JP5150071B2 - Manufacturing method of heating head - Google Patents

Description

The present invention erases the recording of a reversible thermosensitive recording medium such as a rewritable sheet, or prints on a printed material such as paper, plastic, metal, etc., a card, a seal, etc. by a printing method such as a thermal transfer method or an ink jet method. Prior to this, a heating head suitable for heating when an undercoat is applied to the surface of the substrate on which the image is to be printed or an overcoat is applied to the entire print surface or a limited surface after the image is printed. of relates to the production how relates especially large size of the reversible thermosensitive recording preparation how the recording and erasing heating head suitable for such a medium.

  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. 2. Description of the Related Art Reversible thermosensitive recording media (rewritable recording media) provided with a recording portion composed of a reversible thermosensitive recording layer have been widely used.

  Such a thermoreversible recording medium is colored by being heated to a certain temperature (for example, 180 ° C.) or higher, and rapidly cooled to, for example, 80 ° C. or lower, and raised to a temperature lower than the coloring temperature (for example, 120 to 160 ° C.). Is completely erased. 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 the upper surface of a head substrate 11 made of alumina or the like, a strip-shaped heating resistor (layer) 13 is formed on the glass layer, and electrodes (layers) are formed on both ends thereof. ) 12 and 12 are provided. The electrode 12 is led out to the lower surface of the head substrate 11 by wiring or the like, and is connected to a wiring substrate or the like provided on the lower surface side of the head substrate 11 so as to apply a voltage. As a result, a voltage is applied to both ends of the heating resistor 13 via the electrodes 12 and 12, and the resistor generates heat when current flows, and the temperature of the heating resistor 13 can be controlled by the amount of current. it can. The recording can be erased by passing a rewritable recording medium such as a card while pressing the heating resistor 13 with a roller (not shown).
JP 2004-268256 A

  As described above, since the rewritable recording medium is erased by passing the rewritable recording medium by passing the rewritable recording medium by heating while heating the heating resistor, the rewritable recording medium was first used. In the case of the card size, the heating resistor may be as short as about 56 mm. However, the recording medium size is increased due to the diversification of the use of the rewritable recording medium in recent years. Therefore, a long heating resistor (for example, about 160 to 260 mm) is required.

  However, since the heating resistor is generally formed by applying a resistive paste by screen printing and firing, the longer the heating resistor is formed, the more the sheet resistance value depends on the location in the length direction. There is a problem that variations tend to occur and temperature unevenness during heat generation tends to occur. In addition, there is a problem that even if the sheet resistance of the heating resistor itself is substantially uniform, the temperature of the long heating resistor may not be uniform over the entire length of the device due to the equipment on which the heating head is mounted. In the case of a heating head using a heating resistor, it is extremely difficult to obtain a uniform heating temperature over the entire length of the heating resistor.

  As described above, when the high temperature portion and the low temperature portion are partially generated in the longitudinal direction of the belt-like heating resistor and the heating temperature varies (unevenness), for example, when erasing the recording on the rewritable recording medium, Some parts can be erased and some cannot.

  Therefore, the present invention has been made in view of such a situation, and an object of the present invention is to provide a method of making the heat generation temperature uniform throughout the longitudinal direction even when the length of the heating resistor is increased. To do.

  When the present inventors form a resistor for heating (a heating resistor layer) by pattern-printing a resistor paste in a band shape by screen printing and then firing, the cross-sectional shape in the width direction is the thickness of the central portion. We focused on the fact that it is formed in a substantially mountain shape (a bowl shape) with a large thickness and a small thickness at both ends. Further, when a heated object such as a rewritable recording medium is heated by the heating resistor layer, the heating object is brought into contact with the central portion (top) of the heating resistor layer or a protective coating layer immediately above the heating resistor layer. Also focused. Therefore, by erasing the recording on the rewritable recording medium, the resistance value is adjusted by partially removing both ends of the heating resistor that has little influence on the heating of the heated object in the longitudinal direction and the heating temperature is adjusted. It has been found that the variation in heat generation temperature can be made uniform without affecting it.

