JPS6294360A - Thermal recording apparatus - Google Patents

Abstract

PURPOSE:To achieve the lowering of noise by reducing release sound generated by the sticking of a thermal head and recording paper, by applying a heating pulse to a heat generating element before recording paper is moved to the next line when paper feed was interrupted for a predetermined time or more after recording operation. CONSTITUTION:One line is recorded in a time sharing system and the sub- scanning of recording paper is performed by the interval (l) of one line. When the paper feed sub-scanning operation was interrupted for a set time or more, a pulse is outputted from a timer circuit at time t3 after a set time was elapsed from time t2. By the timing of this pulse, the recording information of the line immediately before interruption is again written in a lapped state. In this case, the thermal layer of the recording paper may be heated almost up to the vicinity of m.p. Therefore, this setting may be performed by applying a heating pulse to a part of the heat generating element participated in recording operation. Or, this setting is achieved by making voltage lower than that of the heating pulse when usual printing operation is performed or shortening the width of the heating pulse. Next, the recording of the next line and paper feed operation are rapidly repeated after the completion of lap-writing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a thermal recording device used in facsimiles, printers, etc., and more particularly to a recording device designed to reduce noise.

[Background of the invention]

Recording devices that perform thermal recording using a thermal head do not require a fixing mechanism, are small in size, and can be manufactured at low cost, and are therefore widely used in facsimile machines, printers, and the like.

With the spread of OAI (Office Automation), the field of use of these devices is rapidly expanding to general offices, and from the standpoint of preserving the office environment, there is a strong demand for the development of low-noise, inexpensive equipment. . The noise of this type of recording apparatus includes not only the drive sound of the motor for conveying the recording paper but also the sound of adhesive peeling between the thermal head and the heat-sensitive layer of the recording paper. FIG. 6 shows the temperature change of the heating element during thermosensitive recording. When the heating element receives the heating pulse signal at point A, it is rapidly heated and then gradually cooled down. In this process, the heat-sensitive layer of the recording paper that is in contact with the heating element reaches its melting point near point B and reaches its freezing point near point C, and is colored and recorded.

Since the recording paper reaches a temperature above its melting point, it fuses with the surface of the thermal head and solidifies and sticks over time.

The adhesive force between the thermal head and the recording paper is inversely proportional to the surface temperature of the thermal head. In order to achieve high-speed recording performance, thermal recording devices perform recording operations and paper feeding operations simultaneously.

-10,000, recording operation is performed by time division into multiple blocks for one line in order to downsize the recording power supply.
Compared to the line recording time, the time the recording paper is moving is relatively 'pt' longer. As a result, in some blocks in one line, the recording operation is performed while paper feeding is stopped, so that the thermal head and the heat-sensitive layer of the recording paper solidify and stick together before the next line's recording and paper feeding operations.

FIG. 7 shows the relationship between the surface temperature of the thermal head and the peeling force when peeling recording paper from the thermal head.

This peeling force is inversely proportional to the temperature of the thermal head. The adhesive peeling sound is generated as a result of the recording paper and the thermal head being vibrated by the peeling operation.

FIG. 8 shows the results of frequency analysis of noise in a thermal facsimile. The broken line in the figure shows the characteristics of the driving sound of the motor, etc., and the solid line shows the composite characteristics of this driving sound and the adhesive peeling sound.

As is clear from this characteristic curve, the adhesive peeling sound is 100
0) The main component is a harsh high frequency component of 12 or more, and when the ambient temperature of the device is low or when the paper feed operation is performed after recording has been interrupted for several hundred milliseconds or more, in other words, the paper feed operation occurs after a relatively long cooling time. This is noticeable when doing this. Further, this peeling force is a main cause of an increase in motor load, and is the biggest factor hindering the miniaturization and cost reduction of motors.

Conventional devices, for example, as disclosed in Japanese Patent Application Laid-open No. 59-87405, absorb sound at the thermal head and the recording paper exit opening;
Sound insulation and muffling measures were taken.

However, no consideration was given to improving the noise generation source itself. Furthermore, in JP-A-58-118277, it is stated that in order to equalize the recording density of each recording line, the first printing operation is performed twice in succession after the recording operation is interrupted for a predetermined period of time. However, no consideration was given to noise countermeasures.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal recording device that reduces peeling noise caused by adhesion between a thermal head and recording paper, and achieves low noise.

[Summary of the invention]

In the present invention, in a thermal recording device that moves a recording paper in a direction parallel to the longitudinal direction of a heating element built into a thermal head and applies a heating pulse to the heating element to perform printing, the heating pulse is applied to a 1-maru head. means for applying a heating pulse to at least the heating element involved in the recording operation immediately before moving the recording paper to the next line after the interruption when paper feeding is interrupted for a predetermined time or more after the recording operation is performed by applying a heating pulse. , - It is designed to achieve the purpose described in (E).

