JPS59153376A - Facsimile device - Google Patents

Abstract

PURPOSE:To attain recording with proper density with simple constitution by driving a heater by a dummy data at a low voltage at non-recording during the receiving of the group II in a device in common use for the groups II and III of the CCITT recommendations. CONSTITUTION:In the facsimile device in common use for the groups GII and GIII modes in accordance with the CCITT recommendations T3, a received data is demodulated by a modulation and demodulation device 102, decoded by a controller 103 and stored once in a storage section 106, and transmitted to a therman head 109 and recorded. The recording operation of the head 109 is controlled by the controller 103 via a timing signal generating circuit 107 and a voltage switching circuit 108. The circuit 108 drives the heating elements of the head 109 at the non-recording during the receiving of the GII mode while switching the voltage to a low voltage to the degree that the thermal sensing paper is not developed color by a dummy data so as to keep the temperature of the heating elements. Thus, the data is recorded at a proper density both for the GII and GIII modes.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to facsimile machines, and more particularly to Group 2 facsimile machines that comply with CCITT Recommendation T3 and which use a thermal printer as a recording device.

PRIOR ART Conventional devices of this type, especially facsimile machines that can also be used in group 3 mode and which can be used for both group 2 and group 3, have a minimum transmission time for data in group 2 (hereinafter referred to as 02) mode and group 3 (hereinafter referred to as (G3) mode, so unless some measure is taken, the recording speed will be slower in G2 mode, which will cause the temperature of the thermal head to drop.
There was a drawback that sufficient recording density could not be obtained.

For example, in order to perform electric transmission with a transmission time of 20 m5 per line in G3 mode, a thermal printer as a recording device must be configured to have sufficient recording quality at least at a speed of 20 m5 or more per line. However, G
When performing G2 communication on a dual-purpose machine for 3 and 01, the transmission time for G2 is approximately 167 m5 per line, so if a thermal printer that satisfies 03 in G2 mode is used, the thermal head of the printer will be over 140 m5. A problem arises in that a period of non-driving occurs, and the temperature of the head decreases during this non-driving time, resulting in a lower recording density in G2 mode than in G3 mode.

In view of this, a preheating circuit is installed on the thermal head's heating element board, etc. to preheat the entire thermal head and maintain the ambient temperature of the heating element, thereby achieving a constant image quality regardless of the reception mode. It has been known. However, such a preheating circuit is essentially superfluous considering its function as a recording device, which only records the received take.Providing this preheating circuit increases the external size of the thermal head. Furthermore, since a power source is required for this purpose, the device becomes complicated and the number of assembly steps increases, resulting in an increase in the cost of the entire device.

OBJECTS OF THE INVENTION The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional apparatus, and it is an object of the present invention to provide a facsimile apparatus that can record received data with appropriate recording density using a simpler and cheaper structure.

EXAMPLES Hereinafter, the present invention will be explained in detail based on examples shown in the drawings.

FIG. 1 shows a block diagram of a 7mm 7mm device according to the present invention. Here, reference numeral 101 in FIG.
What is shown is a subdivision. This modulator/demodulator 102 is connected to a control device 103 for overall control by a known microcontroller or the like, and a storage section 106 composed of a RAM (random access memory) and the like.

The control device 103 includes a reading section 105 for reading a document image using a CCD sensor, etc., and an operation panel 1.
04 is connected. The original image read by the reading unit 105 is sampled and
After undergoing known processing such as encoding, the modulator 102
After being modulated into a form that can be carried over the line, it is sent out to the line 110 via NCUlol.

On the other hand, received data sent from the line 110 is demodulated by the modem 102, decoded by the control device 103, and then temporarily stored in the storage unit 106.

The received image data is sent from the storage unit 106 to the thermal head 109 and recorded therein, but is controlled via the thermal head 108 .

Next, FIG. 2 shows a detailed circuit diagram of the voltage switching circuit 108 and the vicinity of the thermal henode 109.

The thermal head 109 shown in the figure has one line 172.
It has a heating element layer of 8 dots to R1728, and these heating elements are simultaneously driven to record received data on one line of recording paper made of thermal paper. The heating element is divided into two blocks, R1-R832 and R833-R172B, and the applied voltage is controlled by the voltage switching circuit 108 for each of these two blocks.

