JP4901519B2 - Heating head, heating head unit and heating head module - Google Patents

Description

  The present invention relates to a heating head, a heating head unit, and a heating head unit having a belt-like heating resistor for heating a medium in order to perform transfer or retransfer of a recording medium, heat transfer or erasure of a transfer film for coating, etc. The present invention relates to a heating head module. More specifically, for example, in order to increase the erasing speed when erasing the recording of the thermoreversible recording medium, even when the medium is moved at a high speed on the heating head, the entire surface is surely erased without causing temperature unevenness. The present invention relates to a heating head, a heating head unit, and a heating head module having a structure capable of performing the above.

  In recent years, for example, reversible coloring and decoloring by heating on a film, sheet, card or other support made of synthetic resin such as paper, non-woven fabric, woven fabric, vinyl chloride, polyethylene terephthalate, metal, glass, etc. A reversible thermosensitive recording medium (rewritable card / rewritable sheet) provided with a recording section composed of a reversible thermosensitive recording layer has been widely used.

  A thermoreversible recording medium such as a rewritable card or rewritable sheet is heated to a temperature (for example, 180 ° C.) or higher and then rapidly cooled (for example, 80 ° C. or lower) to record the color. The color is completely erased by raising the temperature to a low temperature (for example, 120 to 160 ° C.). For example, a heating head as shown in FIG. 8 is used to perform recording / erasing on such a thermoreversible recording medium (see, for example, Patent Document 1).

In FIG. 8, a glass layer (glaze layer) (not shown) is provided on one surface of a head substrate 51 made of alumina or the like, a strip-like heating resistor 52 is formed thereon, and electrodes 53 are provided at both ends thereof. Is formed. The electrode 53 is led out to the back surface of the head substrate 51 by wiring or the like, and is connected to a wiring substrate or the like provided on the back surface side of the head substrate 51 so as to apply a voltage. As a result, a voltage is applied to both ends of the heating resistor 52 via the electrodes 53 and 54, and the heating resistor 52 generates heat when current flows, and the temperature of the resistor 52 is controlled by the amount of current. Can do. Erasing as described above can be performed by passing a recording medium such as a card while pressing the heating resistor 52 with a roller (not shown). Here, the glaze layer is provided as a thermal insulating layer in order to prevent heat from escaping to the head substrate 51 when the heating resistor 52 is heated.
JP 2004-268256 A

  As described above, heating the heating resistor while energizing it, passing a recording medium, etc. over it, and pressing it against the heating resistor with a roller, etc., erases the recording on the recording medium, etc. It can be carried out. In this case, in order to effectively use the applied power for heating the recording medium, a heating resistor is formed on the head substrate with a glaze layer (glass layer) interposed as described above. The generated heat is prevented from escaping to the head substrate as much as possible, and a heating medium such as a recording medium is directly heated from the heating resistor. Further, since the heating resistor only needs to be in a portion pressed by the roller, it is usually formed in a width of 2 to 3 mm from the viewpoint of effective use of electric power.

  However, in recent years, a larger sheet-like medium has begun to be used due to the size similar to that of credit cards that have been widely used in the past. The demand for is increasing. However, if the heating speed of a heating medium such as a recording medium is increased by using a conventional heating head as shown in FIG. 8, the heat capacity of the heating resistor is small, so the temperature is lowered and the temperature of the medium is reduced. It may not be uniform over the entire surface, and erasure unevenness may occur. In particular, in the case of a rewritable sheet, it is required to be completely erased more than the card. In order to solve such a problem, if the recording medium is not continuously transferred while increasing the input to the heating resistor to always generate a large amount of heat, it will not overheat (overheat). In addition, heat must be dissipated through the head substrate and the base to which the head substrate is attached. As a result, power consumption eventually increases and power utilization efficiency deteriorates. Moreover, since the heat generating part is formed in a thin line shape such as a heating resistor, a part where the temperature is low or a part where the temperature is higher than the erasing temperature occurs, and the entire surface of the heating medium such as the recording medium is uniformly heated. There is a problem that heating cannot be performed easily.

  The present invention has been made to solve such a problem, and even if the moving speed of the medium to be heated is high, the temperature of the contact point between the medium and the heating resistor by the roller does not extremely decrease. And it is providing the heating head of the structure which can heat a medium uniformly, without increasing the electric power applied to a heat generating body.

  The present inventor uses a conventional heating head provided with a belt-like heating resistor to increase the processing speed in recording / erasing of a reversible thermosensitive recording medium or overcoating a transparent transfer film. In addition, when heating a medium such as a rewritable sheet, for example, the last part that passes through the heating head found a phenomenon that tends to cause insufficient heating, and conducted extensive studies to solve the problem. . As a result, it has been found that, for example, when the medium feed speed, which is conventionally about 30 mm / second, becomes 80 mm / second or more in accordance with the speedup of processing such as erasing operation, the influence of temperature drop due to heat transfer to the medium is large. It was. In this case, if an attempt is made to increase the power applied to the heating resistor so that the temperature does not drop below a predetermined temperature even if the moving speed of the medium is increased in the conventional structure, for example, the moving speed of the medium is doubled. Then, the amount of heat transferred to the medium needs to be doubled, and while increasing the applied power, the heat conduction must be doubled so that the medium is not heated above its erasing temperature (eg, 160 ° C.). However, as described above, it is also necessary to prevent overheating (overheating). Therefore, there is a problem that power consumption is significantly increased while being restricted by the material, speed, roller pressure, and the like of the medium.

