JPH03214991A - image display device - Google Patents

Abstract

PURPOSE:To reduce cost and to decrease a mount area by adopting the constitution such that R, G, B video signals are converted into digital signals by an analog multiplexer so as to decrease the number of A/D converters from three into one while keeping the same function as a conventional function. CONSTITUTION:An electron beam is generated for each of plural areas of a pattern on a screen divided vertically and plural lines are displayed while deflecting each electron beam in the vertical direction for each area to display a television picture as a whole as the display device, and a luminance signal subjected to color demodulation and synthesized R, G, B video signals are fed to an analog multiplexer 51, in which the signals are multiplexed analogically in the timing of R, G, B switching signals. The analogically multiplexed signal is fed to an A/D converter 52 and multiplexed digital R, G, B video signals in the timing of the sampling signal of the A/D converter 52 are given to sample-and-hold circuits 31a-31n.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention generates an electron beam for each division when a screen on a screen is vertically divided into a plurality of divisions, and generates an electron beam for each division. This invention relates to a device that displays a television image as a whole by displaying a plurality of lines by vertically deflecting a beam. Prior Art First, the basic configuration of the image display element used here will be explained with reference to FIG. The display element 2 includes, in order from the back to the front, a back electrode 1, a line cathode 2 as a beam source, a beam extraction electrode 3,
It consists of a beam flow control electrode 4, a focusing electrode 5, a horizontal deflection electrode 6, a vertical deflection electrode 7, and a screen plate 8, which are housed inside a flat vacuum container (not shown). ．． The line cathode 2 as a beam source is stretched in the horizontal direction so as to generate an electron beam distributed linearly in the horizontal direction, and a plurality of line cathodes 2 are arranged vertically at appropriate intervals. In this figure, only 7 wires (2A to 2G are shown) are provided. In this embodiment, it is assumed that the spacing between the line cathodes is 3cm and the number of line cathodes is 30, and the line cathodes 2A to 27 are provided. The distance between the line cathodes 2 is not allowed to be increased freely, but is regulated by the distance between the vertical deflection electrode 7 and the screen 8, which will be described later. These wire shields 2 are constructed by coating an oxide cathode material on the surface of a tungsten wire having a diameter of 10 to 30 μm, for example. Then, as will be described later, the electron beams are controlled to be emitted sequentially from the upper line cathode 2a for a fixed period of time. The back electrode 1 suppresses generation of electron beams from line cathodes 2 other than the line cathode 2 that is controlled to emit electron beams for a certain period of time, and directs the generated electron beams only in the forward direction. It has the effect of pushing out. This back electrode 1 may be constructed using the inner surface of the rear wall of the vacuum container. The beam extraction electrode 3 has a large number of through holes 1 arranged at predetermined intervals in the horizontal direction facing each of the line cathodes 2a to 27.
0, and the electron beam emitted from the line cathode 2 is taken out through its through hole 10. Next, the control electrode 4 is connected to a vertically long conductive plate 15 having a through hole 14 at a position facing each of the line cathodes 2a to 27.
It consists of a plurality of them arranged horizontally at predetermined intervals. In this embodiment, 120 conductive plates 15a to 15n for control electrodes are provided (only 8 are shown in the figure). This control electrode 4 controls the amount of passage of each of the electron beams divided horizontally into two by the beam extracting electrode 3 in accordance with the video signal for displaying each picture element. One line of video is displayed on the 120 control electrodes 4 at one time. The focusing electrode 5 is a conductive plate 17 having a through hole 16 at a position facing each through hole 14 provided in the control electrode 4,
The electron beam passing through the through hole 14 provided in the control electrode 4 is focused. The horizontal deflection electrodes 6 include a plurality of conductive plates 18 , which are vertically arranged at positions on both sides of the through hole 16 .
18', each electrode 18. 18
'A horizontal deflection voltage is applied to horizontally deflect the electron beam for each picture element, and the RS
Each of the G and B phosphors is irradiated sequentially to cause them to emit light. The deflection range is 2 for each electron beam in this example.
It is the width of a picture element. The vertical deflection electrodes 7 are formed by a plurality of conductive plates 19 arranged horizontally at intermediate positions between the through holes 16 .
19', each electrode 19. 19
A vertical deflection voltage is applied to ', which deflects the electron beam in the vertical direction. In this embodiment, a pair of electrodes 19. 19
' deflects the electron beam generated from one line cathode to eight lines in the vertical direction. The 31 vertical deflection electrodes 7 constitute 30 pairs of conductors corresponding to each of the 30 line cathodes, and the screen 8
Deflect the electron beam so that it draws 240 horizontal lines on the top. The electron beam is mainly transmitted through horizontal and vertical deflection electrodes6.7
However, the screen is divided so that the entire screen can be constructed with a sufficiently small amount of deflection compared to the distance in this space, so that large deflection distortion does not occur. The screen 8 is constructed by applying a phosphor 20 that emits light when irradiated with an electron beam to the back surface of a glass plate 21, and adding a metal glue layer (not shown) if necessary. The phosphors 20 are provided with two pairs of phosphors of three colors R, G, and B for each slit 14 of the control electrode 4, that is, for each horizontally divided electron beam. It is coated in stripes in the vertical direction. In FIG. 3, the broken lines drawn on the screen 8 indicate divisions in the vertical direction that are displayed corresponding to each of the plurality of line cathodes 2, and the two-dot chain lines correspond to each of the plurality of control electrodes 4. This shows the horizontal divisions displayed. As shown in the enlarged view in Figure 4, one section partitioned by both of them has an R of two pixels in the horizontal direction.
, G, and B, and has a width of 8 lines in the vertical direction. The size of one section is, for example,
The horizontal direction is 1 cabinet and the vertical direction is 3gIP, R, G,
The three color B phosphors may be applied in an arrangement other than vertical stripes, for example, in a delta arrangement. Please note that in Figure 3, the length in the horizontal direction is enlarged by about twice the length in the vertical direction for clarity. In addition, in this example, 1
The control electrode 4 of the book, that is, R for one electron beam
, G, B are provided in two pairs for two picture elements, but of course, one picture element or three or more picture elements may be provided. Or 3
R, G, and B video signals for picture elements and above are added sequentially,
Horizontal deflection is performed in synchronization with this. Furthermore, R, GS
The three color B phosphors may be applied in an arrangement other than vertical stripes, for example in a delta arrangement. In that case, horizontal and vertical deflection voltages suitable for the phosphor arrangement are applied. Next, the basic configuration of a drive circuit for displaying an image on this display element will be explained with reference to FIG. First, the driving part for irradiating the screen 8 with an electron beam to emit raster light will be explained. The power supply circuit 22 is a circuit for applying a predetermined bias voltage (operating voltage) to each electrode of the display element, with v1 applied to the back electrode 1, v3 applied to the beam extraction electrode 3, and v applied to the focusing electrode 5
5. Apply the DC voltage of ①8 to the screen 8.