That is, the heating head manufacturing method of the present invention includes a printing process in which a resistive paste for heating resistor and temperature measurement is printed in parallel in a strip shape on a support substrate, and a resistance paste patterned on the support substrate. a firing step of the sintering to the heating resistor layer and the temperature-measuring resistor layer, the temperature measuring resistor layer, by dividing the longitudinal direction of the temperature measuring resistor layer into a plurality, each segment Forming the electrodes so as to measure the temperature of the heat generating resistor layer, and detecting the temperature of the heat generating resistor layer corresponding to the section, while extending the widthwise end of the fired resistor layer And a heat generation temperature adjusting step for adjusting the heat generation temperature in the length direction of the heating resistor layer by partially removing the heat generation resistor layer along the vertical direction.

  In the heating head manufacturing method, the heat generation temperature adjustment step is performed based on the heat generation temperature distribution in the length direction of the belt-shaped heating resistor layer measured in advance, and the widthwise ends of the belt-shaped heating resistor layers are lengthened. You may carry out by removing partially along a direction.

The heating resistor layer formed on the supporting substrate is, the cross-sectional shape in the strip and the width direction is formed in a substantially mountain shape.

In another embodiment of the heating head manufacturing method of the present invention, a heating process and a temperature measurement resistance paste are printed on a support substrate in parallel in a strip pattern, and the pattern printing is performed on the support substrate. A firing step of firing the resistor paste to form a heating resistor layer and a temperature measuring resistor layer, and the temperature measuring resistor layer, the length direction of the temperature measuring resistor layer is divided into a plurality of directions. A step of forming electrodes so that the temperature in each section can be measured ; and the length direction of the heating resistor layer in which the temperature of the heating resistor layer corresponding to the section is measured in advance by the resistor layer for temperature measurement based on the heat generation temperature distribution in, by partially removed along the edge in the width direction of the heat generating resistor layer of the fired strip lengthwise, heat generation in the longitudinal direction of the heating resistor layer exothermic temperature to adjust the temperature And a settling process.

  When the so-called thick film is formed on the heating resistor layer by pattern printing of a resistance paste and firing, the formation cross section is formed in a substantially mountain shape with a thick central portion and a thin end portion. When the heating resistor layer is formed in a strip shape by this thick film technology, the cross-sectional shape in the width direction is formed as an elongated layer having a substantially mountain shape or a bowl shape. The object to be heated, such as a sheet-like rewritable recording medium, is moved in a direction perpendicular to the length direction of the heating resistor layer having a band shape and a substantially mountain-like cross section, and directly to the heating resistor layer or through a protective coating layer. When heated by indirect contact, the central portion (top) in the width direction of the heating resistor layer is heated by directly or indirectly contacting the surface of the object to be heated. Since both end portions in the width direction of the layer are thinner than the central portion, they are not in contact with the surface of the object to be heated or are located away from each other, and there is an influence on the heating of the object to be heated compared to the central portion. small. In the method of the present invention, the heat generation temperature in the length direction is made closer to uniform by partially scraping off both ends or one end in the width direction of the belt-shaped heating resistor layer to adjust the resistance value, and heating Since the central part (heating part) in the width direction of the belt-shaped heating resistor layer, which is an important part that has a great influence on the temperature, is left as it is, the object to be heated can be heated at an extremely uniform temperature. is there.

  In addition, since both end portions in the width direction of the belt-like heating resistor layer are thin, when the partial heating is performed to adjust the heating temperature and the resistance value in the vicinity thereof is changed, the thickness is larger than the thick central portion. However, there is an advantage that it is easy to finely adjust the resistance value, which is convenient for adjusting the heat generation temperature.

As a method of partially removing (scraping) the end portion in the width direction of the belt-like heating resistor layer along the length direction, for example, in addition to the removal shape such as a line shape, a dot shape, or a combination thereof, the size thereof It can be performed by controlling the depth (large and small) and depth (shallow and deep), and the processing methods include, for example, sand blast polishing, ultrasonic polishing, laser grinding using a CO ₂ laser, YAG laser, needle Although known methods such as cutting with a thin cutting blade or rotating blade having a thin tip can be widely used, laser grinding is preferred because it is easy to control.

