JPS5853792Y2 - Horizontal deflection width switching circuit - Google Patents

Description

[Detailed Description of the Invention] A projection display device is known in which an image projected on a cathode ray tube can be enlarged and viewed.

As shown in FIG. 1, it consists of a projection cathode ray tube 1, a reflector 2, a lens 3, and a screen 4, and the image projected on the screen of the cathode ray tube 1 is transmitted through the reflector 2 and lens 3. The image is enlarged and projected onto the screen 4 for display.

The cathode ray tube 1 used is one with particularly high brightness.

By the way, it is known that horizontally elongated and wide images match the human visual field, provide a sense of realism, and increase the impact, as seen in CinemaScope movies. However, since the screen size of a standard television video signal is set at an aspect ratio of 3:4, even with a projection display device, it is desirable to be able to project on the screen 4. Images with an aspect ratio of 3:4 can only be obtained.

Therefore, a projection display device was devised in which the displayed image could be made wider than the standard television image.

FIG. 2 shows an example of a novel projection display device that can obtain a wide image as described above.First, this example will be explained.

In this example, the cathode ray tube 1 has a vertical deflection width of 7%.
, narrower than normal, ie, narrower than the vertical length of the effective screen size (corresponding to the screen size of a cathode ray tube).

Then, the horizontal deflection width is determined according to this narrow vertical deflection width. It can be switched depending on the state.

That is, in FIG. 2, the deflection comb 5 IA is a horizontal deflection circuit, and the deflection current from the horizontal deflection circuit 5 is supplied to the deflection yoke IA. By switching the voltage EL lower than the voltage EH obtained in the circuit 8, the power supply voltage of one circuit 5 is changed, and the deflection width is changed.

For example, when the voltage EH is applied to the horizontal deflection circuit 5 with the switch circuit 6 in a state opposite to that shown in the figure, the horizontal deflection width is equal to the horizontal width of the effective screen.

9 is a video camera, and 9A is its deflection yoke 10 is a vertical deflection circuit.

In this video camera 9, the horizontal deflection width on the target plane T is the same as the normal one, but the vertical deflection width can be switched between a width equal to the normal one and a narrower width n.

That is, the voltage vH obtained at the terminal 11 and the voltage vL lower than the voltage vH obtained at the terminal 12 are connected to the switch circuit 13.
The signal is switched and supplied to the vertical deflection circuit 10, thereby switching the vertical deflection width.

For example, when the switch circuit 13 is switched to a state opposite to that shown in the figure, the vertical deflection width is made narrower.

The switch circuits 6 and 13 are switched by the switching signal Sw, and when the push button switch 14 is off, the signal Sw is rl.
When the signal Sw is "-", the state shown in the figure is turned on when the push button switch 14 is pressed, and when the signal Sw is "-", the state is switched to the state opposite to the state shown in the figure.

15 and 16 are amplifiers, IT is a changeover switch, 1
8 is a terminal to which a detected signal of a standard television broadcast signal is supplied.

Note that the screen is a screen 4' that is longer in width than the aspect ratio of 3:4.

Next, the operation of this device will be explained.

When the switch 17 is switched to the state shown in the figure, a signal from the camera 9 is supplied to the cathode ray tube 1 through amplifiers 15 and 16.

In this state, if the push button switch 14 is off, the signal Sw is in the "L" state and the switch circuit 13 is in the "L" state.
is in the state shown in the figure, so the vertical deflection width at camera 9 is the same width as in the normal case. Therefore, if the subject is a perfect circle and the target plane T of camera 9 is as shown in Figure 3A, When an image is formed, the camera 9 scans the target surface T with the horizontal and vertical deflection widths the same as in the normal case, as shown in Figure B. A standard television video signal is obtained, and this is supplied to the cathode ray tube 1.

At this time, since the switch circuit 6 in the cathode ray tube 1 is switched to the state shown in the figure, the horizontal deflection width is narrower than the screen size.

Therefore, if the effective screen size of the cathode ray tube 1 is a in the vertical direction and b in the horizontal direction as shown in FIG. It becomes an image.

This is then projected onto the screen 4' to display the image, but since the screen 4' is horizontally long as shown in the third diagram, the horizontal width of the image is the same as the screen 4'.
The displayed image has a portion 19, which is narrower than the horizontal width of , and has no image, indicated by diagonal lines in the figure.

