JPS6227596B2 - - Google Patents

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.

Conventional configurations and their problems Traditionally, cathode ray tubes have been mainly used as display elements for displaying color television images, but conventional cathode ray tubes are extremely long and thin compared to the screen size. It was impossible to create a full-sized television receiver. In addition, EL display elements, plasma display devices, liquid crystal display elements, etc. have recently been developed as flat display elements.
All of them are insufficient in terms of performance such as brightness, contrast, and color display, and have not yet been put into practical use.

Therefore, in order to achieve a flat display device using electron beams, the screen on the screen is vertically divided into multiple sections and an electron beam is generated for each section. A system was devised in which the electron beam was deflected vertically to display multiple lines, thus displaying a television image as a whole.

〓〓〓〓〓
First, a basic configuration example of the image display element used here will be explained with reference to FIG.

This display element is arranged in order from the back to the front.
A back electrode 1, a line cathode 2 as a beam source, vertical focusing electrodes 3, 3', a vertical deflection electrode 4, a beam flow control electrode 5, a horizontal focusing electrode 6, a horizontal deflection electrode 7, a beam accelerating electrode 8 and a screen plate 9. They are housed within the evacuated interior of a flat glass bulb (not shown).

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, and a plurality of line cathodes 2 (here, 2-2-4
Only books shown) are provided. In this embodiment, it is assumed that 15 pieces are provided. Let's call them 2i~2yo. These line cathodes 2 are for example
An oxide cathode material for thermionic emission is coated on the surface of a tungsten wire with a diameter of 10 to 20 μφ. These line cathodes 2A to 2Y are heated so as to generate a thermionic electron beam by passing an electric current through them, and as will be described later, the electron beams are generated sequentially for a certain period of time starting from the line cathode 2I. controlled to emit. The back electrode 1 is a line cathode 2 which is controlled to emit an electron beam for a certain period of time.
It functions to suppress the generation of electron beams from other line cathodes 2 and to push out the generated electron beams only in the forward direction. The back electrode 1 may be formed by a coating of a conductive material applied to the inner surface of the rear wall of the glass bulb. Further, instead of the back electrode 1 and the linear cathode 2, a planar electron beam emitting cathode may be used.

The vertical focusing electrode 3 is a conductive plate 11 having a horizontally long slit 10 facing each of the line cathodes 2I to 2Y, and extracts the electron beam emitted from the line cathode 2 through the slit 10, and focus in a direction. An electron beam for one horizontal line (320 pixels) is taken out at the same time. In the figure, only one section in the horizontal direction is shown. The slit 10 may be provided with crosspieces at appropriate intervals in the middle, or may be substantially configured as a slit by a row of many through holes arranged horizontally at small intervals (nearly touching intervals). may have been done. The vertical focusing electrode 3' is also similar.

A plurality of vertical deflection electrodes 4 are arranged horizontally in the middle of each of the slits 10, and are each composed of conductors 13 and 13' provided on the upper and lower surfaces of an insulating substrate 12. has been done. And the opposing conductors 13, 13'
A vertical deflection voltage is applied between them to deflect the electron beam in the vertical direction. In this embodiment, the electron beam from one line cathode 2 is vertically deflected to positions corresponding to 16 lines by a pair of conductors 13, 13'. And, by 16 vertical deflection electrodes 4, 15
Fifteen conductor pairs corresponding to each of the book line cathodes 2 are constructed, and the electron beam is ultimately deflected to draw 240 horizontal lines on the screen 9.

Next, the control electrodes 5 are composed of conductive plates 15 each having a vertically long slit 14, and a plurality of control electrodes 15 are arranged in parallel in the horizontal direction at predetermined intervals. In this embodiment, 320 conductive plates 15a to 15m for control electrodes are provided (only 10 are shown in the figure). Each of the control electrodes 5 separates and extracts the electron beam into one picture element in the horizontal direction, and controls the amount of electron beam passing therethrough in accordance with a video signal for displaying each picture element.
Therefore, if 320 control electrodes 5 are provided, 320 picture elements can be displayed per horizontal line. In addition, in order to display images in color, each picture element is displayed with phosphors in three colors: R, G, and B.
The R, G, and B video signals are sequentially applied to each control electrode 5. In addition, 320 sets of video signals for one line are simultaneously applied to the 320 control electrodes 5, and the video for one line is displayed at one time.