The line cathode drive circuit 26 creates line cathode drive pulses (I-MA) using the vertical synchronization signal (2) and the horizontal synchronization signal (H). Figure 6 shows the relationship between the vertical synchronizing signal (■), the horizontal synchronizing signal (H), and the line cathode drive pulses (I to M). Each line cathode 2a to 27 is heated by a current flowing through it during the high potential period of the driving pulse (i to ma), so that it can emit electrons during the low potential period of the driving pulse (i to ma). The heated state is maintained. As a result, electrons are emitted from the 30 line cathodes 2i to 27 only during the 8H period when a low potential drive pulse (i to ma) is applied to each of them. During the period when a high potential is applied,
This is because the high potential applied to the line cathodes 2-27 becomes more positive than the potential at the position of the line cathode 2 determined by the bias voltage applied to the back electrode 1 and the beam extraction electrode 3. , electrons are not emitted from the line cathodes 2-27. Thus, in the line cathode 2, electrons are sequentially emitted from the upper line cathode 2a toward the lower line cathode 27 for each 8H period during the effective vertical scanning period. The deflection voltage waveform generation circuit 40 includes a direct memory access controller (hereinafter referred to as a DMA controller) 41, a memory for storing deflection voltage wave shoulders (hereinafter referred to as a deflection memory) 42, and a digital-to-analog converter (hereinafter referred to as a D/A converter) 43h, 43.
v, and generates vertical deflection signals v, v' and horizontal deflection signals h, h'. In this embodiment, regarding the vertical deflection signal, there are two sets of memory address areas for storing the vertical deflection signal corresponding to each line of 240H, and regular data is stored in the memory every 8H. , it is possible to obtain two fields of eight-step vertical deflection signals. In addition, for the horizontal deflection signal, it is necessary to horizontally deflect the electron beam in six stages within the IH period, as described below.
There is a memory address area corresponding to each of 240H x 6H - 1440 horizontal deflection waveforms between 1V and 1V, and by storing regular data in the memory every IH minute, 6-step wave horizontal deflection signal can be obtained.

