JPS61256891A - Picture reproducer - Google Patents

Abstract

PURPOSE:To obtain a good black and white reproducing picture image in the case of the black and white picture image, by preventing an output of a color signal processing circuit from being supplied to a mixing circuit when an FM modulating signal of a color difference signal does not exist. CONSTITUTION:A signal recorded on a magnetic disk 1 is picked up by a magnetic head 2. A filter circuit 3 selects an FM modulating signal of a brightness signal and outputs and a filter circuit 6 selects an FM modulating signal of a color difference signal and outputs. When the picture image information recorded on the magnetic disk 1 is black and white picture image, since a signal is not outputted to an output terminal of the filter circuit 6, a signal detecting circuit 10 outputs 0, and a switch circuit 9 interrupts noise of an output of a color signal processing circuit 8 to operate not so as to issue any signal. In a mixing circuit 5, unnecessary noise is not mixed but only the luminance signal is outputted to be supplied to an output terminal a.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an image information reproducing device.

[Conventional technology]

When recording a color image on an information medium, an FM modulation signal obtained by FM modulating the luminance signal of a television signal and an FM modulation signal obtained by FM modulating a color difference signal are frequency multiplexed and recorded on the information medium, and black and white images are recorded on the information medium. When recording an image, image recording apparatuses such as so-called electronic cameras and video floppy apparatuses are known that record only an FM modulated signal obtained by FM modulating the brightness signal of a television signal on an information medium.

FIG. 2 is a schematic diagram showing the frequency band of an image signal recorded on an information medium in this type of image recording device, and FIG. 2(a) shows the frequency of an FM modulation signal of a luminance signal in the case of a color image. A band Y and a frequency band C of the FM modulation signal of the color difference signal are shown. That is, frequency band Y and frequency band C each occupy frequency bands that can be separated from each other, and here, as an example, it is assumed that frequency band C is on the lower frequency side with respect to frequency band Y.

In addition, Fig. 2 (mountain) is a diagram showing the frequency band of the image signal in the case of a monochrome image, and in this case, the FM modulation signal color of the luminance signal is the same as the FM modulation signal color in the case of the above-mentioned color image. The FM modulation signal of the color difference signal is not recorded.

FIG. 3 is a block diagram showing an example of a conventional image reproducing device that reproduces an image signal from an information medium on which such an image signal is recorded, and the figure shows an example in which the information medium is a magnetic disk. ing.

In FIG. 3, 1 is a magnetic disk, 2 is a magnetic head,
3 is a first filter circuit, 4 is a first FM demodulation circuit, 5
is a mixing circuit, 6 is a second filter circuit, and 7 is a second FM
8 is a demodulation circuit, 8 is a color signal processing circuit, and a is an output terminal of the device.

To explain the operation of the conventional device configured in this way, the FM modulation signal of the luminance signal and the FM modulation signal of the color difference signal recorded on the magnetic disk 1 are picked up by the magnetic head 2, and are picked up by the first filter circuit 3 and the FM modulation signal of the color difference signal. The signal is input to the filter circuit 6 of No. 2.

The first filter circuit 3 is a filter that has a frequency band Y of the FM modulation signal of the luminance signal, removes the FM modulation signal of the color difference signal, and selects and outputs the FM modulation signal of the luminance signal. The FM modulation signal of the luminance signal output to the first filter circuit 3 is input to the first FM demodulation circuit 4. The first FM demodulation circuit 4 performs FM demodulation and outputs a luminance signal, and this luminance signal is input to one input terminal of the mixing circuit 5.

On the other hand, the second filter circuit 6 has a frequency band C of the FM modulation signal of the color difference signal, removes the FM modulation signal of the luminance signal, selects the FM modulation signal of the color difference signal, and selects the FM modulation signal of the color difference signal. Supplied to demodulation circuit 7.

do. The second FM demodulation circuit 7 performs FM demodulation and outputs a color difference signal. The color signal processing circuit 8 generates and outputs a carrier color signal from the color difference signal output from the second FM demodulation circuit 7,
It is supplied to the other input terminal of the mixing circuit 5. The mixing circuit 5 mixes the luminance signal and the carrier color signal supplied to the input terminals to synthesize a composite television video signal and supplies the signal to the output terminal a of the apparatus. If the television composite video signal supplied to the output terminal a of this device is further supplied to a television receiver, a good color image can be reproduced.

[Problem that the invention seeks to solve]

However, in the conventional apparatus configured as described above, in the case of a black and white image, the magnetic disk 1 has an FM signal of the luminance signal.
Since only the modulation signal is recorded and the FM modulation signal of the color difference signal is not recorded, no signal is output to the output of the second filter circuit 6, and no signal is output to the input of the second FM demodulation circuit 70. state. This FM demodulation circuit normally performs a powerful operation when a predetermined input signal level is input, but if the input signal level falls below the required level or there is no input signal, severe noise is output. It is known that Therefore, severe noise is also output from the second FM demodulation circuit 7.

If such noise is supplied to the color signal processing circuit 8, the color signal processing circuit 8 will not be able to operate correctly, and will still output noise as its output. The noise output from the color signal processing circuit 8 and the luminance signal correctly reproduced by the first FM demodulation circuit 4 are mixed in the mixing circuit 5 and output to the output terminal a of the device.
When the image is supplied to a television receiver, severe noise appears on the screen of the receiver, and a correct black and white image cannot be reproduced.

The present invention eliminates the drawbacks of the conventional apparatus described above, and in the case of color images, it not only provides good color reproduction images, but also
It is an object of the present invention to provide an image reproducing device that can obtain a good black and white reproduced image even in the case of a black and white image.