The horizontal focusing electrode 6 is composed of a conductive plate 17 having a plurality of vertically long slits 16 (320 slits 16) opposite to the slits 14 of the control electrode 5. Each beam is focused horizontally into a narrow electron beam.

The horizontal deflection electrode 7 is composed of a plurality of conductive plates 18 arranged vertically in the middle of each of the slits 16, and a horizontal deflection voltage is applied between each conductive plate 18 for each picture element. The electron beams are each deflected in the horizontal direction, and the R, G, and B phosphors are sequentially irradiated on the screen 9 to cause them to emit light. In this example, the deflection range is 〓〓〓〓〓
Each electron beam has a width of one picture element.

The accelerating electrode 8 is composed of a plurality of conductive plates 19 provided horizontally at the same position as the vertical deflection electrode 4, and accelerates the electron beam so that it collides with the screen 9 with sufficient energy.

The screen 9 is constructed by coating the back surface of a glass plate 21 with a phosphor 20 that emits light when irradiated with an electron beam, and adding a metal back layer (not shown). The phosphor 20 is arranged for each slit 14 of the control electrode 5, that is, for each horizontally divided electron beam.
A pair of phosphors in each of the three colors R, G, and B are provided, and are applied in stripes in the vertical direction. In FIG. 1, the broken lines drawn on the screen 9 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 5. Indicates the horizontal division displayed. As shown in the enlarged view in Fig. 2, one section partitioned by these two has R, G, and B phosphors 20 for one pixel in the horizontal direction, and 16 lines in the vertical direction. It has a width of
For example, the size of one section is 1 in the horizontal direction.
mm, and the vertical direction is 16 mm.

Note that in FIG. 1, the length in the horizontal direction is greatly enlarged relative to the length in the vertical direction for clarity.

Further, in this embodiment, only one pair of R, G, and B phosphors 20 are provided for one picture element for one control electrode 5, that is, one electron beam, but two
Of course, two or more pairs for more than two picture elements may be provided, and in that case, R, G, and B video signals for two or more picture elements are sequentially applied to the control electrode 5, and synchronized therewith. horizontal deflection.

Next, the basic configuration of a drive circuit for displaying television images on this display element will be explained with reference to FIG. First, a driving portion for irradiating the screen 9 with an electron beam to emit raster light will be described.

The power supply circuit 22 is a circuit for applying a predetermined bias voltage (operating voltage) to each electrode of the display element,
-V ₁ to the back electrode 1, and -V 1 to the vertical focusing electrodes 3 and 3'.
DC voltages of V ₃ , V ₃ ', V ₆ to the horizontal focusing electrode 6, V ₈ to the accelerating electrode 8, and V ₉ to the screen 9 are applied.

Next, a plurality of video signals of television signals are applied to the input terminal 23, and a synchronization separation circuit 24 separates and extracts a vertical synchronization signal V and a horizontal synchronization signal H. The vertical drive pulse generation circuit 25 is composed of a counter that is reset by a vertical pulse and counts horizontal pulses, and is configured to operate during an effective vertical scanning period (here, 240 hours) excluding the vertical retrace period of the vertical period. 15 drive pulses [A, B...Y] each having a length of 16H period are generated sequentially during each period. These drive pulses [A, B...Y] were applied to the line cathode drive circuit 26, where they were inverted and brought to a low potential only during each pulse period, and to a high potential of approximately 20 volts during the rest of the time. It is converted into line cathode drive pulses [A′, B′...Yo′], and each line cathode 2
A, 2ro...Added to 2yo. Each line cathode 2a,
... 2 yo is heated by flowing current during the high potential of the drive pulse [A' to YO'], and electrons are emitted even during the low potential period of the drive pulse [A' to YO']. The heated state is maintained as if it were wet. This results in 15
Electrons are emitted from the main wire cathodes 2a to 2yo only during the 16H period when low potential drive pulses [a' to yo'] are applied to each of them. During the period when a high potential is applied, the potential at the line cathode 2 is lower than the potential at the position of the line cathode 2 determined by the bias voltage applied to the back electrode 1 and the vertical focusing electrode 3. Since the applied high potential becomes positive, no electrons are emitted from the line cathodes 2I to 2Y. Thus, in the line cathode 2, electrons are sequentially emitted from the upper line cathode 2a toward the lower line cathode 2y every 16H period during the effective vertical scanning period. The emitted electrons are pushed forward by the back electrode 1, pass through the opposing slits 10 of the vertical focusing electrode 3, and are focused in the vertical direction to form a flat electron beam.

