JPS5850073B2 - Image projection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video display device that can simultaneously display images of two channels on one color picture tube (CTR) screen of a television receiver.

As a conventional image projection device of this type, Japanese Patent Application Laid-Open No. 49-24
There is one described in Publication No. 19.

This method simultaneously receives first and second different television signals, sequentially writes the two television signals to a plurality of storage means, and reads the second television signal whose time axis has been compressed from each storage means. reading and exchanging a portion of the first television signal with a compressed second television signal to display a second television issue on a portion of the video screen of the first television signal; This is how it was done.

In this type of image projection device, when a main screen is configured using the first television signal as a main signal and a sub screen is configured using the second signal as a sub signal, if the sub screen is to be displayed in color, Requires multiple storage means.

On the other hand, if the sub-screen displays only black and white images, there is a problem that the sub-screen is generally smaller than the main screen and lacks impact.

The present invention provides the following effects by coloring the sub-screen in a specific color.
An object of the present invention is to provide an image display device capable of simultaneously displaying a plurality of screens, which solves the above-mentioned problems.

The present invention will be explained below, but before that, in order to facilitate understanding of the present invention, the basic principles and conventional circuit examples for projecting a plurality of images onto one picture tube will be explained with reference to FIGS. This will be explained with reference to FIG.

As a method of projecting images of two channels A and B on the same projection surface, the method shown in FIG. 1 can be considered.

In other words, the B channel is approximately 1/2 vertically and 17 horizontally of the entire screen.
2 will make the area 1/4 and will be projected in the lower right corner of the screen.

The basic idea of this method is that every other horizontal scan of the B channel, every other picture element (sample points necessary to reproduce an image) of one horizontal scan is stored in the memory circuit corresponding to that scanning line. When the sampled sample value is stored and the horizontal scanning of the A channel sweeps the part B in FIG.
This is based on the principle that the image signal of the channel is compressed to 1/2 vertically and horizontally and displayed on the part B in FIG. 2.

FIG. 2 is a block diagram showing a conventional configuration for realizing this.

In the figure, 1 is an antenna, 2 and 6 are tuners that receive broadcasts on different channels A and B, respectively, and 3
, 7 is a video intermediate frequency amplification circuit, 4 and 8 are video detection circuits,
5. 9 is a video amplification circuit; 10 is a circuit for generating vertical synchronization signal vB and horizontal synchronization signal HB of channel B; 11
is a circuit that generates the vertical synchronizing signal A of channel A and the horizontal synchronizing signal HA.

12 is a flip-flop circuit that inverts its state every time the horizontal synchronizing signal HB is generated and generates an output signal d; 13;
is the applied signal N1. N2. N3. Input p according to C
, q, r, or s and generates an output at the output terminal 23. This circuit operates as shown in the following table.

Note that the * mark in the table indicates that it may be arbitrary.

14.17 are RSS flip-flop circuits each having a reset terminal R and a set terminal S, and outputs a and 17, respectively.
generate b.

15 and 16 are counters, 18 is a gated oscillator, which stops oscillation while the horizontal synchronization signal HA is being generated;
The phase relationship of the output pulse with respect to the horizontal synchronizing signal HA can be made equal in any horizontal scan.

A gated oscillator 19 generates an output f and has a similar relationship to the horizontal synchronizing signal HB.

20 is a control circuit including a memory circuit for writing and reading image information.

21 and 22 are ant gate circuits, respectively.

The oscillation frequency of the gated oscillator 18 described above is 450 fHCHz when the number of pixels per horizontal scan is 450, and the horizontal scanning frequency is fH, and the oscillation frequency of the gated oscillator 19 is 1/2 of that, 225 fH. (
Hz).

The counter 15 is a counter of 525/(2×2)ξ132 [bits] for the number of horizontal scans of one field, 525/2, and sets the flip-flop circuit 14 when 132 horizontal synchronizing signals HA are counted. However, the output a becomes a high potential state.

The counter 15 and flip-flop circuit 14 are reset by the vertical synchronizing signal vA.

The counter 16 counts 450 pixels for 450 picture elements in one horizontal scanning question.
When the /2=225 (bits) counter counts 225 output pulses from the gated oscillator 18, the flip-flop circuit 17 is set and its output becomes a high potential state.

Counter 16 and flip-flop circuit 17 are reset by horizontal synchronizing signal HA.

With this configuration, when sweeping the portion B shown in FIG. 1, the outputs a and b are in a high potential state, and the output of the oscillator 18 appears at the output e of the AND gate 22.

The broadcast signal of the channel selected for reception by the tuner 2 is applied to the signal selection circuit 13 via circuits 3, 4.5 as a video signal p shown in FIG. 3A.

Further, the broadcast signal of channel B selected for reception by the tuner 6 is applied to the control circuit 20 via circuits 7, 8.9.