  Therefore, as a result of further intensive studies by the inventor, heat generated by the conventional heating resistor is directly transferred to the medium so as not to escape to the head substrate as much as possible. When erasing or transferring the recording of a medium at a high speed instead of the idea of effectively using the power used for the head, keep the entire head substrate at a constant temperature, and maintain a uniform temperature over a wide range of the head substrate. Therefore, even if the heat quantity is absorbed by the medium at the part that is pressed by the roller, the heat quantity is immediately supplied from the other part of the head substrate, and a partial temperature drop can be prevented. By heating on the head substrate before heating, the heating can be performed uniformly without increasing the power applied to the heating resistor, and the medium feed speed can be set to 80 mm / sec. Even in the above, it found that it is possible to uniform heating at consequently low power application. In other words, the present invention is based on the technical idea of using the entire head substrate as a heating element, rather than using a local heating element such as a heating resistor on the head substrate.

That is, the heating head of the present invention is provided with a rectangular head substrate having a width of at least 5 mm and extending in the longitudinal direction, and at least one along the longitudinal direction of the head substrate. A belt-like heating resistor to be formed, and first and second electrodes that are respectively connected to both ends of the heating resistor, and the heating resistor comprises: A trimming resistor provided directly on the surface of the head substrate so as to occupy a width of 60% or more of the width of the head substrate , and connected in parallel with the heating resistor on the lower surface side of the head substrate. The body is provided .

  According to the present invention, since a wide range of heating resistors are directly provided on the head substrate surface, the entire head substrate can be heated, so that the heat capacity can be increased and a heated object such as a reversible thermosensitive recording medium can be run at high speed. It is possible to reduce the temperature drop when it is used.

  Further, according to the present invention, since the heating resistors are widely provided, when the object to be heated is pressed against the heating resistor portion on the upper surface side with the roller, the portion for the heating that does not contact the roller is used. By cutting the resistor, the resistance value can be trimmed, and heating unevenness due to the trimming trace can be prevented.

  In the heating head of the present invention, a heating resistor for measuring the substrate temperature may be provided directly on the surface of the head substrate along the belt-like heating resistor on the upper surface side of the head substrate. In the case where the heating resistor is provided through the glaze layer as in the prior art, the measurement temperature of the substrate is different from the temperature at which the heated object is actually heated because the glaze layer is interposed. Then, since the heating resistor is provided directly on the substrate without using the glaze layer, the measured temperature of the substrate is almost equal to the temperature when the heated object is actually heated, and the heating temperature is controlled with high accuracy. Can do.

  In the heating head of the present invention, a heat insulating layer may be provided on the lower surface side of the head substrate. By providing the heat insulating layer, it is possible to effectively prevent the heat of the head substrate heated to the side of the circuit board to which the heating head is attached from being escaped, and to improve the thermal efficiency. As the heat insulating layer, for example, a glass layer can be used.

The heating head of the present invention, since as used to heat the entire head substrate, the lower surface side of the F head substrate, for example be provided with the substrate measuring resistor and / or trimming resistor no trouble, or cutting off the trimming resistor provided on the lower surface side of the head substrate, it is possible to adjust the direction of increasing the resistance value of the heating resistor on the upper surface side or to cut, If the trimming resistor is connected in parallel with the heating resistor on the upper surface side by solder or the like, the resistance value of the heating resistor on the upper surface side can be adjusted in the lower direction. Of course, if the resistance value of the heating resistor on the upper surface side of the head substrate is too higher than a predetermined value after manufacture, an additional heating resistor is arranged in parallel on the lower surface side of the head substrate as described above. If it is provided, the resistance value of the heating resistor on the upper surface side can be lowered and used.

  In the heating head of the present invention, the first and second electrodes provided at the both end portions are formed by being divided along the width direction of the head substrate, and the heating medium is heated by a roller to form a heating resistor on the upper surface side. When pressed against the body part, the portion where the roller contacts is formed in a structure in which the first and second electrodes are not formed, so that the portion where the roller contacts becomes flat, and there is a step in the portion where the roller contacts. Since it cannot, it can heat uniformly.

  A protective film is formed on the surface of the heating resistor on the upper surface side, and when the medium to be heated is pressed against the heating resistor part with a roller, the protective film on the portion where the roller hits the surrounding film By forming it thicker than the protective film on the heating resistor, the medium heated by the roller can be firmly pressed against the heating head, and the heat of the heating head can be sufficiently transferred to the medium. It is preferable that the recording can be erased. In particular, in the present invention, since the glaze layer is not provided under the heating resistor on the upper surface side, the formation of the protruding portion by this protective layer is effective in reducing the pressure contact force with the roller. It is easy to pass through the medium.

  Moreover, the film-like circuit board for drawing out the said 1st and 2nd electrode can be stuck on the lower surface side of the said head substrate of the heating head of this invention, and it can also be set as a heating head unit. As the film-like circuit board, a known film-like or sheet-like resin circuit board having flexibility and heat resistance can be used, and more specifically, for example, a thickness of 0.05 to 0.2 mm. A glass epoxy circuit board, a polyimide circuit board, or the like of a degree can be preferably used. This film-like circuit board is preferably attached to almost the entire lower surface of the head substrate (heating head) with an adhesive, and when connected to the entire lower surface of the head substrate via an adhesive, It is possible to prevent the head substrate from being cracked and damaged when the heated object is pressed by the roller. In addition, the lead wire of the film-like circuit board is electrically connected to the first and second electrodes drawn to the lower surface side of the head substrate with a conductive adhesive, and the other portions are conductive. There is no need to use an adhesive. As the conductive adhesive, for example, an epoxy resin adhesive mixed with Ag powder can be used. Thus, by using a film-like circuit board, expansion and contraction of the heating head due to repeated heating and cooling can be effectively absorbed.

