JP5468211B2 - Thermal head - Google Patents

Description

  The present invention relates to a thermal head incorporated in a printing apparatus or the like.

  FIG. 2 shows an example of a conventional thermal head (see Patent Document 1). The thermal head X shown in FIG. 2 includes a substrate 91, a plurality of heating portions 92 arranged on a heating element 92A, a plurality of driving ICs 93, a plurality of conductive layers 94, and a temperature sensor 95. The plurality of driving ICs 93 are connected to the plurality of heat generating portions 92 through the plurality of conductive layers 94, and selectively heat the plurality of heat generating portions 92. The thermal head X is configured to record a desired image on a recording material by selectively generating heat from the plurality of heat generating portions 92. The plurality of driving ICs 93 operate in accordance with a signal from a system controller 96 provided outside.

  In such a thermal head X, a temperature sensor 95 is incorporated in order to prevent parts from melting or igniting due to abnormal heat generation of the heating element 92A. The temperature sensor 95 has a function of detecting the temperature around the drive IC 93 and transmitting the measurement result to the system controller 96. Based on information from the temperature sensor 95, the system controller 96 determines whether or not the temperature rise of the substrate 91 by the heating element 92A is dangerous. The system controller 96 is set to send a signal to stop the heat generation of the heat generating portion 92 to the drive IC 93 when it is determined that the temperature rise by the heat generating element 92A is dangerous. In this way, the thermal head X is prepared for a failure due to overheating of the heating element 92A.

  However, in the thermal head X, when the communication state with the system controller 96 becomes defective, failure due to overheating of the heating element 92A or ignition accident cannot be prevented. Further, since the system controller 96 also controls a plurality of drive ICs 93, the structure is likely to be complicated, and the number of failures increases accordingly. Even when a failure occurs in the system controller 96, the thermal head X cannot prevent a failure due to overheating of the heating element 92A.

JP 2005-343046 A

  The present invention has been conceived under the circumstances described above, and an object thereof is to provide a thermal head that is less prone to failure and can be used more safely.

  The thermal head provided by the present invention includes a substrate on which a heating element having a plurality of heating portions is formed, a driving IC for selectively heating the plurality of heating portions, and a temperature of the substrate. A thermal head that selectively heats the plurality of heat generating portions to record an image on a recording material, and when the measurement result by the temperature sensor exceeds a predetermined value, Control means for controlling the drive IC so as to stop the heat generation of the heating element is incorporated.

  According to such a configuration, since the control means is built in the thermal head, even when the connection condition with the outside is bad or when an abnormality occurs in the external device, the above-mentioned control means is more sure. Overheating by the heating element can be prevented. For this reason, the thermal head is less likely to fail due to excessive temperature rise and can be used more safely.

  In a preferred embodiment of the present invention, an IC chip in which the temperature sensor and the control means are incorporated is provided. According to such a configuration, since the temperature sensor and the control means are incorporated in one IC chip, the measurement result by the temperature sensor can be more stably transmitted to the control means. For this reason, the thermal head is less likely to fail and can be used safely.

  In a preferred embodiment of the present invention, the substrate is a substrate having good thermal conductivity, and the temperature sensor and the control means are mounted on the substrate. According to such a configuration, the temperature sensor can more accurately detect the temperature of the substrate on which the heating element is formed. For this reason, the thermal head can more reliably prevent overheating by the heating element by detecting the temperature of the substrate.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  FIG. 1 shows an example of a thermal head according to the present invention. A thermal head A shown in FIG. 1 includes a substrate 10, a heating element 20 having a plurality of heating portions 21, a driving IC 30, wiring 40, an IC chip 50, and a connector 60. The thermal head A is used, for example, for printing by heating a thermal paper.

  The substrate 10 is a substrate having excellent thermal conductivity, such as a ceramic substrate or an epoxy resin substrate, and has a long rectangular shape in plan view. On the substrate 10, six drive ICs 30, an IC chip 50, and a connector 60 are mounted, and the heating element 20 and the wiring 40 constituting the circuit are formed.

  The heating element 20 is formed so as to extend along the longitudinal direction at a position near one end in the width direction of the substrate 10, and has a plurality of heating parts 21 arranged along the longitudinal direction. The heating element 20 is formed, for example, by printing and baking a thick film resistor paste containing ruthenium oxide as a conductor component.

  Six drive ICs 30 are arranged along the longitudinal direction of the substrate 10. The drive IC 30 is configured to receive an input from the outside through the connector 60 and selectively heat the plurality of heat generating units 21 according to the input.

  The wiring 40 includes a common wiring part 41 extending in parallel with the heating element 20, an extending part 42 extending from the common wiring part 41, an individual wiring part 43 extending from the driving IC 30 toward the heating element 20, and the driving IC 30 and the IC. A connecting wiring portion 44 that connects the chip 50 is provided. The common wiring portion 41 is disposed between the heating element 20 and one end portion in the width direction of the substrate 10, and one end portion in the longitudinal direction of the substrate 10 leads to a wiring extending from the connector 60. . The extending part 42 is formed so as to extend from the common wiring part 41 toward the heating element 20 at predetermined intervals. A plurality of individual wiring portions 43 extend from each driving IC 30 and are formed so that their respective tips are sandwiched between two adjacent extending portions 42. The connecting wiring portion 44 is formed so as to connect each driving IC 30 and the IC chip 50 and further to the connector 60.

