JP4600372B2 - Thermal head for batch heating, printing apparatus, and method of supplying power to thermal head for batch heating - Google Patents

Description

  The present invention relates to a thermal head, and more particularly, a thermal head for batch heating mounted in various printer devices for business use and consumer use, a printing apparatus equipped with the thermal head for batch heating, and power to the thermal head for batch heating. It relates to a supply method.

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

  In general, one of the characteristics required for a batch heating thermal head is that the temperature distribution is as small as possible.

  Various techniques have been proposed to realize the above characteristics. As one of such techniques, an electrode for supplying electric power to the heating element is provided in the longitudinal direction of the heating element, and the temperature distribution is reduced. A technique for suppressing variation is disclosed (see Patent Document 1). This longitudinal direction is generally called the main scanning direction in the case of a thermal head for printing.

In the technique disclosed in Patent Document 1, in particular, an electrode is disposed oppositely on the long side of the heating element, which is the running direction of the media, to achieve uniform temperature distribution. As a result, an excellent temperature distribution is shown on the entire thermal head for batch heating, and data can be erased satisfactorily.
JP 2005-288918 A

  In recent years, a product management system such as a product slip using a large rewritable medium of about A4 size has been attracting attention for the purpose of dealing with paperlessness and cost reduction in consideration of environmental problems. For this reason, as one of the requirements for a thermal head for batch heating corresponding to a large rewrite medium, it is more important that the temperature distribution on the entire surface sliding with the medium is as uniform as possible.

  By using the technique as described above, it has become possible to reduce variations in temperature distribution. However, as the media used as described above increases in size, a technique for further reducing the variation in temperature distribution has been demanded.

  By the way, in general, in a thermal head, a heating element having a thick film or a thin film structure is provided, and connection terminals for supplying power to the heating element are arranged at both ends of the heating element. Since it is joined to the metal pattern, the heat dissipation effect is high, and it is cooled as compared with parts other than the connection terminals.

  In such a situation, the following issues have become apparent. That is, in order to increase the size of the thermal head, the area of the heating element is increased and the input power is increased. Compared with a small thermal head, the amount of heat generated is concentrated in the lead-out portion of the connection terminal attached to the heating element.

  As a result, the difference between the surface temperature of the heating element near the electrode and the surface temperature of other heating elements tends to increase, making it difficult to obtain a uniform temperature distribution of the entire heating element.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for suppressing variation in temperature distribution of a thermal head.

One embodiment of the present invention relates to a thermal head for batch heating. The thermal head for batch heating is provided by connecting a single-dot belt-like heating element formed so as to be capable of heating in a predetermined direction of the media to be heated all over the entire area in the longitudinal direction of the heating element. comprising a pair of electrodes, was, a batch heating thermal head for the purpose of substantially performing the heating of uniform temperature, in the electrode, the two being provided for being connected to an external power source The connection terminals are arranged at positions 1/4 each from the left and right in the longitudinal direction of the heating element, and the temperature of the heating element due to heat radiation from the heating element caused by the connection terminal Reduce variation in distribution.
Another aspect of the present invention relates to a printing apparatus, and the printing apparatus includes the batch heating thermal head described above.
Yet another embodiment of the present invention relates to a method for supplying power to a thermal head for batch heating. This method includes a single-dot belt-like heating element formed so as to be capable of heating in a predetermined direction of a medium to be heated, and a pair provided by connecting over substantially the entire area at both ends in the longitudinal direction of the heating element. The power for heating the heating element is supplied from two paths to a batch heating thermal head intended to perform heating at a substantially uniform temperature. by the position of the path of feed of the longitudinal direction of the right and left of the heating element and the position of each quarter, the variation of the temperature distribution of the heating element due to heat radiation from the heating element due to the path of the power supply Reduce.

  According to the present invention, it is possible to reduce variation in temperature distribution of the thermal head for batch heating.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Hereinafter, the thermal head for batch heating described in the present embodiment relates to a thermal head for batch erasure unless otherwise specified. In the present embodiment, a plurality of connection terminals for supplying electric power, specifically, two connection terminals are provided, and the heat radiation from the connection terminals is distributed from two places instead of one place. As a result, variations in the temperature distribution of the thermal head are reduced.

