KR100607971B1 - Method of protecting thermal printhead from overheating - Google Patents

Abstract

A method of preventing overheating of a thermal print head is disclosed. The method of preventing overheating of the thermal printhead disclosed may include: monitoring a transfer speed of the thermally reacted paper when printing on the thermally reacted paper with the thermal printhead; It characterized in that it comprises the step of blocking the voltage applied to. According to this, when feeding abnormalities such as jams occur during printing on the thermally reactive paper, it is possible to effectively prevent overheating generated in the thermal printhead, thereby reducing electricity consumption, and also protecting the thermal printhead from overheating.

Description

Method of protecting thermal printhead from overheating

1 is a cross-sectional view illustrating a general thermal reaction paper.

2 is a view for explaining the configuration of a general thermal printer.

3 is a view for explaining a thermal type printing press applied to the method for preventing overheating of a thermal print head of the present invention.

4 is a plan view schematically illustrating some components of an apparatus to which a thermal printhead overheat prevention method according to a preferred embodiment of the present invention is applied.

5 is a flowchart of a method for preventing overheating of a thermal print head according to a preferred embodiment of the present invention.

* Description of Signs of Major Parts of Drawings *

10: thermal reaction paper 40: transfer section

41: Feeding Roller 42,62: Children Roller

45: encoder disc wheel 45a: slit

46: rotary encoder sensor 50: the image forming unit

51: thermal print head (TPH) 52: heating element

53, 54: paper edge detection sensor 55: platen roller

60: paper discharge unit 70: paper storage unit

72: pickup roller 80: control unit

The present invention relates to a method of preventing overheating of a thermal print head by applying predetermined heat to a double-sided thermal reaction paper.

Direct thermal printing presses use a paper (hereinafter referred to as a thermal reaction paper) that produces a predetermined color in response to heat, and an ink ribbon that transfers a predetermined color to the paper in response to heat for printing on ordinary paper. There is a way. The method of using the ink ribbon has to have a driving device for driving the ink ribbon, which is complicated in structure and expensive. In addition, since the ink ribbon must be continuously replaced as a consumable, the printing cost per sheet is high.

Referring to FIG. 1, the thermally reactive paper 10 has ink layers 12 and 13 of a predetermined color formed on both sides of a base sheet 11, that is, on the first and second surfaces thereof. Each ink layer 12, 13 may have a single layer structure by a single color ink or a multi-layer structure for expressing two or more colors. For example, the ink layer 12 of the first side of the ink layer is stacked in two layers for the color of magenta (M) and cyan (C), and the ink layer 13 of the second side is yellow (Y). It can have a single layer structure for the color representation. It is preferable that the said base material 11 is a transparent material. US Patent Publication No. 2003/0125206 describes one example of the thermal reaction paper 10.

A thermal printhead (TPH) in which a heating element is disposed at a predetermined resolution in a direction perpendicular to a printing paper's advancing direction is used in a thermal type printer using the thermally-reactive paper 10. To print on both sides with one thermal printhead (TPH), the first side of the printing paper is printed, and then the second side of the printing paper is printed again with the TPH. When both sides are printed in this way, when viewed from one side of the thermally reactive paper, color images are seen on the paper.

2 is a view for explaining the configuration of a general thermal printer.

Referring to Figure 2, the thermal printing press is a feeding roller (2) for transporting the thermal reaction paper (1), a platen roller (3) for supporting one side of the paper (1), and on the platen roller (3) A thermal printhead 4 for forming an image on the paper 1 is provided. Reference numeral 5 denotes the paper 10 passing through the feeding roller 2 toward the feeding roller 2 as an idle roller.

On the other hand, when the thermal reaction paper 10 is jammed between the platen roller 3 and the thermal printhead 4 during printing, the heat generating portion of the thermal printhead 4 may be kept on. And thus the thermal printhead 4 may overheat. This overheating of the thermal printhead 4 not only consumes a lot of electricity, but may also cause damage to the heat generating portion of the printhead 4.

The technical problem to be achieved by the present invention is to provide a method of preventing overheating of a thermal print head in a thermal printer.

The overheat prevention method of the thermal print head according to the present invention,

A first step of monitoring a feed rate of the thermally reactive paper when printing on the thermally reactive paper with a thermal printhead; And

And a second step of blocking a voltage applied to the thermal print head when it is determined that the feed rate of the thermally reactive paper is abnormal.

The first step,

It characterized in that for monitoring the rotation of the feeding roller for transferring the thermal reaction paper to the printing path.