  Furthermore, when performing partial removal processing of the heating resistor layer on the basis of the heating temperature distribution in the length direction of the belt-like heating resistor layer measured in advance, the length of the temperature unevenness caused by the measured heating temperature distribution ( It is possible to perform processing after determining the removal position corresponding to the change amount (adjustment amount) and the removal shape (shape and size) and the removal depth. During this removal processing, changes in temperature and resistance value may be monitored. The temperature is measured by, for example, heating the heating resistor layer, measuring the temperature by a thermal infrared image analysis method (thermograph), and measuring the resistance value of the temperature measuring resistor layer formed along the heating resistor layer. It can be carried out. In addition to the above method, the monitoring can be performed while measuring a change in the full length resistance value using an electrode layer for energization.

  According to the present invention, the variation (unevenness) in the heat generation temperature over the entire length of the belt-shaped heat generating resistor layer can be reduced or eliminated, so that a long width can be heated at a substantially uniform temperature. A heating head suitable for an object can be provided.

  If the heating head according to the present invention is used, it can be heated at a substantially uniform temperature even in a wide width, so that the erasing unevenness of recording on the rewritable recording medium can be eliminated and almost complete erasing can be performed. In addition, even when the undercoat or overcoat is formed on the surface of a wide-width substrate, heating can be performed at a substantially uniform temperature, so that a uniform coat without unevenness can be formed.

  Furthermore, since heating can be performed at a substantially uniform temperature over the entire length, the processing speed such as the speed of erasing the recording on the rewritable recording medium and the speed of heating when forming a layer such as an undercoat can be improved.

  Since the heat generation temperature can be adjusted over the entire length of the belt-shaped heat generation resistor layer, even the heat generation resistor layer formed under the same conditions can have different heat generation temperatures.

  Further, since the heat generation temperature can be partially changed, the recording layer of the rewritable recording medium can be partially different, which can contribute to diversification of the rewritable recording medium.

Hereinafter, with reference to the drawings about the manufacture how the heating head of the present invention will be described. FIG. 1 is a diagram for explaining an electrode layer forming step, and schematically shows a plan view showing a state in which an electrode layer 2 is formed on the upper surface of a head substrate (supporting substrate) 1. As shown in this figure, in consideration of productivity, a large substrate is used in which a plurality of head substrates 1 having a substantially rectangular planar shape are assembled. As will be described later, the slit grooves 1A partition each head substrate 1 as described later. The head substrate 1 can be individually made independent by folding. The electrode layers 2 and 2 are made of a good conductor such as a silver / palladium alloy with a reduced ratio of palladium (the resistance can be lowered as the amount of Ag increases) or an Ag—Pt alloy, and an electrode paste containing these alloys. After the pattern is printed by screen printing, it is dried and fired to form a pair at both ends of each head substrate 1.

  The head substrate 1 is made of a substantially rectangular plate having a length of about 220 mm, a width of about 12 mm, and a thickness of about 1.0 mm, for example, and has a certain degree of thermal conductivity, that is, a thermal conductivity of 0.5. ˜30 W / K · m, having heat resistance under heat generation temperature conditions during use, and having a surface on which a heating resistor layer to be described later is provided, such as alumina (thermal conductivity: 21 W / K Ceramics such as m), quartz glass (thermal conductivity: 1.4 W / K · m), glass (thermal conductivity: 0.8 W / K · m), and the like can be used. This is because if the thermal conductivity is too low, there is a risk of overheating (overheating) in the case of continuous operation, and if the thermal conductivity is too high, the amount of heat of the heating resistor layer tends to escape. From this viewpoint, a resin material, a metal plate made of stainless steel having an insulating film on the surface, a glass material, or the like can also be used. In the present embodiment, an alumina substrate is used as the head substrate 1.

  The electrode layers 2 and 2 are pulled out to the lower surface side through the side surface or through hole of the head substrate 1 and mounted on the wiring substrate to connect to the terminals of the wiring substrate and connect to an external power source. It has become a structure.

  Next, FIG. 2 shows a heating resistor layer forming step, and schematically shows a plan view showing a state in which the heating resistor layer 3 is formed on the upper surface of the head substrate 1. The heating resistor layer 3 is formed in a strip shape along the longitudinal direction of the head substrate 1 so as to straddle the pair of electrode layers 2 and 2 formed on each head substrate 1. At this time, the electrode layers 2 and 2 at both ends are electrically connected so as to partially overlap both ends of the heating resistor layer 2.

