JP2001051642A - Platelike display element and picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable performing characteristic evaluation in high frequency by allowing unnecessary display not to be performed on a display screen at the time of evaluating electron emitting characteristics of individual electron source for correcting luminance of respective pixels. SOLUTION: This picture display device evaluates electron emitting characteristics by providing a detection electrode 4 between a control electrode 3 controlling the intensity of an electron beam and an anode 5 and by setting an anode voltage so as to become lower than the voltage Vd of the detection electrode 4. Moreover, a mechanism which stores evaluated results and corrects a luminance signal based on the results is provided in this device. Furthermore, the device evaluates the electron emitting characteristics even when luminance of all pixels become zero by checking luminance of pixels which are ought to perform the display in real time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a flat panel display device and an image display device having an electron emission characteristic detecting mechanism and capable of providing a uniform and high-quality image.

[0002]

2. Description of the Related Art A flat-panel display device can be expected to have high image quality equivalent to that of a cathode ray tube, which is a general image display device, and can be expected to be thinner and lighter than a liquid crystal display device. In a cathode ray tube, the same electron source is used to excite the phosphor for the entire display screen, whereas in a flat display device, the phosphor is used by using a plurality of electron sources according to the number of pixels to be displayed. To excite.

[0003] In these flat display devices, the number of electron sources is extremely large, and it is practically impossible to separately provide a drive circuit. Therefore, for example, a data line is formed by connecting cathodes in a straight line, A matrix drive is considered in which control electrodes on a straight line in the vertical direction are connected to form a scan line, and one is selected from each to drive a device at the intersection.

The use of matrix driving requires a selection mechanism for selecting a line, but the display elements can be driven sequentially by a very small number of driving circuits compared to the number of pixels to be displayed. However, since the electron emission characteristics of each electron source vary and the length of the wiring pattern in the display element differs depending on the selected pixel, the selected electron beam source is not affected even if a drive signal of a predetermined intensity is input. It does not always emit the electron beam of the expected intensity. For this reason, a method has been considered in which a correction data table reflecting the characteristics of each electron-emitting device is created in advance, and the input drive signal intensity is corrected based on the correction data table.

[0005] An example of the prior art of this method is disclosed in Japanese Unexamined Patent Publication No.
0-31450. In this conventional example, an intermediate electrode is provided between a surface conduction electron-emitting device that is an electron source and a fluorescent screen that is an anode, and the intermediate electrode voltage is lower than the anode voltage and lower than the intermediate electrode voltage during normal operation. The electron emission characteristic of the electron source corresponding to each pixel is evaluated by applying a voltage and evaluating the intensity of the electron beam flowing into the intermediate electrode, that is, the intermediate electrode current.

[0006]

The display device is a user interface, and it is necessary to consider that the user is always looking at the display screen. Further, in order to evaluate the electron emission characteristics of the electron source of each pixel, it is necessary to actually emit electrons from the electron source. In the above prior art, the anode voltage is set to be higher than the intermediate electrode voltage even when the electron emission characteristics are evaluated. Therefore, even at the time of evaluation, at least a part of the electron beam emitted from the electron source reaches the anode to cause the phosphor to emit light. In this state, there is a problem that a bright spot is generated on the display screen viewed by the user for a short time.

Further, since the electron beam emitted from the electron source is dispersed between the intermediate electrode and the anode, there is also a problem that a difference occurs between the current of the intermediate electrode and the intensity of the electron beam actually emitted from the electron beam source. is there.

An object of the present invention is to consider the above points and evaluate the electron emission characteristics of an electron source without displaying a bright spot on a display screen, and accurately evaluate the electron emission characteristics of each electron source. It is an object of the present invention to provide an image display element and an image display device which can be evaluated and which can display a high-quality image by finely correcting the deviation of the characteristics of each electron source.

[0009]

The above object is achieved by providing a cathode, which is a source of electrons, electrically isolated from the cathode,
An electron source comprising a control electrode for applying a voltage for controlling electron emission from the cathode, and an anode having a luminous body that emits light by receiving electrons emitted from the cathode, the control electrode and the cathode Between the control electrode and the cathode, it is electrically isolated from the control electrode and the cathode, and is used for displaying images and evaluating electron emission characteristics in a flat panel display device having a detection electrode having holes for passing electrons. Means for switching between a plurality of set values at each of the anode voltage and the detection electrode voltage, and means for setting the anode voltage value to be lower than the detection electrode voltage at the time of electron emission characteristic evaluation Achieved by providing.

