JPS6033020B2 - Facsimile recording control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In facsimile recording using a thermal head, the present invention uses a power source whose voltage changes periodically as a driving power source for the thermal head, thereby reducing the size and cost of the power source of a facsimile recording device. It is something.

FIG. 1 is a block diagram of a conventional technique using a thermal head.

In Fig. 1, 1 indicates n of heating elements (r, ~rn) in one row.
This is a thermal head arranged in an array. 2 is a control section of the facsimile receiving device, and its function is to receive a facsimile signal R from the outside, generate a signal D, operate the thermal head drive circuit 3, and generate a heating element corresponding to the signal R. The device controls the thermal head by applying electricity to generate heat and recording on the thermal recording paper that is in close contact with the thermal head.

4 is a power supply that supplies power to the thermal head, and in the conventional technology, a DC power supply is used.
diodes for rectification, RG stabilization circuit, and C
It consists of smoothing capacitors, etc.

In a facsimile recording device using a conventional thermal head shown in Fig. 1, when the number of heat generating elements is increased in order to improve the recording density of the thermal head, it is often necessary to energize a large number of heat generating elements at once. , and the power capacity of the power source 4 increases.

Furthermore, when trying to improve the recording speed, it is necessary to supply more power to the thermal head, which increases the power supply capacity of 4. As a result, the shapes of the transformers, diodes, stabilizing circuits, smoothing capacitors, etc. that make up the power source 4 generally become larger, and the cost becomes higher. Furthermore, as the power supply capacity increases, the heat generated from the stabilization circuit also increases.
The heatsink will also be larger. Therefore, the presence of a DC power source becomes a big problem when trying to make facsimile machines smaller and lower in cost. The purpose of the present invention is to solve these problems, and its feature is to reduce the size and cost of the power supply by devising control so that a power supply whose voltage changes periodically can be used as the power supply for driving the thermal head. It is Moho who does. FIG. 2 is a block diagram of an embodiment of a facsimile receiving apparatus implementing the present invention.

In FIG. 2, 1 is the same as the conventional thermal head shown in FIG. 1, and 2' is a control section modified so that the thermal head can be driven by AC. Reference numeral 5 denotes a shift register, which temporarily records line data to be recorded at one time by the thermal head.

6 is an AND gate, which takes the AND of the control signal Td for the timing and energization time for energizing the thermal head and the recording signal to each heating element of the shift register 5;
The power is input to the drive circuit of the thermal head 1 to energize the heat generating element of the thermal head 1.

A specific example of the drive circuit 7 is a drive circuit in which a heat generating element is inserted as a load in a collector circuit of a transistor.

Next, reference numeral 8 denotes a power source that houses a power source Ed for driving the thermal head and a power source Eb for operating other parts of the facsimile machine (circuits other than the heat generating element). The configuration of this power supply Ed is one of the features of the present invention; it consists only of a transformer T and a rectifier diode DM, and it does not have a stabilizing circuit or a smoothing capacitor like the power supply for the thermal head in the prior art shown in Fig. 1. Not yet. Therefore, it is smaller than conventional power supplies, and the reduction in circuit components also reduces the cost of the device. However, when recording by applying a power source that is simply rectified alternating current to a thermal head, it is necessary to devise a control method to make the recording quality uniform. In the present invention, this control is realized by the method described below. When recording on thermal recording paper by rectifying AC power and applying EO voltage across the ribs to a thermal head, in order to make the recording quality uniform, the power supply voltage changes over time, so it is necessary to stop the heating element of the thermal head. It is necessary to examine the waveform of the power supply at the timing of energization and determine the energization time for that waveform.

As a method of determining the power-on failure that provides uniform recording quality, it is conceivable to synchronize the recording timing with the AC waveform and always drive under the same conditions, as shown in FIG. However, in this method, a periodic waiting time occurs after data is input until the start of driving for recording based on this data. In addition, in order to increase the recording speed, it is necessary to record multiple times during one period of the AC waveform as shown as lj in Fig. 4, which will be described later. It is necessary to determine it according to the condition of the AC waveform. Furthermore, this time setting must be done not only to make the amount of energy applied to the heat generating elements of the thermal head uniform, but also in relation to the heat dissipation characteristics of the recording section. In the present invention, in order to provide uniform recording quality, the energization time for each AC waveform is determined by the following method. The block diagram of FIG. 2 and the time chart of FIG. 4 will be used to explain the present invention.