In this control circuit 20, as shown in FIG. 3, the video signal V of channel B is sampled, each sample value is stored, and the stored signal is read out at twice the sampling speed.

Then, as shown in FIG. 3C, a video signal whose time axis is compressed to 1/2 is obtained.

This video signal appears as q, r, and s for each field.

The signal selection circuit 13 appropriately selects and switches the signals p, q, r, and s, and as shown in FIG. appears at the output terminal 23.

As shown in the table above, when the input selection signal C is 1'', the channel B signal is obtained from the signal selection circuit 13.

According to the present invention, a fourth
The circuits shown in the figure are connected to each other.

The present invention will be described in detail below with reference to FIG.

The signal appearing at the output terminal 23 of the signal selection circuit 13 passes through the video processing circuit 24 and is sent to the luminance signal and color difference signal addition circuit 2.
Enter 5.

On the other hand, the chroma signal enters the chroma signal processing circuit 27 via the switch circuit 26.

This chroma signal processing circuit 27 includes an ACC circuit, an APC circuit, a killer circuit, a color demodulation circuit, a color saturation adjustment circuit, and a hue variable circuit, and its output line receives three demodulated color difference signals (R-Y), (BY) and (G-Y) are obtained.

The color difference signal is added to the luminance signal Y in an adding circuit 25,
Three primary color signals of R (red), G (green), and B (blue) are obtained.

The switch circuit 26 operates to cut off the signal entering the chroma signal processing circuit 27 during the period Q during which the sub-screen is displayed.

Normally, when a main screen is configured using the channel A signal as the main signal, the main screen is displayed as a color image.

At this time, the operation of the chroma signal processing circuit 27 is
The same applies to the period when the sub-screen is displayed on the color picture tube 30.

That is, there is no guarantee that the killer circuit is operating during the period when the sub-screen is displayed.

Therefore, it is necessary to completely cut off the signal entering the chroma signal processing circuit 27 during the sub-screen period using the switch circuit 26.

Note that this switch circuit 26 is connected to a chroma signal processing circuit 27.
It is also possible to provide it at a later stage.

The output of the adder circuit 25 is led to the three primary color drive output circuit 28 and drives the cathode of the color picture tube 30.

A switch circuit 29 that can change the three primary color input signal ratio of the three primary color drive output circuit 28 is connected to the input section of the three primary color drive output circuit 28, and completely blocks the input of, for example, R and G.

This cut-off period corresponds to the period during which the sub-screen is displayed.

The switch circuits 26 and 29 are connected to the three primary colors 1 drive output circuit 2 of the color picture tube 30 only during the period when the sub-screen is projected.
This constitutes means for changing the drive ratio of 8.

The three primary color drive output circuit 28 includes a resistor 31, a variable resistor 32,
It has an amplifier including a B output transistor 37, a resistor 40, a load resistor 43, a resistor 49, a variable resistor 50, and a resistor 46.

Similarly, the G input includes resistors 33 and 34, G output transistor 38, resistor 41, load resistor 44, resistor 51, and variable resistor 5.
2. For the amplifier comprising the resistor 47 and the R input,
The amplifier includes a resistor 35, a variable resistor 36, an R output transistor 39, a resistor 42, a load resistor 45, a resistor 53, a variable resistor 54, and a resistor 48.

The variable resistors 32 and 36 are for adjusting the drive output ratio of the B and R outputs, respectively, and the variable resistors 50 and 52.54 are for adjusting and equalizing the cutoff voltage of the cathode of the color picture tube 30, respectively. be.

Voltage v1 is usually 150-200■, voltage ■2 is 12V
is applied.

Resistors 46, 47, and 48 are connected to B of the color picture tube 30, respectively.
, G, and R cathodes.

The collectors of transistors 55 and 56 of the switch circuit 29 are connected to the bases of the G and R transistors 38 and 39 via resistors 59 and 60, and their respective emitters are grounded.

Normally, the bases of the transistors 55 and 56 are grounded by the resistor 57, and are in a cut-off state, so that the transistor 3
It has no effect on the 8.39 base input.

When a positive pulse is applied via the capacitor 58, the transistors 55 and 56 become conductive, and the transistor 3
8. Block the input of 39.

Therefore, only the B output is displayed on the color picture tube 30.

The pulse input that places transistors 55, 56 in the conductive A state corresponds to pulse C in FIG.

That is, the pulse C is the same as that supplied to the signal selection circuit 13 and the switch circuit 26, and has a time relationship as shown in FIG. 3E.

If you increase the value of resistor 59.60, switch circuit 2
9 will be less affected, and the sub-screen will be less colored.

Therefore, by changing the values of the resistors 59 and 60 and connecting the resistors to the bases of the transistors 37, 38 and 39, it is possible to give the sub-screen any color.

FIG. 5 is a circuit diagram of another embodiment of the present invention.

In this embodiment, the three primary color drive output circuit 28 is almost the same as that in FIG. 4, but the switch circuit 29 is different from that in FIG. It is grounded via a resistor 62.

