JPH08281979A - Line thermal head and thermal recorder - Google Patents

Abstract

PURPOSE: To make it easy to adjust alignment between the heat generating body of a line thermal head and a platen roller. CONSTITUTION: At least two or more pressure sensitive elements 11 are provided at both ends of the heat generating body 3 of a head, respectively in the direction of paper transfer (subsidiary scanning direction). When a thermal head 10 and a platen roller 6 are in a normal position, the distribution of pressure of the pressure-sensitive element 11 is symmetrical. However, when they are displaced from the normal position, the pressure distribution of the pressure- sensitive element 11 is not symmetrical. In consequence, detection and display of the distribution of the pressure of the pressure-sensitive element 11 allow an operator to know the amount and the direction of displacement from the display and adjust alignment easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line thermal head and a thermal recording device.

[0002]

2. Description of the Related Art First, an example of a thermal recording apparatus using a conventional thermal head will be described. FIG. 6 is a side view of a thermal recording apparatus using a conventional thermal head, and FIG. 7 is a perspective view of the thermal recording apparatus. 1 is a thermal head,
A plurality of heating elements 3 are arranged in a line on the substrate 2. Reference numeral 4 is a thermal paper 5 connected to a driving means (not shown).
Is a platen roller (4a is rubber and 4b is a core metal) that conveys the sheet. The platen roller is rotatably attached to the apparatus main body (not shown) through a bearing. Reference numeral 8 is a pressing spring for pressing the thermal head 1 against the platen roller 4.

At the time of recording, the thermal head 1 and the platen roller 4 are pressed against each other via the thermal paper 5, and the platen roller 4 connected to the driving means is rotated in the F direction so that the thermal paper 5
While the sheet is being conveyed, the heating element 3 is selectively heated to cause the heat-sensitive paper 5 to develop a color and recording is performed. At this time, the contact center between the platen roller 4 and the thermal head 1 is located at a desired position, that is, when the platen roller 4 is rotating, the heating element 3 of the thermal head 1 is in the contact portion (width m). Position (the platen roller 4 deforms differently when the platen roller 4 is stationary, so the dimensional relationship of each component is not determined so that the platen roller 4 has a desired positional relationship when rotating when stationary. It is shifted to the downstream side so that it has a desired positional relationship at the time of rotation, and the position and amount are the know-how of each device manufacturer.) ing.

By the way, the pressing force of the thermal head 1 and the platen roller 4 is in addition to the minimum pressure required to color the thermal paper 5 with one heating element 3, the warp of the thermal head 1 and the platen roller 4 Correction force against warpage (the mechanical warpage of the thermal head 1 and the platen roller 4 causes variations in the distribution of the pressing force in the row direction of the heating elements 3, and therefore the lowest pressure portion due to the variations causes the thermal paper 5 to develop color. It is necessary to correct the pressing force so that it does not fall below the required pressure) and platen roller 4
And the correction force for the reduction of the pressing force in the sheet conveying direction due to the mechanical displacement of the heating element 3 of the thermal head 1 (the pressing force is caused by the mechanical displacement of the platen roller 4 and the heating element 3 of the thermal head 1). It is necessary to increase the pressing force so that the pressure does not fall below the pressure required to color the heat-sensitive paper 5 even if the heat-sensitive paper 5 deviates from the center of the distribution in the transport direction.

Moreover, the width m of the contact portion is set so that the heat generating element 3 does not deviate from the width m of the contact portion even if there is a mechanical displacement between the platen roller 4 and the heat generating element 3 of the thermal head 1. Since it is necessary to take a certain amount of space, the normal thermal head 1 has a head size of 7.70 line / mm capable of printing, for example, A4 size, of about 2.5-
3.5kg (platen hardness about 40 degrees, platen diameter about φ12
It is general that the pressing condition is set to ~ 14 mm).

[0006]

However, in the above-mentioned conventional structure, the pressing force is forced to be set to the safe side, that is, to be higher, so that the load at the time of transporting the thermal paper 5 increases and the driving means for the platen roller 4 is increased. There is a problem in that each mechanical component needs to be strong due to the large size and the high pressing force, and each mechanical component becomes large and the entire apparatus becomes large.

It is considered that by using a type in which a fluid is enclosed as the platen roller, it is possible to suppress the variation in the pressing force distribution of the heating elements 3 in the column direction even if the thermal head 1 and the platen roller 4 are warped. However,
Even in this case, even if there is a mechanical displacement between the platen roller 4 and the heating element 3 of the thermal head 1, the width of the contacting portion should be a certain width or more in order to prevent the heating element 3 from deviating from the contacting portion width m. Therefore, there is a problem that the pressing force cannot be extremely reduced and the platen diameter cannot be reduced, which hinders downsizing of the apparatus.

