JPH04183191A - Image display unit - Google Patents

Abstract

PURPOSE:To make it possible to reduce the number of gates of an IC in an image displaying unit where electronic beams are projected deflecting them vertically for every segment of vertically divided screen by converting a digital signal to a broken line approximated exponential function with a boundary value that can be represented with a sum of 2<n>. CONSTITUTION:In an image displaying unit where electronic beam is deflected vertically for every segment obtained by vertically dividing a screen, a driving signal generating IC of beam current control electrodes has a circuit for converting a digital signal to a broken line approximated exponential function with a boundary value that can be represented with a sum of 2<n>. That is, taking a 7-bit video digital signal 23R for the axis of abscissa and a converted 8-bit signal for the axis of ordinate, the input signal remains as it is in a range of 0 to 64, and in a range of 64-96, the output changes by 2 relative to a change of input by 1, and further in an input range of 96-128, the output changes by 4. Therefore, the digital signal can be converted into an exponential function without using a multiplier, thereby being able to reduce the number of gates.

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. The present invention relates to an apparatus for displaying a plurality of lines by vertically deflecting a beam to display a television image as a whole.

2. Description of the Related Art The basic structure of a conventional image display element will be described with reference to FIG.

This display element has a back electrode 1. Line cathode hole as beam source Beam extraction electrode 3. Beam flow control electric camellia 4. Focusing electrode6. Horizontal deflection electrode e, vertical deflection electrode 7. A screen plate 8 and the like are arranged, and these are housed inside the vacuum container.

A line cathode 2 serving as a beam source is stretched horizontally so as to generate an electron beam distributed linearly in the horizontal direction.
A plurality of line cathodes 2 are further provided at intervals in the vertical direction (in this description, only seven line cathodes 2A to 2G are shown). In this configuration, the spacing between the line cathodes is 3 and the number of line cathodes is 30, and the number of the a cathodes is 2 to 27. Admittedly, the spacing between the line cathodes cannot be made large;
It is regulated by the distance between the vertical deflection electrode 7 and the slurry 280, which will be described later. The configuration of these line cathodes 2 is 10 to 3.
An oxide cathode material is applied to the surface of a 0 μmφ tungsten rod. As will be described later, the line cathodes are controlled to sequentially emit electron beams from the upper line cathode 2a to the lower line cathode 27 for a fixed period of time. The back electrode 1 has the function of suppressing the generation of electron beams from line cathodes other than the corresponding line cathode, and also has the function of pushing the electron beams only toward the anode. Although the vacuum vessel is not shown in FIG. 6, it is also possible to adopt a structure in which the back electrode 1 is used as the first electrode and is integrated with the vacuum vessel. The beam ratio electrode 3 is a conductive plate 11 having a large number of through holes 1o arranged at regular intervals in the horizontal direction facing each of the line cathodes 2a to 27, and the electrons emitted from the line cathodes 2. the beam through its through hole 1
Take it out through o. Next, the control electrode 4 is connected to the line cathode 2-2.
A plurality of conductive plates 16 are arranged in parallel in the horizontal direction at predetermined intervals.

In this configuration, there are 120 conductive plates 15a to 15n for control electrodes.
(Only 8 are shown in Figure 6)
. The control electrode 4 controls the passage amount of each of the electron beams divided horizontally by the beam extraction electrode 3 in accordance with the picture elements of the video signal and in synchronization with the timing of horizontal deflection, which will be described later. control. The focusing electrode 6 is a conductive plate 17 having a through hole 16 at a position facing each through hole 14 provided in the control electrode 4, and focuses the electron beam.

The horizontal deflection electrode 6 is composed of a plurality of conductive plates 18 and 18' arranged vertically along both horizontal sides of the through hole 16, and each conductive plate has a horizontal Deflection voltage is applied. The electron beam for each pixel is deflected in the horizontal direction, and on the screen 8
, G, and B are sequentially irradiated to emit light. In this configuration, each electron beam is deflected by two trios. The vertical deflection electrodes 7 include a plurality of conductive plates 19 arranged horizontally at vertically intermediate positions of the through holes 16 .
19', to which a voltage for vertical deflection is applied,
The electron beam is deflected vertically. In this configuration, the electron beam generated from one line cathode is deflected by eight lines in the vertical direction by a pair of electrodes 19 and 19'. The 31 vertical deflection electrodes 7 constitute 30 pairs of vertical deflection conductors corresponding to each of the 30 line cathodes, and 240 horizontal scanning lines are formed vertically on the screen 8. I'm drawing.

As explained above, in this configuration, a plurality of horizontal deflection electrodes 6 and a plurality of vertical deflection electrodes 7 are each arranged in a comb shape. In other words, by setting the distance on the screen 81 longer than the distance between the horizontal and vertical deflection electrodes, it becomes possible to irradiate the screen 8 with the electron beam with a small amount of deflection.

