KR19980050401U - Picture Quality Compensation Point Guidance Device for Video Cassette Recorder - Google Patents

Abstract

The present invention relates to a device for guiding a picture quality compensation time point of a video cassette recorder. The picture quality compensation time point guide device detects an envelope signal of an image signal reproduced from the video cassette recorder and integrates the detected envelope signal to obtain a DC envelope value. A control unit for generating an OSD control signal when the DC envelope value is less than the reference DC value by comparing an envelope detector to be generated and a DC envelope value generated from the envelope detector with a preset reference DC value, and an OSD control signal from the control unit. And an OSD circuit for outputting an OSD message indicating a time point to compensate for the image quality, wherein the predetermined reference DC value has a different value according to a playback speed of the video cassette recorder.

Description

Picture Quality Compensation Point Guidance Device for Video Cassette Recorder

The present invention relates to a picture quality compensation time guide apparatus of a video cassette recorder (hereinafter referred to as a VCR), and more particularly, to a picture quality compensation time guide apparatus capable of informing a picture quality compensation time point of a playback image.

In general, a predetermined recording current is set in a VCR for recording a video signal and an audio signal on a video tape. Such a recording current can compensate to some extent the image quality of the image reproduced from the video tape by adjusting the reference envelope level of the reproduced image. Therefore, the recording current is set in the VCR with an appropriate value. When recording the video signal and the audio signal using the VCR, the video signal and the audio signal are recorded on the video tape according to the predetermined recording current.

However, if the same videotape is repeated for a long time, the envelope level of the reproduced image is lowered due to the aging of the videotape. For this reason, most video tape manufacturing companies that produce video tapes for rental for mass use record video and audio signals on video tapes using current values that are higher than the predetermined reference recording current values. When the video and audio signals are recorded using the recording current value higher than the reference recording current value, the envelope level of the playback video may be higher than the reference level. Therefore, the envelope level of the playback video signal due to frequent use may be due to the characteristics of the rental video tape. The degradation can be prolonged over time.

A tape recorded with a large recording current value does not cause a big problem during playback, but a video tape with a small recording current or repeatedly used frequently has a deterioration in playback quality due to a decrease in envelope level during playback. .

On the other hand, the VCR has a function called automatic gain control (AGC) that compensates for the degraded envelope level of the reproduced image by amplifying the reproduced signal to the basic gain when the videotape is reproduced. However, the automatic gain control function amplifies even the noise component mixed in the playback signal, which causes a spot in addition to the playback image on the screen.

In order to suppress the occurrence of such spots, the VCR is provided with a function called rental. It provides a smoother playback picture by eliminating the high-frequency noise components that cause spots during videotape playback.

However, such a rental function is executed by judging only the visual quality of an image reproduced by the user with the naked eye, and thus there is a problem in that it is not possible to capture the exact time of rental function usage.

Therefore, an object of the present invention is to provide a VCR having a function of automatically detecting a quality state of a playback image for each playback speed and automatically informing a user of an image quality compensation time point. .

No content

1 is a block diagram of a device for guiding a quality compensation time point of a video cassette recorder according to a preferred embodiment of the present invention;

FIG. 2 is a flowchart for describing an operation of a device for guiding a quality compensation time point illustrated in FIG. 1.

<Description of the code | symbol about the principal part of drawing>

10 video head 20 preamplifier

30: envelope detector 40: control unit

50: OSD circuit

According to the present invention for achieving the above object, an envelope detector for detecting the envelope signal of the video signal reproduced from the video cassette recorder and integrating the detected envelope signal to generate a DC envelope value, and generated from the envelope detector A control unit for generating an OSD control signal when the DC envelope value is less than the reference DC value by comparing the DC envelope value with a preset reference DC value, and an OSD message for notifying the timing of image quality compensation in response to the OSD control signal from the control unit. Provided is a quality compensation time guide apparatus of a video cassette recorder including an output OSD circuit unit.