In Fig. 2, 9 is a circuit that detects the timing of volts, which is one of the singular points of the AC waveform.A concrete example of this circuit is a photocolor base and a comparator as shown in Fig. 5. This can be achieved using In FIG. 5, the light emitting diode LED generates light corresponding to the voltage Ed, and the photodiode PHD receives this light and outputs a voltage corresponding to the voltage Ed, which is applied to one input of the comparator CM. The other input of the comparator has a reference voltage Vt
Since h is being applied, when Ed reaches a predetermined voltage, comparator CMP generates output Tr. The output from 9 in FIG. 2 then resets counter 10. T of timing circuit 11 between counter 1 and singularity
c, it is divided by the clock. (In the example of the time chart in FIG. 4, it is divided into 11 stages.) 12 is a fixed memory that uses the contents of the counter 10 as address data. The data in the fixed 0 memory 12 is as shown in the table below. In this example, one word consists of 6 bits, and the number of words is 11, which corresponds to the state of the 10 counters.
It is a word. The table shows the voltage waveforms outside this data. This data is the energization time data in the state of
is set to cause the flip-flop 14 to generate energization times for each waveform shown in FIG.

Next, a description will be given with reference to FIG. 4 and a time chart in FIG. 6, which is a detailed division of part 2 in FIG.

In FIG. 4, e is an AC waveform with a period TH, and a period T
H is 2 skin S in case of 50Hz. Ed is a waveform obtained by full-wave rectification of e, the period is 1/2 of the waveform e, and this waveform is applied to the thermal head. Tr is the output signal of 9 that detects the timing when Ed becomes an enemy, and this signal Tr
When the counter 10 is reset, the counter 10 is reset when the Ed waveform increases, and the counter 10 is synchronized with the AC waveform. This counter 0 operates with the Tc clock and increases the count until it is reset by the next Tr. Next, Tdata is the time for transferring recording data to the shift register 5, and its detailed waveform is shown in FIG.

In FIG. 6, the DATA signal is an R facsimile signal received by the control unit 2', edited in recording units of the thermal head, and set in the shift register 5 by the Ts clock. When the data to be recorded by the thermal head is set in the shift register 5, the control section 2' sends the m signal of T to the counter 3 as a load control signal. This signal is also sent as a set signal to the 14 energization time control flip-flops. This T
The c-signal causes the counter 3 to be set with data that is successively output by specifying the address of the fixed memory 2 based on the current contents of the counter 0. At the same time, flip-flop 14
is also set, the Td signal becomes "1", and the heating element starts to be energized. Next, the counter 13 generates a time indicated by the data in the fixed memory by counting the Tc2 clock, and finally outputs a reset signal for the flip-flop 14. As a result, the flip-flop 14 is reset and the Td signal becomes "0", stopping the power supply to the heating element. As a result, a current waveform indicated by lj flows through the heating element. As is clear from the above explanation, when a power supply whose voltage changes periodically is used as a drive power supply for a thermal head according to the method of the present invention, the heating element is energized to provide uniform recording quality according to the state of the voltage waveform. Time can be controlled.

As a result, it is possible to use a rectified power supply, which is simpler than a DC power supply, as the drive power supply for the thermal head, which is effective in downsizing and cost reduction of facsimile machines. Note that the drive circuit 7
By using a circuit capable of AC drive, the drive power source can be an AC power source.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a recording section of a facsimile recording device according to the prior art, FIG. 2 is a block diagram of a recording section of a facsimile recording device according to the present invention, and FIG. 3 is a characteristic diagram of thermal recording paper. , Fig. 4 is an operation time chart of the device shown in Fig. 2, Fig. 5 is an example of a singular point detection circuit, Fig. 6 is a partial detailed view of the time chart of Fig. 4, and Fig. 7 is an explanatory diagram of energization time. It is.

1... Heat sensitive element, 2'... Control section, 5...
・Shift register, 6...AND circuit, 7...drive circuit, 8...power supply circuit, 9...singularity detection circuit, 1
0...Counter, 11...Clock generator, 12...
Fixed memory, 13...Counter, 14...Flip-flop.

Figure 7 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1. In a method for recording on thermal recording paper using a thermal head equipped with a plurality of heating elements arranged in a row and energized at once, a periodic AC power source is used as the driving power source for the thermal head, and Detects the 0V singular point of the power supply voltage, divides the 0V singular point using a counter that is stepped by a clock pulse, and sets or resets the flip-flop according to the contents of the counter at the moment when the facsimile recording signal is input. 1. A facsimile recording control method, comprising: controlling the time for energizing a thermal head in accordance with the set time of the flip-flop. 2. The facsimile recording control method according to claim 1, wherein the control of the energization time to the thermal head is performed based on the contents of a fixed memory whose address is the contents of a counter.