This makes it possible to reduce both horizontal and vertical deflection distortion.

As shown in FIG. 6, the screen 8 is constructed by coating the back surface of a glass plate 21 with phosphor 20 in stripes. Although not shown, a metal back and carbon are also coated. The phosphor 20 is located in one through hole 1 of the control electrode 4.
By deflecting the electron beam passing through the phosphor 4 horizontally, two trios of phosphor pairs of the three colors pR, G, and H are irradiated. ing.

In FIG. 6, the broken lines drawn on the screen 8 indicate the vertical divisions displayed corresponding to each of the plurality of line cathodes 2, and the two-dot chain lines indicate the sections corresponding to each of the plurality of control electrodes 4. Indicates the horizontal division that will be displayed. FIG. 7 shows an enlarged view of one section partitioned by broken lines and two-dot chain lines. As shown in Figure 7, in the horizontal direction, R, G for two trios,
The H phosphor has a width of 8 lines in the vertical direction.

In this example, the size of one section is 11II+l+ in the horizontal direction and 3 in the vertical direction.

Although the phosphors of each of the three colors R, G, and B are shown in stripes in FIG. 7, they may be arranged in a delta pattern. However, when arranged in a delta shape, it is necessary to apply horizontal and vertical deflection waveforms that are compatible with the arrangement.

In FIG. 7, for convenience of explanation, the vertical and horizontal dimension ratios are different from the image displayed on the actual screen. Further, in this configuration, for one through hole 14 of the control electrode 4, R, G,
Although two trios of B phosphors are provided, it may be composed of one trio or more than three trios. However, the control electrode 4 has one trio or more than three trios of R.
,G.

The B video signal is applied sequentially, and it is necessary to perform horizontal deflection in synchronization with it.

Next, the operation of the drive circuit for driving this display element will be explained with reference to FIG. First, a driving portion that irradiates the screen 8 with an electron beam to display an image will be explained.

The power supply circuit 22 is a circuit for applying a predetermined bias voltage to each electrode of the display element; Apply a DC voltage of The line cathode drive circuit 26 uses the vertical synchronization signal V and the horizontal synchronization signal H to create line cathode drive pulses (I-MA). FIG. 9 shows the timing diagram. Each line cathode 2A to 27 is shown in FIG.
As shown in (ma), a current flows and heats up while the drive pulse is at a high potential, and the heated state is maintained so that electrons are emitted while the drive pulse (a to ma) is at a low potential. . As a result, electrons are emitted from the 930 line cathodes 2a to 27 only during 8 horizontal scanning periods during which low potential drive pulses (i to ma) are applied to each of the 930 line cathodes.

During the period in which a high potential is applied, the line cathode 2 is lower than the potential around the line cathode 2 determined by the bias voltage applied to the back electrode 1 and the beam extraction electrode 3.
Since the potential applied to 27 is higher, no electrons are emitted from the line cathode. To configure one screen,
It is sufficient to sequentially switch the potential from the upper line cathode 2a to the lower line cathode 27 every 8 scanning periods.

Next, the deflection portion will be explained. The deflection voltage generation circuit 4o includes a direct memory access controller (hereinafter referred to as DMA controller) 41. Deflection voltage waveform storage memory (hereinafter referred to as deflection memory) 42° digital-to-analog converter (
(hereinafter referred to as D/A converters) 43h, 439, etc., and vertical deflection signals V, V' and horizontal deflection signals,
Generate h/.

In this configuration, the vertical deflection signal is displayed for 240 horizontal scanning periods in one field, taking O-Harnecan into consideration. Further, the memory address area storing vertical deflection position information corresponding to each line is divided into a first field and a second field, each having one set of memory capacity. When displaying, data is read from the corresponding deflection memory 42, converted to an analog signal by the D/A converter 43v, and applied to the vertical deflection electrode 7.

The vertical deflection position information stored in the deflection memory 42 is composed of almost regular data for every 8 horizontal scanning periods, and the D/A converted waveform also becomes a vertical deflection signal with approximately 8 levels. However, as mentioned above, it has a memory capacity for two fields, so that the position can be finely adjusted for each horizontal scanning line.

Also, for the horizontal deflection signal, 6
It is necessary to horizontally deflect the electron beam in stages, and it has a memory so that the deflection position can be finely adjusted for each horizontal scan.

Therefore, assuming that 480 horizontal scanning periods are displayed between one frame, 480x6 = 2880 bytes of memory are required, but since the data of the first field and the second field are shared, the memory is actually 1440 bytes. using memory.