  In the present embodiment, each heat generating portion 21 is arranged so as to be sandwiched between each extending portion 42 and each individual wiring portion 43 in the longitudinal direction of the substrate 10. For this reason, it is possible to cause the specific heat generating part 21 to generate heat by flowing a current through the specific individual wiring part 43 selected by each extending part 42 and the drive IC 30.

  The IC chip 50 incorporates a temperature sensor 51 and a control means 52 and is disposed between the heating element 20 and the driving IC 30 in the width direction of the substrate 10. Around the IC chip 50, the individual wiring portion 43 is formed so as to avoid the IC chip 50.

  The temperature sensor 51 is a semiconductor element that measures the temperature of the substrate 10 and transmits the measurement result to the control means 52. When the measurement result by the temperature sensor 51 exceeds a predetermined reference temperature, the control means 52 sends a signal to each drive IC 30 through the connection wiring portion 44 so as to stop the current supply to the individual wiring portion 43. It is the comprised semiconductor element. The reference temperature can be appropriately set depending on the material and size of the substrate 10.

  The connector 60 is mounted on the other end in the width direction of the substrate 10 and is configured to connect an external device and the wiring 40.

  Next, the operation of the thermal head A will be described.

  According to the present embodiment, the control means 52 in the IC chip 50 mounted on the substrate 10 can stop the heat generation of the heating element 20 before the temperature of the substrate 10 rises too much due to the heat generation of the heating element 20. . For this reason, even if an abnormality occurs in the connection state of the connector 60 with an external device or a problem occurs in the external device, the thermal head A can prevent overheating by the heating element 20. It is possible. Therefore, the thermal head A is less prone to failure and can be used more safely.

  Furthermore, since the temperature sensor 51 and the control means 52 are built in the same IC chip 50, the transmission from the temperature sensor 51 to the control means 52 is more reliable. For this reason, in the thermal head A, overheating of the heat generating body 20 can be prevented more reliably.

  Further, according to the present embodiment, the heating element 20 and the IC chip 50 are mounted on the same substrate 10. For this reason, by measuring the temperature of the substrate 10 with the temperature sensor 51, it is possible to more accurately determine whether the temperature of the heating element 20 is abnormal or normal.

  Furthermore, in the above embodiment, the signal from the temperature sensor 51 can be sent to the outside through the connector 60. In this case, for example, by raising or lowering the voltage according to the temperature of the substrate 10, the temperature of the heating element 20 can be adjusted to a temperature suitable for heating the thermal paper. When such adjustment is performed, the life of the thermal head A is increased because the substrate 10 is hardly heated excessively.

  The thermal head according to the present invention is not limited to the embodiment described above. The specific configuration of each part of the thermal head according to the present invention can be varied in design in various ways. For example, the substrate may have a configuration in which a substrate on which a heating element is mounted and a substrate on which a driving IC is mounted. In this case, it is preferable that the temperature sensor is mounted on a substrate on which the heating element is mounted.

  Further, the temperature sensor and the control means may be included in separate IC chips. In this case, for example, the function of the control means can be expanded, and the voltage applied to the heating element can be changed according to the measurement result of the temperature sensor.

It is a top view which shows an example of the thermal head concerning this invention. It is a top view which shows an example of the conventional thermal head.

Explanation of symbols

A Thermal head 10 Substrate 20 Heating element 21 Heating part 30 Drive IC
40 wiring 41 common wiring section 42 extension section 43 individual wiring section 44 connection wiring section 50 IC chip 51 temperature sensor 52 control means 60 connector

Claims (4)

A substrate having a longitudinal direction and a shape having a width direction perpendicular to the longitudinal direction, and a heating element having a plurality of heating portions formed along the longitudinal direction ;
A driving IC for selectively generating heat in the plurality of heat generating parts;
A temperature sensor for measuring the temperature of the substrate;
A thermal head that selectively heats the plurality of heat generating portions to record an image on a recording material,
When the measurement result by the temperature sensor exceeds a predetermined value, the control means for controlling the drive IC to stop the heat generation of the heating element is incorporated , and
An IC chip incorporating the temperature sensor and the control means;
The thermal head according to claim 1, wherein the IC chip is disposed between the heating element and the driving IC in the width direction . The thermal head according to claim 1, wherein the substrate is a substrate having good thermal conductivity, and the temperature sensor and the control unit are mounted on the substrate. A plurality of individual wiring portions for extending from the driving IC toward the heating element to heat the heating element;
The thermal head according to claim 1 or 2, wherein any one of the plurality of individual wiring portions is formed so as to avoid the IC chip. A connector for inputting a signal to the driving IC;
A connection wiring portion connecting the drive IC and the IC chip, and
4. The thermal head according to claim 1, wherein the connection wiring portion connects the drive IC and the IC chip and is electrically connected to the connector. 5.

Images