JP2630934B2 - Image display method and image display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image display method and an image display device using an electron source.

[Prior Art] Conventionally, for example, Japanese Patent Publication No. Sho 54-30274,
The solid-state electron beam generators disclosed in JP-A-111272 (USP 4259678), JP-A-56-15529 (USP 4303930), and JP-A-57-38528 have high electron emission densities. There have been various proposals for applying this to an image display device because of its features such as integration.

[Problems to be Solved by the Invention] The present inventors have studied an analog control method of the amount of electrons emitted from the solid-state electron beam generator in the above-mentioned image display device. Since the variation in the electron emission density between the elements of the device has a significant effect on the quality of the displayed image, it has been found that there is a major problem that high uniformity is required between the elements.

FIG. 5 is a diagram showing the relationship between the applied voltage and the emission current density of an electron beam generator used for this type of image display device. This type of beam generator utilizes a pn junction of a semiconductor. because you are, electrons to the applied voltage reaches the threshold voltage V ₀ is not released, the emission current exceeds a threshold voltage V ₀ increases exponentially. When the voltage value is further increased, the emission current density saturates under the influence of the space charge effect near the electron emission surface and the extraction electrode. With such characteristics, when trying to reproduce halftone by applying a voltage of the solid-state electron beam generator, a steep region (between A and B) of the voltage-current characteristics must be used. Since the light emission luminances are greatly different, it is difficult to reproduce a good halftone.

This type of solid-state electron beam generator uses one electron source.
By integrating many on a single substrate and forming a multi-beam, it is possible to differentiate the conventional heat emission type cathode, but when such integration is performed, the applied voltage of each electron source -The emission current characteristics vary as shown by the wiring A'-B 'and the alternate long and short dash line A "-B" in FIG. Therefore, a plurality of integrated electron sources cannot be driven under the same condition, and it becomes more difficult to reproduce halftone due to a change in applied voltage.

Further, when a large number of such solid-state electron beam generators are manufactured, it is easily expected that the characteristics of the individual solid-state electron beam sources will vary at random. In the case of producing a large number of image display devices that can be reproduced, it is necessary to adjust the applied voltage and the fluorescent luminance for each image display device, which causes serious difficulties in terms of a production line.

Further, in order to perform analog control, a large number of analog elements are required in peripheral circuits of the solid-state electron beam generator, and there is a drawback that the circuit becomes complicated and the cost increases.

The present invention has been made in view of such problems,
An object of the present invention is to provide a simple halftone reproduction method that does not require high uniformity among elements in a solid-state electron beam generator, and an image display device that can execute the method.

[Means for Solving the Problems] The configuration of the present invention for achieving the above object is as follows.

That is, the first of the present invention, in an image display method for performing image display by irradiating a light emitting member with electron beams emitted from a plurality of electron sources, according to the luminance level of each pixel of the input image signal, An image display characterized by controlling emission patterns of electron beams from a plurality of electron sources for each pixel, and driving the electron sources with an applied voltage in a region where the emission current density is saturated. In the way.

The first image display method of the present invention further has the following features: "the controlled emission electron beam is focused and irradiated to the light emitting member.""Scanning on a light emitting member", "the electron light emitting source is a cold cathode type electron generating source"
It also includes

According to a second aspect of the present invention, in an image display device having a plurality of electron sources and a light emitting member which emits light by irradiation of an electron beam emitted from the electron sources, each of a plurality of luminance levels of one pixel is provided. And a memory storing information of the emission pattern of the electron beam from the plurality of electron sources set in correspondence with, and according to the luminance level of each pixel of the input image signal from the memory, Address generating means for reading information, and means for irradiating the light emitting member with an electron beam based on the information on the emission pattern of the electron beam read from the memory; and Means for irradiating the electron source with an electron beam includes means for driving the electron source with an applied voltage in a region where the emission current density is saturated. In the image display device.

The second image display device of the present invention further has a feature that "the means for irradiating the light emitting member with an electron beam emits an electron beam based on information on the emission pattern of the electron beam read from the memory. Having means for converging the focused electron beam "," means for irradiating the light emitting member with the electron beam, means for driving the electron source, and means for deflecting the electron beam. "The electron source is a cold cathode type electron source."
It includes.