  The film-like circuit board of the heating head unit may be attached to the circuit board with a heat-resistant soft adhesive via a heat insulating plate to form a heating head module. In the heating head of the present invention, when the heating head is directly attached (attached) to the circuit board in order to heat the entire head board, the difference in material between the head board (eg alumina) and the circuit board (eg glass epoxy) Due to the difference in thermal expansion coefficient, there is a risk that the heating head cracks or the heating head peels off from the circuit board. Therefore, by attaching the heating head to the circuit board via a heat insulating plate with a heat-resistant soft adhesive, the heat transferred from the heating head to the circuit board can be gradually reduced, and the difference in thermal expansion and contraction can be reduced in stages. By doing so, the heating head can be prevented from cracking or falling off the circuit board. Further, by using a heat-resistant soft adhesive, it is possible to effectively absorb expansion and contraction due to heat.

  As the heat-resistant soft adhesive, for example, a commercially available double-sided tape-like material can be preferably used, and as the heat insulating plate, a heat-resistant material such as glass epoxy can be used. The heat insulating plate is preferably thicker than the film-like circuit board and thinner than the circuit board. By doing so, the difference in expansion and contraction of each part can be absorbed more effectively.

  Furthermore, an insulating substrate for mounting a circuit board can be adhered to the lower surface side of the head substrate of the heating head of the present invention with a heat insulating adhesive to form a heating head unit. As the heat insulating adhesive, for example, a known sealing glass can be used, and as the insulating substrate, for example, an insulating substrate made of ceramic such as alumina can be used. By using a heat insulating adhesive, not only as an adhesive to the insulating substrate for circuit board mounting, but also can effectively prevent the heat of the head substrate heated to the insulating substrate for mounting and the circuit board side from diffusing, It also increases the thermal efficiency and can be suitable for further high-speed processing.

  The insulating substrate for mounting the circuit board may be divided into a plurality in the longitudinal direction of the heating head, and thermal expansion can be alleviated by dividing.

  In addition, by using a heating head unit with an insulating substrate for circuit board attachment attached, the insulating substrate for circuit board attachment can be easily attached to the circuit board to form a heating head module.

  According to the heating head of the present invention, the heating resistor is directly formed on the head substrate without passing through the glaze layer, and occupies 50% or more of the upper surface area of the head substrate. For example, in the case of a large heating head with a large head substrate and a large head substrate, the width is 80% or more, and even when the head substrate is small with a small heating head with a small heating body, the width is 60% or more. A heating resistor is provided so as to occupy this portion. Therefore, the temperature of the entire head substrate can be raised to a predetermined temperature. As a result, the temperature of the portion where the heated object is pressed against the roller is averaged, and the temperature unevenness is reduced, and the heated object can be heated at a substantially uniform temperature in the longitudinal direction of the heating head. In addition, the amount of heat absorbed by the heated object is preliminarily heated in contact with the heating resistor on the head substrate even until the heated object reaches the part that is pressed by the roller. Is smaller than the conventional structure, and above all, the entire head substrate is heated to accumulate heat, so even if the heat capacity is large and the object to be heated is continuously scanned at high speed, the temperature of the contact portion by the roller Can be reduced. As a result, the temperature of the head substrate can always be kept almost constant without excessively increasing the power supply to the heating resistor, and recording erasure and transfer by stable heating can be performed at high speed. it can.

  Moreover, as described above, it is not necessary to apply an extremely large input to the heating resistor, and overheating can be avoided, so there are restrictions on heating such as adjustment of roller pressure and heat dissipation from the head substrate. In addition, it takes a little time to stabilize at the time of startup, and there is no such problem when using continuously, rather, when using continuously or at high speed. As described above, there is no need for measures for preventing overheating, and a very low power consumption and stable heating head can be obtained.

  Next, the heating head of the present invention will be described with reference to the drawings. The heating head according to the present invention has an explanatory plan view of one embodiment thereof, an explanatory plan view of a state in which only a terminal electrode is provided before providing a heating resistor, an explanatory drawing of an electrode arrangement on the back surface, and an explanatory sectional view of FIG. It is formed as shown in a) to (d).

  That is, at least one belt-like heating resistor 2 along the longitudinal direction of the head substrate 1 is formed on one surface of a head substrate (head substrate) 1 having a width of at least 5 mm and extending in the longitudinal direction. Are formed, and are electrically connected to both end portions of the heating resistor 2, respectively, so that the first and second electrodes 4 and 5 (in the example shown in FIG. Are formed). In the present invention, the heating resistor 2 may be provided with substantially the entire surface of the head substrate 1, more specifically, as shown in FIG. In that case, a conventional glaze layer is interposed on the head substrate 1 on the surface excluding the substrate temperature measuring resistor 3 and the gap and the periphery of the heating resistor 2. It is characterized in that it is formed directly on the head substrate 1. Therefore, although the size of the head substrate varies depending on the size of the heated object such as the reversible thermosensitive recording medium to be used, even when the head substrate 1 is small, the width is about 12 mm in an area of 60% or more of the width. If it is large, it is provided over 80% or more of the width of the head substrate 1. The heating resistor 2 can be provided on the entire surface of the head substrate 1 without providing the substrate temperature measuring resistor 3.