In addition, the first step,

For a predetermined time, calculating an actual rotation distance of the feeding roller; And

It is preferable to have a step of determining that the feeding roller is abnormally rotated when a predetermined difference is greater than the actual rotation distance and the preset paper feed distance.

On the other hand, the calculation of the actual rotation distance is preferably measured by a rotary encoder sensor formed on the outer periphery of the feeding roller.

Hereinafter, exemplary embodiments of a method for preventing overheating of a thermal print head of the present invention will be described in detail with reference to the accompanying drawings.

Figure 3 is a view for explaining a thermal printer type applied to the method for preventing overheating of the thermal print head of the present invention.

As shown in FIG. 3, the thermal type printer has at least first, second, and third paths and transfers the thermally reacted paper 10 through this transfer path. The first path is a paper feed path for feeding the paper 10 to the second path. The second path is an area that is back fed in the direction of arrow B for printing on paper 10 and forward fed in the direction of arrow F for printing. In addition, the third path is a path where the paper 10 which is being printed is located, and the paper 10 printed only on the first surface may be returned to the second path or the paper on which the printing is completed on the first or second surface ( 10) is the final discharge path.

A paper guide 65 is provided between the first path and the third path. The paper guide 65 guides the paper 10 from the first path to the second path, and guides the paper 10 from the second path to the third path. In addition, the paper guide 65 prevents the paper 10 from the second path to proceed only to the third path and to the first path, and the paper 10 from the first path to the second path. Guide them through the path only. Understanding and designing the structure of this paper guide 65 is general and will not be described any further.

In the second path, image formation by the image forming unit 50 is performed. Such image formation may be performed twice, or more than necessary. However, in the present invention, a total of twice is performed once for each side of the first and second sides of the recording paper 10. The posture or position of the thermal printhead (TPH) 51 and the platen roller 55 of the image forming section 50 is predetermined before the image formation on the first and second surfaces of the paper 10. It must be determined by location. That is, for example, when the image is formed on the first side of the paper 10, the TPH 51 is located in the C portion, and when the image is formed on the second side of the paper 10, the TPH ( 51) shall be located in the D part. The position change or posture change of the TPH 51 preferably rotates the platen roller 55 and the TPH 51 about the rotation axis of the platen roller 55. The position change of the TPH 51 is caused when the interference with the recording paper 10 does not occur, for example, before the paper 10 is fed from the first path or by image formation on the first surface. ) Is not returned to the second path after being transferred to the third path.

If the paper 10, which has already been imaged on the first surface, is back fed with the second path, the image is formed on the second surface by the posture-shifted TPH 51. In this process, the paper 10 is After progressively advancing by the transfer unit 40, after the formation of chemical conversion on the second surface is completed, the second path is further advanced to be discharged through the paper discharge unit 60. The transfer part 40 includes a feeding roller 41 for transferring paper, and an idle roller 42 for pushing the paper entering therebetween toward the feeding roller 41.

Reference numeral 70 denotes a paper storage unit, and reference numeral 72 denotes a pickup roller for feeding paper.

The paper discharge unit 60 is composed of a discharge roller 61 and an idle roller 62, the discharge roller 61 and the pickup roller 72 may be arranged to serve as two rollers with one roller. have.

4 is a plan view schematically illustrating some components of an apparatus to which a thermal printhead overheat prevention method according to a preferred embodiment of the present invention is applied.

Referring to FIG. 4, the control unit 80 drives the feeding roller 41 by an external control signal for the thermal reaction paper 10 entering between the platen roller 55 and the TPH 51. In the TPH 51, a plurality of heat generating elements 52 are arranged in a line or a plurality of rows in a direction perpendicular to the paper conveying direction. Each heating element 52 generates a predetermined time in accordance with the voltage application signal.