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 is an explanatory diagram for explaining the recording operation of this embodiment. It is an example in which one line is divided into multiple blocks and recorded in time division, and the start timing of recording one line and paper feeding operation are the same. The case is shown below.

This condition is for achieving miniaturization of the recording power source and high-speed recording as described above.

In the figure, it is assumed that the recording operation for the first line is started at time t1. Synchronized with the recording start pulse in (a) (~
The timing of the drive start pulse of the paper feed motor (
(C)) As shown in (b), the minutes are recorded in 4 blocks (1) ++, DI, DIS, and DI4 in time division, and the recording paper is recorded in one line as shown in (d). The sub-scan is performed by an interval t. On the other hand, a timer constantly monitors the elapsed time from the motor drive start pulse (starting at time 1 in this case), and starts feeding the next line of recording paper within a predetermined time (hereinafter referred to as set time). When a pulse is input, this timer is reset and the same recording and paper feeding operations as for the first line are performed.

Next, if the elapsed time is longer than the set time, and if the paper feed sub-scanning operation is interrupted for longer than the set time, then at time t,
Time t after the above-mentioned set time has elapsed.

Then, the timer circuit outputs a pulse as shown in (e). Depending on the timing of this pulse, the recorded information on the line immediately before the interruption (blocks I, ms, li, in the figure, i.e., the blocks recorded when paper feeding was stopped) is overwritten again. In this case, the heat-sensitive layer of the recording paper does not necessarily need to be heated to a temperature higher than the recording density, but it is sufficient to heat it to around the melting point. Therefore, in this setting, the heating pulse may only be applied to a part of the heating elements involved in the recording operation. This can be achieved by lowering the voltage of the heating pulse or by shortening the width of the heating pulse than in the case of normal printing operation. Next, as soon as the overwriting is completed, the recording of the next line and the paper feeding operation are repeated.

If the elapsed time is longer than the set time,
In the case of facsimile, communication with foreign countries where the S/N ratio is not high enough, communication of manuscripts that require a lot of time due to dense recorded information, and communication with low-speed recording devices such as GI standard. Occurs frequently.

The timer is started using timing corresponding to the paper feed timing signal, the output signal of the decoding circuit, the temperature of the thermal head or the thermal layer of the thermal paper of the recording paper, or the cooling time.

In the above embodiment, one line is time-divisionally recorded in four blocks, and the motor starting pulse is used to move a distance l at once. The present invention can also be applied to the case where the paper is fed separately.

In addition, in order to accurately specify the block in which a recording operation is to be performed after paper feeding is stopped, this can be realized using a sensor that monitors the movement of the paper feeding axis, such as an encoder output and a recording timing signal for each block.

Further, - the setting time of the above-mentioned timer can be selected to be an appropriate length taking into consideration the level of adhesive peeling sound and performance such as recording unevenness.

FIG. 2 is a configuration diagram of a receiving section of a thermal facsimile to which the present invention is applied. In the figure, a 4-tone modulator 1 demodulates a modulated signal transmitted via a telephone network 2 from a facsimile transmitter (not shown) and converts it into an original digital signal. For example, in the international standard G III facsimile, this digital signal is Mll (ModiNed l1uffrn).
an) code. The decoder 3 decodes this MH code into an image signal.

The recording driver 4 inputs the image signal and drives the thermal head 5 to record the image signal on the recording paper 6''.

The control unit 7 manages the timing of the entire apparatus, and determines the timing of the print pulse (heating pulse) to the recording driver 4 and the drive pulse to the pulse motor 8 based on the generation timing of the image signal. The timing of generation of both values rQ) varies greatly depending on the amount of information contained in the image signal. For example, international standard thermal facsimile (M)
■ Code, minimum transmission time 20m5/line, transmission speed 48
00bI)S, 1 line with 1728 images), the time required to transmit the image signal for one line is from 20 m5 to 1.
Therefore, the control section 7 of the present invention has a function of performing an overwriting operation when the drive interval of the pulse motor 8 is longer than the set value.

Next, control of this overwriting operation will be explained.

FIG. 3 is a block diagram of a circuit configuration of a facsimile machine, in which the received signal 2 is demodulated by a demodulator 1 and stored in a code buffer 9 as an MII code.

