JP2005343046A - Recording head and printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately measure a temperature near a heating element by a simple constitution. <P>SOLUTION: A thermal head 17 of a color thermal printer 2 comprises a head substrate 30, an element substrate 31, and a circuit board 32. In the center of a part, to which a driver IC 35 is attached, of the element substrate 31, a temperature sensor 38 for measuring the temperature near the heating element 34 is attached between the adjacent drivers IC 35. The temperature sensor 38 sequentially transmits the result of the measurement of the temperature near the heating element 34 to a system controller 21. The system controller 21 controls the drive of the heating element 34 via a head driver 22, depending on the result of the measurement of the temperature by the temperature sensor 38. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes a recording head having an element substrate on which a plurality of heating elements are formed and a driver IC for selectively driving these heating elements is mounted, and heats the heating elements to record an image on a recording material. And a printer for recording an image on a recording material using the recording head.

  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, thermal recording is performed by a thermal head in which a plurality of heating elements are arranged in a line while conveying color thermal recording paper.

  The thermal head has a configuration in which an element substrate provided with the above-described plurality of heating elements and a plurality of driver ICs for selectively driving these heating elements is attached to an aluminum head substrate. A temperature sensor for measuring the temperature in the vicinity of the heating element is provided on the head substrate. In conventional color thermal printers, the temperature of each heating element is kept constant by controlling the driving energy applied to the heating element according to the temperature measurement result of this temperature sensor, resulting in non-uniform temperature of each heating element. This prevents the occurrence of density unevenness in the image to be printed.

  When the temperature sensor is provided on the head substrate as described above, the drive heat generated from the heating element is transmitted to the temperature sensor via the element substrate and the head substrate. For this reason, there has been a problem that a difference occurs between the temperature near the actual heating element and the measurement result of the temperature sensor. In order to solve this problem, a line thermal printer that predicts the temperature in the vicinity of an actual heating element using an arithmetic expression based on the measurement result of the temperature sensor has been proposed (see Patent Document 1).

Japanese Patent No. 2627348

  However, in the method described in Patent Document 1, many calculations are required to predict the temperature near the actual heating element, and an arithmetic circuit corresponding to this must be provided, which requires calculation processing time. The manufacturing cost may increase. In addition, there is a problem that it is difficult to obtain a parameter of an arithmetic expression that complements the occurrence of density unevenness.

  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 measuring the temperature in the vicinity of the heating element accurately and with a simple configuration.

  Another object of the present invention is to provide a printer capable of suppressing the occurrence of density unevenness and obtaining high-quality prints.

  In order to achieve the above object, the present invention includes an element substrate on which a plurality of heat generating elements are formed and a driver IC for selectively driving these heat generating elements is mounted. In a recording head for recording an image on a recording material, a temperature sensor for measuring a temperature in the vicinity of the heating element is attached to the element substrate.

  The temperature sensor is preferably arranged between a plurality of driver ICs. Moreover, it is preferable to arrange a plurality of the temperature sensors.

  Furthermore, it is preferable that the temperature sensor is electrically connected to the plurality of heating elements in parallel. In this case, the temperature sensor and the capacitor are electrically connected in parallel, and after charging the capacitor, the time until the capacitor is discharged and reaches a predetermined potential is measured. Based on the measurement result, the temperature sensor It is preferable to calculate a resistance value.

  In addition, the capacitor is connected between one terminal of the temperature sensor and the other terminal of the first switch connected in series to the other terminal of the temperature sensor, and one terminal of the temperature sensor A circuit is formed in which a power source is connected between the other terminal of the first switch via a second switch, the second switch is turned on to charge the capacitor, and then the second switch is turned on. It is preferable that the capacitor is turned off and the first switch is turned on to discharge the capacitor charge through the temperature sensor.

  The printer of the present invention records an image on a recording material using the recording head according to any one of claims 1 to 6. In addition, it is preferable to provide the control means which controls the drive of the said heat generating element according to the temperature measurement result by the said temperature sensor.

  According to the recording head of the present invention, the temperature sensor for measuring the temperature in the vicinity of the heating element is provided on the element substrate on which a plurality of heating elements are formed and the driver IC for selectively driving these heating elements is mounted. Since it is attached, the temperature near the heating element can be measured accurately and with a simple configuration.

  In addition, according to the printer of the present invention, since the image is recorded on the recording material using the recording head according to any one of claims 1 to 6, the occurrence of density unevenness can be suppressed, and high image quality can be achieved. You can get a print.