During display, deflection information corresponding to each horizontal scanning line is read out from the deflection memory 42, converted into an analog signal by a D/A converter 43v, and applied to the horizontal deflection electrode e. To summarize, during the display period excluding the vertical retrace period of the vertical period, the electron beam emitted from the line cathode to which a low-potential drive pulse is applied among the M cathodes 2A to 27 is beam-pulled. It is horizontally divided into 120 sections by the rotor electrode 3, forming 120 electron beam rows.

As will be described later, the amount of beam passing through each section is controlled by the control electrode 4, and after being focused by the focusing electrode 5, the electron beam is passed through a pair of horizontal beams that change in approximately six steps as shown in FIG. Deflection signal.

By horizontal deflection electrodes 18, 18' etc. to which h' is applied,
R1, G1 . of the screen 8 during each horizontal display period. B1 and R2, G2. The phosphors such as B2 are sequentially irradiated horizontally for each display period/6. Thus, the raster of each horizontal line divides the electron beam into R1, G11 for each of the 120 sections.
B1 and R2, G2. By modulating B2 with a corresponding video signal, a color image can be displayed on the NuClean 8.

Next, the modulation control portion of the electron beam will be explained.

First, in FIG. 8, signal input terminals 23R, 23G.

Each R, G, and H video signal added to 23B is 120
m sample-and-hold circuit sets 31a to 31Kl. Each sample hold group 31a to 31n is for R1, G1, B1 and R2, G2, B2.
It consists of six sample and hold circuits. The sampling pulse generation circuit 34 has a horizontal period (63, 5
R1 of each of the 120 sample-and-hold circuits 31a to 3In during the horizontal display period (approximately 6o11g) of .mu.s).

720 (120×6) sampling pulses Ra1 to Rn2 corresponding to the sample hold circuits for G1, B1, R2, G2, and B2 are sequentially generated. Six of the 720 sampling pulses are applied to each of the 120 sample-and-hold circuit sets 31a to 31n, so that each sample-and-hold circuit set has two picture elements for each of the 120 segments in which one line is divided. Minute R1, G1. B1. R2, G2. Each B2 video signal is individually sampled and held. 77'/L
/ Ho /1/ 120 pairs (7) R1, G1
．． B1°R2, G2. The video signal of B2 is stored in 120 sets of memos 1J32a to 3 after completing the sample hold for one line.
2n, they are transferred all at once by a transfer pulse t, and held here for the next one horizontal scanning period. The signal held is 120
switching circuits 35a to 36n. The switching circuits 35a to 35n each have R1 and G1.
．． B1. The switching pulse generating circuit 36 is composed of a circuit having individual input terminals for R2, G2 and B2 and a common output terminal that sequentially switches and outputs them.
Switching pulse r applied from 1. gl,
bl.

r2. g2. Switching is controlled simultaneously by R2.

The switching pulse r1. g1. bl, r2゜g2
．． R2 divides each horizontal display period into 6 and switches the switching circuits 36a to 35n for each horizontal display period/6.
1, G1. B1. The video signals R2, G2°B2 are time-divided and sequentially output, and supplied to pulse width modulation circuits 37a to 37H.

The output of each switching circuit 35a to 35n is transmitted to 120 sets of pulse width modulation (hereinafter referred to as PWM) circuits 37a to 35n.
37 n, R1, G1 . B1°R2, G2.
The pulse reflex width is modulated according to the magnitude of each B2 video signal and output. The outputs of the pulse width modulation circuits 37a to 37n are individually applied to the 100 conductive plates 15a to 15n of the control electrode 4 of the display element as control signals for modulating the electron beam.

Next, horizontal deflection and display timing will be explained.

R1. in the switching circuits 35a to 35n. G1.
B1. R2, G2. B2 video signal switching and electron beam R1, G1 . B1.
R2, G2. The timing and order of switching the horizontal deflection to the B2 phosphor are synchronously controlled so that they completely match. As a result, when the electron beam is irradiating the R1 phosphor, the irradiation amount of the electron beam is controlled by the R1 control signal, and the following G1. B1. R2°G2. B2
R1, G1 . of each picture element are also controlled in the same way. B
1. R2, G2. B2 The light emission of each phosphor is the R1 of that picture element.
, G1. Each picture element is controlled by the video signals of B1, R2, G2 and B2, and each picture element is displayed by emitting light according to the input video signal. Such control is 1
120 sets (2 pixels each) for each line are executed at the same time, and an image of 240 pixels per line is displayed.Furthermore, 240 lines of 1 field are executed sequentially from the upper line, and 7 cleans and 8 upper The image is displayed. Furthermore, the above-mentioned operations are repeated for each field of the input video signal, and a television signal or the like is displayed on the screen 8.