Further, if it is attempted to reduce the pressing force and the platen diameter with this specification, the absolute dimensions of the alignment of all the thermal heads 1 and the platen rollers 4 are actually measured using a tool microscope etc. in the mass production line.・ It is necessary to ship after adjustment. (In terms of print quality, even a barely acceptable product may pass, and it may be defective due to external factors such as vibration after shipping.)
However, there was a problem that the cost was high and it was practically impossible.

[0009]

SUMMARY OF THE INVENTION According to the present invention, at least two pressure-sensitive elements are provided at both ends of a plurality of heating elements forming a row of thermal heads on the main scanning side in the sheet conveying (sub-scanning) direction. It is arranged side by side.

[0010]

According to the present invention, the pressure distribution of the pressure sensitive element is symmetrical when the thermal head and the platen roller are in the regular position, but the pressure distribution of the pressure sensitive element is symmetrical when the thermal head and the platen roller are deviated from the regular position. Therefore, by detecting and displaying the pressure distribution of the pressure sensitive element, the operator can grasp the amount and direction of the deviation between the platen roller and the thermal head by this display, and the alignment adjustment can be easily performed. Become.

[0011]

FIG. 2 is a perspective view of a main part of a thermal recording apparatus using a thermal head according to an embodiment of the present invention, and FIG. 3 is a main part showing a sheet conveying state of the thermal recording apparatus using a thermal head according to the embodiment. FIG. 1 is a perspective view showing an enlarged main part of the thermal recording apparatus, and FIG. 4 is a side view of an essential part of the thermal recording apparatus. Further, FIG. 5A shows a state of the plane and the side surface when the platen roller is in the regular position with respect to the thermal head,
3 shows a graph of output data of the pressure sensitive element. Also in FIG.
(B) shows a graph of the output data of the pressure-sensitive element and the state of the plane and the side surface when the platen roller is displaced from the regular position with respect to the thermal head. 1 to 5
The same numbers are given to the parts having the same functions as those in the conventional example.

A thermal head 10 has a plurality of heating elements 3 arranged in a line on the substrate. Reference numeral 11 is a pressure-sensitive element which is provided at both ends of the plurality of heating elements 3 forming a row of the thermal head 10 on the main scanning side side by side with four heating elements 3 arranged at equal pitches in the paper transport (sub-scanning) direction. The pressure sensitive element 11 is an element whose output changes depending on the magnitude of the pressure applied to the element. Reference numeral 5 is a thermal paper.

A platen roller 6 is connected to a driving means (not shown) and conveys the heat-sensitive paper 5. The platen roller 6 is rotatably attached to the apparatus main body (not shown) through a bearing. In the platen roller 6, 6a is an outer skin, 6b is a core metal, 6c is a fluid, and the platen roller 6 is a fluid enclosing type in which the fluid 6c is enclosed and a thin outer skin 6a is provided. By using the fluid-filled type as described above, even if the thermal head 10 is warped and the platen roller 6 is warped, it is possible to suppress some variation in the pressing force distribution in the column direction.

Reference numeral 8 is a pressing spring for pressing the thermal head 10 against the platen roller 6, 7 is a head mounting plate for movably mounting the thermal head 10 to the apparatus main body (not shown) through the pressing spring 8, and 7a is the apparatus. Thermal head 10 movably attached to the main body
Core plate 6b of the platen roller 6 for aligning (positional relationship) between the row of the heating elements 3 and the platen roller 6.
It is a guide that suits.

Normally, the thermal recording device can be opened and closed around a fulcrum not shown for maintenance such as jam removal of the thermal paper 5 and cleaning of paper dust, and the platen roller 6 and the thermal head 10 are separated from each other. Since it is possible, the guide 7a of the head mounting plate 7 is U-shaped, and is guided by the core metal 6b of the platen roller 6 as it is opened and closed.

The recording operation will be described. As shown in FIGS. 3 and 4, the thermal head 10 and the platen roller 6 are pressed against each other via the thermosensitive paper 5, and the platen roller 6 connected to the driving means is rotated in the F direction to generate heat. While the paper 5 is being conveyed, the heating element 3 is selectively heated to cause the heat-sensitive paper 5 to develop a color and recording is performed.