  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 365 to 390 nm ultraviolet rays. 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. A heating element array 20 in which a plurality of heating elements 34 (see FIG. 2) are arranged in a line is provided on the surface of the thermal head 17 facing the recording paper 10 of the head substrate 19. The heating element array 20 generates heat based on the drive data input from the system controller 21 to the head driver 22, 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 20. 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 20 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 FIG. 2, the thermal head 17 includes a head substrate 30, an element substrate 31, and a circuit substrate 32. The head substrate 30 is made of a heat radiating material such as aluminum. The element substrate 31 is made of, for example, ceramic, alumina, alumina ceramic, or the like.

  A printing protrusion 33 having a semicircular cross section is formed at the front end portion of the upper surface of the element substrate 31, and a plurality of heating elements 34 constituting the heating element array 20 are provided on the printing protrusion 33. . A driver IC 35 for driving each heating element 34 is attached to the rear end portion of the upper surface of the element substrate 31. The driver IC 35 and the heating element 34 are connected by a conductive layer 36 formed on the element substrate 31 and a jumper wire 37. Further, a temperature sensor 38 for measuring the temperature in the vicinity of the heating element 34 is attached between the adjacent driver ICs 35 at the center of the portion of the element substrate 31 to which the driver IC 35 is attached.

  A control circuit for the thermal head 17 is formed on the circuit board 32 and is arranged behind the element substrate 31. The driver IC 35 and the temperature sensor 38 of the element substrate 31 and the circuit board 32 are connected by a jumper wire 39. The driver IC 35, the temperature sensor 38, and the jumper wires 37 and 39 are covered with a transparent protective resin 40 so that the jumper wires 37 and 39 are not disconnected.

  The temperature sensor 38 sequentially transmits the measurement result of the temperature near the heating element 34 to the system controller 21. The system controller 21 controls driving of the heating element 34 via the head driver 22 in accordance with the temperature measurement result by the temperature sensor 38. Specifically, when the temperature measurement result by the temperature sensor 38 is higher than a preset reference value, the driving energy (applied voltage or energization time) applied to the heating element 34 is reduced. On the other hand, when it is lower than the reference value, the drive energy is increased.

  In FIG. 1, a fixing device 23 is disposed facing the recording surface of the recording paper 10 on the downstream side of the conveyance roller pair 15 in the A direction. A cutter 24 for cutting the recording paper 10 into a predetermined print size is disposed between the fixing device 23 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 25 for discharging the recording paper 10 on which the image has been recorded to the outside is provided.

  The fixing device 23 fixes the yellow heat-sensitive color developing layer by emitting a near-ultraviolet light having an emission peak of 420 to 450 nm to fix the yellow thermosensitive color developing layer, and an ultraviolet light having an emission peak of 365 to 390 nm to fix the magenta thermosensitive coloring layer. A magenta fixing light source 23b, and a reflector 23c that reflects light from the light sources 23a and 23b toward the recording paper 10. Each light source 23a, 23b is driven by a lamp driver 26.

  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 20. 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 20 that generates heat based on the driving data input to the head driver 22 while the recording paper 10 is conveyed in the A direction. A yellow image is recorded in

  Prior to recording a yellow image, the temperature sensor 38 attached to the element substrate 31 of the thermal head 17 measures the temperature near the heating element 34. The temperature measurement result by the temperature sensor 38 is sequentially transmitted to the system controller 21.

  When the temperature measurement result by the temperature sensor 38 is higher than a preset reference value, the drive energy applied to the heating element 34 by the system controller 21 is reduced via the head driver 22 when recording a yellow image. . On the other hand, when it is lower than the reference value, the driving energy is increased.

  When the recording of the yellow image is completed, the rear end of the recorded image is conveyed to a position facing the yellow fixing light source 23a of the fixing device 23, 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 23a is turned on by the lamp driver 26, and the yellow thermosensitive coloring layer on which the image has been recorded is fixed while the transport 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 leading edge of the recorded image is conveyed to a position facing the heating element array 20, 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 20. 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. At this time, similarly to the yellow image recording, the temperature in the vicinity of the heating element 34 is measured by the temperature sensor 38 before recording, and the driving of the heating element 34 is controlled by the system controller 21 at the time of recording.

  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 23b of the fixing device 23, and the rotation of the conveying motor 12 is stopped. Similarly to the yellow image fixing, the magenta fixing light source 23b is turned on by the lamp driver 26, 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 where it faces the heating element array 20, 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 24, and then discharged from the paper discharge outlet 25 to the outside by the paper discharge roller pair 16.

