JPH07210986A - Vtr containing liquid crystal projector - Google Patents

Abstract

PURPOSE: To considerably prolong the life of a lamp by controlling the turn-on/ turn-off of the projection lamp on VTR incorporating a liquid crystal projector. CONSTITUTION: VTR incorporating the liquid crystal projector is provided with a video signal detection means 40 receiving output from a VTR video signal processing system 7 and detecting the presence or absence of a video signal in the middle of output and a switching means 41 which is connected between the projection lamp and a current unit and turns on/turns off the projection lamp. The video detection means turns on the switching means by a control signal S generated when the video signal is detected or by a detection signal from a liquid crystal panel driving circuit system 8 and the projection lamp 43 (5) is turned on.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a liquid crystal display device (LC
The present invention relates to a video tape recorder (VTR) incorporating a floodlight (hereinafter, liquid crystal projector) using D).

[0002]

2. Description of the Related Art FIGS. 4 to 7 are explanatory views of a conventional technique. In the Japanese Patent Application No. 5-256906, the present applicant has simplified the wiring of signal lines and power lines by integrating a liquid crystal projector and a VTR to prevent the deterioration of video signals and also to form a part of the housing. We proposed a device that can be used as a small screen display by providing a back screen.

FIG. 4 shows a VT with a built-in liquid crystal projector.
5 is a signal processing circuit of R, FIG. 5 is a configuration diagram of a main part of a projector including a liquid crystal panel, FIG. 6 is a block diagram of a video signal processing circuit of a VTR, and FIG. 7 is a drive circuit of a liquid crystal panel of a liquid crystal projector. It is a block diagram of. Figure 6
The operation of the circuit will be described below. For simplicity of explanation, only the reproduction system will be described. The video signal recorded on the video tape T is read by the head 20, and the preamplifier 21
After being amplified to a predetermined level by, the luminance signal FM-modulated by the high-pass filter 22 is taken out, and the luminance processing circuit 23
The FM signal is demodulated at to obtain the luminance signal Y.

The output of the preamplifier 21 is also sent to the low-pass filter 24, and the low-pass filter 24 obtains a color signal which has been subjected to low-pass conversion processing. The original color signal C is output after the conversion and the crosstalk component is removed by the comb filter. The adder 26 adds (Y + C) the luminance signal Y and the color signal C,
The combined image signal is output to the image output terminal 27. By using an RCA pin jack cable for this terminal 27, it becomes possible to connect to a TV receiver with a video input terminal or a liquid crystal projector, and a video signal can be viewed.

As shown in the circuit of FIG. 7, since a video signal is generally treated as a composite video signal (Y + C), a (Y + C) input terminal 30 is provided as an input terminal. Figure 6
The advantage of combining the circuit and the circuit of FIG. 7 (see FIG. 4) is that it is not necessary to separate the composite video signal into Y and C on the liquid crystal projector side, and it is possible to prevent the deterioration of the signal that occurs when they are separated. Further, it is possible to eliminate the need for the user to connect using the cable for pin jack.

As shown in the circuit of FIG. 4, the VTR video signal processing system 7 and the liquid crystal panel drive circuit system 8 are connected based on the above advantages. Internal connection terminals 28, 29
In, the luminance signal Y reproduced by the VTR system and the color signal C are not combined but guided to the liquid crystal panel drive circuit system 8. As is apparent, the liquid crystal panel drive circuit system 8 of FIG. 4 has the low-pass filter 31 and the band-pass filter 32 of FIG. 7 removed.

By the way, in the circuit of FIG. 4, the liquid crystal panel drive circuit system 8 is mainly described, and the projection lamp (number 5 in FIG. 5) originally required for the projector is used.
The operation of the processing circuit system 7 and the drive circuit system 8 has not been described in detail. In this case, a halogen lamp is mainly used as the light-projecting lamp 5 in the small-sized projector, but its life is generally about 100 to 200 hours, which is not so long. Therefore,
In order to extend the life of the lamp, it is necessary to eliminate unnecessary lighting time as much as possible during use. In FIG. 5, 1 is a projection lens, 2 is a liquid crystal panel, 3 is a condenser lens, 4 is a reflector, and 5 is a halogen lamp for projecting light.

[0008]

As described above, in the VTR with a built-in liquid crystal projector proposed by the applicant of the present invention, no rational combination of the projector light-emitting lamp and the signal processing system is proposed. Therefore, it is not possible to control the lighting time of the halogen lamp for light projection, and therefore, no measures have been taken to extend the life of the lamp as much as possible.

An object of the present invention is to extend the lamp life as much as possible by efficiently controlling the lighting time of the projector lamp of the projector in the liquid crystal projector built-in VTR.