  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 mounted downward with its heating element 16 facing the media conveyance path 12, and an erasing is performed behind the printing thermal head 15 (right side in FIG. 1). The thermal head 30 (hereinafter referred to as “erasing head 30”) is mounted downward with its heating element 40 facing the media transport path 12.

  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 30 (right side in FIG. 1). Each platen roller 18 conveys media. It is rotatably supported so as to face the road 12.

  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.

  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) through the medium conveyance path 12, and sequentially passes below the printing thermal head 15 and the erasing head 30. The rewrite medium M slides in the positive direction with respect to the protective film 46 when passing under the erasing head 30. 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) through the medium conveyance path 12, and sequentially passes below the erasing head 30 and the printing thermal head 15. The rewrite medium M slides in the reverse direction with respect to the protective film 46 when passing below the erasing head 30.

  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 30 to erase the entire data of the rewrite medium M. At this time, since both ends of the rewrite medium M are gripped by the 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 40 of the erasing head 30 near 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 gripped by the platen rollers 17 and 18 and are in tension, the writing operation of the rewrite medium M causes the heating element 16 of the thermal head 15 for printing to generate heat near the rewrite medium M. Certainly done in form. 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 the erasure of data on the rewrite medium M is instructed, the printing thermal head 15 is not driven, and the data rewrite medium M from which the data has been erased is conveyed in the reverse direction on the medium conveyance path 12 to insert the medium. It is discharged from the mouth 11.

  FIG. 3 is an external view of the erasing head 30 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. FIG. 4 is a diagram schematically showing a cross-sectional structure of the erasing head 30 at the left position PA1.

  The erasing head 30 includes a housing 48, a substrate 44, a glaze layer 42, a heating element 40, and first and second electrodes 52 and 62. The 1st and 2nd electrodes 52 and 62 are comprised by the pair provided so that it might oppose. Further, the erasing head 30 includes first and second connection terminals 32 and 36 on the lower side of the casing 48. On the bottom surface of the erasing head 30, that is, the bottom surface of the housing 48, a plurality (six in this figure) of mounting screw holes 2a are formed in a line.

  The substrate 44 is made of ceramic such as alumina and has an insulating property. A glaze layer 42 is generated on the substrate 44, and a heating element 40 is further formed thereon to form a laminated structure. When this laminated structure is formed, as shown in the figure, a convex cross-sectional structure is formed in which the top surface is narrow and the bottom surface is narrow.

  Further, the heating element 40 is made of, for example, a polysilicon (Poly-Si) thin film having a desired thickness doped with boron (B), and has a single-dot, substantially rectangular parallelepiped band shape in the longitudinal direction of the erasing head 30. ing.

  Furthermore, the glaze layer 42 is also called a heat storage layer, and is formed with a desired thickness by softening and baking glass. A housing 48 is attached to the lower side of the substrate 44 in the drawing, that is, the surface opposite to the surface on which the glaze layer 42 and the heating element 40 are laminated. The casing 48 has a heat dissipation function, and is formed of, for example, aluminum.

  Here, the first connection terminal 32 is provided at a position ¼ from the left in the drawing with respect to the longitudinal direction of the erasing head 30. The second connection terminal 36 is provided at a position 1/4 from the right (3/4 from the left) of the erasing head 30 in the longitudinal direction.

  First and second power supply cables 34 and 38 for supplying power from the outside are attached to the first and second connection terminals 32 and 36, respectively. Hereinafter, in this figure, the ¼ position from the left of the erasing head 30 is the “left position PA1,” the ½ position is the “center position PA2,” and the 3/4 position (a 1/4 position from the right). Is called “right position PA3” for convenience. Note that the cross-sectional structure at the right position PA3 is substantially the same as the cross-sectional structure shown in FIG. 4, except for the configuration in which the first connection terminal 32 becomes the second connection terminal 36 and the first power supply cable. Reference numeral 34 denotes a configuration that becomes the second power supply cable 38.

  As shown in FIG. 4, the first electrode 52 is provided in close contact with the left side surface of the erasing head 30 from the heating element 40 to the bottom surface of the housing 48. Here, the first electrode 52 includes an upper electrode layer 54 in the upper part and a lower electrode part 56 in the lower part. The upper electrode layer 54 is formed in a thin film so that the upper end portion thereof is electrically connected to the end portion of the heat generating element 40 in the longitudinal direction over substantially the entire region. On the other hand, the lower end portion of the lower electrode portion 56 is connected to the first and second connection terminals 32 and 36 on the bottom surface of the housing 48.