This voltage switching circuit 108 is composed of a transistor and a diode, and has two types of drive voltages VH and VH.
This is for switching and supplying L to each of the two blocks of the heating element. Is the higher 1 drive voltage VH the transistor TRI? , is applied to the heating element of the first block (R1-R832) through the diode D11, and -! , is applied to the heating elements of the second block (R833 to R1728) via the transistor TR21 and the diode D21. Lower drive voltage VL
Similarly, the voltage is applied to the heating elements of the first block and the second block through the transistor TR12, the diode D12, and the transistor TR22 (diode 22), respectively.

The above transistors TR11, TR12, and TR21.

The ON/OFF control of TR22 is controlled by AND gates 201~
204, respectively. The AND gates 201 and 203 are configured to receive a voltage selection signal SVH of the drive voltage VH, and the AND gates 202 and 204 are configured to receive a voltage selection signal SVL of the drive voltage VL. Furthermore, Antogame 1/2.01,
The first block selection signal BLI described above is input to 203, and the second block selection signal BL2 is input to AND gates 202 and 204. Therefore, each drive voltage is selected by the logical sum of the voltage selection signal and the block selection signal.
A drive circuit including an AND gate and a latch circuit is provided on the other side of the heating element, and image data in the storage unit 106 is recorded by this drive circuit. That is, data signal lines D1 to D4 from the storage unit 106 are sent to latch circuits L1 to L4 using registers,
It is latched and becomes parallel data. This latch circuit L
The latch signal LCI-1 and the clock pulse CLK are supplied to the launch circuits L1 to L4, and the data outputs of the launch circuits L1 to L4 are input to the ant gates provided on the respective heating elements, and the above A block signal S'l input from the timing signal generation circuit 107
Each heating element is driven by the logical sum with rR1 to rR4. Here, the two blocks of the heating element described above are further divided into two, and each of the blocks is connected to the latch circuits L1 to L1.
Uke is held at L4.

Next, the operation of the thermal head drive circuit shown above will be explained in detail with reference to the timing chart of FIG. FIG. 3 shows the waveforms of each signal line in the circuit of FIG. 2, respectively.

Well, here the timing of the recording operation in G2 mode is shown.

During recording, data is transferred at the time of TO. That is, the latch circuits L1 to L4 take in the data on the data signal lines 1) 1 to 1) 4 in accordance with the clock pulse CLK.

This data moth is latched by the latch signals T and C1-1, and then the heating elements are selected in the order of the first block and the second block by the first block selection signal B]'j and the second block selection signal T3L2. Furthermore, these blocks are each divided into four parts and driven by strobe signals 5TRI to S'l'R4, and recording ends at time T1.

At this time, it is assumed that the rate of each signal is set so that recording can be performed using the minimum transmission time in the 03 mode. Therefore, the process of 'I''o-T is completed in approximately 2Qms.

During the above recording operation, the transistor 'I' in FIG.
R11 and TR2+ are the selection signal SVH and the first block selection signal 13L1 or the second block selection signal B, 2.
is selected via the AND gate 201 or 203, and each heating element is driven by the drive voltage VH.If the drive voltage Vll is a voltage that can obtain sufficient recording density at the recording speed in G3 mode, each data is recorded with the same recording density as in G3 mode.

As mentioned above, the operation of the recording section is set to J-- which has a speed sufficient to cover the minimum transmission time in G3 mode, so as shown in FIG. -1. Even if data recording ends at time T2, there is no data to be recorded until time T2, when the next data arrives.

In the present invention, this free time is used to drive each heating element using the drive voltage Vl and dummy data to keep the temperature of the thermal head constant. That is, at the time of T1, the dummy data is The data is taken into the latch circuits Li to L4 by the clock pulse CLK, and then the latched data selects and drives the heat generating elements for each block in the same manner as described above.

At this time, the 5 drive voltage selects the l transistors TR+2 and TR22 via the ant game 1-202 or 204 by the selection signal S V L and the first block selection signal BLI or the second block selection signal 131.2. 1 drive voltage VL is selected. In that case, if the driving voltage (L) is set to a voltage that does not cause the thermal paper to develop color, the above-mentioned dummy data will not be recorded.

