JPH0429485A - Picture display device - Google Patents

Abstract

PURPOSE:To prevent the luminance change and the color deviation by converting deflection data in a deflection memory to an analog current by a D/A converter and converting it to an analog voltage by an operational amplifier and inputting it to a differential amplifier to amplify the voltage and giving a deflecting signal to a horizontal deflecting electrode. CONSTITUTION:Deflection data sent from the deflection memory is converted to an analog current by a D/A converter 50 and is converted to an analog voltage by an operational amplifier 52 and its feedback resistor 52. The analog voltage is inputted to a transistor TR 54 and is shifted by a cascade TR 56 and a resistor 58. Thereafter, the current is amplified by a TR 64 to give horizontal deflecting signals h and h' to horizontal deflecting electrodes 18 and 18' by output buffer TRs 69 and 70. Thus, the variance in center voltage and amplitude voltage of the horizontal deflecting signal due to the voltage variance of horizontal deflecting high power and horizontal deflecting power or the temperature change is difficult, and a picture display device free from luminance change and color deviation is realized.

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 image display device that displays a plurality of lines by deflecting a beam in the vertical direction to display an image as a whole.

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

This display element consists of a back electrode 1, a line cathode 2 as a beam source, a beam extraction electrode 3, a beam flow control electrode 4, a focusing electrode 5, a horizontal deflection electrode 6, a vertical deflection electrode 7, and a screen in order from the back to the anode side. A plate 8, etc. 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.
Furthermore, in the configuration in which a plurality of line cathodes 2 are provided at intervals in the vertical direction (in this explanation, only 7 line cathodes 2A to 2G are shown), the line cathode spacing is 3cm, and the number of line cathodes is 30. The line cathodes provided are 2i to 27. The distance between the line cathodes cannot be freely increased, but is regulated by the distance between the vertical deflection electrode 7 and the screen 8, which will be described later. The configuration of these line cathodes 2 is 10~
An oxide cathode material is applied to the surface of a 30 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 container is not shown in FIG. 3, it is also possible to adopt a structure in which it is integrated with the vacuum container using the back electrode l. Beam extraction electrode 3 is line cathode 2
It is a conductive plate 11 having a large number of through holes 10 provided at regular intervals in the horizontal direction facing each of A to 27, and the electron beam emitted from the line cathode 2 is taken out through the through holes 10. Next, the control electrode 4 is connected to the line cathode 2
The conductive plate 15 is made up of a vertically long conductive plate 15 having a through hole 14 at a position facing each of the conductive plates 27, and a plurality of conductive plates 15 are arranged in parallel in the horizontal direction at predetermined intervals. In this configuration, 1
Twenty conductive plates 15a to 15n for control electrodes are provided (only eight are shown in FIG. 3), and the control electrode 4
controls the amount of passage of each of the electron beams divided horizontally by the beam extraction electrode 3 in correspondence with the picture elements of the video signal and in synchronization with the timing of horizontal deflection, which will be described later.

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, 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 is provided with a voltage for horizontal deflection. is stamped. The electron beams for each picture element are each deflected in the horizontal direction, and in the zero beam configuration in which R, G, and B phosphors are sequentially irradiated on the screen 8 to emit light, each electron beam is deflected horizontally.
It is deflected by a trio. The vertical deflection electrode 7 is composed of a plurality of conductive plates 19 and 19' arranged horizontally at vertically intermediate positions of the through holes 16, and a vertical deflection voltage is applied to the conductive plates 19 and 19'. In the zero-line configuration in which the electron beam is deflected in the vertical direction, 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 draw 240 horizontal scanning lines in the vertical direction on the screen 8. ing. 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. Further, by setting the distance to the screen 8 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 deflection amount. This creates horizontal and vertical deflection electrodes. As shown in FIG. 3, the screen 8 is constructed by coating the back surface of a glass plate 21 with phosphor 20 in a striped pattern. Although not shown, a metal bank and carbon are also coated. The phosphor 20 is provided so that two trios of phosphor pairs of three colors R, G, and B are irradiated by horizontally deflecting an electron beam passing through one through hole 14 of the control electrode 4. It is applied vertically in stripes. In Figure 3, screen 8
The broken lines drawn in indicate the vertical divisions displayed corresponding to each of the plurality of line cathodes 2, and the two-dot chain lines indicate the horizontal divisions displayed corresponding to each of the plurality of control electrodes 4. FIG. 4 shows an enlarged view of one compartment partitioned by broken lines and two-dot chain lines.