  The second electrode 62 has the same structure as the first electrode 52 and is provided in close contact with the right side surface of the erasing head 30 from the heating element 40 to the bottom surface of the housing 48 in the drawing. Yes. The second electrode 62 includes an upper electrode layer 64 in the upper part and a lower electrode part 66 in the lower part. The upper electrode layer 64 is made of, for example, aluminum so that the upper end of the upper electrode layer 64 is electrically connected to the entire end of the heating element 40 in the longitudinal direction. On the other hand, the lower end portion of the lower electrode portion 66 is connected to the first and second connection terminals 32 and 36 on the bottom surface of the housing 48.

Furthermore, the protective layer 46 is formed as a thin film of, for example, SiO ₂ so as to cover the heating element 40, the upper electrode layer 54, and the upper electrode layer 64.

  A description will be given of a result of measuring variation in temperature distribution in the erasing head 30 having the above configuration. For comparison with the configuration of the erasing head 30 shown in FIG. 3 (hereinafter, also referred to as “erasing head 30 of the present invention”), there is one connection terminal 72 and one power supply cable 74 each used conventionally. The erasing head 70 was also tested. FIG. 5 is a schematic external view of a conventional erasing head 70 used in the comparative experiment. FIG. 5 (a) is a top view, FIG. 5 (b) is a side view, and FIG. Is a bottom view, and FIG. 5D is a cross-sectional view along the line BB. The cross-sectional structure of the conventional erasing head 70 is the same as the cross-sectional structure of the erasing head 30 of the present invention, and thus the description thereof is omitted.

  Similarly to FIG. 3, in this figure, the position ¼ from the left of the conventional erasing head 70 is “left position PB 1”, the position ½ is “center position PB 2”, and the position 3/4. (1/4 position from the right) is referred to as “right position PB3” for convenience.

  FIG. 6 is a graph showing experimental results when temperature distribution is measured using the erasing head 30 of the present invention. FIG. 7 is a graph showing experimental results when the temperature distribution is measured using a conventional erasing head 70. Hereinafter, for convenience, an experiment using the erasing head 30 of the present invention is referred to as “Experiment 1”, and an experiment using the conventional erasing head 70 is referred to as “Experiment 2”.

The main measurement conditions for both experiments are as follows.
Heating element width (longitudinal length): 216 mm
Heating element length (length in the short direction): 2.3 mm
Applied voltage: 24.0V
Applied current: 7.8A.

  In Experiment 1, the surface temperatures of the heating elements 40 at the three positions shown in FIG. 3, that is, the left position PA1, the center position PA2, and the right position PA3 were measured. Similarly, in Experiment 2, the surface temperature of the heating element 40 was measured at three positions, the left position PB1, the center position PB2, and the right position PB3.

  In general, 150 ° C. is a practical temperature as a data erasing temperature of media. Therefore, in these experiments, when the temperature of the position (PA2, PB1, PB3) of the heating element 40 corresponding to the position where the connection terminal is not provided reaches 150 ° C., the position where the connection terminal is provided is set. The temperature of the position (PA1, PA3, PB2) of the corresponding heating element 40 is measured.

  FIG. 6 shows the results of Experiment 1. Since the temperature at the right position PA3 shows the same result as the temperature at the left position PA1, it is omitted here. As shown in the figure, in the erasing head 30 of the present invention, when the surface temperature of the heating element 40 at the central position PA2 reaches 150 ° C., the surface temperature of the heating element 40 at the left position PA1 is 144 ° C. It was. That is, the temperature difference is 6 ° C. Here, it took 8.0 seconds for the surface temperature of the heating element 40 at the center position PA2 to reach 150 ° C.

  FIG. 7 shows the results of Experiment 2. Note that the temperature at the right position PB3 shows the same result as the temperature at the left position PB1, and thus is omitted as in FIG. In Experiment 2, as shown in the drawing, in the conventional erasing head 70, when the surface temperature of the heating element 40 at the left position PB1 reaches 150 ° C., the surface temperature of the heating element 40 at the central position PB2 is 138. ° C. That is, the temperature difference is 12 ° C. Here, it took 7.4 seconds for the surface temperature of the heating element 40 at the central position PB2 to reach 150 ° C.

