JPH05137089A - Television receiver - Google Patents

Abstract

PURPOSE:To provide a television receiver capable of setting the luminance level of a background without a signal at appropriate brightness corresponding to peripheral brightness when a video signal with aspect ratio of 4:3 is displayed on the television receiver provided with a display screen with aspect ratio of 16:9. CONSTITUTION:This receiver is comprised in such a way that a control circuit 8 which sets the level of a luminance signal attached at a background luminance attaching circuit 4 corresponding to the detection value of a peripheral light detection circuit 7 which detects the peripheral brightness is provided. Thereby, the luminance level of the background without generating an offensive sight can be obtained in spite of the degree of peripheral brightness.

Description

Detailed Description of the Invention

[0001]

This invention has an aspect ratio of 16:
The present invention relates to a television receiver having a feature in signal processing means when a video signal having an aspect ratio of 4: 3 is projected on the television receiver having a screen of No. 9.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing an aspect conversion circuit for displaying a video signal having an aspect ratio of 4: 3 on a screen having an aspect ratio of 16: 9. An A / D converter for converting an analog signal into a digital signal, 3 a time compression circuit composed of a line memory, etc. The D / A converter 6 for returning the converted signal to the original analog signal is an output terminal thereof.

Next, the operation of the above configuration will be described.
First, the A / D converter 2 converts the input luminance signal (FIG. 3A), which is an input analog signal, into a digital signal. The time compression circuit 3 outputs this digital signal to 1
Writing is performed for each horizontal period, and the written signal is read at a clock having a frequency of 4/3 times the write clock to perform time compression as shown in FIG. 3B. The waveform of the output signal obtained by analog-converting this time-axis-compressed signal by the D / A converter 5 is shown in FIG.
A signalless portion 10 is generated, and the aspect ratio 1
When projected on a display screen of 6: 9, black signalless portions 11 are produced at both ends as shown in FIG.

Therefore, if the no-signal portion 11 is left as it is, only the central portion becomes bright. Therefore, if the fluorescent substance of the cathode ray tube is used for a long time, the central portion of the fluorescent substance deteriorates more quickly than the both end portions.

In order to suppress this, as shown in FIG. 3 (c), the background luminance adding circuit 4 adds a certain level of luminance signal 12 in the background portion to make it slightly brighter.

[0006]

In the background luminance adding circuit of the related art, the background luminance level is constant, so that when viewed in a dark room or the like, the background luminance feels bright, which causes an inconvenience. .

The present invention has been made to solve the above problems, and a television image receiving apparatus capable of changing the background luminance level to an appropriate level in association with the ambient brightness of the television image receiving apparatus. The purpose is to provide a machine.

[0008]

The background luminance adding means in the television receiver according to the present invention detects the ambient brightness of the television receiver by an ambient light detection circuit,
The control circuit is configured to set the background brightness according to the detected value.

[0009]

According to the background luminance adding means of the television receiver according to the present invention, it is possible to add the background luminance signal of an appropriate level according to the ambient brightness of the television receiver.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 is an aspect conversion circuit diagram of a television receiver according to an embodiment of the present invention, in which the same or corresponding parts as in FIG. Omit it.

Reference numeral 7 denotes an ambient light detection circuit for detecting the ambient brightness of the television receiver, and reference numeral 8 denotes a control circuit for the background luminance adding circuit 4 based on the detected value of the ambient light. It is for outputting a brightness level control signal.

Next, the operation of the above configuration will be described. First, the ambient light detection circuit 7 includes a photodiode and Cd.
The brightness around the television receiver is detected by a photo sensor such as an S cell, and the detected value is output as a voltage value. The control circuit 8 controls so that the brighter the surrounding area, the higher the background luminance level, and conversely, the darker the surrounding area, the lower the background luminance level.

Embodiment 2 In the above embodiment, only the background brightness level is changed according to the ambient brightness, but the video signal level may be changed at the same time.

[0014]

As described above, according to the present invention, the ambient brightness of the television receiver is detected, and the background brightness level is adjusted to an appropriate brightness based on this detection level. There is an effect that the background brightness does not become an obtrusive matter whatever the surrounding brightness.

[Brief description of drawings]

FIG. 1 is an aspect conversion circuit diagram in a television receiver according to an embodiment of the present invention.

FIG. 2 is a diagram of an aspect conversion circuit in a conventional television receiver.

FIG. 3 is a waveform diagram of input / output signals of a conventional aspect conversion circuit.

FIG. 4 is a diagram showing a state in which a video signal having an aspect ratio of 4: 3 is displayed on a display screen having an aspect ratio of 16: 9 by a conventional aspect conversion circuit.

[Explanation of Codes] 2 A / D converter 3 Time compression circuit 4 Background brightness addition circuit 5 D / A converter 7 Ambient light detection circuit 8 Control circuit

Claims (1)

[Claims] 1. A means for compressing a horizontal time axis of a video signal having an aspect ratio of 4: 3 so as to be displayed on a display surface having an aspect ratio of 16: 9, and a means for selecting no signal by this time axis compression. And a means for adding a signal of a brightness level, a means for detecting brightness around the television receiver, and a means for controlling the brightness level to be added according to the detected value. A television receiver characterized by being equipped with.