As shown in Figure 4, in the horizontal direction, RC for two trios,
, B has a width of 8 lines in the vertical direction. In this example, the size of one section is 1 square in the horizontal direction and 3 square in the vertical direction. In Figure 4, the phosphors of each of the three colors R, G, and B are shown in a stripe shape, but they may also be arranged in a delta shape. , it is necessary to apply a vertical deflection waveform. In FIG. 3, for convenience of explanation, the aspect ratio is different from the image displayed on the actual screen. Further, in this configuration, two trios of R, G, and B phosphors are provided for one through hole 14 of the control electrode 4, but it may be configured with one trio or more than three trios. However, the control electrode 4 has one trio or three or more trios of R, G.
, B video signals are applied sequentially, and it is necessary to perform horizontal deflection in synchronization with them.

Next, the operation of the drive circuit for driving this display element is as follows.
This will be explained with reference to FIG. First, we will explain the driving part that irradiates the screen 8 with an electron beam to display the image.The power supply circuit 22 is a circuit for applying a predetermined bias voltage to each electrode of the display element. A DC voltage of v3 is applied to the electrode 3, a DC voltage of 5 is applied to the converging electrode 5, and a DC voltage of v8 is applied to the screen 8. 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). The timing chart is shown in FIG. 6. As shown in FIG. 6 (I to M), each line cathode 2A to 27 is heated by a current flowing while the drive pulse is at a high potential. The heated state is maintained such that electrons (i to ma) emit electrons during periods of low potential. This results in 30
Electrons are emitted from the book line cathodes 2a to 27 only during eight horizontal scanning periods to which low potential drive pulses (i to ma) are applied. During the period when a high potential is applied, the potential applied to the line cathodes 2-27 is lower than the potential around the line cathode 2 determined by the bias voltage applied to the front electrode 1 and the beam extraction electrode 3. is higher, so no electrons are emitted from the line cathode, 1! To form a surface, 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 voltage generation circuit 40, whose deflection part will be explained, is as follows.
Direct memory access controller (hereinafter referred to as DMA controller) 41, deflection voltage waveform storage memory (hereinafter referred to as deflection memory) 42, horizontal deflection signal generator 43h,
It is composed of a vertical deflection signal generator 43v and the like, and generates vertical deflection signals v, v' and horizontal deflection signals h'.

In this configuration, regarding the vertical deflection signal, 240 horizontal scanning periods are displayed in the l field, taking overscan into consideration. In addition, the memory address area that stores the vertical deflection position information corresponding to each line is
The field and the second field each have a memory capacity of 1&u. When displaying 0, data is read from the corresponding deflection memory 42 and the vertical deflection signal generator 43
The signal is converted into an analog signal by V 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 waveform converted into a deflection signal is also 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. Regarding the horizontal deflection signal, it is necessary to horizontally deflect the electron beam in six stages during one horizontal scanning period, and a memory is provided so that the deflection position can be finely adjusted for each horizontal scanning.

Therefore, assuming that 480 horizontal scanning periods are displayed between one frame, 480 x 6 = 2880 hides of memory are required, but since the data of the first field and the second field are shared, the memory is actually 1440 bytes. When displaying 0 using the memory, the deflection information corresponding to each horizontal scanning line is read out from the deflection memory 42, deflected into an analog signal by the vertical deflection signal generator 43V, ing.

The operation of the horizontal deflection signal generator 43h will be explained using FIG. 2 and FIG. 7 showing the waveform of the horizontal deflection signal.

Horizontal deflection data is read from the deflection memory 42 and sent to the D/A converter 50 where it is converted into an analog current.

