JP2002027360A - Projection type television receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the blanking circuit of a projection television receiver is designed to have a tolerance, and a CRT emits light even outside the display region, that the beam current flows, and that the beam current or the like during a blanking period is wasteful increasing power consumption. SOLUTION: In the projection television receiver, a photosensor is installed at a screen frame, the beam current which flows to the screen frame is sensed, the blanking period is optimized, the beam current, a convergence correction current and a dynamic focus voltage are muted during the blanking period, and the power consumption of the television receiver can be reduced. Alternately, on the basis of information on an APL current, the blanking period is optimized, and the power consumption of the television receiver can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver having a cathode ray tube (CRT) display, and more particularly to a projection receiver that reduces power consumption by setting an optimal blanking period.

[0002]

2. Description of the Related Art In a conventional projection television receiver (hereinafter abbreviated as "projection television"), when an image is displayed on a screen by a projection television, the image is prevented from being chipped due to terrestrial magnetism, aging and temperature characteristics. In the blanking period, the circuit was designed with a margin.

[0003]

In the blanking circuit design having a margin, the outside of the display area, that is,
Screen frame, or even outside the screen frame,
Since the beam current flows and the CRT is illuminated, the beam current during that period (outside the display area) is wasted, leading to an increase in power consumption. Similarly, since convergence and dynamic focus are performed outside the screen frame, the convergence correction current and dynamic focus voltage during that time are also wasted, leading to an increase in power consumption.

The average luminance level of the video signal (averag
If the e picture level (APL) current is high, the high voltage value of the CRT decreases due to the characteristics of the CRT, and the screen amplitude increases. Conversely, when the APL current is low, the high voltage increases and the screen amplitude shrinks. That is, the APL current changes based on the screen information (video signal), and the screen expands and contracts. For this reason, a design having a sufficient margin must be performed. Current flowed, and the CRT glowed, leading to further increase in power consumption.

[0005]

According to the present invention, there is provided a projection television receiver having a CRT display, wherein an optical sensor is installed at a predetermined position on a screen frame, and a beam is emitted by the optical sensor. By detecting that the current is flowing outside the display area, the blanking period is optimized, and the beam current is muted during the blanking period.

Similarly, the invention is characterized in that the convergence correction current and the dynamic focus voltage are muted by detecting that the beam current is flowing outside the display area.

In a projection type television receiver having a CRT display, an average luminance current of a video signal is detected, a blanking waveform corresponding to a change in a high voltage value caused by the average luminance current is created, and a beam current is detected. Is muted during the blanking period.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1, 2, 3, 4, and 5. FIG.

(Embodiment 1) Referring to FIG.
The light emitted from T1 is reflected by the reflecting mirror 2 and projected on a screen as an image. Part of the light reflected by the reflecting mirror 2 hits the screen frame 3. On this screen frame, the beam current of the shining part is
It is useless. In order to reduce this useless beam current, that is, to reduce power consumption, the optical sensors a4 to h11 are provided. As shown in the figure, the positions of these optical sensors are, for example, two at the top, bottom, left, and right of the screen frame, respectively, at positions where both ends of the screen frame can be detected. Based on the beam current detected by the optical sensor, it is detected that the beam current is flowing outside the display area, and an image blanking period is optimized by an image blanking processing circuit described below.

FIG. 2A is a block diagram of a video blanking processing circuit. FIGS. 6B and 6C are diagrams showing the output timings of the optical sensors in the upper and lower frames of the screen, and the left and right frames of the screen, respectively. The output signals 12 to 19 from the output optical sensors a4 to h11 are input to the blanking processing circuit 20, and the upper frame of the screen is t5 + Δt1 (Δt1 is a value smaller than t2−t1), and the lower frame of the screen is t6 + Δt2 (Δt2 is smaller than t4−t3), and t11 + Δt for the screen left frame
The vertical and horizontal blanking waveforms are created by the blanking processing circuit 20 so that 3 (a value smaller than t8−t7 for Δt3) and t12 + Δt4 (a value smaller than t10−t9 for Δt4) for the right frame of the screen. , The vertical blanking circuit 21 and the horizontal blanking circuit 22 to optimize the blanking period. During the blanking period, the signal is input to the video processing circuit 23, and the beam current is muted. The power consumption of the receiver can be reduced.

