JPH06245038A - Coding/decoding device - Google Patents

Abstract

PURPOSE:To obtain a coding/decoding device which does not generate resonance at a step motor even when a data quantity for one line increases and a coding or decoding speed is slowed down by being provided with a conversion means, an activating means and a delay means, which are respectively specified. CONSTITUTION:A coding circuit 20 as the conversion means converts picture data read by a reading part 23 by a system corresponding to a prescribed standard. In this case, even when coding by the coding device 20 is delayed because the reading data quantity of an original is much, it does not lead a result that the rotation of the step motor 22 drops into a resonance band. Namely, in the case when coding is delayed and the rotation speed comes into the resonance band, CPU 15 of the activating means waits for the output of an actvating signal and executes delay. Thereby, the loss of synchronizm and the inversion of the moter are not caused by the resonance of the step motor 22 to always output a clear transmission image and to prevent the skip-reading of a line because of vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoding / decoding device such as a facsimile device.

[0002]

2. Description of the Related Art When an image on a document is read and transmitted in real time by a facsimile apparatus, the image is read by a scanner, the read line data is encoded by an encoding circuit, and then transmitted through a modem. ing. In this case, reading and encoding by the scanner is performed for each line, and line feeding for each line, that is, sub-scanning drive is performed by a step motor. The rotation of the step motor is controlled by the central processing unit (CP
U) is performed based on a start signal output at the end of encoding. For example, if the step motor is rotating stepwise at 5 ms intervals, 1
After the encoding of the line is completed, the stepper motor is rotated by the drive pulse triggered by the subsequent start signal, and the sub scanning in the direction of the next line is performed.

[0003]

However, when the amount of data is large, such as when the original has many black and white conversion parts, the encoding may not be completed within the step interval of the step motor. In this case, since it is difficult to shift to the next line even after 5 ms has elapsed, the central processing unit (CPU) does not output the activation signal until the encoding is completed. The start signal is output after confirming the end of encoding.

However, in the above example, since the step rotation of the step motor is always maintained at 5 ms intervals, if the start signal is not input within 5 ms, the drive pulse synchronized with the start signal is skipped. ). Since the starting signal is output every predetermined count number of the reference clock, skipping one starting signal means that the excitation state extends from 5 ms to 10 ms. As a result, the stepper motor slows down at this stage. That is, the rotation speed drops from 200 pps when the step rotation is performed at 5 ms intervals to 100 pps when the speed is 10 ms. Generally, the resonance area of the step motor is 100 to 150 pp.
Since it is in the vicinity of s, when the step motor is driven at a speed of 100 pps in this way, resonance starts, which causes step-out and reverse rotation, which causes uneven feeding in the sub-scanning direction, which disturbs the transmitted image and skips line reading. Will end up.

Naturally, the above problem also occurs in decoding in which the operation is reversed from that in encoding. It is an object of the present invention to provide an encoding / decoding device that does not cause resonance in a step motor even when the data amount for one line increases and the encoding or decoding speed decreases. It is a thing.

[0006]

In order to solve the above-mentioned problems, the present invention provides a conversion means for encoding or decoding an image line by line, and a conversion means for each line of encoding or decoding. To the start means for outputting the start signal for rotating the sub-scanning drive step motor to rotate the step motor by a predetermined step, and when the encoding for one line is delayed, the start signal is output accordingly. The gist is that a delay means for delaying is provided.

[0007]

According to the present invention thus constructed, the image data is coded or decoded line by line by the conversion means.
Then, the step motor is rotated by a predetermined number of steps based on the activation signal from the activation means. Then, when the encoding or decoding is delayed, the start signal for rotating the step motor is delayed, and the rotation speed of the step motor falls within the resonance region of the motor, the delay means delays the output of the start signal. By doing so, the rotation speed of the step motor is set to be equal to or lower than the resonance region.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a facsimile machine will be described below with reference to the drawings. As shown in FIG. 2, an operation panel 3 is provided on the front upper surface of the main body case 2 of the facsimile apparatus 1. A numeric keypad 4 is provided substantially in the center of the operation panel 3 so that the number of the called station for facsimile transmission can be input. A liquid crystal display (hereinafter referred to as LCD) 5 is provided on the left side of the numeric keypad 4. Various information at the time of transmission / reception is displayed on the LCD 5. A transmission mode key 6 is provided on the lower right side of the LCD 5. When the transmission mode key 6 is pressed, the memory transmission is converted into real-time transmission. Further, a communication key 7, a copy key 8 and a stop key 9 are arranged below the numeric keypad 4. The communication key 7 is used when starting communication. The copy key 8 is used when copying the document G. The stop key 9 is used to stop transmission and the like. A plurality of one-touch keys 10 are provided on the right side of the ten-key pad 4. The one-touch keys 10 are used when the set called station number is transmitted by one-touch to call the document G. The handset 11 is of an attached telephone connected to an NCU described later.