  As described above, the temperature sensor 38 is attached to the element substrate 31 provided with the heat generating element 34, and the drive of the heat generating element 34 is controlled according to the temperature measurement result by the temperature sensor 38. Can be measured accurately and with a simple configuration. Thereby, the occurrence of density unevenness can be suppressed, and a high-quality print can be obtained.

  In the above embodiment, only one temperature sensor 38 is attached to the center of the element substrate 31. However, a plurality of temperature sensors 38 are arranged in the vicinity of the heating element 34 as in the thermal head 50 shown in FIG. A distribution of the temperature in the main scanning direction (a direction orthogonal to the conveyance direction of the recording paper 10) may be acquired, and the driving of the heating element 34 may be controlled by the system controller 21 based on the distribution. As a result, finer drive control of the heat generating element 34 is possible, and a higher quality print can be obtained.

  In the above embodiment, the temperature sensor 38 is covered with the protective resin 40 together with the driver IC 35 or the like. However, the temperature sensor 38 may not be covered with the protective resin 40. In this way, the response characteristic of the temperature sensor 38 can be accelerated.

  In the above embodiment, the jumper wire 39 from the temperature sensor 38 is directly connected to the circuit board 32, but one end of the temperature sensor 38 is connected to the conductive layer 36 as in the thermal head 60 shown in FIG. The heat generating element 34 and the temperature sensor 38 may be electrically connected in parallel by connecting the other end to the driver IC 35.

  In this case, as shown in FIG. 5, the temperature sensor 38 and the plurality of heating elements 34 and the capacitor 70 are electrically connected in parallel, the switch 71 is turned on, and the capacitor 70 is charged by the power supply circuit 72. Is turned off, and only the transistor 73 connected to the temperature sensor 38 is turned on to measure the time until the temperature sensor 38 discharges the charged charge of the capacitor 70 to reach a predetermined potential, and based on this measurement result Alternatively, the resistance value of the temperature sensor 38 may be calculated, and the temperature may be obtained based on the calculation result of the resistance value. As a result, the configuration of the conventional thermal head can be used effectively, and it is not necessary to provide a new circuit to obtain the measurement result of the temperature sensor 38. This technique is described in detail in, for example, Japanese Patent Laid-Open No. 6-79897. The switch 71 and the transistor 73 correspond to the second switch and the first switch according to claim 6, respectively.

  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 perspective view which shows another embodiment of a thermal head. It is a principal part enlarged view which shows another embodiment of a thermal head. It is an electrical circuit diagram of a thermal head.

Explanation of symbols

2 Color thermal printer 10 Color thermal recording paper (recording paper)
17, 50, 60 Thermal head 20 Heating element array 21 System controller 23 Fixing device 31 Element substrate 34 Heating element 35 Driver IC
38 Temperature sensor 70 Capacitor

Claims (8)

In a recording head in which a plurality of heat generating elements are formed and an element substrate on which a driver IC for selectively driving these heat generating elements is mounted is provided, and the heat generating elements generate heat to record an image on a recording material.
A recording head, wherein a temperature sensor for measuring a temperature in the vicinity of the heating element is attached to the element substrate.   The recording head according to claim 1, wherein the temperature sensor is disposed between a plurality of driver ICs.   The recording head according to claim 1, wherein a plurality of the temperature sensors are arranged.   The recording head according to claim 1, wherein the temperature sensor is electrically connected in parallel with the plurality of heating elements.   The temperature sensor and the capacitor are electrically connected in parallel, and after charging the capacitor, the time until the capacitor is discharged and reaches a predetermined potential is measured. Based on the measurement result, the resistance value of the temperature sensor is determined. The recording head according to claim 4, wherein the recording head is calculated. Connecting the capacitor between one terminal of the temperature sensor and the other terminal of the first switch connected in series to the other terminal of the temperature sensor;
Forming a circuit in which a power source is connected via a second switch between one terminal of the temperature sensor and the other terminal of the first switch;
After the second switch is turned on to charge the capacitor, the second switch is turned off, and the first switch is turned on to discharge the capacitor charge through the temperature sensor. The recording head according to claim 5.   7. A printer that records an image on a recording material using the recording head according to claim 1. 8. The printer according to claim 7, further comprising control means for controlling driving of the heat generating element in accordance with a temperature measurement result by the temperature sensor.

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