[Operation] According to the present invention, an emission pattern of electron beams from a plurality of electron sources is controlled for each pixel in accordance with the luminance level of each pixel of the input image signal. By controlling the number of electron sources that emit an electron beam, the display of halftone is controlled. Further, at this time, a voltage in a region where the emission current is saturated is applied at the time of on-time (during driving) of the on-off operation of the electron generating source, that is, the saturation characteristic in the applied voltage-current density characteristic shown in FIG. Region (B
(Between −C). Therefore, as in the case where halftone is displayed by using an applied voltage in a steep region (between A and B) in the applied voltage-current density characteristics, it is affected by variations in characteristics between individual electron sources. And good halftone reproduction is possible.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a basic configuration of the present invention. In FIG. 1, the image display apparatus has a solid-state electron beam generating apparatus in which three electron generating sources 1 are arranged in a plane of 3 × 3, and an electron beam emitted from the electron generating source 1 Is controlled by the vertical deflection means 3 to scan the phosphor screen 4 in the horizontal direction. In the vicinity of the electron source 1, a focusing electrode 5 is provided, and the electron beam from each electron source 1 is provided. At one point on the phosphor screen 4.

Scanning is performed by focusing on one point. However, since the electron emission and non-emission of the nine electron sources are individually performed independently,
The amount of electrons injected into one pixel is controlled each time, and halftone is reproduced.

FIG. 2 is a diagram showing an example in which nine levels of halftones can be displayed by nine electron sources.

FIG. 3A is a plan view of an integrated solid-state electron generating source according to the present embodiment, and FIG. 3B is a cross-sectional view taken along line XX of FIG. 3A. FIG. 3C is a sectional view taken along line YY in FIG. 3A. In these figures, reference numeral 30 denotes an n-type substrate, in which a low ohmic p-type passage 31 is formed as a common electrode, and a highly doped n-type surface layer 32 (A, B, C…
I) is formed. The pn junction 33 is not exposed on the wall surface of the substrate, but a depletion layer due to the pn junction is exposed as an opening 34. In FIG. 3 (a), the low ohmic p-type channel 31 is indicated by a broken line, the highly doped n-type surface layer 32 is indicated by a chain line, and the openings 34 (A, B, C... I) The highly doped n-type surface layer 32 and the silicon body substrate 30 are shown along the walls of the V-shaped recess.

The low ohmic p-type passage 31 is connected to the connection electrodes 37j, 37k, 37l through the contact region 35 and the contact windows 36j, 36k, 36l.
And the highly doped n-type surface layer 32 is
They are connected to connection electrodes 37a, 37b, 37c via a, 36b, 36c. An accelerating electrode 39 is provided on the insulating layer 38 so as to surround the opening 34.

In such a configuration, the avalanche amplification action is p
A voltage such as that generated at the -n junction is applied to the connection electrodes 37j to 37l and 37a to 37c in a matrix configuration, and at the same time, a desired voltage is applied to the accelerating voltage 39, whereby a desired cathode (A, B, .. I) can be selectively operated to emit electrons. The detailed mechanism of this electron emission is disclosed in the patent.

FIG. 4 is a block diagram showing one configuration example of the image display device of the present embodiment. In reproduction of a video signal according to the fourth map segments present invention, the input video signal S is a synchronous separation circuit 41, is separated into a video signal S _v and sync signal S _t, the timing pulse generating circuit by a synchronization signal S _t 42 Is triggered, a sampling pulse is output to the A / D conversion circuit 43, and the video signal S
_v is the A / D conversion circuit 43
, And is input to the ROM table 44.

Nine ROM tables 44 are prepared corresponding to the number of the electron sources (A, B, C... I), and store the contents as shown in Table 1 below.