The analog current is transmitted through a transistor 80 whose base is grounded,
The level is shifted by current mirror transistors 82 and 83. The level-shifted analog current is converted into voltage by a resistor 86 and input to an amplifier 92. The amplified and scaled horizontal deflection signal determined by feedback resistors 93 and 94,
h' is applied to the horizontal deflection electrode 18.18'. Here, the transistor 87, the resistors 89, 90, 91, and the variable resistor 88 are connected to the center voltage H of the horizontal deflection signal shown in FIG.
Deciding on c.

To summarize, during the display period excluding the vertical blanking period of the vertical period, the electron beam emitted from the line cathode 2A to 27 to which a low potential drive pulse is applied is beam extracted. It is horizontally divided into 120 sections by the electrodes 3, forming 120 electron beam rows. As will be described later, the amount of beam passing through the electron beam is controlled by a control electrode 4 for each section, and a focusing electrode 5
As shown in FIG. 6, the horizontal deflection electrodes 18, 18', etc., to which h' is applied, produce a pair of horizontal deflection signals that change in approximately six steps, as shown in FIG. The phosphors such as R1, Gl, Bl and R2G2, 82 are sequentially irradiated for each horizontal display period/6. Thus, each horizontal line raster directs the electron beam in each of the 120 sections to R1, G1, B1 and R2, G2 . B
A color image can be displayed on the screen 8 by modulating it with a video signal corresponding to 2.

Next, the modulation control portion of the electron beam will be explained. First, in FIG. 5, signal input terminals 23R, 23G 23
The R, G, and B video signals added to B are applied to 120 sample-and-hold circuit sets 31a to 31n. Each sample hold group 31a to 31n is R1
, Gl, Bl, and R2, G2, B2, 6
It consists of several sample and hold circuits. The sampling pulse generation circuit 34 has a horizontal period (63,5μ5e
During the horizontal display period (approximately 50 u 5ec) of c),
Each of the 120 strings of sample hold circuits 31a to 31n is for R1, for Gl, for Bl, and for R2, for G2,
720 pieces (1 piece) corresponding to the sample hold circuit for B2
20×6) sampling pulses Ral to Rn2 are sequentially generated. Six of the 720 sampling pulses are applied to each of the 120 sample-and-hold circuits M31a to 31n, so that each sample-and-hold circuit group has two picture elements for each of the 120 divisions of the l line. R1, Gl, Bl, R2, G2. Each B2 video signal is individually sampled and held.

120 sample-held pairs of R1, GIBl, R
2, G2. After the sample and hold for one line has been completed, the B2 video signal is transferred all at once to the memories 32a to 32n of 120 & 11 by a transfer pulse t, where it is held for the next one horizontal scanning period. The held signals are applied to 120 switching circuits 35a-35n. The switching circuits 35a to 35n each have R1, Gl, Bl,
R2, G2. This circuit is composed of a circuit having individual input terminals of B2 and a common output terminal that sequentially switches and outputs them, and generates switching pulses rl, gl, bl, r2゜g applied from the switching pulse generation circuit 36.
2. Switching is controlled simultaneously by b2.

The switching pulses rl, gl, bl, r2°g2
．． b2 divides each horizontal display period into 6 and switches the switching circuits 35a to 35n for each horizontal display period/6.
1, Gl, Bl, R2, G2. The B2 video signals are time-divided and sequentially output, and supplied to the pulse width modulation circuits 37a to 37n. The output of each switching circuit 35a-35n is applied to 120 sets of pulse width modulation (hereinafter referred to as PWM) circuits 37a-37n, R1, G1 . B1. R2
, G2. The pulse width is modulated according to the magnitude of each B2 video signal and output. These pulse width modulation circuits 37a to 37
The output of 120 conductive plates 15a to 15 of the control mW pole 4 of the display element is used as a control signal for modulating the electron beam.
n separately.

Next, horizontal deflection and display timing will be explained. RIGl and Bl in the switching circuits 35a to 35n
, R2□ G2. B2 video signal switching and electron beams R1, Gl, Bl, R by the horizontal deflection drive circuit 41
2, G2. The switching timing and order of the horizontal deflection to the B2 phosphor are synchronously controlled so that they completely match. As a result, when the R1 phosphor is irradiated with the electron beam, the irradiation amount of the electron beam is controlled by the R1 control signal, and the following Gl, Bl, R2, G2 . B2 is similarly controlled, and the RL and Gl of each picture element.