Next, the vertical deflection drive circuit 27 is composed of a counter that is reset by each of the vertical drive pulses y to y and counts the horizontal synchronizing signal, and a conversion circuit that converts the count output from D/A. , generates a pair of vertical deflection signals v and v' that change in 16 steps by 1H during the 16H period of each vertical drive pulse [I to Y]. The vertical deflection signals v and v' both have a center voltage of _V4 , and are configured to change in opposite directions so that v increases sequentially and v' decreases sequentially. These vertical deflections〓〓〓〓〓
The signals v and v' are respectively applied to the electrode 13 of the vertical deflection electrode 4.
and 13', and as a result, the electron beams generated from each of the line cathodes 2i to 2yo are vertically deflected in 16 steps, and as mentioned earlier, one electron beam is reflected on the screen 9. The raster is deflected to draw 16 lines of raster one line at a time from the top.

As a result of the above, electron beams are emitted for a period of 16 hours from the top of the 15 line cathodes 2A to 2Y, and each electron beam is sequentially emitted for one line from the top to the bottom within the 15 sections in the vertical direction. By being deflected, the electron beam is vertically deflected one line at a time on the screen 9 from the first line at the top end to the 240th line at the bottom end, thereby drawing a raster of 240 lines in total.

The electron beam thus vertically deflected is horizontally deflected by 320 degrees by the control electrode 5 and the horizontal focusing electrode 6.
It is divided into sections and taken out. Figure 1 shows one of these categories. The amount of electron beam passing through each section is controlled by a control electrode 5, and horizontally focused by a horizontal focusing electrode 6 into a single narrow electron beam, which is then controlled by horizontal deflection means described below. The R, G, and B phosphors 20 on the screen 9 are deflected horizontally in three steps.
are irradiated sequentially.

That is, the horizontal drive pulse generation circuit 28 is composed of three cascade-connected monostable multivibrators, etc., and is triggered by a horizontal synchronization signal to generate three horizontal drives with equal pulse widths within one horizontal period. Generate pulses r, g, b. Here, as an example, each pulse width is 17 μsec.
As a result, three pulses r, g, and b are generated during an effective horizontal scanning period of 50 μsec. These horizontal drive pulses r, g, and b are applied to the horizontal deflection drive circuit 29. The horizontal deflection drive circuit 29 generates a pair of horizontal deflection signals h and h' that change in three stages by being switched by the horizontal drive pulses r, g, and b. horizontal deflection signal h,
Both h' are at the center voltage _V7 , and they change in opposite directions such that h increases sequentially and h' decreases sequentially. These horizontal deflection signals h, h' are applied to electrodes 18 and 18' of the horizontal deflection electrode 7, respectively. As a result, each horizontally divided electron beam is transmitted to the screen 9 during each horizontal period.
It is horizontally deflected so that the phosphor B is sequentially irradiated for 17 μsec each. However, in the display element of FIG. 1, one conductor 18 is used in the horizontal deflection electrode 7.
Or, since 18' is used to deflect two adjacent sections of electron beams and is designed to produce a deflection effect on the adjacent electron beams in mutually opposite directions, 320 sections of electron beams can be obtained. is reversed every other section, such that if the odd-numbered sections are deflected in the order of R→G→B, the even-numbered sections are deflected in the reverse order of B→G→R. deflected in the direction

Thus, in each line raster, the electron beam is divided into R, G,
Each phosphor 20 of B is sequentially irradiated.

Therefore, a color television image can be displayed on the screen 9 by modulating the electron beam with R, G, and B video signals for each horizontal section of each line.