It is desirable that the detection electrodes are formed in stripes parallel to the pattern on the side to which luminance data is applied, of the cathode side and the control electrode side. Further, it is desirable that the image display device has a mechanism for detecting that the luminance is substantially zero in all the pixels of the displayed image and evaluating the electron emission characteristics of each electron source.

FIG. 1 shows an example of the structure of a flat panel display device according to the present invention. This display element includes an electron beam source composed of a cathode 2, an insulating film a7, and a control electrode 3 formed on a glass substrate 1, and an electron beam source 6 for evaluating the intensity of an electron beam 6 emitted from the electron beam source. It comprises a detection electrode 4, an insulating film b8 for supporting the detection electrode 4, and an anode 5 provided at a position facing the detection electrode 4 for receiving an electron beam and emitting light to display an image. The cathode 2 is formed in a stripe shape with an insulator interposed therebetween, and the control electrode 3 is formed thereon in a stripe shape so as to be perpendicular to the cathode 2 with an insulating film a7 interposed therebetween to form a matrix structure. are doing.

By selecting one line from each of the striped cathode 2 and control electrode 3, one electron source at the intersection of both lines can be selected. In such a matrix type flat display device,
First, one of the scanning lines is selected, and a signal corresponding to display data of each pixel on the selected scanning line is sequentially applied to each data line or simultaneously to all data lines, thereby selecting the selected scanning line. An image is formed thereon. This is performed while sequentially selecting all the scanning lines, thereby forming an image of the entire screen. In the present invention, the same applies regardless of which of the cathode line and the control electrode line is assigned to the scan line. However, for convenience of the following description, the cathode line is a data line and the control electrode line is a scan line.

FIG. 2 shows an electrode configuration of one pixel of the flat panel display device according to the present invention. The cathode 2, the control electrode 3, the detection electrode 4, and the anode 5 have a cathode power supply 9, a control electrode power supply 11, a detection electrode power supply 12, and an anode power supply 1 for controlling respective voltages.
0 is connected. Among them, the control electrode power supply 11
Is adjusted to a voltage value at which necessary electrons can be obtained from the cathode 2. As the cathode 2 for obtaining the effect of the present invention, any kind of so-called cold cathode which is used without heating to a high temperature can be used. However, it is desirable that the voltage difference applied between the cathode 2 and the control electrode 3 is small, and in that respect, it is desirable to use diamond, diamond-like carbon, or carbon nanotube that can obtain electron emission even in a low electric field.

At the time of displaying an image, the anode voltage switching mechanisms 15 and 16 are connected to the sides indicated by broken lines. The voltage Va of the anode power supply 10 is set to a value necessary and sufficient to cause a fluorescent film (not shown in FIG. 2) formed on the anode 5 to emit light. Voltage Vd of detection electrode power supply 12 at the time of image display
May be a value corresponding to a potential near the detection electrode 4 when it is assumed that the detection electrode 4 is not present in order to minimize the effect on the electron beam 6. If the electron beam 6 spreads, the voltage may be set so that the trajectory of the electron beam 6 appropriately converges, and the detection electrode 4 may be used as a focusing electrode.

When the detection electrode power supply 12 and the anode power supply 10 are set in consideration of the above conditions, the magnitude relation between the power supply voltage values is Va> Vd. The voltage Vk of the cathode power supply 9 is
The luminance data determined by the image signal is set to a value obtained from a signal corrected based on the characteristics of each pixel based on the result of the electron emission characteristic evaluation. With the above setting, the electron beam emitted into the vacuum from the surface of the cathode 2 due to the potential difference applied between the control electrode 3 and the cathode 2 is accelerated by the electric field between the anode 5 and the detection electrode 4. Anode 5
And the fluorescent film emits light to display an image.

On the other hand, when evaluating the electron emission characteristics, the characteristics are evaluated as Va <Vd by changing the voltages Va and Vd of the anode power supply 10 and the detection electrode power supply 12, respectively. Further, as shown in FIG. 2, the anode voltage switching mechanisms 15 and 16 may be replaced with the sides shown by solid lines, and the detection electrode power supply 12 may be connected to the anode 5 and the anode power supply 10 may be connected to the detection electrode 4.

As described above, the voltage of the anode 5 is applied to the detection electrode 4
, The space between the detection electrode 4 and the anode 5 becomes a deceleration electric field with respect to the electron beam.
The electron beam 6 does not enter the anode 5 as shown in FIG.
Since the electron beam is inverted and enters the detection electrode 4, the electron beam intensity can be detected as a current flowing through the detection electrode 4.