The M[I code is sent from the code buffer 9 to the decoder 3, and the decoder 3 converts the MH code into an image signal and stores it in the line buffer 10. When the decoder 3 finishes decoding the image signals for one line, it instructs the microcomputer (hereinafter referred to as microcomputer) 11 to complete the decoding. The microcomputer 11 inputs the elapsed time from the start of recording of the previous line from the timer 12, and determines whether recording of the previous line has ended or whether the elapsed time is longer than a predetermined value. If the elapsed time is longer than a predetermined value, the microcomputer 11
After re-driving the recording driver 4 by outputting a print pulse through the line buffer (referred to as o) 13 and overwriting the image signal of the previous line in the recording driver 4, a transfer command is output to the decoder 3 and the image signal in the line buffer lo is re-driven. Based on the signal information, the image signal of the next line is transferred to the recording driver 4 for one line. When the decoder 3 completes the transfer, it instructs the microcomputer 11 to complete the transfer.

When the microcomputer 11 receives the transfer end signal, it transfers T/.

13 to the recording driver '4,
A drive pulse is output to the pulse motor 8, and the timer 2 is reset.

Repeat the following series of operations until the end of recording.

Note that 14 is a control program for controlling the entire apparatus.

FIG. 4 is a block diagram of the control program.

In the figure, a microcomputer 11 controls the entire system by executing a control program 14.

The control program is initialization 15, communication control 16,
It consists of four tasks: a decoding control 17 and a recording control 18, and a scheduler 19 manages the activation and status of these four tasks.

An example of the procedure of the recording control program will be explained using the flowchart of FIG. 5.

When the recording control 18 is activated by the scheduler 19,
In step 1, a timer value is input.

Regarding this input value, in step 2 it is determined whether recording of the previous line has been completed. If the recording has not ended, the process returns to the scheduler 19, but if the recording has ended, it is determined in step 3 whether or not there is one or more new image signals in the line buffer 10. If there is no new image signal for one line or more, the process returns to the scheduler 19, but if there is, in the next step 4 it is determined whether the elapsed time from the printing of the previous line is greater than the set value than the timer value. do. If the timer value is smaller than the set value, proceed to step 6. If the timer value is greater than the set value, the process proceeds to step 5, where a print pulse is output to the recording driver 4 to overwrite the image signal of the previous line. In step 6, a transfer command is issued to the decoder 3 to transfer one line of new image signals from the line buffer 10 to the recording driver 4.

In step 7, the completion of the transfer is confirmed. In step 8, printing pulses are output to the recording driver 4 and drive pulses are output to the pulse motor 8 to perform recording. Then, in step 9, the timer is reset, and the process returns to the scheduler 19.

〔Effect of the invention〕

As explained below, according to the present invention, if paper feeding is interrupted for a predetermined period of time or more after the recording operation, a heating pulse is applied to the heating element before moving the recording paper to the next line after the interruption. In this case, it is possible to feed the recording paper with a small peeling force, and as a result, the noise of adhesive peeling is greatly reduced, so that the noise of the recording apparatus can be reduced to only the sound of the motor drive. Furthermore, this allows the use of a smaller and cheaper drive motor for paper feeding than conventional products.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram for explaining the recording operation in the recording apparatus of the present invention, FIG. 2 is a configuration diagram of a receiving section of a thermal facsimile to which the present invention is applied, and FIG. 3 is a circuit configuration of the facsimile of FIG. 2. A block diagram, FIG. 4 is a block diagram of the control program shown in FIG. 3, FIG. 5 is a flowchart showing the procedure of the control program shown in FIG. 4, and FIG. FIG. 7 is an explanatory diagram showing the relationship between the surface temperature of the thermal head and the peeling force when separating recording paper from the thermal head, and FIG. 8 is a frequency analysis diagram of noise in a thermal facsimile. 1... Post-adjuster, 3... Decoder, 4... Recording driver, 5... Thermal head, 6... Recording paper, 7...
・Control unit, 8... Pulse motor, 9... Code buffer, 10... Line buffer, 12... Timer, 1
4...Control program.

Claims (1)

[Scope of Claims] 1. A thermal recording device that moves a recording paper in a direction intersecting the longitudinal direction of a heating element built into a thermal head, and applies a heating pulse to the heating element to perform printing,
If paper feeding is interrupted for a predetermined time or longer after a recording operation is performed by applying a heating pulse to the thermal head, at least the heating element involved in the recording operation is heated immediately before moving the recording paper to the next line after the interruption. A thermal recording device characterized by comprising means for applying pulses. 2. The thermal recording according to claim 1, wherein the voltage of the heating pulse first applied to the heating element after paper feeding is interrupted is lower than the voltage of the heating pulse when performing a normal printing operation. Device. 3. In claim 1 or 2, the width of the heating pulse initially applied to the heating element after paper feeding is interrupted is shorter than the width of the heating pulse when performing a normal printing operation. Features of thermal recording device.