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

First, the composite video signal applied to the television signal input terminal 23 is applied to the color demodulation circuit 30,
Here, the RY and BY color difference signals are demodulated,
The G-Y color difference signals are matrix-synthesized, and further, they are combined with the luminance signal Y to generate R, G,
B primary color signals (hereinafter referred to as R, G, and B video signals) are output. These R, G, and B video signals are processed by 320 sample and hold circuit sets 31a to 320.
31n. Each sample and hold circuit group 31a to 31n has three circuits for R, G, and B.
It has several sample and hold circuits. The sample and hold outputs of these sample and hold circuit sets 31a to 31n are each held by a memory set 32a.
~32n.

On the other hand, the sampling reference clock oscillator 33
is composed of a PLL (phase locked loop) circuit, etc., and generates a reference clock of about 6.4 MHz in this embodiment. The reference clock is controlled to always have a constant phase with respect to the horizontal synchronizing signal H. This reference clock is applied to the sampling pulse generation circuit 34, where it is delayed by one clock period by a shift register, etc., so that the reference clock is applied to the sampling pulse generating circuit 34, where it is delayed by one clock cycle by a shift register, so that the reference clock is Samples〓〓〓〓〓
Transfer pulses a to n are sequentially generated, followed by one transfer pulse. These sampling pulses a to n correspond to each picture element when one line of the video to be displayed is divided into 320 picture elements in the horizontal direction, and their positions are always constant with respect to the horizontal synchronizing signal H. controlled by.

These 320 sampling pulses a to n are respectively connected to the above 320 sample and hold circuit set 31.
a to 31n, thereby providing one line to each sample and hold circuit set 31a to 31n.
When divided into 320 picture elements, the R, G, and B video signals of each picture element are individually sampled and held. The sampled and held 320 sets of R, G, and B video signals are stored in 320 sets of memories 32a to 32a after completion of sample and hold for one line.
32c by a transfer pulse t,
Here it is held for the next one horizontal synchronization.

The R, G, and B video signals for one line held in the memories 32a to 32n are respectively applied to 320 pulse width modulation circuit sets 37a to 37n, where the sampled and held R, G, and B video signals are The reference pulse signal is pulse width modulated according to the magnitude of the pulse width and is output. It is desirable that the repetition period of the reference pulse signal is sufficiently smaller than the pulse width of the horizontal drive pulses r, g, b in the horizontal deflection circuit, for example, 1:10 to 1:10.
A ratio of about 1:100 is used.

The output signals of the pulse width modulation circuit sets 37a to 37n are sent to switching circuits 35a to 35, respectively.
added to n. Switching circuits 35a to 35
Each of the switching circuits 35a to 35n has individual input terminals for R, G, and B and a common output terminal that sequentially switches and outputs them, and the output of each switching circuit 35a to 35n is displayed as a control signal for modulating the electron beam. 320 conductive plates 15a to 1 of the control electrode 5 of the element
5n separately. Each of the switching circuits 35a to 35n is simultaneously switched and controlled by a switching pulse applied from a switching pulse generating circuit 36. The switching pulse generation circuit 36 is the horizontal drive pulse generation circuit 2 described above.
The switching circuits 35a to 35 are controlled by pulses r, g, and b from 8, and the switching circuits 35a to 3 divide approximately 50 μsec at the center of each horizontal period into three parts and each time the switching circuits 35a to 3
5n, the R, G, and B video signals are time-divided and output alternately and sequentially to the control electrodes 15a to 15n.
Switching signals r, g, and b are generated so as to be supplied to the input terminals. However, among the switching circuits 35a to 35n, the odd numbered switching circuits 35a and 3
5c... is switched in the order of R→G→B, and even-numbered switching circuits 35b, 35d...35
Conversely, n is switched in the order of B→G→R.

What should be noted here is that the switching circuit 3
The switching of the supply of R, G, and B video signals in 5a to 35n and the horizontal deflection of the horizontal deflection of the irradiation of the electron beams R, G, and B to the phosphor by the horizontal deflection drive circuit 29 are performed perfectly in both timing and order. It is synchronously controlled to match. As a result, when the electron beam is irradiating the R phosphor, the irradiation amount of the electron beam is controlled by the R video signal, and G and B are similarly controlled, so that the R and G of each picture element are controlled in the same manner. , B phosphors are respectively controlled by the R, G, and B video signals of the picture elements, and each picture element is displayed by emitting light in accordance with the input video signal. Such control is performed simultaneously on 320 pixels for one line to display one line of video, and then sequentially performed for 240 minutes from the upper line to display one video on screen 9. That will happen.