The data in the ROM table 44 is referred to as stored information based on the input from the A / D conversion circuit 43 and the input from the timing pulse generation circuit 42, and according to the intensity of each pixel, the on-off timing of the electron generation source After a signal is output and amplified to a desired voltage by the electron source driver 45, it is input to the connection electrodes (A, B, C...) Of the solid-state electron beam source 46, and the electron beam is turned on and off. The emitted electrons are focused to one point on the phosphor screen 52 by the focusing electrode 47. Vertical deflection driving circuit 48 in accordance with the vertical synchronizing signal of the synchronizing signal S _t, to apply a desired driving voltage to the vertical deflection electrode 49.
Horizontal deflection drive circuit 50 in accordance with the horizontal synchronizing signal of the synchronizing signal S _t, to apply a desired driving voltage to the horizontal deflection electrode 51.
While being controlled in this manner, the electron beam emitted from the solid-state electron beam source 46 is scanned on the phosphor surface 52, and an image is displayed.

In the present embodiment, the number of electron beam sources is equal to the number of divisions of one pixel. However, the number of electron sources is an integral multiple of the number of divisions of one pixel, and the image is formed by one horizontal deflection. Can be reproduced at the same time. In this case, the horizontal scanning synchronization becomes longer, and the irradiation time of the electron beam per pixel can be made longer, so that a high definition image display can be realized.

[Effects of the Invention] As described above, according to the present invention, the emission pattern of the electron beam from the plurality of electron sources is controlled for each pixel according to the luminance level of each pixel of the input image signal. In addition, when the on / off operation of the electron source is on (driving)
Since the halftone is displayed by applying a voltage in the region where the emission current is saturated, a good halftone can be easily reproduced without being affected by variations in characteristics between individual electron sources. can do.

[Brief description of the drawings]

FIG. 1 is a basic structural view of the present invention, FIG. 2 is an explanatory view of an emission pattern of a solid-state electron beam source, FIG. 3 is a plan view and a sectional view of the solid-state electron source, and FIG. Figure,
FIG. 5 is a characteristic diagram of the electron beam generator. 1,46; electron source, 2,50,51; horizontal deflection means, 3,48,49; vertical deflection means, 4,52; phosphor screen, 5,47; focusing electrode, 43; sampling pulse generation circuit, 44 ; ROM table.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ichiro Nomura 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-49-102238 (JP, A) JP-A-52 -106737 (JP, A) JP-A-60-49540 (JP, A) JP-A-49-98930 (JP, A)

Claims (8)

(57) [Claims] 1. An image display method for displaying an image by irradiating an electron beam emitted from a plurality of electron sources to a light emitting member, wherein each pixel is provided with an input image signal in accordance with a luminance level of each pixel. An image display method for controlling an emission pattern of an electron beam from a plurality of electron sources, and driving the electron sources with an applied voltage in a region where an emission current density is saturated. 2. The image display method according to claim 1, wherein said controlled emission electron beam is focused and applied to said light emitting member. 3. The image display method according to claim 1, further comprising scanning the controlled emission electron beam on the light emitting member. 4. The image display method according to claim 1, wherein said electron source is a cold cathode type electron source. 5. An image display apparatus comprising: a plurality of electron sources; and a light-emitting member which emits light when irradiated with an electron beam emitted from the electron sources, wherein each of the plurality of brightness levels corresponds to one pixel. A memory for storing information of emission patterns of electron beams from a plurality of set electron generating sources; and for reading out information of the emission patterns of the electron beams from the memory in accordance with a luminance level of each pixel of an input image signal. Address generating means, and means for irradiating the light emitting member with an electron beam based on the information on the emission pattern of the electron beam read from the memory; and The means for irradiating includes means for driving the electron source with an applied voltage in a region where the emission current density is saturated. Indicating device. 6. The means for irradiating the light emitting member with an electron beam includes means for focusing the emitted electron beam based on information on an emission pattern of the electron beam read from the memory. Item 6. The image display device according to Item 5. 7. A means for irradiating the light emitting member with an electron beam includes: means for driving the electron generating source;
7. The image display device according to claim 5, further comprising means for deflecting the electron beam. 8. The image display device according to claim 5, wherein said electron source is a cold cathode type electron source.