JPS6369666A - Thermal recorder - Google Patents

Abstract

PURPOSE:To prevent the breakdown of a thermal head, by providing a paper feed detection means detecting the presence of paper feed and a conduction control means receiving a signal from the detection means and stopping electric conduction to the thermal head in a paper feed stop condition. CONSTITUTION:A period from a point wherein a preceding sprocket hole 7 is detected by a sprocket hole detection circuit 9 to a point wherein a present sprocket hole 7 is detected is calculated. If the period is within a predetermined value, a paper feed is judged to be normal; on the contrary, if the sprocket hole 7 is not detected after the predetermined period is elapsed, the paper feed is not conducted and judged to be in a stop condition or abnormal. If the aforesaid paper feed stop condition is generated in a printing processing, conduction to a thermal head 2 is stopped by a conduction control circuit 13. Namely, a printing action is forcibly stopped. Therefore, even if a recording paper 5 is wrinkled and jammed in the vicinity of a heating portion of the thermal head 2 for some reason or other, the thermal head 2 free from conduction is prevented from being excessively heated and the failure such as breakdown caused by heat fatigue is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a thermal recording device in which a thermal head is devised to prevent burnout.

(b) Conventional technology In general, thermal recording devices have seven
~ A small thermal head with 14 dots arranged in a row,
There is a serial type that records by moving the recording paper in a direction perpendicular to the traveling direction of the recording paper, and a line type thermal head that has 6 to 16 dots per Ins per ins per paper width perpendicular to the traveling direction of the recording paper. There is a parallel type used. In either type, a recording paper is interposed between the platen and the thermal head, and the energized part of the thermal head is thermally sensitive to the recording paper to record.
It is designed to be fed by a sprocket.

(c) Problems to be Solved by the Invention In a thermal recording device having a paper feeding means as described above, when dew adheres to the recording paper and it becomes moist, the recording paper becomes extremely soft (and when the paper is fed, the recording paper cannot be recorded). If the sprocket hole in the paper is torn, the recording paper may not be fed properly, and the recording paper may become crumpled near the thermal head. If this continues, the heat generating part of the thermal head and the recording paper will not be in close contact with each other, and printing will be performed with an air layer formed, resulting in a significant decrease in the degree of heat dissipation.This state continues for a long time, and There is a problem in that when electricity is applied for printing, thermal fatigue occurs and the thermal head is destroyed.

In view of the above, it is an object of the present invention to provide a thermal recording device in which electricity can be stopped when paper feeding is not performed normally, thereby preventing damage to the thermal head.

(d) Means for Solving the Problems In order to solve the above problems, the thermal recording apparatus of the present invention includes a paper feed detection means for detecting the presence or absence of paper feed, and a signal from the paper feed detection means. It is characteristically provided with energization #111 means for stopping energization to the thermal head when paper feeding is stopped.

(E) Function In this thermal recording apparatus, when the paper feed detection means detects that paper is not being fed during the recording operation, the energization control means stops energization to the thermal head in response. Therefore, even if the recording paper is crumpled near the heat generating part of the thermal head, the thermal head does not continue recording operation, so it is protected from destruction due to thermal fatigue or the like.

(f) Examples The present invention will now be explained in more detail with reference to Examples.

FIG. 1 is a schematic diagram of a printing section of a window thermal recording device according to an embodiment of the present invention. In the figure, a thermal head 2 is pressed against a platen roll 1 by a biasing spring 3. A recording paper 5 wound around a recording paper roll 4 is interposed between the platen roll 1 and the heat generating part of the thermal head 2, and a paper feed mechanism such as a motor (not shown) records the data as shown by the arrow along with printing. Paper 5 is now sent. Here, the thermal head 2 uses a line head with the same width as the paper width, that is, a parallel type.

As shown in FIG. 2, the platen roll 1 has a sprocket 6 formed around its end, and the sprocket hole 7 of the recording paper 5 is fitted into this sprocket 6, and the sprocket 6 is rotated by a motor or the like. , the paper is fed.

An optical sensor 8 for detecting paper feed is provided on the feeding side of the recording paper 5 of the platen roll 1 and on the path through which the recording paper 5 passes through the sprocket hole 7 . The sensor 8 is a reflective switch, and when the light emitted from the optical sensor 8 is projected onto the sprocket hole 7, it does not go straight back, but it hits the surface of the recording paper 6 other than the sprocket hole 7. When projected, the light is reflected back. Therefore, the optical sensor 8 has a function of detecting the sprocket hole 7. When paper feeding is being performed normally, the sprocket hole 7 is detected at regular intervals, but if the paper is not being fed normally, such as when paper feeding has stopped, the sprocket hole 7 is detected at regular intervals. It is not detected. This makes it possible to detect the presence or absence of paper feeding.