Next, the main electrical structure of this facsimile will be described. As shown in FIG. 1, a ROM is provided in the CPU (central processing unit) 15 which is the activation means and the delay means.
A (read only memory) 16 is connected, and the CPU 15 controls the operation of the device based on a program stored in the ROM 16. RAM (random access memory) 17
Has a function as a buffer, and temporarily stores transmission / reception data or read data, and temporarily stores count data of printed paper.

An NCU (network control unit) 18 controls connection with a telephone line and detects transmission of a dial pulse corresponding to a facsimile number of a called station via a modem 19 and reception of the dial pulse. The modem 19 modulates / demodulates transmitted / received data. The encoding circuit 20 serving as a conversion unit converts the image data read by the reading unit 23 into a signal according to the CCITT G3 standard.
It is designed to be encoded by the MH system or the MR system. Further, the encoding circuit 20 outputs an encoding end signal to the CPU 15 when the encoding is completed. Similarly, the decoding circuit 25 as a converting means decodes the encoded received image data to reproduce the original image. The decoding circuit 25 also sends a decoding end signal to the CPU 15 upon completion of decoding.
It is designed to output to. A step motor 22 is connected to the CPU 15 via a driver 21. The driver 21 is composed of a control circuit and an amplifier circuit. The step motor 22 is a PM (permanent magnet) type two-phase pulse motor, and its resonance region is set to 100 to 150 pps.

Further, a reading section 23 and a recording section 24 are connected to the CPU 15. The reading unit 23 is composed of a scanner including a CCD image sensor and its peripheral circuits, and reads the image on the original G line by line. The recording unit 24 forms an image on a recording paper line by line based on the received image data received or the read image data read by the reading unit 23.

The relationship between the starting signal and the driving pulse will be described with reference to both graphs of FIG. 3 and FIG. When an encoding end signal indicating that one line has been encoded is input from the encoding circuit 20 to the CPU 15 which is the activation means, CP
U15 sends the start signal a to the driver 21 based on the signal.
Is output. The output interval of the start signal a is the program and C
The timing is set to 2.5 ms based on the reference clock pulse output from the PU 15, and is output on condition that the encoding end signal is input. on the other hand,
The driver 21 is also 2. based on the reference clock pulse.
The drive pulse b is carved at the timing of 5 ms. Usually, this drive pulse b is output to the step motor 22. Then, the step motor 22 is driven to rotate by one step, conveys the original G by one line, and performs sub-scanning. In this case, since the pulses are transmitted at 2.5 ms intervals, the speed of the step motor 22 is steady at 400 pps.
Is. Then, the next one line is read again by the reading unit 23 and encoded by the encoding circuit 20.

However, there are cases in which the amount of read data in one line is too large to encode in 2.5 ms. Then, since the encoding end signal is not input within 2.5 ms, the activation signal a is not output within 2.5 ms, and after the encoding end signal is input, the activation signal c is output with a delay.

Therefore, if this is left as it is, the drive pulse d, which should have been output if there is no delay, is not output and is skipped. As shown in the graph of FIG. 3, if the start signals a are delayed by three, the speed of the step motor 22 decreases from 400 pps to 100 pps. As shown in the graph of FIG. 5, the resonance region of the PM type step motor 22 is between 100 and 150 pps. Therefore, when the line is read at the speed of 100 pps, the step motor 22 starts to resonate, causing step out or reverse rotation. Then, unevenness in the sending occurs and the transmitted image is disturbed, or line skipping occurs.

Therefore, the CPU 15 has an encoding time of 2.5 ms.
If it is determined that the start signal a is not output within three times and the start signal a is not output three times at the specified timing, as shown in the graph of FIG. 4, the drive pulse d is skipped one more time and then the start signal c is output. Output. Then, the drive pulse b is delayed by four activation signals. As a result, the drive pulse b is output to the step motor 22 12.5 ms after the previous drive pulse output.
The rotation speed of the
ps), and the resonance region is exited.

Next, the operation of the facsimile apparatus thus constructed will be described with reference to the flowchart of FIG. This flow chart proceeds under the control of the CPU 15 by the program stored in the ROM 16.