The paper 10 is conveyed by the feeding roller 41 in the arrow B direction in the back feeding direction and in the arrow F direction in the printing progress direction. The encoder disc wheel 45 is attached to the outer periphery of one side of the feeding roller 41. Slits (45a) are formed at regular intervals at the edge of the encoder disk wheel 45, the rotary encoder sensor 46 consisting of a light emitting portion 46a and a light receiving portion (46b) is mounted on both sides of the slit (45a). have. The light emitting unit 46a of the rotary encoder sensor 46 emits light at a constant speed, and each time the slit 45a meets, the light receiving unit 46b generates a pulse signal, and the control unit 80 generates the pulse signal. By counting, the actual rotation distance of the feeding roller 41 corresponding to the feeding distance of the paper 10 conveyed by the feeding roller 41 is measured. The driving motor 47 is driven to feed the feeding roller 41. The feed distance of the paper 10 is controlled. Thus, the conveyance state of the sheet 10 is monitored by the rotary encoder sensor 46. The rotary encoder sensor 46 is a rotary encoder wheel 45 attached to the outer circumference of the feeding roller 41 rotated by the driving motor 47 when the drive signal reaches the feeding roller drive motor 47 from the control unit 80. Rotation of the slit 45a is detected periodically. The detection period of the rotary encoder sensor 46 may vary depending on the number of slits of the rotary encoder wheel 45 and the feeding speed of the paper 10.

On the other hand, the thermal printer is a non-illustrated rotation means for rotating the TPH 51 and the platen roller 55 to print the second surface after the first surface of the image forming paper 10 is printed, The TPH 51 may be provided with an unshown shandong means for separating and approaching the TPH 51 at a predetermined height from the printing path. A predetermined distance from the platen roller 55 to the TPH 51 using the shank moving means so that the paper 10 easily passes between the TPH 51 and the platen roller 55 when the paper 10 is back fed. For example, 1 to 2 mm apart. In printing, the TPH 51 is brought into close contact with the paper 10 by using the shandong means.

A method of preventing overheating of a thermal print head according to a preferred embodiment of the present invention will be described in detail with reference to the drawings.

5 is a flowchart of a method for preventing overheating of a thermal print head according to a preferred embodiment of the present invention.

First, when a printing signal is input to the controller 80 from a printer or a computer device connected to the printer, the controller 80 causes the thermal reaction paper 10 to be aligned between the feeding roller 41 and the platen roller 55. In operation 101, the feeding roller driving motor 47 is started while the thermal print head 51 is in close contact with the sheet 10. The paper 10 is fed into the printing path at a predetermined speed.

Subsequently, the rotary encoder sensor 46 counts the slit 45a of the rotary encoder wheel 45 and transmits a pulse signal to the controller 80. The controller 80 measures the actual rotation distance of the feeding roller 41 by counting the accumulated number of pulses every predetermined period (step 102).

The controller 80 compares the rotation distance of the feeding roller 41 with the predetermined feeding distance of the paper 10 to determine whether the feeding roller 41 is normally rotated (step 103).

In step 103, when the rotation distance of the feeding roller 41 is determined to be equal to or less than a predetermined value of the paper 10 transport distance, the controller 80 supplies power to the heating element 52 of the TPH 51. The application signal is sent, and each of the heat generating elements 52 is turned on in accordance with the print file to apply a predetermined heat to the paper 10 (step 104).

Subsequently, it is determined whether printing is finished (step 105), and when it is determined that printing is not finished, the process returns to step 102.

In step 105, if it is determined that printing is finished, the printing step is terminated.

On the other hand, in step 103, if the rotation distance of the feeding roller 41 differs from the predetermined distance by more than a predetermined value, the controller 80 cuts off the power supply signal from the TPH 51 to the heating element 52 (the Step 106).

Then the printing step is terminated and the cause of feeding failure is investigated.

According to the method for preventing overheating of the thermal printhead described above, when feeding abnormalities such as jams occur during printing on a thermally reactive paper, it is possible to effectively prevent overheating generated by the thermal printhead, thereby reducing electricity consumption, and overheating the thermal printhead. Protect from

For the purpose of understanding the slip amount measurement method of the present invention, it has been described with reference to the embodiment shown in the drawings, but this is only exemplary, those skilled in the art of various modifications and other equivalent implementation therefrom It will be appreciated that examples are possible. Therefore, the true technical protection scope of the present invention should be defined only in the appended claims.

Claims (4)

A first step of monitoring a feed rate of the thermally reacted paper by monitoring the rotation of the feeding roller which transfers the thermally reacted paper to the printing path when printing on the thermally reacted paper with a thermal printhead; And And a second step of blocking a voltage applied to the thermal print head when it is determined that the conveyance speed of the thermal reaction paper is abnormal. delete The method of claim 1, wherein the first step, For a predetermined time, calculating an actual rotation distance of the feeding roller; And And determining that the feeding roller is abnormally rotated by a predetermined difference when compared with the actual rotation distance and a preset paper feeding distance. 2. The method of claim 3, wherein The calculation of the actual rotation distance is measured by a rotary encoder sensor formed on the outer periphery of the feeding roller.

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