[0010]

In the first embodiment of the present invention, a head 20 for reproducing a video tape T, a VTR video signal processing system 7 for receiving and processing a reproduction output of the head, and
A liquid crystal panel drive circuit system 8 for driving a liquid crystal panel by processing a luminance signal and a color signal from the VTR video signal processing system,
A projection lamp 43 for projecting a reproduced image on the screen,
Ammeter 4 for converting the AC power supply into DC and supplying it to the VTR video signal processing system, the liquid crystal panel drive circuit system, and the projection lamp.
In a VTR with a built-in liquid crystal projector equipped with
Video signal detecting means 40 for receiving the output from the VTR video signal processing system 7 and detecting the presence or absence of the video signal being output.
And a switching means 41 connected between the light-projecting lamp and the current generator and for turning on / off the light-emitting lamp.
The switching means is turned on and the projection lamp is turned on by a control signal S generated when the video signal is detected by the video signal detecting means.

According to a second aspect of the present invention, in the above VTR with a built-in liquid crystal projector, a switching means 41 which is connected between the light projecting lamp and an ammeter to turn on / off the light projecting lamp, An amplifier 45 for amplifying the detection signal K from the liquid crystal panel drive circuit system, and the control means K'amplified by the detection signal turns on the switching means to turn on the projection lamp. Is characterized by.

Further, in the second embodiment, the detection signal K preferably uses a color killer signal in the color signal demodulator 33 in the liquid crystal panel drive circuit system. Further, as another mode of the detection signal K, a color killer signal in a color signal demodulator in the VTR video signal processing system can be used.

[0013]

According to the present invention, in the VTR with a built-in liquid crystal projector, the video signal detector is provided inside the VTR in order to prolong the lamp life as much as possible by efficiently controlling the lighting time of the projector lamp. The projection lamp is turned on only when it exists.

Originally, the projector projects an image. Therefore, if the presence or absence of an image (video signal) is automatically discriminated and the projection lamp is made to blink based on the discrimination result, it is particularly useful for projectors. There is no need to provide a power switch. The present invention pays attention to this point and controls so as to eliminate unnecessary lighting time of the lamp and extend the life of the lamp.

[0015]

1 is a block diagram of an essential part of one embodiment of the present invention. As shown, in a VTR with a built-in liquid crystal projector, a VTR video signal processing system 7 and a liquid crystal panel drive circuit system 8 are shown.
And the projection lamp 43 (or 5) are combined. In the figure, 40 is a video signal detection circuit, 41 is a switching means,
Reference numeral 42 denotes an ammeter for converting an AC power source input from the AC power source plug 44 into a DC power source. This current unit 42 is + B as a DC power source of the VTR video signal processing system 7.
1, + B2 as a DC power source for the liquid crystal panel drive circuit system 8,
+ B3 is supplied as the DC power source for the light-projecting lamp.

The operation of this circuit will be described below. When the video tape T is reproduced by the head 20 and the video signal is viewed by the projector, the luminance signal Y and the color signal C reproduced by the VTR signal processing system 7 are guided to the liquid crystal panel drive circuit system 8 as described above. The luminance signal Y is simultaneously guided to the video signal detection circuit 40, and the video signal detection circuit 40 determines the presence / absence of a video signal. As an example, the video signal detection circuit 40 is composed of a one-chip IC for synchronization detection.

The output signal S from the video signal detection circuit 40 controls the switching means 41 to close when a video signal is present. As a result of closing the switching means 41, the DC power supply + B3 can be supplied to the light projecting lamp 43 (reference numeral 5 in FIG. 5). With this configuration,
The power switch (not shown) provided for the projector may be unnecessary. That is, the switching means 41 may be turned on to supply power. However, in this case, the light-projecting lamp 43 is turned on even if there is no video signal, which is not preferable from the viewpoint of life as described above.

Further, when the recorded portion on the tape T ends and a noise screen is displayed while the VTR is being reproduced, the video signal detection circuit 40 operates, so that unnecessary lighting time can be prevented in this case as well. it can. In addition, liquid crystal projectors are usually
A heat-dissipating fan (not shown) is installed, but the description is omitted because it is not directly related to the present invention.

FIG. 2 is a block diagram of another embodiment of the present invention. As is apparent from the configuration of FIG. 1, in this example, the synchronization signal detection circuit 40 of FIG. 1 is removed, the detection signal K is taken out from a part of the liquid crystal panel drive circuit system 8, and the current is amplified by the amplifier 45 before switching. A control signal K ′ equivalent to the control signal S of the means 41 is taken out of the amplifier 45. Opening / closing control of the switching means 41 is performed by this detection signal K '.

As the detection signal K, a DC signal generated at the color killer detection terminal, which is a part of the function of the color signal demodulator 33 in FIG. 7, is used. The color signal demodulator 33 has substantially the same function as the demodulation circuit of the TV receiver. As is well known, the color signal demodulator 33 creates a gate pulse from the horizontal synchronizing signal included in the composite video signal, extracts the burst signal in the composite video signal, and uses this as a reference signal to extract the color signal in the composite video signal. Demodulating. The color killer operation is that when the burst signal extracted by the gate pulse is below a certain reference level, the signal input to the demodulation circuit is regarded as noise and the color demodulation circuit operation is stopped.