The above operations are repeated for each field of the input television signal, and as a result,
The screen 9 is similar to a normal television receiver.
A television image of the video is displayed above.

As described above, a television image is projected on this display device. In order to display the image accurately in this device, multiple electron beams are sent to the source, that is, the line cathode in this case. It is necessary to synchronize the drive for generating the electron beam well with the television signal and to prevent the generation of the electron beam when it is not necessary.

First, FIG. 4 shows a conventional configuration example of the vertical drive pulse generation circuit 25 and the line cathode drive circuit 26. The vertical drive pulse generation circuit 25 is first provided with a counter/decoder 38 for generating vertical drive pulses. This counter decoder 38 is provided.
This counter decoder 38 is used for horizontal synchronization signals, etc.
It counts horizontal pulses and sequentially generates 16H width drive pulses [A, B...Y] every 16H period.

In order to control the drive pulse generation in the counter decoder 38, the monostable multivibrator 39 is triggered by the vertical synchronization signal V obtained from the synchronization separation circuit to create a pulse Vd up to just before the effective vertical scanning period. The trailing edge sets flip-flop 40 to terminate the vertical blanking pulse VBL. flipflop 4
The vertical blanking pulse VBL with an output of 0 is applied to the counter decoder 38 as a reset signal, and the counter decoder 38 receives this pulse.
Count and decode operations are performed only when VBL is high. Therefore, by controlling with the pulse VBL as described above, the counter decoder 38 can always start operating from the start of the effective vertical scanning period, and the vertical drive pulse can be output from its output terminals [I to YO]. [I~Yo]
can be generated. Then, the trailing edge of the last drive pulse [y] causes the flip-flop 4 to
0 is reset, the pulse VBL is brought to a low level, and no output is generated from the counter decoder 38 until the start of the next valid vertical scanning period.

The drive pulses [I to YO] created in this manner are applied to the bases of the transistors 41A to 41Y of the line cathode drive circuit 26, respectively, and are rendered conductive only during the pulse period. This transistor 41
The collectors of I~41Yo are resistors 42I~4, respectively.
The emitter is connected to the positive power supply +B1 via the 2-Yo, and the emitter is connected to the negative power supply -B2.

Therefore, the collectors of the transistors 41A to 41Y are at the low potential of -B2 only during the pulse period of each drive pulse [A to YO], and at the low potential of about 10V during the other periods.
A line cathode drive pulse with a high potential of volts [A'~
yo′] is output. Therefore, these are added to one end of the line cathodes 2I to 2Y, respectively, and the other end is grounded via the diodes 43I to 43Y. In this way, during the period when the pulses [A' to Y'] are at a high potential, a current is passed through each of the wire cathodes 2A to 2Y to heat them to a temperature at which they can emit electrons. However, during this high potential period, the line cathode 2 is determined by the bias voltage applied to the back electrode 1 and the vertical focusing electrode 3.
The line cathode 2i~ than the potential at the position i~2yo
Since the high potential applied to 2yo becomes higher, no electrons are emitted. Then, when the driving pulses [A' to YO'] applied to each of the line cathodes 2A to 2Y become a low-potential pulse period, each of the diodes 43A to 43Y is cut off, and the line cathodes 2A to 2Y are cut off. Since the potential at y becomes lower than the surrounding potential, an electron beam is emitted. During this low-potential pulse period, no heating current flows through the wire cathodes 2I to 2Y, but the heating state up to that point is maintained, so that sufficient electrons are emitted.

In this way, electrons are sequentially emitted from the line cathodes 2i to 2yo during the effective vertical scanning period from the upper line cathode 2a to the lower line cathode 2yo for each 16H period.
The screen is illuminated.

In addition to the counter decoder 38, the 16H
Fifteen monostable multivibrators generating period-specific pulses may be connected in cascade, the first stage of which is triggered by the pulse VBL of the output of flip-flop 40 at the beginning of a valid vertical scan period.

Also, for the vertical blanking pulse VBL, in addition to the one in the above embodiment, the vertical synchronizing signal may be used as is, or it may be integrated once and then shaped into a waveform.
It may be created by any means.

