JP2008068419A - Thermal head for batch heating and printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate temperature control of a heating element equipped in an eraser head used for various printers such as a video printer, a facsimile and a ticket machine. <P>SOLUTION: The eraser head 50 comprises a thin film part 74, a substrate 56 and a case 62. A temperature sensor 60 is set between the case 62 and the substrate 56 to be located right below the heating element 52. The temperature sensor 60 includes a thermistor 64 and a resin material 66. The resin material 66 is arranged to cover the whole surface of the thermistor 64. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermal head for batch heating used for thermal recording of various printing apparatuses such as a video printer, a bar code printer, a label printer, a card printer, a facsimile machine, and a ticket vending machine, and a printing apparatus incorporating the batch heating thermal head. It is about.

  A batch heating thermal head is used in batch erasure of data on a rewritable recording medium (also referred to as “rewrite media”), overcoating for transfer onto the medium, and the like. This batch heating thermal head is not intended for printing, but by heating to a predetermined temperature, the information printed on the medium is erased or overcoated for transfer.

  In general, a temperature detecting means called a thermistor is used to detect the surface temperature of the thermal head for batch heating. The prior art has a problem that the thermal head has a large difference between the actual surface temperature of the heating element and the temperature detected by the thermistor (hereinafter also simply referred to as “detected temperature”). That is, the flow of heat to the thermistor is not always good, and there is a problem in the responsiveness to the temperature of the thermistor. As a result, it has been difficult to control the surface temperature of the heating element.

As a technique to improve the control of the surface temperature of such a heating element, a technology that measures the temperature by directly contacting the thermistor with the surface opposite to the surface where the heating element is provided on a ceramic substrate with a heating element Is disclosed.
JP-A-11-138881

  According to the technique disclosed in Patent Document 1, the thermistor that is in direct contact with the back surface of the substrate detects the temperature of the heating element, but a large divergence still occurs between the surface temperature of the heating element and the detected temperature. A deviation of about 100 ° C. may occur. This is because the detected temperature varies greatly and heat transfer is not performed smoothly.

  For this reason, particularly during the initial operation under a low temperature environment, the temperature rise of the thermistor is significantly delayed compared to the rise of the heating element. That is, the temperature change detected by the thermistor is very small. As a result, a measurement error is included in addition to a small temperature change, and thus there is a problem that it is very difficult to control the temperature of the heating element at the temperature detected by the thermistor.

  The present invention has been made in view of such circumstances, and an object of the present invention is to easily control the temperature of a heating element provided in a thermal head for batch heating used in various printing apparatuses such as a video printer, a facsimile machine, and a ticket vending machine. It is to provide technology to make.

One embodiment of the present invention relates to a thermal head for batch heating. This batch heating thermal head is a batch heating thermal head provided with temperature detection means, and the temperature detection means is covered with a resin material.
The temperature detection means may be covered with a configuration in which a resin material is applied or printed.
The resin material may be a silicon resin or a fluorine resin.
The resin material may be 1 to 4 times the volume of the temperature detecting means.
Another embodiment of the present invention relates to a printing apparatus. This apparatus includes the thermal head for batch heating described above.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which makes easy temperature control of the heat generating body with which the thermal head for batch heating used for various printing apparatuses, such as a video printer, a facsimile, and a ticket vending machine, can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram of a rewrite printer 10 according to the present embodiment. FIG. 1A is a top view of the rewrite printer 10, and FIG. 1B is a diagram schematically showing an AA cross section. FIG. 2 is a functional block diagram relating to the main part of the rewrite printer 10. As shown in the figure, the rewrite printer 10 has a hexahedron-shaped casing 13, and a media transport path 12 in which the rewrite media M is transported in the forward and reverse directions (right and left directions in FIG. 1). Is formed horizontally.

  One end (left end in FIG. 1) of the media transport path 12 is opened to form a media insertion slot 11. Further, the other end (right end in FIG. 1) of the media transport path 12 is closed to form the deepest portion 12a. Further, in the casing 13, a printing thermal head 15 is attached downward with its heating element 16 facing the media conveyance path 12. Further, behind the printing thermal head 15 (right side in FIG. 1), an erasing thermal head 50 (hereinafter simply referred to as “erasing head 50”) faces the heating element 52 toward the media transport path 12 and faces downward. It is attached.