  As described above, the head substrate 1 varies depending on the size of the object to be heated. For example, the head substrate 1 is made of a substantially rectangular plate having a length of about 40 to 240 mm, a width of about 5 to 12 mm, and a thickness of about 0.635 to 1.0 mm. The material has a certain degree of thermal conductivity, that is, a thermal conductivity of about 1 (for example, soda glass) to 200 W / (m · K), and has heat resistance in the heat generation temperature condition during use. The surface on which the heating resistor is provided has insulating properties, for example, ceramics such as alumina (thermal conductivity: about 17 to 30 W / (m · K)), low-temperature fired substrate (one type of crystallized glass: heat) Conductivity: about 2.8 W / (m · K)), aluminum nitride (thermal conductivity: about 200 W / (m · K)), or the like can be used. This is because, in the present invention, as described above, the overall temperature of the head substrate 1 is raised to prevent a local temperature effect, so that a material having excellent thermal conductivity is preferable. . From this viewpoint, a metal plate made of stainless steel having a thin insulating film on the surface can also be used. In the present embodiment, an alumina substrate (96% alumina: thermal conductivity 20 W / (m · K)) is used as the head substrate 1.

  At both ends of the upper surface of the head substrate 1, as shown in FIG. 1 (b), for example, a silver / palladium alloy or an Ag—Pt alloy with a reduced ratio of palladium as a material of the heating resistor 2 described later is used. First and second electrodes 4 and 5 made of a good conductor are formed by printing. The first and second electrodes 4 and 5 are connected to the terminals of the wiring board by using the front surface, side surface and back surface of the head substrate 1 or by through-hole connection, and are connected to an external power source. Yes. In the example shown in FIG. 1, the substrate temperature measuring resistor 3 is provided, and the pair of electrodes 6 and 7 are formed at the same time in exactly the same manner. In the example shown in FIG. 1, the first and second electrodes 4 and 5 are each divided into two, and portions where the electrodes 4 and 5 are not formed are provided along the width direction of the head substrate 1. This will be described later. The example shown in FIG. 1B is an example of the head substrate 1 having a width w of 7 mm and a length L of 104 mm. Specific dimensions a to f of the positions and sizes of the electrodes 4 to 7 are as follows. 0.8 mm, b is 0.5 mm, c is 1.2 mm, d is 3 mm, e is 1.5 mm, and f is 2.5 mm. However, it is not limited to this example.

The heating resistor 2 is provided so as to cover a part of the first and second electrodes 4 and 5. In the example shown in FIG. 1, a substrate temperature measuring resistor 3 is provided so as to be connected to a pair of electrodes 6 and 7 provided at both ends along with the heating resistor 2. The heating resistor 2 and the substrate temperature measuring resistor 3 are formed, for example, by applying and baking a paste such as Ag + Pd + glass or silver and glass. It is also possible to use a further added and RuO ₂ thereto. When composed of an Ag—Pd alloy formed by firing, a sheet resistance of 100 mΩ / Sq to 500 mΩ / Sq is obtained (depending on the blending, amount of solid insulating powder, printing thickness, firing conditions, etc.), the ratio of both Thus, the resistance value and the temperature coefficient can be changed. For example, when the sheet resistance is about 200 mΩ, the width is 5 mm, the length is 100 mm, the thickness is about 10 μm (total resistance is about 3.6Ω), and the resistance temperature coefficient is about 1500 ppm / ° C. (when the temperature changes by 100 ° C.) The resistance value changes by 15%). The heating resistor 2 is printed and formed so as to overlap a pair of electrodes 4 and 5 provided at both ends in the longitudinal direction which is the longitudinal direction of the head substrate 1.

  The sheet resistance of the heating resistor 2 is set according to the size of the medium to be heated, the processing speed of the medium (speed of erasing recording, that is, the speed of passing over the heating head), and the like. For example, when the head substrate 1 has a width × length × thickness of 7 mm × 104 mm × 0.8 mm in the above example and is made of alumina, the amount of heat required to raise the head substrate 1 by 1 ° C. is 1 In order to increase 150 ° C. at .76 J, 150 × 1.76 = 264 J is required. For example, if the resistance between both ends of the heating resistor 2 is 3.6Ω, a heat of 160 W is generated by applying a voltage of 24 V, so 264 J / 160 W = 1.65 seconds. Thus, the necessary amount of heat can be supplied. That is, it is necessary to wait 1.65 seconds for the substrate temperature to rise to a predetermined temperature at the time of startup, but after that, even if the medium is passed at a high speed, the heat capacity of the head substrate 1 is the conventional thin heating resistor. Since it is much larger than the body 2 alone, the medium can be heated continuously with almost no temperature unevenness.

  As described above, the heating resistor 2 is formed on almost the entire surface of the head substrate 1 excluding a width of about 2 mm in total, including the substrate temperature measuring resistor 3 and the peripheral portion. Therefore, when the width of the head substrate 1 is 5 mm, the width of the heating resistor 2 is 3 mm and is approximately 60% of the width. When the width of the head substrate 1 is 12 mm, the width of the heating resistor 2 is Is formed to about 10 mm, and the ratio to the width is 83%. However, if the substrate temperature measuring resistor 3 is not provided, the area of the heating resistor 2 can be further increased. The heat generation characteristic of the heating resistor 2 is not limited to the above-described example, and can be freely set. However, it is preferable that the temperature coefficient of resistance of the heating resistor 2 is positively higher, particularly 1000 to 3500 ppm / ° C. It is preferable to use this material in order to detect and control the temperature using a heating resistor 2 described later, or to prevent overheating due to thermal runaway. Even when the temperature is not directly measured by the heating resistor 2, as will be described later, when the temperature measuring resistor 3 of the substrate 1 is formed, it can be formed at the same time as the heating resistor 2, and an accurate temperature can be set. Easy to measure.

