JP2006007665A - Thermal printer and head cleaning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain both diameter enlargement of a platen roller and miniaturization of a thermal head in a thermal printer which cleans the thermal head by moving the platen roller in a sub scanning direction, and also to prevent a breakage of the thermal head. <P>SOLUTION: A head shifting mechanism is provided which shifts the thermal head 28 between a first position and a second position. At the first position, a normal (n) extending from the rotation axis of the platen roller 32 toward an intersection between the platen roller 32 and the thermal head 28, and a head substrate where each heating element is formed are made nearly orthogonal to each other. At the second position, the head substrate is inclined by a predetermined angle to the normal (n). The thermal head 28 is set at the first position when carrying out image recording. The thermal head 28 is set at the second position when carrying out cleaning. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermal printer that cleans dirt adhering to a thermal head and a head cleaning method thereof.

  As one of thermal printers, there is known a thermal printer that records an image by heating a thermal recording paper that self-colors by thermal energy with a thermal head. A heat-sensitive recording paper has a plurality of heat-sensitive color-developing layers that are colored in cyan, magenta, and yellow on a support, and a protective layer that protects the heat-sensitive color-developing layer in that order. ), The heat sensitivity is lower, and the uppermost layer (yellow) and the intermediate layer (magenta) heat-sensitive color-developing layer are given fixing property to ultraviolet rays.

  As shown in FIG. 5, the thermal head 80 is provided with a ceramic substrate 82 in which a plurality of heating elements 81 are linearly formed along a direction orthogonal to the drawing, and a driver IC 83 that drives each heating element 81. A printed board 84 that controls the thermal head 80, an aluminum board 85 that holds the ceramic board 82 and the printed board 84, and a head cover 87 that is fixed to the aluminum board 85 via screws 86 and protects the driver IC 83. ing.

  A platen roller 90 is provided at a position facing each heat generating element 81 of the thermal head 80. Each thermal recording paper 92 is sandwiched between the thermal head 80 and the platen roller 90 and conveyed to the right in the figure. By causing the heating element 81 to generate heat, the heat-sensitive coloring layer of each color is colored and a color image is recorded. In addition, in order to stabilize the contact state between each heating element 81 and the thermal recording paper 92, the ceramic substrate 82 is formed with a so-called partial glaze 82a in which a part of the surface is raised on a cylindrical protrusion, and each heating element is formed. The element 81 is disposed near the apex of the partial glaze 82a.

  When the thermal head 80 records an image on the thermal recording paper 92, each heating element 81 reaches a high temperature, so that the protective layer formed on the surface of the thermal recording paper 92 is softened, and a part thereof melts and partially glazes. It adheres to the peripheral surface of 82a. This adhering matter is a factor that deteriorates the image quality by obstructing the contact state between each heating element 81 and the thermal recording paper 92. Therefore, for example, various methods for cleaning the thermal head 80 by feeding a cleaning sheet having a surface coated with an abrasive instead of the thermal recording paper 92 have been proposed.

  Moreover, the deposits are hardened and hard to remove as the temperature of the thermal head 80 decreases. Patent Document 1 discloses a method for efficiently removing hardened deposits by moving the platen roller 90 in the sub-scanning direction (left-right direction in the figure) along the curved surface of the partial glaze 82a.

  By the way, when the diameter of the platen roller 90 is increased, the contact state between each heating element 81 and the thermal recording paper 92 is stabilized, and the image quality of the recorded image can be improved. Further, the cost can be reduced by downsizing the thermal head 80. However, in such a case, if the platen roller 90 is moved in the sub-scanning direction as described in Patent Document 1, the platen roller 90 and the head cover 87 may come into contact with each other.

  As a solution to this problem, there is a method of securing a clearance between the head cover 87 and the platen roller 90 by attaching the thermal head 80 obliquely (see FIG. 6) as known in the above-mentioned Patent Document 2.