Bl, R2, G2. B2 The light emission of each phosphor corresponds to the R of that picture element.
1, Gl, Bl, R2, G2. By being controlled by the B2 video signal, each picture element is displayed by emitting light according to the input video signal. Such control is executed for 1 line of 120&ll (2 picture elements each) minutes to display an image of 240 picture elements for 1 line, and then sequentially executed for 240 lines of 1 field from the upper line to display the screen. The image is displayed on 8. Furthermore, the above operations are repeated for each field of the input video signal, and the television signal etc.
will be displayed.

The basic clock necessary for this configuration is supplied from a pulse generation circuit 39 shown in FIG. 5, and the timing is controlled by a horizontal synchronizing signal H1 and a vertical synchronizing signal V.

Problems to be Solved by the Invention However, in the configuration of the horizontal deflection signal generator 43h as described above, when the voltages of the horizontal deflection high power supply 75 and the horizontal deflection low power supply 76 fluctuate, the center voltage Hc of the horizontal deflection signal fluctuates. Furthermore, since the collector-emitter voltages of the current mirror transistors 82 and 83 are different, the mirror coefficient changes depending on the temperature, and the amplitude voltage Hd of the horizontal deflection signal changes. As the center voltage HC1 and amplitude voltage Hd of the horizontal deflection signal change, the beam diameter of the electron beam changes and the deflection angle changes, resulting in brightness changes and color shifts.

In view of the above problems, the present invention provides an image display device that realizes a circuit in which the center voltage and amplitude voltage of a horizontal deflection signal are less likely to fluctuate, and does not cause brightness changes or color shifts.

Means for Solving the Problems In order to solve the above problems, the image display device of the present invention has a screen coated with a phosphor that emits light when irradiated with an electron beam, and a screen above the screen that is vertically divided. a plurality of line cathodes that generate an electron beam for each vertical segment, a deflection memory that stores deflection data for deflecting the electron beam, and a digital-to-analog converter (D) that converts the deflection data into an analog current. /A converter), an operational amplifier and resistor that converts analog current to voltage, a transistor and resistor that differentially amplifies the converted voltage, and cascade-connected transistors, forming a current source for differential amplification. Transistors, resistors and! #, a transistor that current amplifies the differentially amplified voltage, a transistor and a resistor that are current sources for the current amplification, and an output buffer transistor,
It has a feedback resistor that determines the degree of amplification, and a horizontal deflection high power supply and a horizontal deflection low power supply that supply a power supply voltage to the amplifier.

Effect of the Invention With the above-described configuration, the present invention converts the deflection data in the deflection memory into an analog current using a D/A converter and converts it into an analog voltage using an operational amplifier. The analog voltage is applied to a differential amplifier for voltage amplification, current amplification, and output buffer transistors to provide a deflection signal to the horizontal deflection electrode. The amplification degree of the amplifier after the operational amplifier is determined by the feedback resistor. Since the reference voltage of the feedback resistor is grounded and the voltage shift is achieved with a cascade transistor, the center voltage and amplitude voltage of the horizontal deflection signal will not change even if the voltage of the horizontal deflection high power supply or horizontal deflection low power supply fluctuates. There's nothing to do.

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 a circuit diagram of a horizontal deflection signal generation circuit of an image display device according to an embodiment of the present invention.

In FIG. 1, 50 is a D/A converter that converts horizontal deflection data from the deflection memory into an analog current, 51 is an operational amplifier, 52 is a resistor, 53 is an operational amplifier reference power supply, 54 to 57 are transistors, and 58 to 61 are Resistor, 6
2 is a t-current source power supply, 63 is a cascade basemi source, 64
-65 are transistors, 66-68 are resistors, 69-7
0 is a transistor, 71 to 74 are resistors, 75 is a horizontal deflection high power supply, and 76 is a horizontal deflection low power supply.

The operation of the horizontal deflection signal generation circuit of the image display device configured as described above will be explained below.