Unlike the screen of a television receiver, even if there is a portion 19 where no image is displayed, the screen 4'
Visually, it doesn't feel that unnatural.

Next, a case will be described in which the image photographed by the camera 9 is made into a horizontally long wide image.

That is, the push button switch 14 is turned on, the signal Sw becomes "0", and the switch circuits 6 and 13 are switched to a state opposite to that shown in the figure.

Therefore, in the camera 9, the vertical deflection width Am is made narrow.

Therefore, the image formed on the target surface T as shown in FIG. 4A is scanned with a narrow vertical width as shown in FIG. 4B.

The video signal obtained from the camera 9 is thus supplied to the cathode ray tube 1. At this time, if the horizontal and vertical deflection widths are the same as those of the standard system signal described above, the video signal on the cathode ray tube 1 is The output image appears to have been enlarged only in the vertical direction.

However, at this time, as described above, the switch circuit 6
Since the horizontal deflection width is changed to the opposite state to that shown in the figure, the horizontal deflection width is made wider than in the case of the standard signal. A horizontally long image with only the vertical width narrowed is produced.

Since the image of the cathode ray tube 1 can be projected onto the screen 4', a horizontally long and wide image is displayed on the screen 4'.

Next, when the switch 17 is switched to the opposite state to that shown in the figure, the detected signal of the standard television broadcast signal from the terminal 18 is supplied to the cathode ray tube 1 through the amplifier 16.

In this case, the push button switch 14 is turned off.

Therefore, on the screen of the cathode ray tube 1, an image as shown in Figure 3C, which is smaller than the effective screen size, is projected, and on the screen 4', an image with an aspect ratio of 3:4 as shown in Figure 3 is projected. This is what is displayed.

In this way, according to this device, the screen 4 can be adjusted simply by performing purely electronic processing such as modifying the deflection device.
A projection image display device on which a horizontally elongated image is projected can be realized.

By the way, to obtain a color image on the screen 4',
Images from three cathode ray tubes for red, periphery, and blue are combined on a screen 4' (referred to as registration registration).

In the above-mentioned device, the horizontal deflection width is changed by switching the power supply voltage of the horizontal deflection circuit as described above, depending on whether a wide image is obtained on the screen 4' or a normal image with an aspect ratio of 3:4. However, as mentioned above, in the case of a color display device using three cathode ray tubes, if the power supply voltage of the horizontal deflection circuit is switched to change the deflection width, the registers will not match.

Therefore, it is necessary to be able to adjust registration alignment independently for wide images and normal images.

One of the adjustments for this registration is the adjustment of the horizontal deflection width, that is, the horizontal size, and this invention relates to %K and the adjustment of this horizontal size.

By the way, left and right bin cushion distortion correction signals and a trapezoidal distortion correction signal to prevent the image on the screen 4 from becoming trapezoidal are added to the horizontal deflection circuit. Therefore, it is necessary to take into account that the amount of correction by these correction signals does not change.

This idea is based on a horizontal deflection width switching circuit that allows the horizontal size to be adjusted independently for wide images and normal images without changing the amount of correction for left and right bin cushion distortion and trapezoidal distortion. This is what we are trying to propose.

Hereinafter, an example of the horizontal deflection/swing switching circuit according to this invention will be explained with reference to FIG.

As shown in the figure, 20R, 20G and 20B are respectively red,
Green and blue horizontal deflection width adjustment circuits・These circuits 20R,
The configurations of 20G and 20B are exactly the same.

21 is a power supply terminal from which a DC voltage of 10 EB can be obtained, and 22 is a switch for changing the power supply.

The power supply terminal 21 is grounded through a series circuit of resistors 23 and 24 and connected to one contact W of the switch 22 through a resistor 25, and the connection point of the resistors 23 and 24 is connected to the other contact N of the switch 22. Connected.

Further, the movable contact of the switch 22 is grounded via the capacitor 26 and connected to the base of the transistor 270.

The collector of this transistor 27 is connected to the power supply terminal 21, and a capacitor 28 is connected between the emitter and ground.