  A glass layer (glaze layer) (thermal conductivity: 0.8 W / K · m) (not shown) is provided on the upper surface of the head substrate 1 as a base of the heating resistor layer 3 to a thickness of about 0.08 mm. The heating resistor layer 3 is provided thereon. In addition, the glaze layer may be formed on the entire lower layer as the same width or larger as the heating resistor layer 3 or may be formed only on the central portion in the width direction. It is preferable to form the same width.

The heating resistor layer 3 is formed by pattern printing a resistor paste containing, for example, Ag + Pd + glass or the like by screen printing, drying and baking. It is also possible to use a further added and RuO ₂ thereto. When made of an Ag—Pd alloy formed by firing, a sheet resistance of about 100 mΩ / Sq to about 500 mΩ / Sq is obtained (depending on the blending, amount of solid insulating powder, printing thickness, firing conditions, etc.), The resistance value and temperature coefficient can be changed by the ratio. The size of the heating resistor layer 3 is, for example, a straight line having a width of about 2.5 mm and a thickness of about 25 μm, a length of about 165 mm, and a sheet resistance value of about 40 mΩ resistance (total resistance of about 2.7Ω). ), The temperature coefficient of resistance is about 1500 ppm / ° C. (when the temperature changes by 100 ° C., the resistance value changes by 15%). The heat generation characteristics of the heat generating resistor layer 3 are not limited to this, and can be freely set. However, it is preferable that the temperature coefficient of resistance of the heat generating resistor layer 3 is positively higher, particularly a material of 1000 to 3500 ppm / ° C. Is preferably used for detecting the temperature using the heating resistor layer 3. The fact that the temperature coefficient of resistance is positively high means that the change in resistance value with respect to temperature change is large, so it is easy to estimate the actual heat generation temperature due to deviation from the reference resistance value by measuring the resistance value in a heated state. It can be performed well and is advantageous for the exothermic temperature adjustment process (removal process) described later. Even when the temperature is not directly measured by the heating resistor layer 3, the heating temperature can be measured by forming a temperature measuring resistor as described later.

  In this way, the heating resistor layer 3 formed by pattern printing of the resistance paste on the upper surface of the glaze layer (not shown) formed on the head substrate 1 and firing (thick film formation) is shown in FIG. 2 (schematically showing the II cross-sectional view of FIG. 2), the thickness of the central region 3A in the width direction is thicker than the thickness of both end regions 3B and 3B, and is substantially mountain-shaped in cross section. It is formed in a bowl shape. When the recording on the rewritable recording sheet R (refer to the alternate long and short dash line in the figure) is erased by heating using the heating resistor layer 3 having such a substantially mountain-shaped cross section, the direction orthogonal to the length direction of the heating resistor layer 3 Since the rewritable recording sheet R is heated while being moved against the heat generating resistor layer, the rewritable recording sheet is heated from the central region 3A of the heat generating resistor layer 3, and the both end portions are heated. Regions 3B and 3B (removable regions that will be described later) do not significantly affect the thermal erasure of the sheet. As described above, when the width d1 of the heating resistor layer 3 is about 2.5 mm, depending on the formation conditions of the heating resistor layer 3, the type of the rewritable recording sheet R, the pressing conditions at the time of heating erasure, etc. The width d2 of the central region can be about 2.0 mm, and the width of the end region 3B can be about 0.25 mm. Note that a plurality of heating resistor layers 3 may be stacked to form a stacked layer. That is, it can be formed by repeating the printing and drying of the resistance paste, followed by firing, thereby increasing the thickness and reducing the resistance value with the same material. At this time, by forming the upper layer with a width narrower than that of the lower layer, as shown in FIG. 4, the heating resistor layer 3 having a step-like or step-like band-like cross-sectional shape in the width direction is formed. You can also

  Next, a description will be given of a heat generation temperature adjustment process using both end regions 3B and 3B in the width direction of the heating resistor layer 3. FIG. FIG. 5 is a diagram schematically showing a plan view showing a state in which the removal groove 4 is formed in the end region 3B in the state of a large substrate, and FIG. 6 is a diagram showing the large substrate divided by the slit grooves 1A. FIG. 2A is a partial enlarged view of the heating resistor layer 3 including a portion where (a) a plan view, (b) a side view and (c) a removal groove 4 are formed.

