the recorded image faces the heating element array 19 and the rotation of the conveying motor 12 is stopped. As in the yellow image recording, the platen roller 18 is raised by the shift mechanism, and the recording paper 10 is sandwiched between the heating element array 19. In this state, the conveyance motor 12 is driven again, and a magenta image is recorded on the magenta thermosensitive coloring layer of the recording paper 10 while the recording paper 10 is conveyed in the A direction.

  When the recording of the magenta image is completed, the rear end of the recorded image is conveyed to a position facing the magenta fixing light source 22b of the fixing device 22, and the rotation of the conveying motor 12 is stopped. Then, as in the yellow image fixing, the magenta fixing light source 22b is turned on by the lamp driver 25, the conveyance motor 12 is reversed, and the recording paper 10 is rewound in the B direction. Is established.

  After fixing the magenta thermosensitive coloring layer, the leading edge of the recorded image is conveyed to a position facing the heating element array 19, and the rotation of the conveying motor 12 is stopped. A cyan image is recorded on the cyan thermosensitive coloring layer of the recording paper 10 in the same manner as when recording yellow and magenta images.

  The recording paper 10 after image recording is transported in the A direction by the transport roller pair 15, cut to a predetermined print size by the cutter 23, and then discharged from the paper discharge port 24 to the outside by the paper discharge roller pair 16.

  At the time of recording each image, the temperature in the vicinity of the heating element 36 is measured by a plurality of temperature sensors 40 attached to the back surface of the element substrate 31 of the thermal head 17. The measurement results by each temperature sensor 40 are sequentially transmitted to the system controller 20. Then, according to the measurement result transmitted from each temperature sensor 40, the driving of the heating element 36 is controlled by the system controller 20 via the head driver 21 so that the density unevenness of the image does not occur.

  As described above, the temperature sensor 40 is disposed on the back surface of the element substrate 31, the wiring pattern 41 connected to the temperature sensor 40 is formed, and the circuit pattern of the control circuit is formed on both surfaces of the circuit board 32. Since the flexible printed circuit board 46 for electrically connecting the wiring pattern 41 and the circuit pattern is attached between the circuit board 32 and the circuit board 32, the platen roller and the conventional technique for attaching the temperature sensor to the surface of the element board are installed. There is no problem with printing due to contact with the temperature sensor. In addition, unlike the method of mounting the temperature sensor in the driver IC row portion, the size of the head in the main scanning direction does not become larger than necessary.

  Further, since the relief portions 33 and 34 are formed in the portion where the temperature sensor 40 and the flexible print substrate 46 of the heat radiating plate 30 are in contact with each other using the flexible printed board 46, a recess is formed in the element substrate that is difficult to process. Compared with the conventional method of embedding the driver IC and the temperature sensor, the manufacturing cost is not required.

  Furthermore, since the temperature sensor 40 is attached to a location where the distance d from directly below the heating element 36 is within 10 mm in the sub-scanning direction S, the temperature near the heating element 36 can be measured more reliably.

  Here, if the temperature sensor 40 is disposed in the immediate vicinity of the heating element 36, the output of the temperature sensor 40 is affected by the pattern of the image data. For example, when only one temperature sensor 40 is arranged in the center, if black image data is recorded only in the center, the output of the temperature sensor 40 increases, but the temperature in other parts of the main scanning direction M is low. An error between the temperature and the detected temperature becomes large, and appropriate density unevenness correction cannot be performed. As a countermeasure against this problem, in the above-described embodiment, a plurality of temperature sensors 40 are arranged in the main scanning direction M, and the detected temperatures are averaged so that a difference between the actual temperature and the detected temperature does not occur. Therefore, finer density unevenness correction can be performed.

  In the above embodiment, the flexible printed circuit board 46 has been described as an example of connection means for electrically connecting the wiring pattern 41 and the circuit pattern. However, the present invention is not limited to this, and a general connection connector, Wire bonding or the like may be used.

  In the above embodiment, the thermal head 17 used in the color thermal printer 2 has been described as an example. However, the present invention is not limited to this, and the thermal head used in other thermal printers, thermal transfer printers, and thermal sublimation printers. Needless to say, the present invention can also be applied to, for example, a recording head of an ink jet printer that ejects ink by the heat of a heating element.

1 is a schematic diagram illustrating a configuration of a color thermal printer to which the present invention is applied. It is a perspective view which shows the structure of a thermal head. It is a disassembled perspective view which shows the structure of a thermal head.

Explanation of symbols

2 Color thermal printer 10 Color thermal recording paper (recording paper)
17 Thermal Head 19 Heating Element Array 20 System Controller 21 Head Driver 22 Fixing Device 30 Heat Dissipating Plate 31 Element Board 32 Circuit Board 33, 34 Relief 36 Heating Element 37 Driver IC
40 Temperature Sensor 41 Wiring Pattern 46 Flexible Printed Circuit Board

Claims (4)

An element substrate having a plurality of heating elements arranged on the surface; a circuit board on which a control circuit is mounted; and a driver IC mounted on either the element substrate or the circuit board for selectively driving the heating elements; ,
In a recording head that is fixed to the back surface of the element substrate and the circuit board, and includes a heat radiating plate that dissipates heat stored by the heat generated by the heat generating element to the outside.
A plurality of temperature sensors for measuring the temperature in the vicinity of the heating element are arranged on the back surface of the element substrate, and a wiring pattern connected to these temperature sensors is formed.
Forming a circuit pattern of the control circuit on both sides of the circuit board;
A recording head, wherein a connection means for electrically connecting the wiring pattern and the circuit pattern is attached between the element substrate and the circuit board.   The recording head according to claim 1, wherein the connection unit is a flexible printed circuit board.   The escape portion is formed in a portion of the heat radiating plate where the temperature sensor and the connecting means come into contact so that the temperature sensor and the connecting means do not contact the heat radiating plate. Recording head. 4. The temperature sensor according to claim 1, wherein the temperature sensor is attached to a location within a distance of 10 mm or less from a position immediately below the heating element in a direction orthogonal to the direction in which the heating elements are arranged. Recording head.

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