In the case of the structure shown in FIG. 1, since the detection electrode 4 is a solid film, a plurality of electron beam sources cannot be evaluated at the same time. Therefore, by making the detection electrode 4 have the same shape as the data line (the cathode line in FIG. 3), the characteristics of the electron beam sources on the same scanning line can be evaluated at the same time.

FIG. 3 shows the structure of the flat panel display element in that case. In this structure, the detection electrodes 4 are formed in stripes parallel to the data lines, and partitions are provided between the lines to suppress electrons from flowing between adjacent detection electrode lines. Irrespective of whether the detection electrode 4 has a solid film or a stripe shape, electrons do not enter the anode 5, so that the electron emission characteristics can be evaluated without displaying anything on the display screen. Therefore, in addition to power-on / power-off,
The electron emission characteristics can also be evaluated when a signal is input such that the luminance of the entire screen becomes zero, or when there is no need to display the screen such as in a standby state.

The electron emission characteristics evaluated as described above are subjected to appropriate data conversion and stored in a correction data table. At the time of displaying an image, by correcting the drive signal on the data line side based on the correction data, it is possible to suppress a variation in luminance between pixels and display a high-quality image.

FIG. 4 shows an example of an apparatus having a mechanism for correcting the above-mentioned electron emission characteristics. At the time of image display, an image signal input from an external device is temporarily stored in a buffer memory. At this time, if the input signal is an analog signal, the image signal is subjected to analog / digital (A / D) conversion, and a digital address is assigned to an address corresponding to a pixel position obtained based on the horizontal synchronization signal and the vertical synchronization signal. Stored in memory as a value. The luminance of all the pixels is checked in real time, and if the luminance of all the pixels is zero, the electron emission characteristic evaluation control unit is notified of the dark surface.

From the address in the pixel buffer memory to be displayed, a signal serving as a reference for performing scanning control is generated and sent to the control unit, and a signal for sequentially selecting scanning lines is sent to the control electrode driving unit by the scanning control unit. Can be The control electrode driver generates a scanning signal set to a predetermined voltage and applies it to the scanning line of the display element. The luminance data to be applied to the data line is created in the luminance data generation unit based on the value in the buffer memory, and the corrected luminance data is generated based on the above-mentioned corresponding value in the previously stored correction data table. You.

The cathode driving section converts the corrected luminance data into a signal necessary for actually driving the cathode.
At this time, the anode drive unit supplies a voltage necessary for causing the fluorescent film to emit light to the anode 5 in the display element, and the detection electrode drive unit, for example, emits an electron beam emitted from an electron beam source as described above. Is supplied to the detection electrode 4 so as to converge appropriately.

The electron emission characteristic evaluation control unit starts the electron emission characteristic evaluation when it is notified that the screen is dark, or when it detects that at least one signal constituting the input signal has been interrupted. I do. In this case, the anode drive unit and the detection electrode drive unit switch their respective electrode voltages according to a signal from the evaluation control unit. In this state, image data for electron emission characteristic evaluation is written in the buffer memory, but nothing is displayed on the screen because the anode voltage is lower than the detection electrode voltage.

By selecting a scan line and a data line, the electron source of each pixel is sequentially selected, and the correction data table is updated so that a detection electrode current corresponding to the data input to the buffer memory is obtained. When an update of the correction data table for all pixels is detected, the anode drive unit and the detection electrode drive unit use the signal from the electron emission characteristic evaluation control unit to reduce the electrode voltage in the state during image display or to reduce power consumption. Change to the waiting state. At the same time, the electron emission characteristic evaluation controller erases the characteristic evaluation image data written in the buffer memory.

Through the series of processes described above, the electron emission characteristics can be evaluated and the correction data table can be updated without displaying extra bright spots on the display screen in contact with the user. This update is automatically performed in a short time only in the image display device by the electron emission characteristic evaluation control unit. Therefore, the evaluation of the electron emission characteristics can be performed not only when the power is turned on or off, but also during a period when the user is using the image input signal, for example, when the image input signal is temporarily lost in a standby state or the like. For this reason, the correction data table is updated in a relatively short cycle, and appropriate correction is always performed on each pixel to display an appropriate luminance for the input signal. A high-quality image can be provided with improved reproducibility.