  The fact that the temperature coefficient of resistance is positively high means that the resistance value increases greatly as the temperature rises, so it is easy to detect the actual heat generation temperature due to deviation from the reference resistance value by measuring the resistance value in the heated state. It is easy to correct the deviation from the desired heat generation temperature by adjusting the applied voltage or adjusting the duty of the applied pulse. Also, since the temperature coefficient of resistance is positive, if the temperature rises too much, the resistance value increases, the current value decreases, and the amount of heat generated by the resistance decreases, so the temperature becomes saturated sooner, This is because it is excellent in temperature stability and can prevent overheating due to thermal runaway. In addition, the width of the heating resistor 2 is not limited to the above example, and may be set according to the application and may be arranged in parallel.

  Note that the heating resistor 2 can be corrected in resistance value by, for example, a laser trimming method or the like to form a full length in the length direction or partially a cutting groove. In the present invention, since the heating resistor 2 is formed wide, trimming can be performed by forming a cutting groove in a portion where the heated object is not pressed by the roller.

  The substrate temperature measuring resistor 3 is a resistor having a large temperature coefficient because it is intended to detect the temperature of the surface of the head substrate 1 as close as possible to the heating resistor 2. The substrate 2 is provided in parallel, and substrate temperature measuring electrodes 6 and 7 are provided at both ends thereof. It is preferable from the viewpoint of sensitivity that the substrate temperature measuring resistor 3 has the same resistance value as that of the voltage dividing resistor 31 described later with reference to FIG. Therefore, it is desirable that the resistance values of the substrate temperature measuring resistor 3 and the voltage dividing resistor 31 are increased and the voltage dividing resistor 31 has a small temperature coefficient. The substrate temperature measuring resistor 3 may be formed of the same material as that of the heat generating resistor 2, but preferably the absolute value (%) of the temperature coefficient is as large as possible (positive or negative). The substrate temperature measuring resistor 3 has a width of, for example, about 0.3 to 0.5 mm, is provided along the heating resistor 2 or in the vicinity thereof, and is formed to have a thickness of about 50Ω, for example. The applied voltage is kept low so that the resistor 3 itself does not generate heat, and about 5 V is applied. Depending on the position of the roller, the heating resistor 2 can be divided along the longitudinal direction of the head substrate 1 and provided therebetween. That is, since the substrate temperature measuring resistor 3 is provided in a thin layer on the head substrate 1, its temperature is almost the same as that of the head substrate 1, and the temperature of the substrate temperature measuring resistor 3 is measured. The temperature of the head substrate 1 surface can be estimated.

  If the substrate temperature measuring resistor 3 is made of the same material as the heating resistor 2, it can be formed simultaneously with the heating resistor 2 when it is formed by printing or the like. However, when the accuracy of the measurement temperature is required, it is possible to change the mixing ratio of Ag and Pd or use a completely different material having a large temperature coefficient. Even with the same material, the properties can be changed by changing the thickness and firing temperature. Further, if different materials are used, the substrate temperature measuring resistor 3 can be formed to about 500Ω.

  As described above, in the example shown in FIG. 1, the first and second electrodes 4 and 5 are divided and provided along the width direction of the head substrate 1. As will be described later, when the medium is heated by the heating head, the medium is pressed against the heating head by a roller, but the roller has a step between the portion with the electrodes 4 and 5 and the portion without the electrode, This is to prevent the medium from being firmly pressed against the heating head. That is, the first and second electrodes 4 and 5 have a thickness of about 10 μm, and the heating resistor 2 is formed to a thickness of about 10 μm. Therefore, a portion where the first and second electrodes 4 and 5 are present has a height of 20 μm from the surface of the head substrate 1, whereas a portion where the electrodes 4 and 5 are not present is a heating resistor as described above. Since the body 2 is formed directly on the surface of the head substrate 1, its height is about 10 μm, and when it is pressed by a roller, the roller is made of rubber, but hardly deforms, so the electrodes 4 at both ends This is because a portion of the heating resistor 2 between the two and the heat generating resistor 2 has a gap of about 10 μm and cannot be sufficiently pressed.

  The width of the roller in contact with the heating resistor 2 is about 2.5 to 4 mm, although it depends on the pressure when the roller is pressed. Therefore, the distance d for dividing the first and second electrodes 4 and 5 is about 2.5 to 4 mm, and is 3 mm in the above example. As will be described later, a protective film is provided on the surface of the heating resistor 2 and the like, and further, the protective film is formed so as to be thicker by about 10 μm at the portion where the roller hits. If there is no step due to the first and second electrodes 4, 5, the roller can be uniformly pressed over the entire width of the roller (the entire longitudinal direction of the heating resistor 2). In the portion where the electrodes 4 and 5 are not formed, the current hardly flows along the longitudinal direction, but a detour current flows to some extent, and the current flows on the lateral side to generate sufficient heat. It is about the same as its vicinity. In addition, since it is difficult for the current to flow in this portion, when adjusting the resistance value of the heating resistor 2, the adjustment amount becomes insensitive by trimming and adjusting the resistance value in this portion. The resistance value can be adjusted.

  On the surface on the upper surface side of the head substrate 1 so as to cover the heating resistor 2, the substrate temperature measuring resistor 3, and the like, as shown in FIG. In order to improve and prevent short circuit due to wear and foreign matter adhesion, for example, a glass layer 8 having excellent thermal conductivity such as glass mixed with alumina powder is provided as a protective layer, and if necessary, excellent wear resistance is also provided. Carbon hard films such as DLC (diamond-like carbon) and TAC (tetrahedral amorphous carbon), nitrides, and the like may be provided on the upper surface of the glass protective layer 8 as a surface coat layer. The glass layer (thermal conductivity: about 1 W / (m · K)) 8 is provided with a thickness of about 10 μm, but the portion pressed by the roller is a protrusion with a thickness of about 10 μm and a width of about 3 mm. 8a is formed. By forming the protruding portion 8a, the pressure contact between the roller and the heating head can be more reliably performed, and the heat of the head substrate 1 can be reliably transmitted to the object to be heated.