JP 2001-150708 A JP-A-6-336041

  Generally, rubber having a high friction coefficient is used on the outer periphery of the platen roller 90 in order to prevent the thermal recording paper 92 from slipping. This rubber has elasticity, and has a nip width L that is elastically deformed along the curved surface of the partial glaze 82a by pressing of the thermal head 80, as shown in FIG. When the thermal head 80 records an image on the thermal recording paper 92, the platen roller 90 and the thermal recording paper 92 heated by each heating element 81 are softened, and elastic deformation occurs as shown in FIG. 7B. As a result, the nip width L increases. When the thermal head 80 is attached obliquely as in the above-mentioned Patent Document 2, the thermal recording paper 92 or the platen roller 90 which is deformed when the nip width L is expanded is applied to the end 80a of the thermal head 80. Since the edge 80a receives a force at the edge of the glaze 82a that receives a force on a curved surface, the stress concentrates, causing a problem that the glaze 82a or the ceramic substrate 82 is damaged.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a thermal printer and a thermal head cleaning method in which both the increase in the diameter of the platen roller and the miniaturization of the thermal head are prevented and the thermal head is prevented from being damaged. The purpose is to provide.

  In order to achieve the above object, a thermal printer according to the present invention includes a partial glaze having a cylindrical ridge formed in the main scanning direction, and a plurality of heating elements arranged linearly along the vicinity of the apex of the partial glaze. A thermal head provided on a head substrate facing a recording material conveyance path pressed against each of the heating elements, a driver IC for driving each of the heating elements and a head cover for protecting the driver IC; A platen roller provided at a position facing each heating element and sandwiching the recording material together with each heating element, and a contact between the cleaning material and the partial glaze fed instead of the recording material when cleaning the thermal head A platen that reciprocates the platen roller in a sub-scanning direction substantially perpendicular to the main scanning direction so as to widen the range. A moving mechanism, a first position where the partial glaze is pressed against the recording material during image recording, and the partial glaze is pressed against the cleaning material during cleaning of the thermal head. And a head displacement mechanism for displacing the thermal head between a second position where the distance between the head cover and the platen roller is widened.

  The first position is a position where a perpendicular extending from the rotation axis of the platen roller toward the intersection of the platen roller and the thermal head and the head substrate are substantially orthogonal to each other, and the second position is It is preferable that the head substrate is inclined at a predetermined angle with respect to the perpendicular.

  The head cleaning method of the present invention includes a cylindrical glaze formed in the main scanning direction, a plurality of heating elements arranged linearly along the vicinity of the apex of the partial glaze, A thermal IC provided on a head substrate facing a conveying path of a recording material pressed against each of the heating elements, a driver IC that drives the heating elements, and a head cover that protects the driver IC; and each of the heating elements A platen roller that is provided at a facing position and sandwiches the recording material together with each of the heating elements, and the head cover is separated from the platen roller than the first position where the thermal head is pressed against the recording material during image recording. Displacement to a second position that separates the cleaning material fed in that state with the partial glaze and the platen roller Pinching and carrying out head cleaning while reciprocating said platen roller in the sub-scanning direction.

  According to the thermal printer and the head cleaning method of the present invention, the first position where the partial glaze is pressed against the recording material at the time of image recording, and the partial glaze are pressed against the cleaning material at the time of cleaning the thermal head. Since the head displacement mechanism for displacing the thermal head between the second position where the distance between the head cover and the platen roller is wider than the first position is provided, the thermal head is in the second position when cleaning is performed. Since the interval between the thermal head and the platen roller is widened, it is possible to achieve both the enlargement of the diameter of the platen roller and the miniaturization of the thermal head.

  Further, if the first position where image recording is performed is a position where the perpendicular extending from the rotation axis of the platen roller toward the intersection of the platen roller and the thermal head and the head substrate are substantially orthogonal, the elastically deformed recording material or platen Since the roller does not hit the end of the thermal head, the thermal head can be prevented from being damaged.