First, in step (hereinafter referred to as S) 1, the document G is set and converted to real-time transmission by the transmission mode key 6, and then the communication key 7 is pressed to start communication. In S2, the reading unit 23 reads the first line of the original document G conveyed in the main body case 2, and the data is simultaneously encoded and transmitted from the NCU 18 to the called station side via the modem 19. CPU1
In S3, it is determined in S3 whether the encoding for one line is completed within 2.5 ms and the encoding end signal is input to the CPU 15. When the input within 2.5 ms is confirmed, the start signal a is output to the driver 21 in S4 after 2.5 ms has elapsed from the start of reading. Then S5
At 2, the driver 21 outputs a drive pulse b at 2.5 ms intervals, and at step S6, the step motor 22 is rotated by one step to perform sub scanning.

Further, when the reading unit 23 detects the next one line in S7, the process returns to S2 and the above-described flow is repeated. During this period, the step motor steps are always set to 2.5 ms, and the speed of the step motor 22 is 400 pps.

On the other hand, in S3, the encoding of one line cannot be completed within 2.5 ms, and the encoding end signal is CP.
If not input to U15, the CPU 15 returns to S8.
At, the number of times the pulse d of the driver 21 is skipped is counted. Here, within two times, the step motor 22 does not enter the resonance region even if the speed decreases. In that case, the flow moves to S4. Then, the stepping motor 22 slows down its rotation speed and is rotated one step in S6.

However, in the case where the number of skips is three in S8, when the start signal is input next time, the step motor 22 remains in the resonance region as it is. Therefore, the CPU 15 delays the output of the activation signal a in S9 until the pulse d is emitted again. When it is determined that the pulse d has been skipped four times, the process proceeds to S4, the step motor 22 reduces the rotational speed (80 pps) below the rotational speed of the resonance region, and one step is performed in S6. When the number of skips of the pulse d is four or more due to the delay in encoding, the step motor 22 has already left the resonance region, and therefore the process of S9 is unnecessary.

As described above, in the facsimile apparatus according to the present embodiment, even if the amount of read data of a document is large and the encoding by the encoding circuit 20 is delayed, as a result, the step motor 22 is obtained.
The rotation of the will not fall into the resonance region.
That is, in the case where the encoding is delayed and the rotation speed enters the resonance region, the CPU 15 which is the starting unit causes the starting signal a.
Wait for the output of to delay. Therefore, a clear transmission image can always be output without causing step-out or motor reverse rotation due to the resonance of the step motor 22, and the line is not skipped due to vibration.

The present invention is not limited to the above embodiment, but can be modified and implemented as follows. For example, in the above embodiment, the delay is set to three start signals in order to avoid the resonance region, but it may be set to five or more delays as long as it is possible to avoid the resonance region. The length of this delay time is determined by the characteristics of the step motor. For example, PM type has 4 phases or 5
The resonance region of the phase type and the HB type are different.

In the above embodiment and in the above embodiment, the present invention is embodied in the encoding.
It may be embodied in the decoding. In this case, the present invention is implemented in the process of decoding the encoded signal, and the step motor is used for feeding the paper on which the image is output. Furthermore, although the present invention has been embodied in real-time transmission in the above embodiments, it may be embodied in memory transmission in which line data is temporarily stored in a memory. In addition, the present invention can be applied to a copying apparatus and the like, and the present invention can be modified and implemented without departing from the spirit of the invention.

[0024]

As described above in detail, in the present invention, even if the data amount increases and the encoding or decoding speed becomes slow, resonance does not occur in the step motor, and the encoding / decoding does not occur. An excellent effect is obtained in that no trouble occurs.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a main electrical configuration of an encoding / decoding device that is an embodiment of the present invention.

FIG. 2 is a perspective view for explaining the outline of the encoding / decoding device in the same manner.

FIG. 3 is a graph illustrating a synchronization relationship between an excitation state of a step motor and a pulse of a driver and a start signal of a CPU in the encoding / decoding device.

FIG. 4 is a graph for explaining the synchronization relationship between the excitation state of the step motor and the pulse of the driver and the CPU start signal in the encoding / decoding device.

FIG. 5 is a graph showing a resonance region in the step motor of the encoding / decoding device.

FIG. 6 is a flowchart for explaining reading of an original in the encoding / decoding device.

[Explanation of symbols]

15 ... CPU as starting means and delay means, 20 ... Encoding circuit as converting means, 22 ... Step motor.

Claims (1)

[Claims] 1. A conversion means for encoding or decoding an image line by line, and a start signal for rotating a sub-scanning drive step motor each time the encoding or decoding for one line is completed. Then, the encoding / decoding device includes a starting means for rotating the step motor by a predetermined number of steps and a delay means for delaying the output of the starting signal in response to the delay of the encoding of one line.