Then, the voltage obtained on the emitter side of the transistor 27, that is, across the capacitor 28, is applied to the circuit 20R22.
The power supply voltage is 0G and 20B.

As mentioned above, the configurations of the circuits 20R, 20G, and 20B are the same, so here, the red horizontal deflection width adjustment circuit 2
Let's explain about 0R.

That is, 29 is a transistor for correction such as right and left bin cushion distortion correction, the collector of this transistor 29 is connected to the emitter of the transistor 27, and the resistor 31 is connected between the collector base of this transistor 29. The connection point between the transistor 290 and the base of the transistor 290 is connected through a resistor 32 to the collector of the transistor 33, the emitter of the transistor 33 is grounded through a series circuit of resistors 34 and 35, and the connection point between the resistors 34 and 35 is connected to a capacitor. 36 to ground.

Parabolic wave current for right and left bin cushion distortion correction and sawtooth wave current for trapezoidal distortion correction are supplied from terminal 37 to the base of transistor 330 through capacitor 38 .

Also, the emitter of the transistor 27 and the transistor 29
The connection point with the collector of is grounded through a series circuit of a resistor 39, a variable resistor 40, and a resistor 41.
is connected to the base of transistor 330.

The emitter of the transistor 29 is connected to the capacitor 42.
The transistor 29 is grounded through the emitter of the transistor 29, and an output terminal is led out from the emitter of the transistor 29.

In other words, the output terminal 30R is more connected to the circuit 20R than the circuit 20R.
An output terminal 30G is derived from 0G, and an output terminal 30B is derived from the circuit 20B, and the outputs obtained from these output terminals are supplied to each of the red, green, and blue horizontal output circuits.

And, furthermore, the transistor 33
The collector of is connected to the collector of the transistor 43,
The emitter of this transistor 43 is grounded through a resistor 44.

Further, the connection point between the emitter of the transistor 27 and the collector of the transistor 29 is grounded through a series circuit of a resistor 45, a variable resistor 46, and a resistor 4T, and the movable element of the variable resistor 46 is connected to the other contact N of the switch 4B. One contact W of this switch 48 is grounded via a resistor 49.

A movable contact of this switch 48 is connected to the base of the transistor 430 via a resistor 50, and a connection point between the base and the resistor 50 is grounded via a capacitor 51.

In this case, the switch 22 and the switch 48 are connected to each other by a relay 52 so that they are connected to one contact W when a wide image is displayed, and connected to the other contact N when a normal image is displayed.

In the circuit configured as above, when the switches 22 and 48 are connected to one contact W, the transistor 2
A resistor 25 is connected between the collector bases of 7, and
Since the capacitor 26 is connected between the base of the transistor 27 and the ground, the circuit including the transistor 27 operates like a ripple filter, and the emitter potential of the transistor 27 becomes a voltage EH approximately equal to the voltage 1 EH.

Therefore, the emitter body of transistor 29, that is,
This voltage E is applied to each output terminal 30R, 30G and 30B.
The output signal of each color is obtained at a high level corresponding to It will be served.

At this time, in the circuit 53 surrounded by the broken line, the base of the transistor 43 is grounded through the resistors 50 and 49, so the transistor 43 is turned off.

Therefore, if the variable resistor 40 is adjusted at this time, the emitter potential of the transistor 29 changes, the DC level of the output signal changes, and the horizontal size is adjusted.

Next, when the switches 22 and 4B are connected to the other contact N, the base potential of the transistor 27 is reduced to the voltage obtained by dividing the voltage +EB by the resistors 23 and 24, and therefore the emitter potential of the transistor 27 is also reduced to the voltage Go down to EL.

At this time, the base potential of the transistor 270 slowly decreases with a time constant determined by the resistor 21 and the capacitor 26.
7 is prevented from being destroyed between the base and emitter.

On the other hand, at this time, in the circuit 53 within the broken line, the base of the transistor 430 is connected to the variable resistor 46 via the resistor 50.
is connected to the mover.

Therefore transistor 430 pace potential is resistor 50
The voltage rises slowly with a time constant determined by the voltage and the capacitor 51, and this transistor 43 is turned on.

Then, a direct current flows through the transistor 43 via the resistors 31 and 32, thereby lowering the base potential of the transistor 290.