Deflection Memo The deflection data sent from January 2nd is D/A.
It is converted to an analog current by a converter 50 and converted to an analog voltage by an operational amplifier 52 and its feedback resistor 52. The lower limit of the converted analog voltage is determined by the operational amplifier reference voltage 11153. The analog voltage enters a transistor 54 constituting a differential amplifier, is voltage shifted by a cascade transistor 56 and a resistor 58, is current amplified by a transistor 64, and is sent to the horizontal deflection electrode 18.
A horizontal deflection signal h' is applied to 18'. Here, the amplification degree of the amplifier after the operational amplifier is determined by the feedback resistors 73 and 74. The transistor 57, the resistors 59 to 61, and the current source power supply 62 constitute a current source of the differential amplifier, and the transistor 65 and the resistors 66 to 68 constitute a current source of the transistor 64 for current amplification.

Resistors 71 and 72 are output buffer transistors 6970
It is a protective resistor. The D/A converter 50 outputs complementary analog currents, and by having two of the above circuits, the symmetrical horizontal deflection signal is generated.
' can be applied to the horizontal deflection electrode 18.18'.

As described above, according to this embodiment, the horizontal deflection height 1ts and the horizontal deflection image are controlled so that the center voltage and amplitude voltage of the horizontal deflection signal are not varied due to source voltage fluctuations or temperature changes.

Effects of the Invention As described above, according to the present invention, there is provided a screen coated with a phosphor that emits light when irradiated with an electron beam;
A plurality of line cathodes that generate electron beams for each vertical division of the above-mentioned screen, a deflection memory that stores deflection data for deflecting the electron beam, and a deflection data that is converted into an analog current. A digital-to-analog converter for converting, an operational amplifier and a resistor for converting an analog current into a voltage, a transistor and a resistor for differentially amplifying the converted voltage, a cascaded transistor, and a current of the differential amplifier. A transistor, a resistor, and t'fIJ that constitute a source, a transistor that current amplifies the differentially amplified voltage, a transistor that is a current source for the current amplification, a resistor, and a transistor that is an output buffer. By providing a feedback resistor that determines the amplification degree, and a horizontal deflection high source and a horizontal deflection low power source that provide the power supply voltage to the amplifier, horizontal deflection signals due to horizontal deflection height tIN+, voltage fluctuations of the horizontal deflection low power source, and temperature changes are provided. It is possible to realize a circuit in which the center voltage and amplitude voltage of the circuit do not easily fluctuate, and to realize an image display device that does not cause brightness changes or color shifts.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a horizontal deflection signal generation circuit of an image display device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a horizontal deflection signal generation circuit of a conventional image display device, and FIG. 3 is a circuit diagram of a horizontal deflection signal generation circuit of a conventional image display device. FIG. 4 is an enlarged view of the fluorescent screen of the image display device used, FIG. 5 is a block diagram of the driving circuit of the image display device, and FIG. 6 is an explanation of the operation of the image display device. FIG. 7 is a waveform diagram of the horizontal deflection signal of the image display device. 50...D/A converter, 51...
Operational amplifier, 52...Resistor, 53...
- Operational amplifier reference power supply, 54-57...Transistor, 58-61...Resistor, 62...
...source for IT current source, 63...cascade heath power supply, 64~65...transistor, 66~
68...Resistor, 69-70...Transistor, 71-74...Resistor, 75...
...Horizontal deflection height is the source, 76...Horizontal deflection image x
i. Name of agent: Patent attorney Shigetaka Awano (1 person) Figure 1 Horizontal division Figure

Claims (1)

[Claims] A screen coated with a phosphor that emits light when irradiated with an electron beam, and a plurality of line cathodes that generate an electron beam in each vertical section of the above-mentioned screen. , a deflection memory that stores deflection data for deflecting the electron beam, a digital-to-analog converter that converts the deflection data to analog current, and an operational amplifier and a resistor that converts the analog current to voltage. Transistors and resistors that differentially amplify voltage, cascade-connected transistors, transistors, resistors, and power supply that constitute the current source of the differential amplifier, and transistors that amplify the differentially amplified voltage. , a transistor and a resistor that are the current source for the current amplification, a transistor for the output buffer, a feedback resistor that determines the degree of amplification, and a horizontal deflection high power supply and a horizontal deflection low power supply that supply the power supply voltage to the amplifier. Image display device.