However, this circuit has disadvantages in that power is consumed by the resistors 42a to 42y and that transistors 41a to 41y require large current transistors. This is because the line cathode 2
To heat 2yo and emit electrons, use a wire cathode 2
A current I of about 50mA is required for I to 2Y. When a current I of 50 mA flows, a loss of R x I occurs due to resistances 2 I to 2 Y (hereinafter referred to as R). If the resistors 42i to 42yo are made smaller, the loss will be reduced, but the transistor 4
When 1A to 41Y conduct, a large current flows from power supply +B1 to power supply -B1 through resistors 42A to 42Y, increasing power consumption, so resistors 42A to 42
The power consumption due to YO does not change much. At the same time, the collector currents of the transistors 41i to 41y flow considerably. For example, if the resistance values of resistors 42A to 42Y are 200Ω and the line cathode is 200Ω, +B1 is (200Ω+200Ω)×0.05A=20V. -B2 is-
At about 15V, transistors 41A to 41Y become conductive.
When this happens, a current of 175mA will flow. As described above, the power consumption by the resistors 42a to 42y is large, the collector currents of the transistors 41a to 41y are large, and transistors with large current capacity are required, resulting in an increase in cost.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide an image display device that can eliminate such disadvantages and reduce power consumption in a circuit for driving a line cathode.

Structure of the Invention In the present invention, a push-pull circuit of a switching element is used to drive each line cathode, and in addition to a switching element to which a vertical drive pulse is connected in a push-pull manner, one end of the push-pull circuit is connected to a first power source, and the other end of the push-pull circuit is connected to a first power source. Connect each to the reference potential point. Then, one end of the series circuit including the line cathode and the diode is connected to the intermediate point of the push-pull circuit, and the other end of the series circuit is connected to the point where the first power supply is divided, thereby controlling the switching of the push-pull circuit. The device is characterized in that the heating period and the electron beam generation period are switched by alternately switching the elements, and the current is cut off during the latter period.

DESCRIPTION OF EMBODIMENTS FIG. 5 shows a specific circuit diagram of an embodiment of the present invention. In FIG. 5, the same reference numerals as in FIG. 4 have the same functions.

In this circuit, each vertically divided section has a first switching element and a second switching element.
Two transistors of PNP type and NPN type 44
A push-pull circuit is provided in which 44 yo and 45 y to 45 yo are connected in a push-pull manner. Transistors 44-44 of each push-pull circuit
Apply vertical drive pulses [I to YO] to the bases of 45 I to 45 YO, and apply one of the transistors 44 I to 45 Yo.
The emitter of transistor 44 is connected to the first positive power supply (+B), and the collectors of the other transistors 45 to 45 are connected to a reference potential point (ground potential point). In addition, a line cathode 2 is placed in each section at the midpoint between those two transistors 44i to 44yo and 45i to 45yo.
I~2yo and diode 43I~43yo and resistor 42
One end of the series circuit with A to 42 Y is connected, and the other end is connected to the intermediate voltage (+B2) obtained by dividing the first power supply (+B) by the resistor 46 and the voltage regulator diode 47. ing.

Next, the operation of such a configuration will be explained.
Transistor 44 of each push-pull circuit
When a vertical drive pulse [I to YO] is applied to the bases of A to 44 Y and 45 I to 45 Y, during the low level period of the pulse, that is, the heating period, transistors 45 A to 45 Y are cut off, and transistor 44 A to 44Y conducts, and the voltage dividing point (+B
2) A current flows through and heats the wire cathodes 2I to 2Y. On the other hand, during the period when the vertical drive pulses [I to Y] are at a high level, that is, during the period when an electron beam should be generated in each division, the transistors 44I to 44
y is cut off, transistors 45 y to 45 y are conductive, and diode 4 is turned off by the divided voltage (+B2).
Blocks 3i to 43yo. Therefore, at this time, the line cathodes 2-2 to generate the electron beam are
No current from the heating power source flows through y, and the potential is low, so that a constant electron beam is emitted regardless of the resistance value of each of the line cathodes 2a to 2y.