  Further, a heat insulating layer such as a glass layer (thermal conductivity: about 1 W / (m · K)) may be provided on the lower surface side of the head substrate 1. By providing the heat insulating layer, the heat of the head substrate 1 can be reduced from escaping to the lower member.

  The head substrate 1 provided with the heating resistor 2 and the like is used to draw out the first and second electrodes as shown in FIGS. 2 (a) and 2 (b) in the plane and its longitudinal sectional view. The film-like circuit board 9 is attached to form a unit.

  The film-like circuit board 9 can be made of a flexible resin and has a substantially rectangular shape. Specifically, for example, a glass epoxy circuit board or a polyimide circuit board having a thickness of about 0.05 to 0.2 mm can be preferably used. The film-like circuit board 9 has a length approximately the same as or slightly wider than the head substrate 1, has a width larger than that of the head substrate 1, and the head substrate 1 and both ends thereof so that one end side in the width direction protrudes. The portion (the lower layer of the first and second electrodes 4 and 5) is attached with a conductive adhesive (conductive layer 10), and the middle portion is attached with a non-conductive adhesive, and is attached to almost the entire lower surface side of the head substrate 1. ing. As the conductive adhesive, a known conductive adhesive obtained by kneading Ag powder in an epoxy resin can be used, and as the non-conductive adhesive, one made of the epoxy resin can be used.

  Next, as shown in FIG. 3, the head substrate 1 as a unit attached to the film-like circuit board 9 is combined with the heat insulating plate 11, the main circuit board 12, and the attachment base 15 to be modularized. .

  First, the film-like circuit board 9 is attached to the heat insulating plate 11 with a heat-resistant soft adhesive (heat-resistant soft layer) 14. The heat insulating plate 11 is thicker than the film-like circuit board 9 and can be a plate-like body made of, for example, glass epoxy resin or polyimide resin having a thickness of about 0.5 to 3 mm, and has a substantially rectangular shape. The size is preferably larger than that of the head substrate 1 and approximately the same as or smaller than that of the film circuit board 9.

  Next, the heat insulating plate 11 is attached to the main circuit board 12 with the heat-resistant soft adhesive 14, and the main circuit board 12 is attached to the mounting base 15 with the heat-resistant soft adhesive 14.

  The head substrate 1, the film-like circuit substrate 9, the heat insulating plate 11, the main circuit substrate 12, and the mounting base 15 are attached with one end side in the width direction aligned.

  The main circuit board 12 has the same length as the film-like circuit board 9 and has a larger width. The main circuit board 12 is electrically connected to the lead wires of the first and second electrodes 4 and 5 of the film-like circuit board 9 via connection leads 16 on the upper surface side. At this time, the connection lead 16 may be used as a thermal fuse using a wire spring or the like. A connector 13 is connected to the lower surface side of the main circuit board 12.

  The mounting base 15 is a substantially rectangular thick plate made of, for example, aluminum. Aluminum is used because it is convenient for tapping screws and is lightweight and easy to process. As described above, in the present invention, the temperature of the head substrate 1 itself is increased to heat the medium. It is configured to do. Therefore, it is preferable that the heat of the head substrate 1 is not released as much as possible, and a material that is inherently heat resistant and has low thermal conductivity is preferable. Therefore, for example, from heat-resistant plastic with low thermal conductivity such as PES (polyethersulfone; thermal conductivity of about 0.2 W / (m · K)) or FR-5 (normal glass epoxy substrate (FR-4)) It is preferable to use a glass epoxy substrate having a high heat resistance of 40 ° C. However, plastics such as PES cannot be threaded and are expensive. Therefore, in the present embodiment, aluminum is used, and the aluminum is fixed to the mounting base 15 via the heat insulating layer (heat insulating plate) 11 and the main circuit board so that heat does not escape from the head substrate 1 to the aluminum. ing.

  As the heat insulating plate 11, PES, FR-5, etc. can be used, for example. The heat-resistant soft adhesive 14 is preferably a material having a low thermal conductivity. For example, a heat-resistant double-sided tape-like adhesive can be used, and the expansion and contraction and strain of each member due to heat can be absorbed.

  A heat-resistant cover case 17 (for example, glass epoxy resin, polyimide resin, etc.) for forming a space for accommodating the temperature spring fuse 16 and the connection point is attached to the exposed portion on the upper surface side of the main circuit board 12. A wear-resistant lid 18 made of a metal such as stainless steel is provided on the upper side of the cover case 17 without protruding from the upper surface of the head substrate 1.

  Next, another embodiment of the unit will be described. In this embodiment, as shown in FIG. 4, the heating resistor 2, the substrate temperature measuring resistor 3, the first and second electrodes 4, 5 and the substrate temperature measuring electrode 6 are the same as described above. , 7 is bonded to the insulating substrate 19 (19a to 19c) divided into three by a heat insulating adhesive (heat insulating layer) 20 to form a unit.