  FIG. 1 is an explanatory diagram schematically showing the configuration of a color thermal printer (thermal printer) 10 to which the present invention is applied. The color thermal printer 10 is loaded with a long thermal recording paper (recording material) 12 wound in a roll. As is well known, the heat-sensitive recording paper 12 has a cyan heat-sensitive color forming layer, a magenta heat-sensitive color developing layer, and a yellow heat-sensitive color developing layer sequentially provided on a support. The yellow thermosensitive coloring layer as the uppermost layer has the highest thermal sensitivity and develops yellow with a small amount of thermal energy, and the cyan thermosensitive coloring layer as the lowermost layer has the lowest thermal sensitivity and develops into cyan with a large thermal energy. In addition, the yellow thermosensitive coloring layer and the magenta thermosensitive coloring layer have a light fixing property that loses the coloring ability when irradiated with light of a specific frequency. It is fixed by light when irradiated with light, and the magenta thermosensitive coloring layer is fixed by being irradiated with near ultraviolet rays of about 365 nm.

  A paper feed roller 14 that rotates and draws out the thermal recording paper 12 to a conveyance path 15 (shown by a two-dot chain line in the figure) is provided at a position where it contacts the thermal recording paper 12 wound in a roll. The conveyance path 15 is composed of, for example, a plurality of roller pairs and guide plates, and guides the drawn thermal recording paper 12. Further, on the downstream side (right side in the figure) of the paper feed roller 14, a pair of transport rollers 20 including a capstan roller 16 and a pinch roller 18 are arranged, and the thermal recording paper 12 drawn by the paper feed roller 14. Is sent further downstream.

  The paper feed roller 14 and the capstan roller 16 are rotationally driven in both forward and reverse directions by a transport motor 22 that is a pulse motor, and transport the thermal recording paper 12 in the A direction that is the feed direction and the B direction that is the return direction. The conveyance motor 22 is connected to a system controller 26 that controls the entire color thermal printer 10 via a motor driver 24, and the rotation amount and the rotation speed are counted by counting drive pulses that the system controller 26 applies to the conveyance motor 22. And the position of the thermal recording paper 12 and the transport amount are specified.

  A thermal head 28 for recording an image on the thermal recording paper 12 is provided on the downstream side of the conveying roller pair 20. As shown in FIG. 2, the thermal head 28 includes a partial glaze 60 having a cylindrical protrusion formed in the main scanning direction and a plurality of heating elements 61 arranged linearly along the vicinity of the apex of the partial glaze 60. In addition, a driver IC 62 that drives each of the heat generating elements and a head cover 63 that protects the driver IC 62 are provided on a head substrate 64 that faces the conveyance path 15 of the thermal recording paper 12 that is pressed against the heat generating elements 61. ing.

  The head substrate 64 includes a ceramic substrate 65 on which the partial glaze 60 and each heating element 61 are formed, a printed substrate 66 to which a driver IC 62 is attached, and an aluminum substrate 67 that holds the ceramic substrate 65 and the printed substrate 66. It is configured. Also, a hinge 67 a that rotatably holds the thermal head 28 is formed at one end of the aluminum substrate 67.

  Each heating element 61 and the driver IC 62 are connected via a conductive layer 68 formed on the upper surface of the ceramic substrate 65 and a jumper wire 69. The driver IC 62 and the jumper wire 69 are protected resin 70 that prevents disconnection and the like. Covered with.

  The head cover 63 is formed by punching a metal plate such as aluminum or stainless steel and bending it into a substantially triangular shape, and has a mounting stay 72 punched from the inclined surface 71 and molded into a substantially L shape. The head cover 63 protects the driver IC 62 and guides the thermal recording paper 12 to each heat generating element 61 on the inclined surface 71. The head cover 63 is fixed to the aluminum substrate 67 by screws 73 that fasten the attachment stay 72 and the printed circuit board 66 together.