[0027]

FIG. 5 shows a cross section of a flat panel display device according to one embodiment of the present invention. The electron source panel 20 having the cathode 2, the control electrode 3, and the detection electrode 4 having the element structure of FIG. 3 was manufactured as follows. On the surface of the glass substrate 1, grooves having a width of 80 μm and a depth of 10 μm are formed at a pitch of 100 μm by a sandblaster method. ,
A mixture of diamond powder of about 1 μm and graphite paste is filled on it so as to have a thickness of 8 μm,
Further, in order to remove the graphite component covering the diamond powder on the surface, the cathode 2 was heated at 400 ° C. for 30 minutes in the air.

On this, a glass panel having a thickness of 100 μm serving as the insulating film 7 was laminated. On this glass panel, the control electrode 3 has a stripe shape of 80 μm width and 100 μm pitch so as to be perpendicular to the line of the cathode 2, and a diameter at which an intersection with the cathode 2 passes for electrons to pass. A hole of 60 μm is formed.

On top of that, a thickness 20 to be the insulating film 8 is formed.
Glass panels of 0 μm were stacked. On this glass panel 8, a nickel film having a thickness of 10 μm is formed as a detection electrode 4 so as to have the same pattern as the cathode 2, and a hole having a diameter of 60 μm through which electrons pass also is formed. A width of 40 μm and a height of 50 μm is provided between the lines of the detection electrodes 4 which are striped.
A 0 μm glass partition 14 was arranged. On the side of the anode 5 serving as a display screen, a black matrix (not shown), a fluorescent film 17 and an aluminum back 18 were formed on a glass panel serving as a display panel 19 by the same manufacturing process as for a cathode ray tube.

The anode 5 prepared as described above and the electron source panel 20 were joined so that the positions of the partition walls 14 and the black matrix coincided with each other. The display panel 19 and the rear panel 21 were joined by frit glass to evacuate the entire panel. A getter 22 mainly made of barium was attached to the back surface of the glass substrate 1. After exhausting to about 100 Pa from an exhaust pipe 23 previously attached to the back panel 21 while heating to about 200 ° C. using an oil diffusion pump, the exhaust pipe 23 is cut off, the getter 22 is heated, and the inside of the back panel 21 is heated. A barium getter film was formed. By connecting a peripheral circuit having the configuration shown in the block diagram of FIG. 4 to the flat panel display element completed by the above steps, an image display device having an electron emission characteristic correction mechanism could be manufactured. .

In the completed image display device, the voltage of the cathode 2 before correction is -100 V, and the voltage of the control electrode 3 is about 200 V
And In addition, the voltage of the anode 5 is set to 3 for image display.
kV, the voltage of the detection electrode 4 was set to about 800 V, and the voltage of the anode 5 was set to 500 V and the voltage of the detection electrode 4 was set to 1 kV at the time of evaluating the electron emission characteristics.

In this embodiment, the brightness of each pixel is controlled by the duty ratio of the voltage pulse applied between the cathode 2 and the control electrode 3. The evaluation is performed without changing the voltage applied to. However, when the brightness is controlled by changing the electron beam intensity, it is better to measure the detection electrode current while changing the voltage applied between the cathode 2 and the control electrode 3 and measure the voltage-current characteristics. Clearly preferred.

Also, in the case of controlling the luminance by changing the electron beam intensity, if the curve of the voltage-current characteristic can be estimated by prior measurement, the voltage is changed in the same manner as in the case of controlling by the duty ratio. Obviously, it is also possible to evaluate the electron emission characteristics by measuring only one point without performing the measurement. When the luminance distribution after correction on the display surface of the image display device obtained by the above configuration was measured, the spread was 3% or less with respect to the average luminance.

In the above embodiment, diamond powder was used as the electron emission material of the cathode 2, but other electron emission materials may be used. A mixture of carbon nanotube powder and graphite powder mixed in a ratio of about 5: 5 as an electron emission material of the cathode 2 is dispersed in acetone, and then the same structure is used by using a cathode settled at a predetermined place on the glass substrate 1. Was manufactured. In this embodiment, the same level of luminance uniformity as in the above embodiment was obtained, although the required control electrode voltage was different.

[0035]

According to the present invention, the electron emission characteristics of the electron source can be evaluated without displaying a bright spot on the display screen, and the electron emission characteristics of the individual electron sources can be evaluated with high frequency. This makes it possible to finely correct the deviation of the characteristics of the electron source, and to provide an image display device and an image display device capable of displaying a high-quality image.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of a flat panel display device according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram of an electrode portion forming a pixel in the flat panel display element according to one embodiment of the present invention.