As mentioned above, the line cathode 2
1 to which a low potential drive pulse is applied among A to 27
The electron beam emitted from the main line cathode is divided horizontally into 120 sections by the beam extraction electrode 3.
It is extracted as a train of 20 electron beams. This electron beam is controlled by the control electrode 4 for each section as described later.
A horizontal deflection electrode 18.18' to which a pair of horizontal deflection signals h and h' which change in six steps as shown in FIG.
Therefore, R1,cl, of the screen 8 during each horizontal period
B+. Rt. Gz. Bt, (15 each of the control electrodes 5
The phosphors corresponding to a to 15n are R, G, and B for two picture elements, but for convenience of explanation, one picture element is Rl, cl. E31,
and the other one is R x, G t. B x,) is sequentially irradiated with H/6. Thus, in each line raster, the horizontal direction 12
For each section of 0, the electron beam is R l. G +, B
InR O. Gt. Each phosphor 20 of Bz is sequentially irradiated. Therefore, for each horizontal section of each line, the electron beam is
+, G +. B I+ R t, G z. B x
The screen 8 is modulated by the video signal of
Color images can be displayed on top of the . Next, we will explain the modulation control part of the electron beam. First, the composite video signal applied to the television signal input terminal 23 is applied to the color demodulation circuit 30, where the R-Y
The G-Y color difference signals are demodulated, the G-Y color difference signals are matrix-synthesized, and these are further combined with the luminance signal Y to generate R, G, and B primary color signals (hereinafter referred to as R, G, B A video signal) is output. These R and GSB video signals are sent to an analog-to-digital converter 45R. 45G
, 45B (hereinafter referred to as an A/D converter), and is converted into digital R, G, and B video signals. These digital R, G, and B video signals are applied to a digital multiplexer 46, digitally multiplexed using a switching signal from a sampling pulse generation circuit 34, and applied to 120 sample and hold circuit sets 31a to 31n. Each sample and hold circuit set 31a to 31n has Rl
It has six sample and hold circuits for G1, G1, B1, R2, G2, and B2.

The sampling pulse generation circuit 34 generates Rl of each of the 120 sets of sample and hold circuits M31a to 31n during the growth horizontal scanning period (approximately 50 psec) of the horizontal period (63.51 sec).
Compatible with sample and hold circuits for G1, G1, B1, R2, G2, and B2. 120X 6-7
20 sampling pulses Ral-Bn2 are generated in sequence. These 720 sampling pulses Ral~Bn
2 is a set of 120 sample and hold circuits 31a each.
.about.31n, and as a result, each sample-and-hold circuit set has Rl, Gl, Bl. R2. G2
, B2 are individually sampled and held. The sample held 120 pairs of R+,
G+. B+. Rg, Gt, Bt video signals are stored in 120 sets of memo IJ32a after completion of sample hold for 1 line.
~32n, are transferred all at once by a transfer pulse t, and are held here for the next horizontal period. This retained Rl
．． Gl. Br. The Rt, Gt, and Bt signals are applied to 120 switching circuits 35a to 35n. The switching circuits 35a to 35n each have Rl. c,,B
l, Rt. This circuit consists of a circuit that has individual input terminals for G and B8, and a common output terminal that sequentially switches and outputs them. Each switching circuit 35a to 35n
is the switching pulse r l+ g Inb+ . applied from the switching pulse generation circuit 36 . r*. g*+
Switching is controlled simultaneously by b*. Switching pulse rlrgl+bI+rt+gt+b! divides each horizontal period into six, and the switching circuits 35a to H/6 are divided into six.
35n, R l+ G +. B In R
t. A switching signal rI+g++ b++ r! is applied so that the video signals G t, B, are time-divided and sequentially output, and supplied to the pulse width modulation circuits 37a to 37n. +gl+b* is generated. The output of each switching circuit 35a to 35n is
120 sets of pulse width modulation (PWM) circuits 37a to 37n
where the sampled and held R+,G
I, B+, Rz. The pulse width is modulated according to the magnitude of the Gt and Bt video signals and output. This pulse width modulation circuit 3
The outputs of 7a to 37n are used as control signals for modulating the electron beam to the 120 conductive plates 1 of the control electrode 4 of the display element.
5a to 15n individually. What should be noted here is that R, , G in the switching circuits 35a to 35n. ,B. , R*. G.K. Bt video signal supply switching and electron beam R r, cl, B +, R t, Gt. ,B
*The horizontal deflection of the irradiation switching to the phosphor is controlled synchronously so that both the timing and the order match perfectly. This causes the electron beam to RI
When the phosphor is irradiated, the irradiation amount of the electron beam is controlled according to the R+ video signal, and G +, B
+. Rt. Gt. B snow is controlled in the same way, and R +, G +, B +, R *,
cl, B x The emission of each phosphor is the RI+cl of that picture element
．． B++Rz. Gz. B! Each picture element is controlled by the input video signal, and each picture element is displayed by emitting light according to the input video signal. Such control is performed simultaneously for 120 sets (2 picture elements each) for one line.
An image of 240 picture elements is displayed in a line, and the processing is sequentially performed for 240 lines starting from the upper line, so that one image is displayed on the screen 8. The above-mentioned operations are repeated for each field of the input video signal, and as a result, a moving image is displayed on the screen 8 in the same way as in a normal television receiver. The clock necessary for controlling this image display device is supplied from a pulse generating circuit 39 whose timing is controlled by a horizontal synchronizing signal H and a vertical synchronizing signal ■. Problems to be Solved by the Invention The image display device as described above adds R, G, and B video signals to three A/D converters, respectively, and sends three sets of RSG and B signals, which have become digital values, to a digital multiplexer. In addition,
Since time-divided digital RGB signals were created, the following problems were encountered. 1. Three A/D converters are required, which increases costs.