Further, the transistor 61 is connected in parallel with the resistor 62,
The voltage applied to the base by the resistor 57 keeps it in a conductive state at all times.

Therefore, the resistor 62 is normally short-circuited by the transistor 61, and in this state the variable resistor 32 is optimally driven.

A pulse is applied to the base of transistor 61 via capacitor 58 .

This pulse is obtained by inverting the polarity of pulse C in FIG. 4 using an inverter 65, and the period during which this pulse is applied is when the sub-screen is being displayed intruding into the main screen.

On the other hand, the resistor 34 is connected in series with the resistor 64 in the switch circuit 28, and furthermore, the transistor 6 is connected in parallel with the resistor 64.
3 is connected, and its base is connected to the base of transistor 61.

Therefore, the G drive output and the B drive output are enhanced only during the sub-screen period.In this case, for example, by appropriately setting the values of the resistors 62 and 64q, the R, G, and B drive outputs are increased only during the sub-screen period. The color temperature can be changed.

That is, in the embodiment shown in FIG. 5, the color temperature of the monochrome image can be increased only during the sub-screen period.

If you do this, the secondary screen will look very clean.

Normally, the color image part (main screen) is selected based on the reference white point specified by the color broadcasting system, but in current color television receivers, the chromaticity point of the phosphor differs from that specified by the NTSC system, for example. To compensate for this, the color temperature of the reference white color is selected to be slightly higher on the receiver side.

It is usually around 9000.

However, for monochrome images, it is preferable to increase the reference white color to 100OOK or more.

Therefore, in this embodiment, among the multiple screens, the reference white color of the main screen part is selected to have a preferable color temperature from the point of view of color reproduction, and the color temperature of the reference white color is increased only during the sub-screen period, so that a sub-screen with a preferable monochrome image is selected. This makes it possible to make the sub-screen more impressive.

As is clear from the above description, according to the present invention, it is possible to easily color the sub-screen in a specific color, which not only increases the power of the sub-screen but also makes it easier to distinguish it from the main screen. can be facilitated.

■ The reference white point of only the sub-screen portion can be selected to be the optimal value for monochrome images, and this selection can be made completely independent of the reference white point of the main screen.

It is possible to obtain very excellent effects such as.

[Brief explanation of drawings]

FIG. 1 is a pattern diagram showing an example of displaying a plurality of images simultaneously, FIG. 2 is a block diagram of a main part of a conventional multiple image simultaneous display device, and FIG. 2 and E are signal waveform diagrams, FIG. 4 is a circuit diagram of a main part of an embodiment of the present invention, and FIG. 5 is a diagram of a circuit diagram of a main part of another embodiment of the present invention. 13...Signal selection circuit, 24...Video processing circuit, 25...Addition circuit, 26...
...Switch circuit, 27...Chroma signal processing circuit, 28...Primary color drive output circuit, 29...
...Switch circuit, 30...Color picture tube, 3
1.32, 33, 34, 35, 36°59, 60,
62, 64...Resistance, 37, 38. 39.55, 56, 61.63...transistor.

Claims (1)

[Claims] 1. A screen of a plurality of television signals is displayed on a single color picture tube, one of the plurality of television signals is used as a main signal, and a synchronization signal of the main signal is used to display the screen of a plurality of television signals. The main screen is projected by deflecting the beam of the color picture tube, and the remaining signal is used as a sub signal to form a sub screen, and this is synchronized with the synchronization signal of the main signal to form a part of the screen of the main signal. The display is configured so as to display the image on the sub-screen, and includes means for changing the drive ratio of the three primary color drive output circuits of the color picture tube only during the period when the sub-screen is displayed, so that the image on the sub-screen is displayed. An image projection device characterized in that the image projection device is configured to project images at a color temperature different from that of the image on the main screen. The means for changing the drive ratio of the 23 primary color drive output circuit includes a first circuit that changes the 3 primary color input signal ratio of the 3 primary color drive output circuit, and a means for changing the color difference signal output of the main signal only during the period when the sub screen is displayed. 2. The image projection apparatus according to claim 1, further comprising a second circuit to be cut off. 3 The first circuit includes a resistor and a transistor connected in series between at least one signal input path of the three signal input paths of the three primary color drive output circuit and ground, and the transistor is connected to the sub screen. 3. The image projecting device according to claim 2, wherein the image projecting device is configured to be switched by a pulse for projecting the image. 4 The first circuit includes a resistor and a transistor connected in series between the blue and green signal input paths of the three primary color drive output circuit and the ground, and a resistor connected in parallel to each of these transistors. and each of the transistors is switched by a signal obtained from a pulse for projecting the sub-screen, and only during the period of projecting the sub-screen, the color temperature of the black and white image on the sub-screen is changed to that of the black body. The image projection device according to claim 2, characterized in that the image projection device is configured to change on a trajectory.