The above and other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an apparatus for notifying a picture quality compensation time point of a playback image according to an exemplary embodiment of the present invention.

As shown, the image quality compensation viewpoint guidance device of the present invention is a video head unit 10, pre-amplifier 20, envelope detector 30, control unit 40 and on-screen display (OSD) circuit And 50.

When the VCR is operated in the playback mode, the video head section 10 installed on the rotating head drum (not shown) detects the video signal reproduced from the video tape in contact with the head drum and converts the detected video signal into the preamplifier 20. To provide.

The preamplifier 20 amplifies the video signal provided from the video head unit 10 and outputs the amplified video signal to the envelope detector 30.

The envelope detector 30 detects the envelope of the amplified video signal and generates a DC envelope value by integrating the detected envelope at every predetermined time interval. The DC envelope value thus generated is provided to the controller 40.

The controller 40, which may be configured as a microcomputer used in the VCR, compares the DC envelope value transmitted from the envelope detector 30 with a preset reference DC value.

According to the present invention, the predetermined reference DC value described above has a different value according to the playback mode of the VCR. For example, when the playback speed of the VCR is a standard play mode in which the VCR is a standard speed, the reference DC value is It has a value of about 4.5V, and the reference DC value has about 3.5V and 3V, respectively, when the playback speed of the VCR's playback mode is LP (long play) mode and EP (extended play) mode. Therefore, the controller 40 compares the DC envelope value detected by the envelope detector 30 with each reference DC value according to the current reproduction speed of the VCR. If it is determined that the detected DC envelope value is smaller than the reference DC value, the controller 50 generates an OSD control signal to the OSD circuit 50. This OSD control signal includes a signal that controls the generation of a message informing the user to perform the rental function.

In response to the OSD control signal of the controller, the OSD circuit 50 generates a message indicating that the image quality of the video signal currently being played in the VCR is deteriorated so that the user can immediately execute the rental function.

Referring to the flowchart of FIG. 2, the operation of the image quality compensation time guide device having the above-described configuration will be described below.

First, when the VCR is operated in the playback mode in step 62, the controller 40 detects the speed of the playback mode from the control signal detected from the video tape.

In step 64, the envelope signal of the video signal to be reproduced is detected at the envelope detector 30 and converted into a DC envelope value.

In step 66, the transformed DC envelope value is compared with a reference DC value corresponding to the speed of the playback mode. If the DC envelope value is greater than the reference DC value, processing proceeds to step 68 to continue the playback operation.

However, if the DC envelope value is less than the reference DC value, the process proceeds to step 70 to cause the OSD circuit 50 to generate an OSD message for the user to compensate for the quality of the playback image.

Therefore, the user can watch the OSD message generated while watching the playback video and perform the rental function of the VCR, thereby allowing the user to watch the video with the compensated image quality (step 72). When the rental operation is finished, the flow advances to step 68 to continue the playback operation.

Although the present invention describes a device for notifying a user of an image quality compensation time as a message, a person having ordinary knowledge in the art may configure the rental function to automatically perform a rental function while notifying the image quality compensation time. There will be.

As described above, according to the present invention, by detecting the DC envelope value from the envelope signal and comparing the value with the reference DC value, it is possible to know the generation of the reproduced image having deteriorated image quality, and in this state, the rental operation is performed on the reproduced image. This has the advantage that the user can watch the image with quality compensation.

Claims (2)

In the device for guiding the compensation time point of the video cassette recorder, An envelope detector for detecting an envelope signal of a video signal reproduced from the video cassette recorder and integrating the detected envelope signal to generate a DC envelope value; A controller configured to generate an OSD control signal when the DC envelope value is less than the reference DC value by comparing the DC envelope value generated from the envelope detector with a preset reference DC value; And an OSD circuit unit for outputting an OSD message indicating an image quality compensation time point in response to the OSD control signal from the controller. The apparatus of claim 1, wherein the preset reference DC value has a different value according to a playback speed of the video cassette recorder.