In the present invention, the same function as the video signal detector 40 shown in FIG. 1 can be realized by regarding the detection signal of the color killer operation as the presence or absence of the video signal. With this configuration, the circuit can be configured at a lower cost than the configuration of FIG. Originally, the color killer operation is an operation in which the operation of the color demodulation system is stopped and the signal is changed to a black and white signal. However, since the signal reproduced by the VTR has a sufficient color burst signal, there is no practical problem.

FIG. 3 shows the color killer detection terminal (A) and its amplification circuit (B). FIG. 3A is an example of the color killer detection terminal of the color demodulator IC. Detection terminal 4
A condenser 47 is connected to the ground 6 between the grounds. When a color burst signal is present, it is demodulated, and the capacitor 47 produces a voltage which is demodulated and converted into direct current. When there is no input signal, that is, when there is no color burst signal, the potential of this terminal 46 becomes the ground potential. As shown in FIG. 3B, this DC potential is current-amplified by the NPN transistor 48, and the switching means 41 is connected to the output terminal 50.
Is output as the control signal K'and the switching means 41 is turned on, the light projecting lamp 43 can be efficiently operated.

Further, as another embodiment, the color killer detection terminal is also present in the color signal demodulation IC used in the VTR signal processing system 7, so that the detection signal (control signal) K'is utilized. You can also take out.

[0024]

As described above, according to the present invention,
Between the DC power supply and the light-emitting lamp, turn on the light-emitting lamp /
A changeover switch that controls the turning off is provided, and the changeover switch is turned on / off depending on the presence or absence of a video signal or a color killer signal, thus preventing unnecessary lighting of the light emitting lamp and extending the lamp life. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of an embodiment of the present invention.

FIG. 2 is a block diagram of another embodiment of the present invention.

FIG. 3 shows a color killer detection terminal (A) and its amplification circuit (B).

FIG. 4 is a signal processing circuit of a VTR incorporating a conventional liquid crystal projector.

FIG. 5 is a configuration diagram of a main part of a projector including a conventional liquid crystal panel.

FIG. 6 is a block diagram of a video signal processing circuit of a conventional VTR.

FIG. 7 is a block diagram of a drive circuit of a liquid crystal panel of a conventional liquid crystal projector.

[Explanation of symbols]

 5, 43 ... Projection lamp 7 ... VTR video signal processing system 8 ... Liquid crystal panel drive circuit system 40 ... Video signal detection circuit 41 ... Switching means 42 ... Current generator 45 ... Amplifier

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04N 5/93

Claims (4)

[Claims] 1. A head (20) for reproducing a video tape (T) and a VTR for receiving and processing a reproduction output of the head.
A video signal processing system (7), a liquid crystal panel drive circuit system (8) for processing a brightness signal and a chrominance signal from the VTR video signal processing system to drive a liquid crystal panel, and for projecting a reproduced image on a screen A VTR with a built-in liquid crystal projector, comprising: a lamp (43); and a current converter (42) for converting an AC power supply into a DC and converting the VTR video signal processing system, a liquid crystal panel drive circuit system, and a projector lamp. A video signal detecting means (40) for receiving the output from the video signal processing system (7) and detecting the presence or absence of the video signal being output, and the video signal detecting means (40) connected between the light projecting lamp and the current generator, A switching means (41) for turning on / off the lamp for lighting, the switching means is turned on by the control signal (S) generated when the video signal is detected by the video signal detecting means, and the light is projected. Lamp LCD projector built VTR, characterized in that so as to light up. 2. A head (20) for reproducing a video tape (T) and a VTR for receiving and processing a reproduction output of the head.
A video signal processing system (7), a liquid crystal panel drive circuit system (8) for processing a brightness signal and a chrominance signal from the VTR video signal processing system to drive a liquid crystal panel, and for projecting a reproduced image on a screen A VTR with a built-in liquid crystal projector, comprising: a lamp (43); and a current converter (42) for converting an AC power supply into a DC and converting the VTR video signal processing system, a liquid crystal panel drive circuit system, and a lamp for projecting light. A switching means (41) connected between the light lamp and the current generator for turning on / off the light emitting lamp; and an amplifier (45) for amplifying a detection signal (K) from the liquid crystal panel drive circuit system. And a control signal (K ′) obtained by amplifying the detection signal so that the switching means is turned on and the projection lamp is turned on.
R. 3. The liquid crystal projector built-in VTR according to claim 2, wherein the detection signal (K) is a color killer signal in a color signal demodulator (33) in the liquid crystal panel drive circuit system. 4. The liquid crystal projector built-in V according to claim 2, wherein the detection signal (K) is a color killer signal in a color signal demodulator in the VTR video signal processing system.
TR.