Thus, output terminal 3 of circuits 20R, 20G and 20B
At 0R, 30G, and 30B, output signals of each color on which the correction signal from the terminal 37 is superimposed are obtained at a level corresponding to the voltage EL, and these are supplied to each horizontal output circuit to output the horizontal output signal of the cathode ray tube. The deflection width is narrower than the horizontal width of the effective screen.

At this time, if the variable resistor 46 is adjusted,
The collector current of transistor 43 changes and therefore the emitter potential of transistor 29 changes to provide horizontal size adjustment.

Furthermore, in this case, since the correction signal is supplied to the transistor 330,
This correction signal current flows through the collector current of 3.
Since the AC impedance on the transistor 43 side seen from the collector side of this transistor 33 is high, no correction signal current flows through this transistor 43 side, and only a DC component flows through this transistor 43.

Therefore, even if the transistor 43 is turned on and the horizontal deflection width becomes smaller, the correction current flowing through the transistor 33 does not change, and the correction amounts of left and right bin cushion correction and trapezoidal correction do not change.

Next, when the switches 22 and 48 are switched to the one contact W side, the base potential of the transistor 270 rises slowly with the time constant of the resistor 25 and the capacitor 26, and its emitter potential also rises slowly.

Therefore, transistor 29 has switches 22 and 48
A rush current flows when switching, destroying it.1
There's nothing like that.

Further, the base potential of the transistor 430 slowly decreases according to the rise in the emitter potential of the transistor 27, that is, the collector potential of the transistor 29, with the time constant of the resistor 49.50 and the capacitor 51, and is turned off.

As described above, according to this invention, by providing the circuit 53 surrounded by the broken line in FIG. 5, it is possible to change the horizontal deflection width without changing the correction amount of trapezoidal distortion correction or left and right bottle cushion distortion correction. Moreover, the horizontal size can be adjusted independently.

In addition, in the example shown in the figure, by providing a time constant circuit consisting of a resistor 24.25 and a capacitor 26, and a time constant circuit consisting of a resistor 49.50 and a capacitor 51, when the horizontal deflection width is switched, these time constant circuits are provided. Since the horizontal size is switched slowly using the time constant of the constant circuit, it is possible to prevent a rush current from flowing into the correction transistor 29 at the time of switching and destroying it.

Although the above example is an example in which this invention is applied to a horizontal deflection circuit of a projection display device, this invention is not limited to this.

Further, a configuration may be adopted in which a correction signal for trapezoidal distortion and a correction signal for left and right bottle cushion distortion are supplied from the emitter side of the transistor 33.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a general configuration of an example of a projection display device, FIG. 2 is a system diagram of an example of a device that switches the horizontal deflection size to determine a wide image and a normal image portion, and FIG. Figures and Figure 4 are for explanation, Figure 5.
The figure is a circuit diagram of an example of the essential parts of the horizontal deflection circuit according to this invention. 22 and 48 are switches, 29 is a first transistor,
30R, 30G, and 30B are horizontal output terminals for each color, 33 is a second transistor, 37 is a terminal to which a correction signal is supplied, 40 is a first variable resistor, 43 is a third transistor, and 46 is a second transistor. It is a variable resistor.

Claims (1)

[Scope of utility model registration request] A first power supply voltage is applied to the first controlled electrode of the first transistor such that the horizontal deflection width is narrower than the horizontal width of the effective screen of the screen of the cathode ray tube, and the horizontal deflection width is the horizontal width of the effective screen. The control electrode of the first transistor is connected to the first controlled voltage of the second transistor via a resistor. a control electrode or a second controlled electrode of the second transistor to apply a correction signal such as right and left bin cushion distortion correction;
An output signal is taken out from a second controlled electrode of the first transistor, the control electrode of the second transistor is connected to a first variable resistor, and the first controlled electrode of the first transistor is connected to the control electrode of the second transistor. When the second power supply voltage is supplied to the electrode, the horizontal deflection width is adjusted by the first variable resistor, and the first controlled electrode of the second transistor is the control electrode of the third transistor is connected to the first controlled electrode of the third transistor, and when the first power supply voltage is supplied to the first controlled electrode of the first transistor; A second variable resistor is connected to the horizontal deflection circuit, and the horizontal deflection width is adjusted by the second variable resistor.