  Further, a pair of platen rollers 17 and 17 are horizontally arranged in two upper and lower stages at a predetermined interval in front of the thermal heads 15 for printing (left side in FIG. 1). Reference numeral 17 is rotatably supported so as to face the media conveyance path 12.

  In addition, a pair of platen rollers 18 and 18 are horizontally arranged in two upper and lower stages at a predetermined interval behind the erasing head 50 (right side in FIG. 1), and each platen roller 18 conveys media. It is rotatably supported so as to face the road 12.

  FIG. 3 is an external view of the erasing head 50 according to the present embodiment. 3A is a top view, FIG. 3B is a side view, FIG. 3C is a bottom view, and FIG. 3D is a BB cross-sectional view. The heating element 52 of the erasing head 50 has a single dot band shape extending in the left and right directions in the drawing. As shown in FIG. 1B, the heating element 52 is mounted in the casing 13 so as to face the media transport path 12. A plurality (eight in this figure) of mounting screw holes 2 a are formed in a line at equal intervals on the bottom surface of the erasing head 50, that is, the bottom surface of the housing 62.

  When rewriting (rewriting) the data on the rewrite medium M using the rewrite printer 10, the data on the rewrite medium M is temporarily erased and then new data is written. This process will be briefly described with reference to FIGS.

  First, when the rewrite medium M is inserted into the medium insertion slot 11, the main control unit 20 commands rewriting of data on the rewrite medium M.

  Then, the first sensor 21 detects that the rewrite medium M has been inserted into the medium insertion slot 11 and outputs a detection signal to that effect to the main control unit 20. In response to this, the main control unit 20 instructs the roller driving unit 23 to rotate the platen roller 17 forward. Then, the roller drive unit 23 drives the platen roller 17 to rotate in the forward direction.

  As a result, the rewrite medium M is conveyed in the forward direction (rightward in FIG. 1) along the medium conveyance path 12, and sequentially passes below the printing thermal head 15 and the erasing head 50. The rewrite medium M slides in the positive direction with respect to the protective film 58 when passing below the erasing head 50. Thereafter, the rewrite media M is guided by the platen roller 18 and reaches the deepest portion 12 a of the media transport path 12.

  Then, the second sensor 22 detects that the rewrite medium M has reached the deepest portion 12 a of the media transport path 12, and outputs a detection signal to that effect to the main control unit 20. In response to this, the main control unit 20 instructs the roller driving unit 23 to rotate the platen roller 17 in the reverse direction. Then, the roller drive unit 23 drives the platen roller 17 to rotate in the reverse direction. As a result, the rewrite medium M is conveyed in the reverse direction (leftward in FIG. 1) along the medium conveyance path 12, and sequentially passes below the erasing head 50 and the printing thermal head 15. Then, the rewrite medium M slides in the reverse direction with respect to the protective film 58 when passing under the erasing head 50.

  Here, the main control unit 20 instructs the head control unit 25 to erase data on the rewrite medium M. Then, the head controller 25 drives the erasing head 50 to erase the entire data of the rewrite medium M. At this time, since both ends of the rewrite medium M are held by two sets of platen rollers 17 and 18 and are in tension, the data erasing operation of the rewrite medium M is performed by the heating element 52 of the erasing head 50 in the vicinity of the rewrite medium M. It is done properly in a form that generates heat.

  Next, the head control unit 25 drives the printing thermal head 15 to newly write data on the rewrite medium M. At this time, since both ends of the rewrite medium M are held by the platen rollers 17 and 18 and are in tension, the data write operation to the rewrite medium M is performed by the heating element 16 of the printing thermal head 15 being connected to the rewrite medium M. It is performed reliably in the form of generating heat in the vicinity. Thereafter, the rewrite medium M is continuously conveyed in the reverse direction on the medium conveyance path 12 and discharged from the medium insertion port 11.

