JPS5918912B2 - TV multiplexed still image broadcast receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television multiplexed still image broadcasting receiver that receives still image signals multiplexed and transmitted during the vertical blanking period of a standard television signal. obtained from the color burst signal of a standard television signal.

By using a pseudo-horizontal synchronization signal obtained by frequency-dividing a color subcarrier, the reproduction precision of the vertical synchronization signal is improved, thereby contributing to the improvement of the image quality of reproduced still images. Figure 1A shows a still image signal (
This figure shows a part of a standard television signal that is multiplexed and transmitted with SPB signals (hereinafter referred to as SPB signals).

Various methods for multiplexing SPB signals have been announced, but in explaining this invention, we will discuss the transmission methods announced in "Image Transmission Study Group Materials of the Television Society/f6.9-6/1974". , the SPB signal of the first channel is transmitted during the 14th to 16th H period of the first field of the standard television signal, and the 277th to 27th H period of the next field is
The explanation will be based on a method in which the SPB signals of the second channel are respectively transmitted during the 9H period. The opening in Figure 1 shows the SPB signal of the first channel transmitted by this transmission method.The signal is composed of 261H, and the first H is used to reproduce the vertical synchronization signal of this SPB signal. The 14th H is provided with a control signal (VC) for channel switching and cut switching, and the 4th to 6th H are provided with a control signal (VC) for the vertical synchronization signal of this SPB signal. It is planned as a section. Such an SPB signal can be transmitted in a transmission time of 87 frames of a standard television signal, or 2.9 seconds. SPB like this
The most commonly considered method for reproducing the vertical synchronization signal of the SPB signal from the standard television signal containing the signal is to pass the horizontal synchronization signal separated from the standard television signal through an AFC circuit, and output the output from the AFC circuit. Control signal (C
V) Count with a 261-decimal counter that is reset by the control signal (CV) detected by the detection circuit, and create a pulse corresponding to the 4th to 6th H periods, that is, a reproduction vertical synchronization signal of the SPB signal. However, if the vertical synchronization signal is regenerated using this method, the correct horizontal synchronization signal may not be obtained when the reception condition of the television receiver is poor, for example when receiving in a weak electric field.
As a result, the vertical synchronization signal of the reproduced SPB signal may be inserted at a different position from its original position.

Therefore, the present invention does not use a horizontal synchronization signal that is susceptible to fluctuations depending on reception conditions, but divides the color subcarrier obtained from a burst control oscillator to obtain a pseudo horizontal synchronization signal, and uses that signal to obtain a pseudo horizontal synchronization signal. The purpose is to reproduce the vertical synchronization signal of the SPB signal.

FIG. 2 shows a main part block diagram of one embodiment of the receiver according to the present invention. Terminal 1 receives a standard television signal including an SPB signal. The signals are input to a clamp circuit 2, a synchronous separation circuit 3, a control signal detection circuit 4, and a subcarrier generator 5, respectively.
The subcarrier generator is triggered by a burst signal in a standard television signal, and its output is about 3.58
Outputs MHz subcarrier. This subcarrier is input to the 2/455 frequency divider circuit 6, and its output is approximately 1
Outputs a 5.75KHz pseudo horizontal synchronization signal. This pseudo-horizontal synchronization signal and the control signal (CV) detected by the detection circuit 4 are input to a vertical synchronization signal regeneration circuit 9 consisting of a 261-decimal counter 7 and an OR gate 8 that allows only its predetermined output to pass through, and its output is A reproduced vertical synchronization signal of the SPB signal is derived. The counter receives a control signal (
C) is reset and counts the pseudo-horizontal sync signal, and the OR gate passes counter outputs 3, 4, and 5. The vertical synchronization signal thus reproduced is added to the standard television signal clamped through the clamp circuit 2 by an additional circuit 10. The purpose of clamping the standard television signal is to prevent the magnitude of the added vertical synchronization signal from changing due to fluctuations in the DC level of the signal. Further, the horizontal synchronization signal separated by the synchronization separation circuit 3 and the control signal (C
C) is input to the 3H gate generation circuit 11, which generates a gate signal for extracting the 3H period from the 14th to the 16th H of the standard television signal, and uses the gate signal to generate the 3H period as described above. A predetermined 3H signal is gated by a gate circuit 13 from a signal obtained by modulating a signal to which a vertical synchronizing signal for SPB signal is added by an FM modulator 12 . The output, that is, the SPB signal, is amplified by an amplifier 14 and sent onto a concentric track of a magnetic sheet 16 whose rotation is controlled by a motor 15.
H minutes are recorded one after another. And 87 of the magnetic sheet
By rotation, one unit of still image is recorded on the concentric track. Although not shown, a continuous signal obtained by repeatedly tracing this track is supplied to a display circuit of a television receiver, and the still image is displayed on the screen. Incidentally, the motor 15 has its rotation detection head 17.
The phase is controlled by the servo output from the servo circuit 18, which uses the rotation detection signal extracted from the above as a comparison signal and the above-described pseudo horizontal synchronization signal as a reference signal. In addition, in this type of system, the reproduced vertical synchronization signal is not synchronized with the horizontal synchronization signal, so the position of the reproduced vertical synchronization signal is ±1 from the original vertical synchronization signal position.
Although there is a possibility of H deviation, this deviation poses no problem in practice. As mentioned above, in the receiver of the present invention, in order to reproduce the vertical synchronization signal for the SPB signal, the pseudo horizontal synchronization signal created based on the burst signal included in the standard television signal is used. Even when the reception condition is not strong, such as in a weak electric field, the reproduced vertical synchronization signal can be obtained correctly, and therefore the reproduced image quality of the SPB signal does not deteriorate.

[Brief explanation of drawings]

Figure 1A is a model diagram of a standard television signal multiplexed with a still picture (SPB) signal, Figure 1A is a model diagram of an SPB signal extracted from this standard television signal, and the numbers in the figure are SPB This is the scanning line number of the signal. FIG. 2 is a block diagram of a main part of one embodiment of the receiver of the present invention. Explanation of main drawing numbers, 2...Clamp circuit, 3...Synchronization separation circuit, 4...Control signal detection circuit, 5...Subcarrier generator ,6
...2/455 frequency divider circuit, 9 ... Vertical synchronization signal regeneration circuit, 7 ...261 counter,
8...OR gate, 10...additional circuit, 11...3H gate creation circuit, 13...
...Gate circuit, 14...Amplifier, 15...
...Motor, 16...Magnetic sheet, 17...
... Rotation detection head, 18 ... Servo circuit.

Claims (1)

[Claims] 1. Receive a standard television signal in which still image signals constituting a still image are multiplexed during a vertical blanking period, extract the still image signal, and store it on one track of a recording medium; In a television multiplexed still image broadcasting receiver, a continuous signal obtained by repeatedly tracing the track is supplied to a display circuit of the television receiver, and the still image is displayed on the screen. In order to reproduce the vertical synchronization signal of the signal, a continuous color subcarrier is obtained from the color burst signal of the standard television signal, and a pseudo horizontal synchronization signal obtained by frequency-dividing this is used. Broadcast receiver. 2. The television multiplexed still image broadcast receiver according to claim 1, wherein the frequency dividing circuit is a 2/455 frequency dividing circuit.