The basic clock necessary for this configuration is supplied from a PALNU generation circuit 39 shown in FIG. 8, and the timing is controlled by a horizontal synchronizing signal H and a vertical synchronizing signal V.

Problems to be Solved by the Invention However, in the above configuration, since a multiplier was used in the circuit that converts the video R1G and B digital signals into an exponential function, there was a problem in that the number of gates in the IC increased. .

The present invention lacks the above-mentioned problems, and the present invention solves the problems described above.
The present invention provides an image display device in which the number of gates of an IC that generates beam flow control electrode drive signals is reduced by converting G and B digital signals into exponential functions.

Means for Solving the Problems In order to solve the above problems, the image display device of the present invention, when converting video R, G, B digital signals into an exponential function,
The digital signal value is converted into an exponential function approximated by a polygonal line whose boundary is a value that can be expressed by the sum of 2n.

Operation The present invention is capable of converting the video R, G, B digital signals into an exponential function without using a multiplier by using the above-described configuration, and therefore an IC that generates a beam amount control electrode drive signal that includes this circuit therein can be used. The number of gates can be reduced.

Embodiment Hereinafter, an image display device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an IC for generating beam flow control electrode drive signals of an image display device in an embodiment of the present invention.
This shows the main parts of the circuit inside.

In Fig. 1, 51a to ei1e are selectors that switch three output terminals according to the MSB 2 bits of the video R digital signal, 62 is an adder for adding 2 bits, and 23R is the same as 231 in Fig. 5. A video digital signal 53 is a selector that switches and outputs 3-bit data.

The operation of the image display device configured as described above will be described below with reference to FIGS. 1 and 2.

First, FIG. 1 shows a part of the internal circuit of the drive signal generating IC for the beam flow control electrode of the image display device of this embodiment, and as shown in FIG. If we take the horizontal axis as the abtt signal and the vertical axis as the converted abtt signal, we can see that the input signal remains unchanged from 0 to 64, and 6
4 to 96, the output changes by 2 for every 1 change in input, and 96
In the input range of ~128, the output changes by 4. When the 2 bits of the video digital signal 23R(7) MSB are -oo'' or I'01'', the selector 51aNe makes the 7-bit data correspond to 8 bits as is. 23R(D
When M S B 2 bit is 10″, 23 RL
In order to double 5 bits from SB, 61a to 61e are shifted 1 bit upwards to become abtt data, and to add "01000000", selector 53
．． The adder 62 adds "o10" to 17 bits, and s
Bi meeting data. When the MS B 2 bit of 23R is 111'', 5s bit from 23RLSB is multiplied by 4, so 51a to 51e are shifted 2 bits to the higher order, and in order to add "10000000" to this, selector 53 and adder 62 select the upper Add "100" to 2 bits to obtain abtt data.

Thereby, the video digit/L' can be converted into an exponential function without using a multiplier.

Effects of the Invention As described above, according to the present invention, a video digital signal can be converted into two
By having a circuit inside the IC that generates the drive signal for the beam flow control electrode, which converts the value that can be expressed by the sum of can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main parts of the internal circuit of a beam flow control electrode driving IC of an image display device in an embodiment of the present invention, FIG. 2 is a characteristic diagram expressing the operation of FIG. 1, and FIG. 3
The figure is an exploded perspective view of an image display element used in a conventional image display device, Figure 4 is an enlarged front view of the image display element, and Figure 6 is a block diagram showing the basic configuration of the drive circuit of the image display element. , FIG. 6 is a waveform diagram for explaining the operation of the drive circuit of FIG. 6. 51a-51s, 53...Selector, 62.
...Adder. Name of agent: Patent attorney Akira Okaji and two others
l v No. 2I, 1 8 Kuwai Pritar Detective Tongue 232 (, 7 Bee Iv) No. 41
: Illusion 5 “a

Claims (1)

[Claims] A screen coated with a phosphor that emits light when irradiated with an electron beam, and a line that generates an electron beam in each vertical division of the screen divided into a plurality of vertical divisions. a cathode; a deflection electrode that separates the electron beam generated by the line cathode into each horizontal section and deflects it in multiple stages in the vertical and horizontal directions until it reaches the screen; a beam flow control electrode that controls the amount of emitted light from each pixel on the screen by controlling the amount of electron beams separated into the horizontal sections irradiated onto the screen; and fluorescence caused by the electron beam in each pixel; A focusing electrode that controls the size of light emitted on the body surface, a back electrode that controls the amount of electron beam from the line cathode, an IC that generates a drive signal for the beam flow control electrode, and an image R, G image inside this IC. , the digital signal of B is 2^
An image display device comprising: a circuit for converting a value that can be expressed by the sum of n into an exponential function approximated by a polygonal line.