Moreover, according to this circuit, even if the transistors 45a to 45y are conductive during the period when an electron beam is to be generated, the transistors 44a to 44i are conductive at this time.
4) is cut off, the first power supply (+B
No current flows from 1) to the reference potential point. Therefore, at this time, transistors 45i to 4
The current flowing through 5Y is only an extremely small current associated with electron beam emission from the line cathodes 2A to 2Y, and these transistors 45A to 45Y may be small ones with small current capacity, and their Almost no power consumption occurs. Furthermore, the current flowing through the transistors 44a to 44b during the heating period is only the heating current flowing to the line cathodes 2a to 2y, and this is also about 50 mA, so the transistors 44a to 44b are heated.
The transistors 44b may also be small, and since the transistors 44i to 44b operate in the saturation region when conductive, their power consumption is low. In addition, the line cathode 2
The currents from A to 2Y are determined by the difference between the first power supply (+B1) and the divided voltage (+B2), the resistors 42A to 42Y, and the line cathodes 2A to 2Y. If the resistance value of y is set appropriately, resistors 42a to 42y can be omitted. And this resistance 42
〓〓〓〓〓
Since current flows through resistors A to 42Y only during the heating period, their resistance values can be determined based only on the heating current, and power consumption in resistors 42I to 42Y can be extremely reduced.

Thus, according to this circuit, in the driving circuit for driving the line cathodes 2a to 2y in each vertical section, the transistors 44i to 44y and 45i to 45
y can be made small with a small current capacity,
Moreover, the power consumption of those transistors, resistors, etc. can be significantly reduced. Therefore, it is also easy to implement these driving parts as integrated circuit elements.

In the above explanation, NPN type and PNP type transistors were used as the first and second switching elements, but by using transistors of the same polarity for both and applying a vertical pulse of reversed polarity to one. Good too. Further, other types of switching elements such as field effect transistors or switching elements made of composite circuits may be used.

Note that the terms "horizontal direction" and "vertical direction" in the above explanation refer to the horizontal direction, which is the direction in which line units are displayed when an image is projected, and the vertical direction, which is the direction in which the lines are stacked. It is used in this sense, and is not directly related to the vertical and horizontal directions on the actual screen.

Effects of the Invention As described above, according to the present invention, a line cathode in an image display device in which a line cathode is provided for each section in which a screen is divided in the vertical direction and is sequentially driven to generate an electron beam. In addition to accurately controlling the drive of the drive unit, the power consumption of the drive part can be significantly reduced.

Furthermore, since the present invention can be configured using only one polarity power source, the overall circuit configuration can be simplified.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing the basic configuration of an example image display element used in the image display device of the present invention;
Figure 2 is an enlarged view of the screen, Figure 3 is a block diagram showing the basic configuration of the drive circuit of the device, and Figure 4 is a block diagram showing the basic configuration of the drive circuit of the device.
The figure is a circuit diagram of an example of the vertical deflection section in the same circuit.
The figure is a circuit diagram of a vertical deflection section used in an image display device according to an embodiment of the present invention. 2, 2 I~Y... Line cathode, 3... Vertical focusing electrode, 4... Vertical deflection electrode, 9... Screen, 1
3, 13'... Conductor, 25... Vertical drive pulse generation circuit, 26... Line cathode drive circuit, 27... Vertical deflection drive circuit, 38... Counter decoder,
39...monostable multivibrator, 40...flip-flop, 41i~41yo...transistor, 42i~42yo...resistor, 43i~43yo...
...Diode, 44i to 44yo, 45i to 45yo...transistor, 46...resistor, 47...constant voltage diode. 〓〓〓〓〓

Claims (1)

[Claims] 1 The screen on the screen is vertically divided into a plurality of sections, and each section is provided with a line cathode for generating an electron beam to generate an electron beam. vertical deflection means are provided, and a vertical deflection signal is applied to each vertical deflection means to vertically deflect the electron beam to display a plurality of lines in each section, and A drive circuit is provided to generate a vertical drive pulse for sequentially driving the line cathodes for electron beam generation in a plurality of sections for a certain period of time starting from one section to sequentially generate an electron beam for each section. In addition to push-pull connected switching elements,
One end of the push-pull circuit is connected to a first power supply, the other end is connected to a reference potential point, one end of a series circuit including the line cathode and the diode is connected to the intermediate point of the push-pull circuit, and the other ends of the series circuit are connected to the middle point of the push-pull circuit. An image display device characterized in that an end thereof is connected to a point where the first power source is divided.