2. When implemented with a low-inch image display device, the mounting area becomes large and it is difficult to implement. The present invention is based on the above l! The purpose is to reduce costs and reduce the mounting area. Means for Solving the Problems In order to solve the above problems, the image display device of the present invention includes an analog multiplexer that performs analog multiplexing of RGB video signals output from a color demodulation circuit, and an output terminal of this analog multiplexer. Analog R
It consists of an A/D converter that converts GB video signals into digital values. Effect: By using the configuration of the present invention that analog multiplexes the RSGSB video signal and then converts it into a digital value, it is possible to reduce the number of A/D converters from three to one while maintaining the same functions as before. The mounting area can be reduced. EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of essential parts that realize an image display device in an embodiment of the present invention. In Figure 1, 51
52 is an analog multiplexer that inputs the output of the color demodulation circuit 30 (R, G, B video signal), and 52 is A that converts the output of the analog multiplexer 51 from analog to digital.
/D converters 31a to 31n are sample and hold circuits. The operation of the image display device of this embodiment configured as described above will be explained below. First, the R, G, and B video signals that have been color demodulated and combined with the luminance signal are applied to the analog multiplexer 51, and are converted into analog multiplexers according to the timings of the R switching signal, G switching signal, and B switching signal shown in FIG. It will be done. This analog multiplexed signal is applied to the A/D converter 52, and at the timing of the sampling signal of the A/D converter 52, multiplexed digital R, G, B video signals are provided to the sample hold circuit 31a. ~Added to 31n. As described above, according to this embodiment, the number of A/D converters is reduced from three to one by performing analog multiplexing before converting R, G, and B video signals from analog to digital, thereby reducing the number of components. be able to. In this embodiment, three switching signals are used for analog multiplexing, but two switching signals may be used. Effects of the Invention By performing analog multiplexing on R, G, and B video signals before A/D conversion, the present invention can reduce costs by reducing the number of components while achieving the same functions as conventional ones. Furthermore, it is possible to realize an excellent image display device with a smaller mounting area.

[Brief explanation of drawings]

Claims (1)

[Claims] Divide the screen into multiple sections vertically,
The electron beam generated from the line cathode provided in each vertical section is deflected in the vertical direction and then irradiated onto the phosphor coated on the screen, resulting in the formation of many electron beams on the screen. In an image display device that forms an image using beam spots, there is an analog multiplexer that performs analog multiplexing of R, G, and B video signals output from a color demodulation circuit, and an analog-digital system that converts the output signal of this analog multiplexer into a digital value. 1. An image display device comprising a converter, which applies a control signal proportional to the digital value to an electron beam flow control electrode, and displays an image corresponding to the video signal on a screen.