  The thermal head 28 is connected to the head controller 30. The head control unit 30 converts the image data input from the system controller 26 into a drive signal after performing, for example, a temperature correction process, and sends the drive signal to the thermal head 28.

  A platen roller 32 that sandwiches the thermal recording paper 12 together with the thermal head 28 is provided at a position facing each heating element 61. The platen roller 32 is driven to rotate in accordance with the conveyance of the thermal recording paper 12 and stabilizes the contact state between the thermal recording paper 12 and each heating element 61. The platen roller 32 is provided with a platen moving mechanism 34 for cleaning the thermal head 28 by moving the platen roller 32 in the vertical direction and the sub-scanning direction (left-right direction in the figure). The platen moving mechanism 34 is configured by, for example, a combination of an electric motor such as a motor or an actuator and a transmission member such as a cam or a gear. The combination of the electric motor and the transmission member may be any configuration as long as it moves the platen roller 32 in the vertical direction and the sub-scanning direction. The platen moving mechanism 34 is connected to the system controller 26, and the operation is controlled by the system controller 26.

  Further, in the thermal head 28, a perpendicular line n extending from the rotation axis of the platen roller 32 toward the intersection of the platen roller 32 and the thermal head 28 and a head substrate 64 on which the respective heating elements 61 are formed are substantially orthogonally crossed. A head displacement mechanism 36 that displaces the thermal head 28 between a position (see FIG. 3A) and a second position (see FIG. 3B) in which the head substrate 64 is inclined at a predetermined angle with respect to the normal n. It is attached. The head displacement mechanism 36 is configured by, for example, a combination of an electric motor such as a motor or an actuator and a transmission member such as a cam or gear, and the thermal head 28 is positioned between a first position and a second position about a hinge 67a. Move with. The combination of the electric motor and the transmission member may be any configuration as long as the thermal head 28 is moved between the first position and the second position. The head moving mechanism 36 is connected to the system controller 26 and its operation is controlled by the system controller 26. The system controller 26 places the thermal head 28 in the first position when performing image recording, and places the thermal head 28 in the second position when cleaning the thermal head 28.

  On the downstream side of the thermal head 28, a conveyance roller pair 42 including a capstan roller 38 and a pinch roller 40 is provided in the same manner as the conveyance roller pair 20. The conveyance roller pairs 20 and 42 are not limited to the illustration, and may be provided on the conveyance path 15 of the thermal recording paper 12 as necessary.

  An optical fixing device 44 for optically fixing the thermal recording paper 12 is provided on the downstream side of the conveying roller pair 42. The light fixing unit 44 includes a yellow ultraviolet lamp 46 for fixing the yellow thermosensitive coloring layer, a magenta ultraviolet lamp 48 for fixing the magenta thermosensitive coloring layer, and a reflector 50 covering the back thereof, and a lamp driver 52. Accordingly, the ultraviolet lamps 46 and 48 are driven. The lamp driver 52 is connected to the system controller 26 and the operation is controlled by the system controller 26.

  On the downstream side of the optical fixing unit 44, a cutter 54 that cuts a recorded portion of the thermal recording paper 12 on which image recording has been completed into one sheet, and the thermal recording paper 12 that has been cut by the cutter 54 is color thermal. A discharge port 56 for outputting to the outside of the printer 10 is provided. The unrecorded portion of the thermal recording paper 12 is conveyed in the B direction and rewound into a roll.

  Next, the operation of the color thermal printer 10 having the above configuration will be described. The system controller 26 instructed to record an image by the user drives the head displacement mechanism 36 to displace the thermal head 28 to the first position, and drives the platen moving mechanism 34 to heat the thermal head 28 together with the thermal head 28 at the first position. The platen roller 32 is moved to an appropriate position where the recording paper 12 is to be sandwiched.