  By the way, depending on the media, the difference between the erasing temperature and the coloring temperature (writing temperature) may be as narrow as 20 ° C. If the temperature distribution has a variation of 15 ° C. or more, there may be a case where sufficient quality cannot be obtained when data on the entire surface of the medium is erased collectively. Further, when the erasing processing speed is increased, it is necessary to further suppress variation in temperature distribution. Actually, when the temperature difference is 12 ° C. due to variations in the temperature distribution, quality sufficient for erasing data may not be obtained.

  That is, as shown in Experiment 2, when there is one connection terminal, a temperature difference of 12 ° C. occurs in the temperature distribution, which is not preferable. On the other hand, as shown in Experiment 1, by using two connection terminals, the temperature difference generated in the temperature distribution could be suppressed to 6 ° C., which is half. In general, by providing n connection terminals, the temperature difference generated in the temperature distribution can be reduced to 1 / n.

  FIG. 8 is a graph showing the relationship between the effective heat generation width of the erasing heads 30 and 70 and the difference in surface temperature of the heat generating element 40. Here, the width of the connection terminal was 18 mm, and the experiment was performed under the same measurement conditions as in Experiment 1 and Experiment 2.

  As shown in the figure, when the effective width of the heating element 40 is 100 mm, the temperature difference is 6 ° C., and when the effective width is 216 mm, the temperature difference is 12 ° C. That is, in this experiment, when the effective width exceeds 216 mm, it is desirable to use a plurality of connection terminals. Further, the number of connection terminals to be provided need not be limited to two, and may be three or more.

  As described above, according to the present embodiment, by disposing a plurality of connection terminals for drawing out a cable for supplying power to a pair of electrodes extending in the longitudinal direction of the heating element 40, heat dissipation in the connection terminal portion is distributed. can do. As a result, the temperature drop of the heating element in this portion can be reduced, and variations in temperature distribution over the entire heating element can be reduced. Further, since the thickness of the cable for supplying power can be reduced, the degree of freedom in selecting the cable is increased, and the adjustment range of the rigidity of the cable is expanded.

  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 diagram of a printing apparatus 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. FIG. 3 is a schematic external view of a conventional erasing head, particularly viewed from the side. It is the graph showing the experimental result at the time of measuring temperature distribution using a new type erasing head. It is the graph showing the experimental result at the time of measuring temperature distribution using the conventional erase head. 6 is a graph showing the relationship between the effective heat generation width of the erasing head and the temperature difference of the surface of the heating element.

Explanation of symbols

30 ... Erasing head (thermal head for batch heating)
32... First connection terminal 36... Second connection terminal 40... Heating element 42 .. Glaze layer 44 .. Substrate 46 .. Protective film 48 .. Case 52. Upper electrode layer 56 …… Lower electrode portion 62 …… Second electrode 64 …… Upper electrode layer 66 …… Lower electrode portion

Claims (3)

A single-dot belt-shaped heating element formed so as to be able to heat a predetermined direction of a medium to be heated collectively, and a pair of electrodes provided to be connected over substantially the entire region in the longitudinal direction of the heating element, A thermal head for batch heating for the purpose of heating at a substantially uniform temperature,
Each of the electrodes includes two connection terminals provided to be connected to an external power source,
The connection terminals are respectively arranged at 1/4 positions from the left and right in the longitudinal direction of the heating element,
A thermal head for batch heating, wherein variation in temperature distribution of the heating element due to heat radiation from the heating element due to the connection terminal is reduced.   A printing apparatus comprising the batch heating thermal head according to claim 1. A single-dot belt-like heating element formed so as to be capable of heating in a predetermined direction of a medium to be heated, and a pair of electrodes provided so as to be connected over substantially the entire area at both ends in the longitudinal direction of the heating element. In addition to supplying power for generating heat to the heating element from two paths to a thermal head for batch heating intended to perform heating at a substantially uniform temperature, the power supply path Variations in temperature distribution of the heating element due to heat radiation from the heating element due to the power supply path are reduced by setting the positions to 1/4 positions from the left and right in the longitudinal direction of the heating element. A method of supplying power to a thermal head for batch heating, characterized by

Images