JPS585632B2 - Frame memory hand warmer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frame memory readout circuit that converts a composite color signal stored in a frame memory into a signal that maintains a so-called interleaving relationship by inverting the phase of the color signal for each frame. It is.

When a signal is directly read out from a one-frame memory in which a composite signal is directly recorded, the phase of the color signal superimposed on the luminance signal at one point remains the same no matter how many times the frame is read out.

On the other hand, in the NTSC system and the like, the phase of a certain point is inverted every frame to prevent dot damage caused by color signals, and the phase of the subcarrier of the receiver is also the same.

Therefore, by inverting the phase of only the color signal of the signal read from the one-frame memory every other frame, the waveform of the NTSC system itself can be continuously obtained.

Conventionally, composite signals are mainly recorded on magnetic disks, magnetic sheets, etc., and from the viewpoint of recording performance, a low-frequency conversion superimposition method is used that converts the color signal to a low frequency and records it. The problem was solved by a conversion circuit.

There were also cases where dot damage prevention was ignored and used as a signal as is.

The present invention provides a device that inverts the phase of a color signal for each frame of a signal reproduced from a one-frame memory, and an embodiment thereof will be described below.

In FIG. 1, reference numeral 1 denotes a one-frame memory, which is composed of an IC memory or a magnetic memory, and records video signals as composite signals.

2 is a bandpass filter that extracts components of the color signal band; 3
is a 1H (one horizontal scanning period) delay line, 4 is a subtraction circuit, and 5 is a 1H (1 horizontal scanning period) delay line.
is a phase inversion amplification circuit, 6 is a gate circuit, 7 is a delay line for compensating for the time difference between the color signal and the luminance signal, and 8 is for adding the output signal of delay line 7 and the output signal of gate circuit 6. It is a circuit.

Next, the operation of the embodiment configured as described above will be explained.

The composite signal recorded in the one-frame memory 1 is repeatedly reproduced and applied to a bandpass filter 2, where color signal band components are extracted.

This signal is separated into a color signal component and a luminance signal component by a comb filter constituted by a delay line 3 and a subtraction circuit 4, and only the color signal component is extracted as an output.

This color signal has the same phase in each frame as shown in FIG. 2a.

The phase of the color signal obtained by the comb filter is inverted by the phase inversion amplification circuit 5.

The amplitude of this color signal is twice the color signal component of the output from the one frame memory 1.

This signal is gated every other frame by the gate circuit 6 to obtain, for example, the signal shown in FIG. 2b.

Note that the instruction for the operation of the gate circuit is synchronized with the video signal from the synchronization circuit 9, and the gate circuit 6 is opened and closed by an instruction pulse that switches every other frame.

The signal thus obtained is added to the original signal that has passed through the delay circuit 7 in the adder circuit 8, resulting in a series of signals in which the color signals are in opposite phase every other frame, as shown in FIG. 2c. Become.

Now let the output of the delay line 7 be Y+C (Y is the luminance signal,
C is a color signal), and if the output of the gate circuit 6 is -2C, the 2nth frame remains Y+C, but 2n+1
In the th frame, Y+C-2C=Y-C, and the color signal is inverted to Y+C, Y-C, Y+C, Y-C every other frame.

As is clear from the above embodiment, since the original signal, especially the luminance signal, is left as is and only the color signal is passed through the comb filter, the ringing and transients that tend to occur in the comb filter do not occur in the luminance signal.

Moreover, for this reason, a good image with high resolution can be obtained.

Also, the circuit configuration is relatively simple.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a frame memory read circuit according to an embodiment of the present invention, and FIG. 2 is a signal waveform diagram thereof. 1...Frame memory, 2...Band pass filter, 3...Delay line, 4...
Subtraction circuit, 5... Phase inversion amplification circuit, 6...
...gate circuit, 8...addition circuit.

Claims (1)

[Claims] 1. A one-frame memory that stores one frame of composite video signal and repeatedly reads out the signal, a filter that separates the color signal components of the read composite video signal, and a filter that separates the color signal components of the separated color signal. An amplifying circuit that inverts and doubles the amplitude, a gate circuit that gates the amplifying circuit output signal every other frame, and a composite signal read out from the one frame memory and the gate circuit every other frame. and an adder circuit for adding together a gated color signal and a gated color signal.