  As the heat insulating adhesive 20, for example, a known sealing glass (thermal conductivity: about 0.8 to 1 W / (m · K)) can be used. As the insulating substrate 19, for example, an alumina substrate is used. it can. The insulating substrates 19a to 19c have a substantially rectangular shape, are wider than the head substrate 1 as a whole, and have a length slightly shorter than that, and the electrodes 4, 5, 6, 7 at both ends of the head substrate 1. It is adhered so that is exposed. Here, the insulating substrate 19 is divided into three parts in the longitudinal direction of the head substrate 1 so as to reduce the influence of expansion and contraction due to heat from the head substrate 1. In the case where the size is small enough not to cause adverse effects due to expansion and contraction due to heat and distortion, a single insulating substrate may be used.

  The heating head unit formed in this way can be used by being fixed entirely or partially using a heat-resistant soft adhesive on the circuit board and the mounting base, for example, as described above with reference to FIG. Since the effects of expansion and contraction due to heat are reduced by interposing the heat insulating layer 20 and the insulating substrate 19, it is mechanically fixed to a circuit board or the like with a heat-resistant adhesive, screws and nuts, or the like. You can also. The electrodes 4, 5, 6, and 7 of the head substrate 1 can be electrically connected to the wiring of the circuit board using, for example, a flexible cable.

  Next, a modification of the heating resistor 2 will be described. As shown in FIG. 5, the shape of the strip-shaped heating resistor 2 ′ provided on the head substrate 1 is a shape in which a plurality of strip-shaped resistors having different thicknesses (width dimensions) are connected at both ends. Here, both ends of the first resistor 2a having a thick line shape and the three resistors, the second and third resistor members 2b and 2c having a thin line shape, are connected to each other. By using such a heating resistor 2 ′, if one or both of the thin wire-like second and third resistors 2b and 2c are cut, the resistance of the heating resistor 2 ′ can be easily obtained. The value can be modified.

  Further, in the case of cutting a thin wire-like resistor or forming a cutting groove in the heating resistor by laser trimming as described above, a method of correcting the heating resistor 2, 2 ′ by increasing the resistance value. However, in the heating head of the present invention, the resistance value of the heating resistor 2 is increased by providing a separate resistance layer on the lower surface side of the head substrate 1 so as to form a parallel circuit with the heating resistor 2. The resistance value of what is formed too much can be lowered and can be reused.

  In order to detect the temperature of the head substrate 1 using the above-described substrate temperature measuring resistor 3, for example, as shown in FIG. 6, both ends of the substrate temperature measuring resistor 3 are connected via voltage dividing resistors 31. A DC or pulse power supply 32 is connected. As described above, the substrate temperature measuring resistor 3 is made of a material having a temperature coefficient as large as possible (for example, 1000 to 3500 ppm / ° C.), and the voltage dividing resistor 31 is located away from the head substrate 1 where the temperature changes. Since it is provided, there is almost no temperature change, but it is preferable that the temperature coefficient is small so as not to be affected by changes in the environmental temperature. As a specific example, for example, the resistance value of the substrate temperature measuring resistor 3 is about 50Ω, the resistance value of the voltage dividing resistor 31 is about 50Ω, and a DC power source of about 5V can be used as the power source.

  With such a configuration, the voltage at both ends of the substrate temperature measuring resistor 3 is measured (V detection), the change in the voltage is obtained, the temperature change is calculated, and the substrate temperature measuring resistor at that time is calculated. A temperature of 3 can be determined. That is, the substrate temperature measuring resistor 3 has a temperature coefficient in which the resistance value changes at a constant rate depending on the temperature, and the temperature coefficient is measured by measuring in advance (determined depending on the material, but varies depending on the component). More accurately). Therefore, as described above, the voltage dividing resistor 31 is connected in series with the substrate temperature measuring resistor 3, the power source 32 is connected to both ends thereof, and a constant voltage is applied, whereby the substrate temperature measuring resistor is applied. When the temperature of the body 3 changes, the resistance value changes and the current changes. Since the resistance value of the voltage dividing resistor 31 does not change, the voltage across the substrate temperature measuring resistor 3 changes according to the resistance change of the resistor 3. From the voltage change, the resistance value of the substrate temperature measuring resistor 3 can be found, and the amount of change in temperature relative to the temperature before the change can be known from the temperature coefficient. The temperature of the substrate temperature measuring resistor 3 at that time can be determined. I can know.

  Note that the voltage change is measured at both ends of the substrate temperature measuring resistor 3 (V detection). This is because the higher the change rate of the voltage at both ends due to the temperature change, the more accurately it can be detected. The temperature change can be detected by measuring the voltage between both terminals. Where the electrode is provided, the voltage can be accurately measured even if there is a resistance component.

  In the above example, the substrate temperature measuring resistor 3 is provided separately from the heating resistor 2, and the temperature is measured. However, the substrate temperature measuring resistor 3 is not provided, and the heating resistor 2 is used. Similarly, the temperature of the heating resistor 2 can be directly measured by connecting a voltage dividing resistor in series with the power source. Furthermore, since the heating resistor 2 is intended to generate heat by itself, the heating resistor 2 is formed so that the resistance of the heating resistor 2 is much larger than the voltage dividing resistance. For example, the heating resistor 2 The resistor is 3.6Ω and the voltage dividing resistor 31 is 0.1Ω (set to be small so as not to consume power even if the current is large), and the applied voltage is as high as about 24V. A voltage is applied. For this reason, voltage detection (V detection) is performed by the voltage dividing resistor on the smaller resistance side, but the voltage across the heating resistor 2 can also be detected.

  When the temperature is measured using the heating resistor 2, when the heating resistor 2 is pulse-driven, the temperature can be measured during the energization time of the pulse. Can not do it. Therefore, the measurement is performed only when the device is turned on in synchronization with the pulse, but the actual temperature of the heating resistor is an average temperature of on and off, and in the measurement only when the device is on, the temperature is higher than the average temperature. Therefore, it is necessary to consider that much.