  The system controller 26 that has moved the thermal head 28 and the platen roller 32 drives the conveyance motor 22 via the motor driver 24 to pull out the thermal recording paper 12 wound in a roll shape and to input an image input by the user. Data is output to the head controller 30. The head control unit 30 creates a drive signal for driving the thermal head 28 based on the input image data, and outputs this drive signal to the thermal head 28. The thermal head 28 causes each heating element 61 to generate heat in accordance with the drive signal, and performs image recording on the drawn thermal recording paper 12.

  Image recording on the thermal recording paper 12 is performed from a yellow thermal coloring layer having high thermal sensitivity. The thermal recording paper 12 having an image recorded on the yellow thermal coloring layer is sent to the optical fixing device 44, and the yellow thermal coloring layer is fixed by the ultraviolet lamp 46 for yellow. The thermal recording paper 12 on which the yellow thermosensitive coloring layer is fixed is sent again to the thermal head 28, and image recording on the magenta thermosensitive coloring layer, fixing of the magenta thermosensitive coloring layer, and image recording on the cyan thermosensitive coloring layer are sequentially performed in the same manner. Thus, the image recording on the thermal recording paper 12 is completed. The recorded portion of the thermal recording paper 12 on which image recording has been completed is cut out by the cutter 54 and then output from the discharge port 56 to the outside of the color thermal printer 10.

  On the other hand, the system controller 26 instructed by the user to clean the thermal head 28 drives the head displacement mechanism 36 to displace the thermal head 28 to the second position. When cleaning the thermal head 28, instead of the thermal recording paper 12, for example, a cleaning sheet (cleaning material) whose surface is coated with an abrasive is fed. The system controller 26 drives the platen moving mechanism 34 to move the platen roller 32 to an appropriate position where the cleaning sheet should be held together with the thermal head 28 in the second position.

  The system controller 26 that has moved the thermal head 28 and the platen roller 32 drives the conveyance motor 22 via the motor driver 24 and sends the cleaning sheet to the thermal head 28.

  The system controller 26 that has sent the cleaning sheet until the thermal head 28 and the platen roller 32 are nipped drives the platen moving mechanism 34 to reciprocate the platen roller 32 in the sub-scanning direction. The platen roller 32 moves so as to follow the surface shape of the partial glaze 60 to bring the cleaning sheet into sliding contact with the partial glaze 60 and clean the dirt adhering to the peripheral surface of the partial glaze 60.

  The cleaning sheet after cleaning the partial glaze 60 of the thermal head 28 is continuously conveyed in the A direction and discharged from the discharge port 56 to the outside of the color thermal printer 10.

  According to the color thermal printer 10 of this embodiment, when recording an image on the thermal recording paper 12, the thermal head 28 extends from the rotation axis of the platen roller 32 toward the intersection of the platen roller 32 and the thermal head 28. Since the perpendicular n and the head substrate 64 on which each heating element 61 is formed are in the first position that is substantially orthogonal, the thermal recording paper 12 and the platen roller 32 even when the nip width L is widened by thermal energy during image recording. Is not applied to the end of the thermal head 28, and the thermal head 28 can be prevented from being damaged.

  On the other hand, when cleaning the thermal head 28, the thermal head 28 is set to the second position where the head substrate 64 is inclined at a predetermined angle with respect to the perpendicular n, so that the clearance between the head cover 65 and the platen roller 32 is reduced. Even if the platen roller 32 is expanded and moved in the sub-scanning direction, there is no fear of coming into contact with the head cover 63, and both the increase in the diameter of the platen roller 32 and the miniaturization of the thermal head 28 can be achieved.

  Further, since the thermal head 28 does not generate heat during cleaning, the nip width L is narrow. Therefore, by appropriately setting the amount of movement of the platen roller 32 that is moved by the platen moving mechanism 34, only the dirt can be removed without the thermal recording paper 12 or the platen roller 32 being applied to the end of the thermal head 28. .