  Thereby, rewriting of the rewrite medium M by the rewrite printer 10 is completed. When only erasure of the data on the rewrite medium M is instructed, the printing thermal head 15 is not driven, and the rewrite medium M on which the data has been erased is conveyed in the reverse direction on the medium conveyance path 12, and the medium insertion slot 11 is discharged.

  FIG. 4 is a diagram schematically showing a cross-sectional structure of the erasing head 50 according to the present embodiment. The erasing head 50 includes a housing 62, a substrate 56, and a thin film portion 74. On the substrate 56, the heat storage layer 54 and the heating element 52 are laminated in this order from the bottom to form a thin film portion 74. A temperature sensor 60 is provided between the housing 62 and the substrate 56 so as to be positioned immediately below the heating element 52.

  The substrate 56 is made of an insulating ceramic such as alumina. The heat storage layer 54 is also called a glaze layer, and is formed with a desired thickness by softening and baking glass, for example. A heating element 52 having a desired thickness is formed on the heat storage layer 54. The heating element 52 is made of, for example, a polysilicon (Poly-Si) thin film doped with boron (B).

The heating element 52 is provided with an electrode layer (not shown) for supplying electric power. This electrode layer is formed of, for example, aluminum. A protective film 58 having a desired thickness made of, for example, SiO ₂ is formed on the heating element 52. The casing 62 is made of, for example, aluminum, and functions as a casing and as a heat dissipation material.

  The temperature sensor 60 includes a thermistor 64 and a resin material 66. The resin material 66 is provided so as to cover the entire surface of the thermistor 64. As the resin material 66, a material excellent in compatibility with glass is preferable, and particularly excellent in heat resistance in a temperature range of 0 ° C. to 180 ° C., and further has rubber elasticity, such as a silicon (Si) material or a fluorine-based material. Material is preferred. There may be a plurality of temperature sensors 60 provided in the erasing head 50. When a plurality of temperature sensors 60 are provided, the temperatures detected by the plurality of temperature sensors 60 may be averaged and used for temperature control of the erasing head 50.

  The amount of the resin material 66 is preferably 1 to 4 times the volume of the thermistor 64. This is because if the volume of the resin material 66 is less than one time that of the thermistor 64, effective heat transfer is hindered. On the other hand, when the volume of the resin material 66 exceeds four times, the possibility that the variation in temperature distribution on the surface of the heating element 52 becomes large increases. Further, the thermistor 64 is provided with a lead wire 68 extending to the outside. In addition, the resin material 66 may be provided by application or may be provided by printing. When the resin material 66 is provided by printing, the amount of the resin material 66 can be easily controlled.

  As described above, the thermistor 64 is in close contact with the substrate 56 via the resin material 66, so that heat transfer to the thermistor 64 is stabilized. As a result, variation in the detected temperature in the thermistor 64 can be reduced.

  With the above configuration, the relationship between the surface temperature of the heating element 52 in the erasing head 50 and the detected temperature of the thermistor 64 was examined. For comparison, the temperature was also measured for a connection mode of a conventional thermistor 64 in which the thermistor 64 is not covered with the resin material 66.

  FIG. 5 is a diagram schematically showing a cross-sectional structure of an erasing head 70 provided with the thermistor 64 of such a conventional connection mode. The erasing head 50 shown in FIG. 4 is different from the erasing head 70 shown in FIG. 4 in the connection mode of the thermistor 64. The thermistor 64 is not covered with the resin material 66 and is provided on the lower side of the substrate 56. It is provided in direct contact with the surface. Since the configuration other than the connection mode of the thermistor 64 is the same, the same reference numerals as those in FIG.

  For the sake of convenience, the thermistor 64 of the type covered with the resin material 66 is referred to as “thermistor 64 of the present invention”, and the thermistor 64 of the type not covered with the resin material 66 is referred to as “the conventional thermistor 64”. Call it.