  The removal process for reducing unevenness in the heat generation temperature is to apply power to the heat generating resistor layer 3 by energizing the electrode layers 3 and 3 to generate heat, while measuring the average temperature and temperature distribution in the length direction. You may perform based on the data measured beforehand. The average temperature and temperature distribution can be measured by, for example, a known thermal infrared image analysis method. Further, as an alternative method, it can be performed by estimating from the measured values of the total resistance value and the partial resistance value in consideration of the temperature coefficient of the heating resistor layer 3.

  In the present embodiment, the removal process is performed by using a YAG laser and dividing the heat generating resistor layer 3 into a plurality of regions to form, for example, dot-like or linear removal grooves 4. The removal groove 4 may completely remove the heating resistor layer 3 in the end region 3B, or may be removed so as to leave a lower layer portion. Here, the removal groove 4 is provided only in the end region 3B on one side, but the removal groove 4 may be provided in the end regions 3B and 3B on both sides as necessary. Further, it may be removed from the edge so as to be removed from the edge to narrow the width dimension of the heating resistor layer 3, and the removal groove 4 is provided so that a hole or a hole is formed in the end region 3B. You may do it. Alternatively, the removal processing may be performed after the heating resistor layer 3 is thinly coated with a green glass layer that absorbs laser light.

  The shape, size, and depth of the removal groove 4 differ depending on the temperature width (resistance value width) to be corrected and the material of the heating resistor layer 3, and can be determined based on experimental data or theoretical values of resistance value change. A series of heat generation temperature adjustment steps including the step of measuring the heat generation temperature of the belt-shaped heat generation resistor layer 3 and partially removing the end portion in the width direction of the heat generation resistor layer 3 is easily automated. be able to. Further, by performing removal processing with a laser, processing can be performed in a short time. Furthermore, the baking for forming the electrode layer 2 and the heating resistor layer 3 can be performed in a single step after the layers 2 and 3 are printed and dried.

  On the heating resistor layer 3 thus removed, a protective coating layer such as glass may be formed as necessary.

  The heating head thus formed is used, for example, by being mounted on a wiring board as a unit and then being used in a predetermined device.

  Next, another embodiment will be described. As shown in FIG. 7, in this embodiment, the resistor layer 6 for measuring the heat generation temperature of the belt-like heat generating resistor layer 3 is formed in parallel along the heat generating resistor layer 3 on the upper surface of the head substrate 1. Like to do.

  First, in the same manner as in the previous embodiment, the electrode layers 2 and 2 are formed by pattern printing, drying and firing on both ends of the upper surface of the head substrate 1 in the longitudinal direction. Further, the electrode layers 5A to 5E for the resistor layer 6 for temperature measurement are arranged in a line at predetermined intervals along the longitudinal direction at the position of the upper surface of the head substrate 1 shifted from the electrode layers 2 and 2. Pattern printing, drying and firing are arranged. The electrode layers 2 and 2 for the heating resistor layer 3 and the electrode layers 5A to 5E for the resistor layer 6 for temperature measurement can be simultaneously formed by printing and baking.

  Next, the heating resistor layer 3 and the temperature measuring resistor layer 6 are formed by pattern printing, drying and firing in a strip shape so as to be parallel to each other at a predetermined interval along the longitudinal direction of the head substrate 1. . The heating resistor layer 3 is formed linearly with the same size as in the above-described embodiment so as to straddle the electrode layers 2 and 2 at both ends of the head substrate 1, and the resistor layer 6 has a narrower width than this. It is formed in a straight line so as to connect the five electrode layers 5A to 5E. The resistor layer 6 is divided into four by the electrode layers 5 </ b> A to 5 </ b> E and is disposed to face the heating resistor layer 3. In the other embodiment, the resistor layer 6 is divided into four by the electrode layers 5A to 5E. However, the resistor layer 6 is not limited to this and may be divided into an appropriate number.