  The present invention may be used for purposes other than cleaning, such as when the characteristics are improved by changing the angle of the thermal head 28. For example, it is known that water vapor is generated from the thermal recording paper 12 when image recording is performed using the thermal head 28. If the water vapor condenses on the downstream end of the partial glaze 60, the water droplets are transferred to the thermal recording paper 12 to increase the surface irregularities and become one of the factors that degrade the gloss of the recorded image.

  When recording the image on the cyan thermosensitive coloring layer, if the thermal head 28 is displaced in the direction opposite to the second position (see FIG. 4) using the head displacement mechanism 36, the downstream end of the partial glaze 60 is obtained. And the heat-sensitive recording paper 12 are spread by an angle θ, making it easier for water vapor to escape. Thereby, it can suppress that the glossiness of a recording image deteriorates by the water droplet which condensed.

  In the above-described embodiment, as an example of a thermal printer, a thermal recording paper that self-colors by heating is used, and a thermal printer that presses a thermal head against the thermal recording paper to record an image is shown. The present invention may be applied to other thermal printers such as a thermal transfer printer that heats the ink and transfers the ink onto a recording sheet to record an image.

It is explanatory drawing which shows the structure of a color thermal printer roughly. It is sectional drawing which shows the structure of a thermal head roughly. It is explanatory drawing which shows the 1st position and 2nd position of a thermal head. It is explanatory drawing which shows the other use of this invention. It is explanatory drawing which shows the structure of the conventional thermal head roughly. It is explanatory drawing which shows the structure of the conventional thermal head roughly. It is explanatory drawing which shows the difference in the elastic deformation of a recording material and a platen roller.

Explanation of symbols

10 Color thermal printer (thermal printer)
12 Thermal recording paper (recording material)
15 Transport Path 28 Thermal Head 32 Platen Roller 34 Platen Movement Mechanism 36 Head Displacement Mechanism 60 Partial Glaze 61 Heating Element 62 Driver IC
63 Head cover 64 Head substrate

Claims (3)

A partial glaze with cylindrical ridges formed in the main scanning direction, a plurality of heating elements arranged linearly along the vicinity of the apex of the partial glaze, a driver IC that drives each of these heating elements, and this A thermal head provided on a head substrate facing a conveying path of a recording material pressed against each of the heating elements, and a head cover for protecting the driver IC;
A platen roller provided at a position facing each of the heating elements, and sandwiching a recording material together with the heating elements;
The platen roller is reciprocated in the sub-scanning direction substantially perpendicular to the main scanning direction so that the contact range between the cleaning material fed instead of the recording material and the partial glaze when cleaning the thermal head is expanded. A platen moving mechanism
A first position where the partial glaze is pressed against the recording material during image recording, and the partial glaze is pressed against the cleaning material during cleaning of the thermal head, and the head cover is positioned more than the first position. A thermal printer comprising: a head displacing mechanism for displacing the thermal head between a second position where the distance from the platen roller is widened.   The first position is a position at which a perpendicular extending from the rotation axis of the platen roller toward the intersection of the platen roller and the thermal head and the head substrate are substantially orthogonal to each other, and the second position is at the perpendicular. 2. The thermal printer according to claim 1, wherein the head substrate is at a position inclined by a predetermined angle. A partial glaze with cylindrical ridges formed in the main scanning direction, a plurality of heating elements arranged linearly along the vicinity of the apex of the partial glaze, a driver IC that drives each of these heating elements, and this A head cover that protects the driver IC is provided at a position facing the heating element, a thermal head provided on a head substrate facing a conveyance path of the recording material pressed against the heating elements, and the heating elements. In a thermal printer head cleaning method including a platen roller that sandwiches a recording material together with an element,
The thermal head is displaced to a second position where the head cover is separated from the platen roller, rather than a first position where the thermal head is in pressure contact with the recording material during image recording. A head cleaning method for a thermal printer, wherein the head cleaning is performed while being sandwiched between platen rollers and reciprocating the platen roller in the sub-scanning direction.

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