FIG. 6 is a graph showing the relationship between the surface temperature of the heating element 52 and the detected temperature of the thermistor 64. In this figure, the surface temperature TS2 of the erasing head 50 including the conventional thermistor 64, the surface temperature TS1 of the erasing head 50 including the thermistor 64 of the present invention, the detection temperature TH1 of the thermistor 64 of the present invention, The detection temperature TH2 of the thermistor 64 is shown. The vertical axis indicates the detected temperature, and the horizontal axis indicates the time during which the voltage is applied to the heating element 52. The experimental conditions are as follows.
Applied power: 72W / dot
Applied voltage: 24V
Resistance value: 8.0Ω
Applied pulse width 1.99 ms
Application cycle 2.00ms
Further, regarding the structure of the erasing heads 50 and 70 to which this experiment is applied, the thickness of the heat storage layer 54 is 70 μm and the thickness of the substrate 56 is 1 mm. The resin material 66 is a silicon-based resin and has a volume twice that of the thermistor 64. In addition, the same result was obtained also when the fluororesin was used as the resin material 66.

  First, focus on the period from the start of the experiment to 0.5 seconds. During this period, the surface temperature of the heating element 52 changes rapidly. At 0.5 seconds, the temperature change ΔT of the thermistor 64 is 4K (° C.) for the conventional thermistor 64, whereas the temperature change ΔT for the thermistor 64 of the present invention is 25K (° C.). .

  As described above, the temperature detected by the thermistor 64 of the present invention has a large amount of temperature change immediately after the start of heating of the erasing head 50, as compared with the temperature detected by the conventional thermistor 64. Therefore, in the erasing head 50 including the thermistor 64 of the present invention, it is possible to effectively control the heating element 54 even in consideration of measurement errors and variations. On the other hand, at this point, the temperature difference is small in the erasing head 70 including the conventional thermistor 64. For this reason, it is difficult to effectively control the heating element 54. Therefore, the erasing head 50 including the thermistor 64 of the present invention can respond to a rapid temperature change as compared with the erasing head 70 including the conventional thermistor 64. As a result, the accuracy can be controlled with respect to the surface temperature of the heating element 52.

  Further, when the heating element 52 is heated to some extent, for example, 3 seconds after the start of heating, the temperature difference between the temperature detected by the conventional thermistor 64 and the temperature of the heating element 52 is about 100 K (° C.). On the other hand, the temperature difference between the thermistor 64 of the present invention and the heating element 52 is about 40 K (° C.). That is, since the difference between the temperature of the heating element 52 and the detected temperature of the thermistor 64 is small, more accurate temperature control is possible in the heating element 52 including the thermistor 64 of the present invention.

  In the present embodiment, the batch heating head is applied to the erasing head. However, the present invention is not limited to this, and can be applied to a thermal head used for transfer overcoating.

  The present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

  The present invention can be widely used for a thermal head mounted on various types of printers for business use and consumer use, and a printing apparatus equipped with the thermal head. In particular, the present invention can be widely used in a batch heating thermal head for erasing data collectively or overcoating for transfer and a printing apparatus equipped with the thermal head.

1 is a schematic view of a rewrite printer according to an embodiment of the present invention. 1 is a block diagram illustrating a main configuration of a rewrite printer according to an embodiment of the present invention. 1 is a schematic external view of an erasing head according to an embodiment of the present invention. It is the figure which showed typically the cross-section of the erasing head which concerns on embodiment of this invention. It is the figure which showed typically the cross-sectional structure of the erase head provided with the connection aspect of the conventional type thermistor. It is the graph which showed the relationship between the surface temperature of a heat generating body, and the detection temperature of a thermistor.

Explanation of symbols

10: Rewrite printer (printing device)
50 …… Erase head (thermal head for batch heating)
52 …… Heating element 54 …… Heat storage layer 56 …… Substrate 58 …… Protective film 60 …… Temperature sensor 62 …… Case 64 …… Thermistor 66 …… Resin material 68 …… Lead wire 74 …… Thin film part

Claims (5)

  A thermal head for batch heating provided with temperature detection means, wherein the temperature detection means is covered with a resin material.   2. The thermal head for batch heating according to claim 1, wherein the temperature detecting means is covered with a configuration in which the resin material is applied or printed.   The thermal head for batch heating according to claim 1 or 2, wherein the resin material is a silicon resin or a fluorine resin.   The thermal head for batch heating according to any one of claims 1 to 3, wherein the resin material is 1 to 4 times the volume of the temperature detection means.   A printing apparatus comprising the thermal head for batch heating according to any one of claims 1 to 4.

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