Means for Solving Problem C] The image reproducing apparatus according to the present invention includes a signal detection circuit for detecting the presence or absence of an FM modulation signal of the cough color difference signal at the output of the filter circuit for extracting the color difference signal, and When there is no FM modulation signal, the control signal of the signal detection circuit prevents the output of the color signal processing circuit from being supplied to the mixing circuit.

[Effect]

In this invention, in the case of a black and white image, the noise of the color signal processing circuit is not input to the mixing circuit, so only the correctly reproduced luminance signal is output to the mixing circuit, and therefore the video signal is output to the output terminal of the device. When reproduced on a television receiver, a good black and white image can be obtained.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram showing an embodiment of the present invention, and the configuration of this embodiment is similar to the configuration of the conventional device shown in FIG. 3 except for the following points. That is, a switch circuit 9 is inserted between the output of the color signal processing circuit 8 and the other input of the mixing circuit 5, and a signal detection circuit 10 receives the output signal of the second filter circuit 6. is provided, and the switch circuit 9 is configured to be controlled by the output signal of the signal detection circuit 10.

Next, the operation will be explained.

The signal detection circuit 10 is a kind of signal level detector, which outputs a 1" signal when a signal of a predetermined level or higher is input, and outputs an "O" signal when the input level is a predetermined level or lower. It is designed to output a signal.

That is, when the image information recorded on the magnetic disk 1 is a color image, an FM modulation signal of a color difference signal of a predetermined level or higher is output to the second filter circuit 6, and when this is input to the signal detection circuit 10, The signal detection circuit 10 outputs 1". At this time, the switch circuit 9 outputs the signal detection circuit 10.
The color signal processing circuit 8 operates so that the carrier color signal output from the color signal processing circuit 8 is output as is to the output terminal of the switch circuit 9. Therefore, the carrier color signal outputted to the output terminal of the switch circuit 9 is supplied to the other input terminal of the mixing circuit 5, and as in the conventional device, the mixing circuit 5 mixes the luminance signal and the carrier color signal to produce a composite video signal. is created and this signal is supplied to output terminal a of the device. If the composite video signal obtained at the output terminal a of this device is further supplied to a television receiver, a good color image can be reproduced.

Furthermore, if the image information recorded on the magnetic disk 1 is a black and white image, no signal is output to the output terminal of the second filter circuit 6, so the signal detection circuit 10 outputs "0". At this time, the switch circuit 9 is controlled by the output signal of the signal detection circuit 10 and operates to cut off the noise that is the output of the color signal processing circuit 8 and not output any signal to the output of the switch circuit 9. Therefore, in the mixing circuit 5, unnecessary noise is not mixed into the properly reproduced luminance signal, and only the luminance signal is outputted to the output terminal of the mixing circuit 5 and supplied to the output terminal a of the device. Ru. If the luminance signal obtained at the output terminal a of this device is further supplied to a television receiver for image reproduction, a correct black and white image without noise can be obtained.

In the device of this embodiment, the presence or absence of the FM modulation signal of the color difference signal is detected, and the output of the color signal processing circuit 8 is controlled based on the detection result, so that a good reproduced image can be obtained even in the case of a monochrome image. can be obtained.

In the above embodiment, in the case of a black and white image, the switch circuit is controlled by the signal detection circuit and the output signal of the color signal processing circuit is cut off, thereby preventing noise from being input to the other input terminal of the mixing circuit. Although an example of the configuration has been described, the configuration of the present invention is not limited to this, and any means other than the switch circuit may be used as long as the output signal of the color signal circuit is not supplied to the mixing circuit. Although an example in which the signal detection circuit is a level detector has been described, other means may be used as long as the presence or absence of a signal can be detected.

〔Effect of the invention〕

As described above, according to the present invention, a signal detection circuit that detects the presence or absence of an FM modulation signal of a color signal is provided, and the output signal of the color signal processing circuit is supplied to the mixing circuit by the control signal from the signal detection circuit. Since it is possible to control whether or not the information is displayed, it is possible to obtain a good reproduced image regardless of whether the image signal recorded on the information medium is a color image or a monochrome image.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an image reproducing apparatus according to the present invention, FIG. 2 is a frequency band diagram of an image recording apparatus for recording a snow scene according to the present invention, and FIG. 3 is a block diagram of a conventional image reproducing apparatus. be. 2... Magnetic head, 3, 6... Filter circuit, 4゜7... FM demodulation circuit, 5... Mixing circuit, 8... Color signal processing circuit, 9... Switch circuit, 10 ...Signal detection circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In the case of a color image, the brightness signal of the television signal and the color signal are each FM-modulated and recorded, and in the case of a black-and-white image, the brightness signal of the television signal is recorded as FM-modulated from the information medium. An image reproducing device for reproducing a signal, comprising a pickup means for picking up a signal from an information medium, an output signal of the pickup means is input, an FM modulated signal of a luminance signal is extracted, and the signal is FM demodulated to produce a luminance signal. a luminance signal processing means for inputting the output signal of the pickup means, extracting an FM modulated signal of a color signal, FM demodulating the signal, processing the signal, and producing a carrier color signal; Mixing means for mixing the output signal of the signal processing means and the output signal of the color signal processing means, and detecting whether or not the output of the pickup means includes an FM modulation signal of the color signal, and if the modulation signal is not detected; An image reproducing device comprising: signal cutoff means for cutting off the output signal from the color signal processing means.