Television – Image signal processing circuitry specific to television – Selective image modification
Reexamination Certificate
1999-07-23
2001-09-25
Hsia, Sherrie (Department: 2614)
Television
Image signal processing circuitry specific to television
Selective image modification
C348S651000, C348S682000
Reexamination Certificate
active
06295095
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a video signal character detecting and converting device for converting video signal, which is transmitted from a visual transmitter to a visual apparatus such as a television receiver for displaying images. More specifically, a device of the present invention converts a video signal, if the signal contains images that include an intense flashing, a possible cause of an adverse effect mentally and/or physically to a viewer, into images having less effect to the viewer, according to prescribed specifications.
BACKGROUND OF THE INVENTION
Incidents in the recent year, in which children watching a television program of animated cartoon had suffered a seizure, has lead the broadcasting industry to set a guideline for video images to be broadcasted, and to place great importance on technique pertaining to detection and conversion of a video scene that may cause an adverse effect to human beings. It has been pointed out specifically that video images, in which a bright image having a duration of three vertical scanning and a dark image having a duration of three vertical scanning are displayed repeatedly, may cause an adverse effect mentally and/or physically to the viewers.
A video signal character detecting device for detecting a video scene based on presence or absence of a synchronizing signal has been known heretofore such as one disclosed in Japanese Patent Laid-Open Publication No. H06-233235, in order to avoid recording of signals that need not be recorded in apparatuses such as video recorders.
FIG. 7
shows a block diagram of a video signal character detecting device of the prior art. In
FIG. 7
, a synchronization detector
201
detects the presence or absence of a synchronizing signal. A microcomputer
202
suspends a recording operation of the video recorder when an unnecessary signal is detected. A signal separation circuit
203
separates a video signal from an input signal. A synchronizing signal separation circuit
204
separates a synchronizing signal contained in the video signal. A first differential circuit
205
differentiates the synchronizing signal. A second differential circuit
206
differentiates the video signal and the synchronizing signal. A subtraction circuit
207
generates a subtraction signal between the two differential signals. The subtraction signal corresponds to a differential signal of a video signal without a synchronizing signal.
The video signal character detecting device constructed as above operates in a manner, which will be described below.
First, the subtraction circuit
207
outputs the subtraction signal to the microcomputer
202
. If the subtraction signal does not exceed a predetermined threshold, the microcomputer
202
determines the input signal as an unnecessary signal, and suspends a recording operation of the video recorder.
The foregoing structure has a problem, however, that it is unable to detect video scenes, which may cause an adverse effect to viewers, such as a scene, in which light and darkness are repeated periodically on an entire screen, or a scene, in which red and blue are repeated periodically.
DISCLOSURE OF THE INVENTION
A video signal character converting device of the present invention comprises:
(1) a sampling window signal generator for generating a sampling signal for a purpose of sampling an input video signal according to a vertical synchronizing signal and a horizontal synchronizing signal;
(2) a video scene amplitude discrimination circuit for sampling the video signal in response to the sampling signal, detecting a change in image every duration of vertical scanning of the sampled video signal, and outputting a resetting pulse according to a result of comparison of the change in image level with a predetermined value;
(3) a video scene periodicity discrimination circuit for measuring a time interval between two of the resetting pulses, and outputting a control signal by comparing the measured time interval with a predetermined period of time; and
(4) a video scene conversion circuit for reducing the change in image level in response to the control signal.
The video signal character detecting device of the present invention as described above is thus able to determine whether or not an input video signal is equivalent to the video scene that causes an adverse effect physically and/or mentally to viewers, such as a scene, in which light and darkness are repeated periodically on an entire screen, or a scene, in which red and blue are repeated periodically. Accordingly, a visual apparatus provided with the device of this invention is able to display video scenes, which are determined as containing an adverse effect, after converting them into scenes harmless to human beings. Video scenes of this nature will be hereinafter referred to as video scenes “harmful” to human.
REFERENCES:
patent: 5-22704 (1993-01-01), None
patent: 6-38074 (1994-02-01), None
patent: 6-95632 (1994-04-01), None
patent: 6-233235 (1994-08-01), None
patent: 7-30796 (1995-01-01), None
patent: 2543990 (1996-07-01), None
patent: 10-23421 (1998-01-01), None
Kageyama Atsuhisa
Kawabata Minoru
Hsia Sherrie
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
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