FIG. 3 is a perspective view showing a structure of a flat panel display element having a partition.

FIG. 4 is a block diagram showing a configuration of an image display device having an electron emission characteristic correction mechanism.

FIG. 5 is a sectional view of a flat panel display device according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Cathode, 3 ... Control electrode, 4 ... Detection electrode, 5 ... Anode, 6 ... Electron beam, 7 ... Insulating film a, 8 ... Insulating film b, 9 ... Cathode power supply, 10 ... Anode power supply, 11: control electrode power supply, 12: detection electrode power supply, 13: detection electrode current measurement unit,
14 ... partition wall, 15 ... detection electrode voltage switching mechanism, 16 ... anode voltage switching mechanism, 17 ... fluorescent film, 18 ... aluminum back, 1
9: display panel, 20: electron source panel, 21: rear panel, 22: getter, 23: exhaust pipe.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01J 29/62 H01J 29/62 31/12 31/12 C (72) Inventor Susumu Sasaki 3300 Hayano, Mobara-shi, Chiba Stock Hitachi, Ltd. Display Group (72) Inventor Naoko Mori 3300 Hayano, Mobara-shi, Chiba F-term (reference) 5C036 EE02 EF06 EG22 EH05 5C041 AA01 AB19 AC26 AD10 5C080 AA18 BB05 DD05 EE28 FF09 GG02 JJ02 JJ06 5C094 AA07 AA41 AA42 AA55 BA21 CA19 EA03 EA10 FA02 FB02 FB12

Claims (11)

[Claims] An electron source comprising: a cathode serving as a source of electrons; a control electrode electrically isolated from the cathode and applying a voltage for controlling emission of electrons from the cathode; In a flat panel display device including an anode having a luminous body that emits light upon receiving electrons, the detection electrode is electrically isolated from any of the control electrode and the cathode, and has a hole through which electrons pass. The anode voltage and the detection electrode voltage are switched between a plurality of set values during image display and electron emission characteristic evaluation, and the anode voltage value is detected during the electron emission characteristic evaluation. A flat panel display device comprising a mechanism for setting a value lower than a voltage. 2. The flat panel display device according to claim 1, wherein the cathode contains at least one of diamond, diamond-like carbon, and carbon nanotube as a main component of an electron-emitting material. 3. The flat panel display device according to claim 2, wherein said detection electrode functions as a converging electrode for converging an electron beam during image display. 4. The flat panel display device according to claim 2, wherein said detection electrodes are formed in stripes parallel to either the cathode or the control electrode. 5. The flat panel display device according to claim 4, further comprising a partition wall made of an electrically insulating material between one of said detection electrodes and another detection electrode adjacent thereto. . 6. An electron source comprising: a cathode serving as a source of electrons; a control electrode electrically isolated from the cathode and applying a voltage for controlling emission of electrons from the cathode; In a flat panel display device having an anode having a luminous body that emits light upon receiving electrons, the detection electrode is electrically isolated from both the control electrode and the cathode, and has a hole through which electrons pass. The anode voltage and the detection electrode voltage are switched between a plurality of set values at the time of image display and electron emission characteristic evaluation, and the anode voltage value is detected at the time of electron emission characteristic evaluation. An electron emission characteristic which is a relationship between an electron source drive signal applied between the cathode and the control electrode and an intensity of an actually emitted electron beam, provided with a flat panel display element having a mechanism for setting a value lower than a voltage; A storage device for storing, and a drive device for calculating a drive signal actually required based on the electron emission characteristics stored in the storage device and an input image signal, and inputting the result to a display element An image display device characterized by the above-mentioned. 7. The image display device according to claim 6, wherein said cathode comprises a flat display element containing at least one of diamond, diamond-like carbon, and carbon nanotube as a main component of an electron-emitting material. 8. The image display device according to claim 7, wherein said detection electrode includes a flat panel display element having a function of converging an electron beam during image display. 9. The image display device according to claim 7, wherein said detection electrode includes a flat display element formed in a stripe shape parallel to either the cathode or the control electrode. 10. A flat panel display device having a partition wall made of an electrically insulating material between one of said detection electrodes and another detection electrode adjacent thereto. The image display device as described in the above. 11. A system for evaluating an electron emission characteristic of an electron source of each pixel when an image signal which makes the luminance of all pixels zero is input. Image display device.