JPS6338914B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a color facsimile signal transmission system for documents having patterns such as characters in two colors such as black and red.

[Prior Art] A method for efficiently transmitting a black and white binary facsimile signal is to cyclically allocate N carrier waves having a certain phase difference each time a black signal appears, and modulate the amplitude of the carrier wave. A method of creating and transmitting signals is well known.

In recent years, corrections have been written in red ink on office documents,
There is an increasing demand for a technology for easily and efficiently transmitting manuscripts containing red and black characters, such as red stamps.
As a transmission method for documents containing such color information, a method in which amplitude information is increased and transmitted by multi-value conversion can be applied. However, this method has the drawback that it is easily affected by level fluctuations and noise in the transmission path, and requires means for converting multi-level information, which generally complicates the reception and reproduction process. Furthermore, there is a drawback that compatibility with transmission systems that do not perform such special conversion is poor.

[Purpose of the invention]

An object of the present invention is to provide a color facsimile signal that can transmit facsimile signals for originals containing two colors such as red and black with a simple configuration, and that can also be used in common with a modulator/demodulator for binary facsimile signals of white and black. The purpose of the present invention is to provide a Kushimi signal transmission system.

[Structure of the invention]

In the present invention, on the transmitting side, the state identification information of the color signal is obtained, and the phase of the carrier wave is selected based on this color signal state identification information. A phase carrier wave is selected and amplitude modulated according to the state identification information of the color signal, and an opposite phase carrier wave is selected according to the state identification information of the color signal for the signal that appears after changing from one of the first color signal and the second color signal to the other. Transmit with amplitude modulation. On the other hand, on the receiving side, the first color signal and the second color signal are separated from the phase of the carrier wave, and recording density information is obtained from the amplitude value.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a color facsimile signal transmission system according to the present invention, and FIG. 2 is a waveform diagram for explaining the operation of the embodiment.

Black signal B input from terminal 11 and terminal 12
The red signal R input from the two is synthesized by the image signal circuit 13, and is supplied to the amplitude modulation circuit 14 as a signal as shown in FIG. 2A. On the other hand, the set-reset type flip-flop 35 is reset by the black signal B, and this flip-flop 35 is set by the red signal. The output changes as shown in FIG. 2B, and the state of the change is
Therefore, the output of the flip-flop 36 is delayed by one signal with respect to the output of the flip-flop 35, as shown in FIG. 2C. The outputs of the flip-flops 35 and 36 are exclusive-ORed in a circuit 37, and the output becomes high level at the portion where there is a change from a red signal to a black signal or from a black signal to a red signal, as shown in FIG. 2D. When the black signal B continues and when the red signal R continues, the state identification information 15 of the color signal which becomes a low level is obtained.

From the output terminal 18 of the carrier wave generation circuit 17, the second
A 0-phase carrier wave as shown in Figure E is output from the output terminal 19, and a π-phase carrier wave with an opposite phase is output to the phase selection circuit 1.
The signal is supplied to analog gates 21 and 22 in 6, respectively. The analog gates 21 and 22 are controlled by the color state identification information 15, and the gate 21 opens when the color state identification information 15 is at a high level "1".
Each gate 22 is opened at a low level "0". Therefore, as shown in Figure 2 F, when the black signal B or red signal R continues, the 0-phase carrier wave is amplitude modulated, and when the black signal changes from the red signal or vice versa, the π-phase carrier wave is amplitude modulated. be done.

To receive and demodulate such a modulated output signal, the signal from the terminal 25 is passed through a line filter and automatic gain control circuit 38 and an initial signal detection circuit 3 as necessary.
9. The initial signal detection circuit 39 detects the first signal when the signal is sent out, and detects the first signal when the signal is sent out. is reset and its output is taken to a low level. The output of the circuit 38 is transmitted to the synchronous detection circuit 2 by the 0-phase carrier of the carrier regeneration circuit 28.
As shown in FIG. 2G, when the input modulated output signal is 0 phase, a positive output is obtained, and when it is π phase, a negative output is obtained. full-wave rectification. On the other hand, the synchronous detection circuit 27
The output of is separated into a positive pulse and a negative pulse in circuit 43, the positive pulse resetting flip-flop 44, which is set by the negative pulse. Therefore, the output of flip-flop 44 is at a low level during positive pulses and at a high level during negative pulses, as shown in FIG. 2H. Its high level output is the enable terminal of flip-flop 41.
EN, and during its high level, each pulse of the output of the full-wave rectifier circuit 42 is applied to the flip-flop 41.
The output of the flip-flop 41 is inverted every time the signal is applied to the clock terminal of the flip-flop 41, and the output becomes as shown in FIG. The output of the output signal is supplied to a terminal 32 and the output of the terminal 34 is supplied at a high level to a terminal 34, respectively. In this way, a black signal is obtained at the terminal 32, and a red signal is obtained at the terminal 34.

In the above embodiment, there are two types of carrier wave phases (0 phase and π phase), but FIG. 1 shows that the transmission efficiency is improved by providing the phase selection circuit 16 with a function of shifting the phase at regular intervals. is also possible. Furthermore, by assigning color information to the phase of the carrier wave, it becomes possible to transmit many types of color signals, although the transmission efficiency does not improve. In other words, a phase is assigned to each color combination in advance, and a 0-phase carrier wave is transmitted while one color signal is continuous.
When a color signal is switched to another color signal, a carrier wave having a phase assigned to that color combination is selected, and the carrier wave having the selected phase is amplitude-modulated and transmitted.
If the color signals are continuous after the switching, the carrier wave phase may be returned to 0 phase.

Furthermore, in the present invention, since the amplitude value includes the density information of the color signal, halftones can also be transmitted.

〔Effect of the invention〕

As explained above, the color facsimile signal transmission system according to the present invention is capable of transmitting black and white binary AM signals without using a special modulator/demodulator for color signal transmission.
A modulator/demodulator can be easily configured by simply adding a few additional circuits to a PM mode modulator/demodulator, making it possible to easily configure a modulator/demodulator using conventional
There is an advantage that values can also be shared with a modem.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a color facsimile signal transmission system according to the present invention, and FIG. 2 is a waveform diagram for explaining its operation. 11, 12: image signal input terminal, 13: image signal circuit, 14: amplitude modulation circuit, 16: phase selection circuit,
17: Carrier wave generation circuit, 23: Transmission output terminal, 2
4: Transmission path, 25: Reception input terminal, 27: Synchronous detection circuit, 28: Carrier wave regeneration circuit, 32, 34: Regeneration output terminal, 42: Full wave rectifier circuit, 45: Distributor.

Claims (1)

[Claims] 1 Obtain color state identification information from the facsimile signal indicating whether the first color signal or the second color signal is continuous or discontinuous, select the phase of the carrier wave based on this color state identification information, and select the continuous first color signal. Alternatively, the positive phase carrier wave is amplitude modulated by the second color signal, and the first
A carrier wave having a phase different from the normal phase carrier wave is amplitude-modulated and transmitted by a signal changing from one of the color signal and the second color signal to the other, and the receiving side detects the phase of the carrier wave of the received signal. The first color signal and the second color signal are identified by separating whether the first color signal or the second color signal is continuous or a change between the first color signal and the second color signal, and the carrier wave of the received signal is identified. A color facsimile signal transmission method characterized by obtaining recording density information based on amplitude values.