  And by applying a voltage to the heating resistor layer 3 and generating heat, by measuring the resistance value of each of the temperature measuring resistor layers 6 divided into four by the electrode layers 5A to 5E, The temperature distribution of the heating resistor layer 3 (the variation in the heating temperature) is obtained by knowing the heating temperature for each region obtained by dividing the heating resistor layer 3 into four in the length direction, and for each divided region based on this measurement result The removal groove 4 is formed in the end region 3B in the width direction of the sheet, and the removal process is partially performed to adjust the heat generation temperature in the entire length direction to be uniform. At this time, if the removal groove 4 is provided in the end region 3B on the temperature measurement resistor layer 6 side, the surface of the heated object is bent when the heated object such as a rewritable recording medium is heated. However, since it can prevent that a to-be-heated material contacts a process area (edge part area | region 3B, the removal groove | channel 4), and it can heat at predetermined | prescribed temperature, it is more preferable. For this reason, in the present invention, a removal processing region protection layer thicker than the thickness of the end region 3B may be provided along one side or both sides of the belt-like heating resistor layer 3.

  As described above, the resistor layer 6 for temperature measurement is preferably a material having a positive resistance temperature coefficient, for example, a material having a temperature of 1000 to 3500 ppm / ° C. in order to enable more accurate temperature measurement.

  In addition, the method using the resistor layer for temperature measurement is a technique disclosed in more detail in JP-A-2005-262850, JP-A-2005-305567, and the like.

  Thus, according to the present invention, even if the heating resistor layer 3 becomes longer, the entire length direction can be heated to a uniform temperature. Moreover, if a removal process is applied to partially increase the temperature, it is possible to generate heat at partially different temperatures.

It is explanatory drawing which shows the state which formed the electrode layer in the upper surface of a head substrate. It is explanatory drawing which shows the state which formed the heating resistor layer on the upper surface of the head substrate. It is explanatory drawing which shows the II cross section of FIG. It is explanatory drawing which shows the cross section in the width direction when heat-generating-resistor layer 3 is made into lamination | stacking of two layers. It is explanatory drawing which shows a mode that the removal groove | channel was formed in the edge part area | region of the width direction of a heating resistor layer. It is explanatory drawing which shows a part of the heating resistor layer containing the (a) plane, (b) side surface, and (c) removal groove formation part of the heating head manufactured by the method of embodiment. It is explanatory drawing which shows the plane of the heating head manufactured by the method of another embodiment. It is explanatory drawing which shows the structural example of the conventional heating head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Head substrate 2, 5A-5E Electrode layer 3 Heating resistor layer 3B Removal processable area | region 4 Removal groove | channel 6 Temperature measurement resistor layer

Claims (3)

A printing process in which a resistive paste for heating resistor and temperature measurement is printed in parallel in a strip shape on a support substrate; and
A firing step of firing a resistor paste patterned on a support substrate to form a heating resistor layer and a temperature measuring resistor layer;
Dividing the temperature measuring resistor layer into a plurality of length directions of the temperature measuring resistor layer and forming electrodes so that the temperature in each section can be measured; and
While detecting the temperature of the heating resistor layer corresponding to the section, the end of the fired strip-like heating resistor layer in the width direction is partially removed along the length direction, thereby generating the heat. And a heating temperature adjusting step for adjusting the heating temperature in the length direction of the resistor layer. A printing process in which a resistive paste for heating resistor and temperature measurement is printed in parallel in a strip shape on a support substrate; and
A firing step of firing a resistor paste patterned on a support substrate to form a heating resistor layer and a temperature measuring resistor layer;
Dividing the temperature measuring resistor layer into a plurality of length directions of the temperature measuring resistor layer and forming electrodes so that the temperature in each section can be measured; and
Based on the heat generation temperature distribution in the length direction of the heating resistor layer, the temperature of the heating resistor layer corresponding to the section measured in advance by the temperature measuring resistor layer , the fired belt-like heating resistor layer A heating temperature adjusting step for adjusting the heating temperature in the length direction of the heating resistor layer by partially removing the end in the width direction of the heating resistor layer ;
A method for manufacturing a heating head, comprising: 3. The method of manufacturing a heating head according to claim 1 , wherein the heating resistor layer formed on the support substrate is formed in a band shape and a cross-sectional shape in a width direction in a substantially mountain shape.

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