Next, the alignment adjustment will be described.
When the pressing force is reduced and the platen diameter is reduced with the conventional configuration shown in FIG. 7, the absolute dimensions of the alignment of the thermal head 1 and the platen roller 4 are actually measured using a tool microscope etc. in the mass production line. -While it was necessary to ship after adjustment, with this configuration, the heating element 3 is used during test printing.
The thermal head 10 with respect to the platen roller 6 is monitored by monitoring the output of each of the four pressure-sensitive elements 11 provided side by side in the conveyance (sub-scanning) direction of the thermal paper 5 at both ends on the main scanning side.
It is possible to easily understand in which direction and how much is offset.

That is, when the platen roller 6 is at the normal position with respect to the thermal head 10, the pressure distribution of the pressure sensitive element 11 is symmetrical as shown in FIG. 5A, but deviates from the normal position. In this case, the pressure distribution of the pressure sensitive element 11 is not symmetrical as shown in FIG. 5 (B). By detecting and displaying the pressure distribution of the pressure-sensitive element 11 on the mass production line, the operator grasps the amount and direction of the displacement between the platen roller 6 and the thermal head 10 by this display, and the thermal head 10 and the platen roller. 6 can be adjusted to have a regular positional relationship.

Since the adjustment work is facilitated in this way,
The alignment of the thermal heads 10 and the platen roller 6 can be confirmed and adjusted on the mass production line. Therefore, the width m'of the contact portion between the thermal head 10 and the platen roller 6 can be reduced, and the platen diameter can be reduced and the pressing force of the thermal head 10 and the platen roller 6 can be reduced to reduce the size of each mechanical component. This leads to downsizing of the device body.

In this embodiment, four pressure sensitive elements 11 are arranged at equal pitches around the heating element 3, but the number, center position and pitch need not be limited to this embodiment. Is clear.

[0021]

According to the present invention, the thermal paper is conveyed (sub-scanning) to both ends of the heating element on the main scanning side during test printing.
By monitoring the output of each of the four pressure-sensitive elements arranged side by side, it is possible to easily understand in which direction and how much the thermal head is displaced with respect to the platen roller. Since it is possible to easily check and adjust the alignment of all thermal heads and platen rollers on the mass production line, it is possible to reduce the pressing force and the platen diameter of the thermal recording device, which was not possible with the conventional configuration. The size can be easily reduced.

[Brief description of drawings]

FIG. 1 is an enlarged perspective view of essential parts of a thermal recording apparatus using a thermal head in an embodiment of the present invention.

FIG. 2 is a perspective view of a main part of a thermal recording apparatus using a thermal head according to an embodiment of the present invention.

FIG. 3 is a perspective view of an essential part showing a sheet conveyance state of a thermal recording apparatus using a thermal head in an embodiment of the present invention.

FIG. 4 is a side view of a main part of a thermal recording apparatus using a thermal head according to an embodiment of the invention.

FIG. 5A is a diagram showing a graph of the output data of the pressure-sensitive element and the state of the flat surface and the side surface when the platen roller is at the regular position with respect to the thermal head in the thermal recording apparatus of the embodiment. FIG. 8A is a graph showing a state of planes and side surfaces and a graph of output data of the pressure sensitive element when the platen roller is displaced from the normal position with respect to the thermal head in the thermal recording apparatus of the embodiment.

FIG. 6 is a side view of essential parts of an example of a thermal recording apparatus using a conventional thermal head.

FIG. 7 is a perspective view of an essential part of an example of a thermal recording apparatus using a conventional thermal head.

[Explanation of symbols]

 3 heating element 5 thermal paper 6 platen roller 6a outer skin 6b core metal 6c fluid 7 head mounting plate 7a guide 8 pressing spring 10 thermal head 11 pressure sensitive element

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Taro Ura 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A line thermal head, wherein at least two pressure-sensitive elements are arranged side by side in the sheet conveying direction at both ends of a plurality of heating elements in a row on the main scanning side. 2. A heating element array in which a plurality of heating elements are arranged in a line is provided, and at least two heating element rows are provided at both ends on the main scanning side.
A line thermal head in which at least one pressure-sensitive element is arranged side by side in the paper transport direction, a platen roller for transporting the paper, a pressing unit for pressing the line thermal head and the platen roller against each other, and the platen roller A heat-sensitive recording apparatus comprising: a guide unit that guides a cored bar. 3. The heat-sensitive recording apparatus according to claim 2, wherein the platen roller has an outer cover and a shaft, and a fluid is sealed between the outer cover and the shaft.