FIG. 3 shows a circuit block diagram of the control section of the thermosensitive recording apparatus of this embodiment. Based on the output of the optical sensor 8, the sprocket hole detection circuit 9 detects the presence or absence of the sprocket hole 7 in the recording paper 5, and then the microcomputer (
(hereinafter referred to as CPU) 10. CPU10 is
It executes control operations such as print processing and paper feeding according to the built-in program. Due to the paper feed command from the CPU 10,
The motor drive circuit 11 operates, and the paper feeding motor 12 rotates. As a result, the sprocket 6 moves by a predetermined pitch, and the paper is fed. Further, in response to a print command from CPU10, print data is sent to the energization control circuit 13 via the bus 14, and the energization control circuit 13 is activated.
The dot of thermal head 2 according to the data is selected,
It is now energized.

Next, the operation of the thermal recording apparatus of the above embodiment will be explained with reference to the flowchart shown in FIG.

When the power of the device is turned on and operation starts, it is first determined whether printing is to be performed (step 5TI).
When the print start key or the like of U10 is operated and CPU10 issues a print command, the determination becomes YES and the process moves to printing processing (step 5T2).

This printing process is performed by the energization control circuit 13 energizing only the dots selected according to the print data.Next, the process moves to step ST3, where it is determined whether or not printing has ended. If printing is completed, the operation ends now, but if print data remains or if changing amounts are to be continuously printed for a certain period, the determination is No until the end of the period, and step ST4 is completed. Move on to paper feeding processing. Here, C.P.
A paper feed command is output from U10, and the motor drive circuit 11
In response to this, the motor 12 is rotated to drive the sprocket 6 one pitch.

Subsequently, in step ST5, it is determined whether or not paper feeding is detected. This determination is made by calculating the period from the previous detection to the current detection of the sprocket hole 7 detected by the sprocket hole detection circuit 9, and if the period is within a predetermined value, it is determined that paper feeding is normal; If it is not detected even after 0 has passed, it is determined that the paper is stopped without being fed or is abnormal.
Normally, the spacing between sprocket holes 7 is 10 mm, so
For example, if the feeding speed of the recording paper 5 is 100 m+i/min, the next sprocket hole should come every 0.1 minute, so this 001 minute can be used as the reference. If the number of paper feed processes in ST4 is large for the period, paper feed detection is performed in a separate routine, and when normal, the process proceeds with a YES decision in step ST5, and when paper feed is not performed, step ST5 is executed with an interrupt. The determination may be NO.

As described above, when the paper feed is stopped while printing is continued, the determination in step ST5 becomes No, and the process moves to step ST6, where the subsequent printing operation is forcibly stopped. That is, the power supply to the thermal head 2 by the power supply control circuit 13 is stopped. Therefore, even if the recording paper 5 becomes crumpled or jammed near the heated part of the thermal head 2 for some reason, no electricity will be applied.
The thermal head 2 does not generate excessive heat, and problems such as destruction due to thermal fatigue are avoided.

In addition, in the example device, even when the recording paper runs out,
The detection period of the sprocket hole 7 is not normal (that is, the paper is not fed, so the printing operation stops as well. Therefore, it is also possible to know if the recording paper is out.

In the above embodiment, a reflective type optical sensor 8 is used to detect paper feed, but a transmissive type may also be used, and the paper feed detection means in the present invention is not limited to these. , proximity switches, contact switches, and other means may also be used.

Further, when the stoppage of paper feeding is detected, a sound or light alarm may be issued.

(G) Effects of the Invention According to the present invention, the paper feed detection means is provided, and when the stop of paper feed is detected during printing processing, the power supply to the thermal head is stopped. Even if the head is crumpled, printing will not continue, so there is no risk of thermal fatigue due to poor heat dissipation, and thermal damage to the thermal head can be prevented. In addition, there is an advantage that the paper feed detection means can also detect when the recording paper runs out.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the printing section of a thermal recording device according to an embodiment of the present invention, FIG. 2 is a perspective view showing the main parts of the device, and FIG. 3 is a circuit block diagram of the control section of the device. Figure 4 is
FIG. 3 is a flow diagram for explaining the operation of the device. 1 Nibraten roll 2: Thermal head, 5: Recording paper, 6: Sprocket, 7: Sprocket hole, 8: Optical sensor, 9: Sprocket hole detection circuit, 10: Microcomputer, ll: Motor drive circuit, 12: Current control circuit. Patent applicant: Shimadzu Corporation Agent
Patent Attorney Shigeru Nakamura Figure 1 Figure 2

Claims (1)

[Claims] (1) energize the thermal head to print thermally on recording paper,
A thermal recording device that feeds the recording paper by a paper feed means every predetermined printing includes a paper feed detection means for detecting the presence or absence of paper feed, and a signal from the paper feed detection means to detect the above when the paper feed is stopped. 1. A thermal recording device comprising: energization control means for stopping energization to a thermal head.