(Embodiment 2) FIG. 3 shows a convergence blanking processing circuit. The same operation as in the first embodiment is performed, the optimum blanking waveform is input to the convergence circuit 24, and the convergence correction current is muted, so that the power consumption of the television receiver can be reduced.

(Embodiment 3) FIG. 4 shows a dynamic focus blanking processing circuit. The same operation as in the first embodiment is performed, the optimal blanking waveform is input to the dynamic focus circuit 25, and the dynamic focus voltage is muted, so that the power consumption of the television receiver can be reduced.

(Embodiment 4) In FIG. 5, an APL current detection circuit 28 is provided to input a video signal 26 to a field memory 27 and obtain an APL current for each field.
To enter. When the APL current detected by the APL current detection circuit 28 is large, it is determined that the entire screen is brightly lit, and is input to a blanking processing circuit 29 for setting a long blanking period. A signal processed by the blanking processing circuit 29 and an image 30 delayed by one field because the processing takes about one field are input to the video processing circuit 31 and timed and synthesized. Accordingly, the beam current outside the display area can be reduced, and the power consumption of the television receiver can be reduced.

[0014]

As described above, according to the present invention, an optical sensor is installed on a screen frame to optimize a blanking period, and during the blanking period, mute is applied to a beam current, a convergence correction current, and a dynamic focus voltage. By reducing the power consumption of the television receiver, the power consumption of the television receiver can be reduced by optimizing the blanking period based on the APL current information. Can be.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a projection television.

FIG. 2 is a block diagram of a video processing circuit that performs video blanking processing.

FIG. 3 is a block diagram of a convergence blanking processing circuit that performs video blanking processing.

FIG. 4 is a block diagram of a dynamic focus blanking processing circuit that performs video blanking processing.

FIG. 5 is a block diagram of a video processing circuit that performs a video blanking process by detecting an APL current.

[Explanation of symbols]

 Reference Signs List 1 CRT 2 Reflecting mirror 3 Screen frame 4 Optical sensor a 5 Optical sensor b 6 Optical sensor c 7 Optical sensor d 8 Optical sensor e 9 Optical sensor f 10 Optical sensor g 11 Optical sensor h 12 Output waveform of optical sensor a 13 Optical sensor b Output waveform 14 Optical sensor c output waveform 15 Optical sensor d output waveform 16 Optical sensor e output waveform 17 Optical sensor f output waveform 18 Optical sensor g output waveform 19 Optical sensor h output waveform 20 Blanking process Circuit 21 Vertical blanking processing circuit 22 Horizontal blanking processing circuit 23 Video processing circuit 24 Convergence circuit 25 Dynamic focus circuit 26 Video processing signal 27 Field memory 28 APL current detection circuit 29 Blanking processing circuit 30 1 field delay circuit 31 Video processing circuit

Claims (4)

[Claims] In a projection type television receiver having a CRT display, an optical sensor is installed at a predetermined position on a screen frame, and the optical sensor detects that a beam current is flowing outside a display area. , A blanking period is optimized, and the beam current is muted during the blanking period. 2. In a projection type television receiver having a CRT display, an optical sensor is installed at a predetermined position on a screen frame, and the optical sensor detects that a beam current is flowing outside a display area. , A blanking period is optimized, and a convergence correction current is muted during the blanking period. 3. In a projection television receiver having a CRT display, an optical sensor is installed at a predetermined position on a screen frame, and the optical sensor detects that a beam current is flowing outside a display area. , A blanking period is optimized, and a dynamic focus voltage is muted during the blanking period. 4. In a projection television receiver having a CRT display, an average luminance current of a video signal is detected, and a blanking waveform corresponding to a change in a high voltage value caused by the average luminance current is created. Mute is applied during the blanking period.