  Next, a method for erasing the recording on the reversible recording medium using the heating head will be described. FIG. 7 is a schematic side view of the main part. The heating head A of the heating head module B is connected to a control circuit (not shown) through a main circuit board 12 (not shown). A circular rubber roller C, which is a rotating means, is arranged so as to face the heating resistor 2 of the heating head A. Any rotating means can be used as long as it is in the form of a roll. For example, the surface of a core material such as metal is coated with an elastic material having excellent heat resistance such as silicone rubber and a high friction coefficient. Those can be preferably used.

  Further, although not shown, a position adjusting means for adjusting the positional relationship between the rubber roller C and the heating head A is provided. The position adjusting means is not particularly limited, and it is widely used as long as it can move relatively horizontally in a direction substantially perpendicular to the perpendicular line from the rotation shaft of the rubber roller C to the heating resistor 2 of the heating head A. For example, if a ball screw is screwed to the mounting base 15 of the heating head module B and the ball screw is connected to the stepping motor via the reduction gear, the rotation of the ball screw accompanying the rotation of the stepping motor The heating head A can be moved horizontally by a predetermined dimension. However, the positional relationship between the heat generating portion and the rubber roller C can also be changed by rotating the heating head A around the rotation axis of the rubber roller C.

  Then, as shown in FIG. 7, a medium D for erasing the recording such as a thermoreversible recording medium (rewritable sheet, rewritable card) is passed between the heating head A and the rubber roller C so that the medium D becomes a roller. When passing through the portion pressed by C, the temperature can be raised and erased. Even before being pressed by the roller C, the entire head substrate 1 has risen to a substantially predetermined temperature, so that it has been heated and the corresponding temperature has also increased even before being pressed by the roller C. For this reason, the surface temperature of the head substrate 1 does not decrease so much even if pressed, and even if it decreases, the amount of heat is immediately replenished from the surroundings and the temperature does not decrease locally.

  As described above, since the heat capacity of the temperature rising portion is increased by using the heating head of the present invention, the temperature of the heating resistor is maintained even when recording is erased by moving the medium at a high speed. The medium can be stably heated without sudden drop and uneven heating. As a result, it is not necessary to apply a large input to the heating resistor, and it is not necessary to apply a large input. it can.

It is a plane explanatory view of a head substrate showing one embodiment of a heating head of the present invention, an explanatory view of a plane and a bottom in a state where an electrode is formed, and a cross sectional explanatory view of a head substrate. FIG. 2 is an explanatory view of a plane and a cross section in a state where the heating head of FIG. 1 is attached to a film-like circuit board and unitized. FIG. 3 is a cross-sectional explanatory view of a state in which the heating head unit of FIG. 2 is assembled into a module. It is explanatory drawing of the cross section and plane of a modification of the heating head unit of this invention. It is a plane explanatory view of the modification of the shape of the resistor for heat generation in the heating head of the present invention. FIG. 2 is a diagram illustrating an example of a circuit that measures the temperature of a head substrate using the substrate temperature measuring resistor of FIG. 1. It is explanatory drawing of the example which heats a medium using the heating head of this invention. It is explanatory drawing which shows the structural example of the conventional heating head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Head substrate 2 Heat generating resistor 3 Substrate temperature measuring resistor 4 First electrode 5 Second electrode 6, 7 Substrate temperature measuring electrode 9 Film-like circuit board
10 Conductive adhesive layer
11 Insulation plate
12 Main circuit board
14 Heat-resistant soft adhesive layer A Heating head B Heating head module C Roller D Medium

Claims (10)

A rectangular head substrate having a width of at least 5 mm and extending in the longitudinal direction, and a belt-like heating resistor provided on the upper surface side of the head substrate and formed at least one along the longitudinal direction of the head substrate And a first electrode and a second electrode that are respectively electrically connected to both ends of the heating resistor. The heating resistor is 60 with respect to the width of the head substrate. %. A heating head provided with a trimming resistor provided directly on the surface of the head substrate so as to occupy a width of at least% and connected in parallel with the heating resistor .   The heating head according to claim 1, wherein a substrate temperature measuring resistor is directly provided on the surface of the head substrate on an upper surface side or a lower surface side of the head substrate.   The heating head according to claim 1, wherein a heat insulating layer is provided on a lower surface side of the head substrate. When the first and second electrodes provided at the both end portions are divided and formed along the width direction of the head substrate, a heating medium is pressed against the heating resistor portion on the upper surface side with a roller. heating head according to any one of claims 1 to 3 formed by forming a structure in which the first and second electrodes are not formed in the portion corresponding with the roller. A protective film is formed on the surface of the heating resistor on the upper surface side, and when the medium to be heated is pressed against the heating resistor part with a roller, the protective film on the portion where the roller hits the surrounding film is thicker than the protective layer on the heat generating resistor claims 1 composed to heating head according to any one of 4. The lower surface of the head substrate heating head according to any one of claims 1 to 5, the heating head unit film circuit board for drawing said first and second electrodes is formed by sticking. A heating head module in which the film-like circuit board of the heating head unit according to claim 6 is bonded to the circuit board with a heat-resistant soft adhesive via a heat insulating plate. The lower surface of the head substrate heating head according to any one of claims 1 to 5, the heating head unit insulating substrate for circuit board mounting the insulation adhesive is is adhered. The heating head unit according to claim 8 , wherein the insulating substrate for mounting the circuit board is divided into a plurality of parts in the longitudinal direction of the heating head. Heating head module insulating substrate is mounted to a circuit board for a circuit board mounting the heating head unit according to claim 8 or 9.

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