The driving of the heating element using the dummy data described above is T
Continue at the trench where the next data arrives at point 2. In other words, if the transmission time in G2 mode is about 167m5,
Perform dummy recording six times in the interval T, -'I"2. T2
If the next data arrives at the time point, the drive voltage VH is selected in the same manner as described above, and data is recorded. However, the evening data at this time can be arbitrarily set by a person skilled in the art depending on the specific heat of the head, etc.

In the manner described above, it is possible to keep the head warm in preparation for the next recording.

FIG. 4 is a timing chart showing how the heating element is driven in the G3 mode in the above configuration for reference.

In ()3 mode, first, data signal lines D1 to D4 are connected to latch circuits L1 to L4 according to clock signal CLK.
This data is then latched by the latch signal LCH. Next, the first block selection signal BLI
is set to the no-low level, and then the slave signal 5TR1 is set to the no-low level.
Strobe each heating element in the order of ~5TR4, then the second
The block selection signal BL2 is set to high level, and each heating element is similarly strobed to perform recording. In G3 mode, the recording iIt speed is set to cover the minimum transmission time of 20m5 in 03 mode, so
■As soon as line recording is finished, data transfer for the next print begins.

Next, control of the recording operation in the above configuration will be explained in detail with reference to the flowchart shown in FIG. Fifth
In step S1 in the figure, it is first determined whether data for one line exists in the storage unit 106. If the data for the next one line is complete, the process moves to step S2, and the data for one line is transferred to the latch circuit of the thermal head as described above.

Subsequently, in step S3, the voltage switching circuit 108
Accordingly, the driving voltage Vl+ is selected as described above.

Next, in step S4, the timing signal generation circuit 1
07, each block of heating elements is selected, each heating element is driven by a strobe signal, and one line of recording is performed.

Subsequently, in step S5, it is determined whether or not data recording for one line has been completed. 3. If it is confirmed in step S5 that recording of the line has been completed, that line is determined to be the final line in step S6. It is determined whether or not the next line exists, and if the next line exists, the process returns from step S6 to step S1, and if the recording has ended at the last line, the process moves to the next processing routine.

On the other hand, in step S1, if the data for the next line is not available in the storage unit 106, the process moves to step S7.

In step S7, it is determined whether predetermined dummy data has already been transferred to the latch circuit of the thermal head. Here, if the dummy data has not yet been sent to the head, the dummy data is sent to the latch circuit in step S8, and if it has already been transferred, the process moves directly to step S9.

In step S9, it is determined whether the selection signal SVL is being sent to the voltage switching circuit 108. Here, if the drive voltage VL has already been selected by the selection signal SvL, the process moves directly to step S4, and if the drive voltage VH has been selected, the selection signal SVL is sent to the voltage switching circuit 108 in step S10. After sending, the process moves to step S4.

As described above, in the G2 mode, the head is prevented from cooling down during recording idle time, and the same recording quality as in the 03 mode can be expected in the G2 mode.

The above configuration does not have the 03 mode (of course, it can also be applied to the 12 aircraft).

Effects As is clear from the above explanation, according to the present invention, a structure is adopted in which a voltage is applied to the heating element of the recording device to the extent that the thermal paper does not develop color when not recording, and the heating element is kept warm. As a result, the temperature of the thermal head can be kept constant without the need to provide a preheating circuit like in the past.
It is possible to provide an excellent facsimile device that can record images with constant recording density in both facsimile 7mm modes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of a facsimile apparatus of the present invention, FIG. 2 is a circuit diagram showing a detailed configuration around the thermal head in FIG. 1, and FIGS. 3 and 4 are the circuits shown in FIG. 2. FIG. 5 is a flowchart explaining the control fil1 procedure of the facsimile/millimeter apparatus of the present invention. 103...Control device 106...Storage unit 10
7...Timing signal generation circuit 108...Voltage switching circuit 709...Thermal heads 201-204...Antoge-1-L 1-L4.
...Latch circuit patent applicant Canon Corporation

Claims (1)

[Claims] CCITT Recommendation T3 using a thermal printer as a recording device
In a facsimile machine equipped with Group 2 and Group 3 that match the above, the heating element of the recording device is driven by dummy data during non-recording with a voltage that does not color the thermal paper during reception in Group 2 mode, and the heating element is driven by dummy data. A facsimile machine that is characterized by maintaining a temperature of .