JP2000020038A - Flat-panel display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable monochromatic display on a blue base in a medical flat- panel display and also to enable display in a luminance range superior in discriminating brightness and darkness. SOLUTION: A liquid crystal panel is used in which one pixel 41 of a monochromatic picture is displayed by three cells 41a, 41b, 41c by replacing the color filter of a color liquid crystal panel with a blue monochromatic filter as a display device. An inputted monochromatic picture signal SO is uniformly distributed in density into each cell by a controller 50. Eight bit intensity modulation is carried out by an intensity modulating means 10; and this output is time-modulated in four steps in accordance with the FRC(frame rate control) method by a time modulation means 20, and is thereby provided with the distributed density. As a result, the display gradation of 256×4 levels, which is the case by only the intensity modulation means 10 and the time modulation means 20, is further increased to the number of levels by cell number times (three times), with the maximum luminance range designed to be 100-10,000 cd/m2 per pixel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display, and more particularly, to a monochrome medical flat panel display.

[0002]

2. Description of the Related Art Conventionally, in the medical field, various diagnostic image acquisition apparatuses utilizing X-rays or the like have been used.
An X-ray imaging apparatus, a CR (Computed Radiography) apparatus, and the like are practically used.

[0003] Medical image information acquired by each of these devices is subjected to desired image processing such as frequency processing and gradation processing, and then converted into a TV image signal of the NTSC system or the like, and is converted into a visible image. The presence or absence of lesions or injuries at medical sites, such as electronically displayed on a soft copy device such as a CRT display device, or recorded on a photographic material (film) by an LP (laser printer) and observed on a Shakasten It is used for diagnosis such as grasping the contents. Conventionally, a CRT display device has been used as a soft copy device. However, a flat panel display using a liquid crystal panel, an organic EL panel, or the like has been widely used today. Compared to CRTs, they are considered to be more and more popular in the medical field in the future because of their advantages such as space saving, light weight, and low power consumption.

[0004] A "CR (Computed Radiography) device" is a device in which a part of radiation energy is accumulated by irradiating radiation and then irradiating with excitation light such as visible light or infrared light. Stimulable phosphor (stimulable phosphor) that shows stimulated emission in response to radiation energy accumulated by
A radiation image recording / reading apparatus that records radiation image information of a subject such as a human body, and scans the stimulable phosphor with excitation light to photoelectrically read stimulated emission light generated to obtain an image signal. In recent years, it has become widespread and has been put to practical use (JP-A-62-18536, etc.).

[0005]

As described above, when a medical image is recorded on a film and observed with a Schaukasten, when a blue-based film is used, the display color tone becomes a blue-based monochrome image. Is done. In medical practice, X-ray films have long been based on blue, so doctors and radiologists are accustomed to diagnosing with blue-based images. Under these circumstances, when displaying a medical image on a soft copy device, there is a demand for displaying the medical image on a film and displaying it as a blue-based monochrome image in the same way as when observing on a Schaukasten. There is.

[0006] However, some flat panel displays such as liquid crystal display can display a predetermined color tone, but they can display a green-based or amber-based monochrome image. Cannot be displayed. Accordingly, if a blue-based monochrome image is to be displayed on a soft copy device, for example, R (red), G (green), B
There has been no other option but to adjust the level of each signal to display a blue-based monochrome image of a desired color tone on a display device using a color display device corresponding to each signal input of (blue).

Here, in a display device using a display device for color display, in order to match with a display device for monochrome display, the ratio of each display output of R, G, and B is known, as is well known. Approximately "R: G: B = 0.3: 0.6: 0.1"
And the same as the spectral sensitivity characteristic of the display device for black and white display, and the mixed value “Y = R +
G + B "is the luminance level. In this case, for example, when the R, G, and B signal input levels are set to 100%, that is, when the white level is output, the display luminance level is also 100%, and when the display luminance level is 100%, for example, CR
In the case of a T display device, its maximum luminance is usually 100 to 20.
It was about 0 cd / m ² . Further, the maximum luminance of a liquid crystal panel or an organic EL panel is generally lower than that of a CRT.

For this reason, in a display device using a display device for color display as described above, if the levels of R and G are lowered to achieve a blue base display with a blue color tone, the overall luminance is lowered, and recording on a film is performed. 5,000 to 6000
A remarkable difference occurs as compared with the case where the display can be performed up to cd / m ² .

Further, from the viewpoint of the visual light / dark discrimination ability, it is known that the best discrimination ability is obtained when the luminance level is in the range of 50 to 500 cd / m ^2. But 100-200 cd / m ²
When the display can be performed only in the degree, the expression range of film density 1 (-1 digit of the maximum luminance), which is often observed for medical use, becomes about 10 to ²⁰ cd / m ^2, which is also a problem from the viewpoint of light / dark discrimination ability. come. Further, from the viewpoint of visual acuity (resolution), for example, it is said that an average luminance of 10 cd / m ² or more is necessary to maintain a normal visual acuity of 1.0 or more,
If it is possible to display at most only about 10 to ²⁰ cd / m ² , there is no room for visual acuity, which is a problem.

In other words, for medical use, the expression area corresponding to a film density of 1 is well observed, and in order to make this the best light-dark discrimination ability of 50 to 500 cd / m ² , the maximum brightness is required. The range is 500-5000 cd /
m ² is preferred.

Further, since each of the RGB image signals is generally an 8-bit signal, if each signal is mixed to represent a monochrome gradation, the display gradation will be 256 levels, resulting in a medical use. An image display device has an insufficient number of display gradation steps.

The present invention has been made in view of the above circumstances. Even when a blue-based medical image is displayed by a soft copy device, the image can be displayed with sufficient brightness from the viewpoint of light / dark discrimination ability and visual acuity. Allows recording on a blue-based film and displaying with the same brightness as when observing with Shakasten,
It is an object of the present invention to provide a flat panel display which is one mode of an image display device capable of providing a sufficient number of display gradations for medical image use.

[0013]

SUMMARY OF THE INVENTION A flat panel display according to the present invention is a display using a flat display device, and the display device has a display color whose coordinate point on a CIE chromaticity diagram is (x, When shown in y),
Each coordinate (0.174,0), (0.4,0.4),
The device is characterized in that the device is a single-color display device that outputs an image within an area surrounded by (α, 0.4). Here, α is a coordinate value in the x-axis direction represented by an intersection of a spectrum locus and a straight line having a coordinate value of 0.4 in the y-axis direction.

In order to make the display color of the display device a single-color display device within the above-described region, for example, the display device may be a substrate for a device such as a glass substrate, a face plate, a diffusion plate, a color filter, It is preferable that at least one member of a film, a collimator film, a prism film, and a polarizing film is provided, and at least one of these members is colored in a predetermined color.

Here, the "predetermined color" may be any color as long as the display color of the display device is consequently within the above-mentioned area. The fact that the display color is within the above-described region means that a blue-based display with a blue color tone is obtained. In general, it is preferable that the member is also colored with a blue-based color tone, but it is not necessarily blue. It is not limited to coloring to a system color tone.

The face plate is a plate which is disposed on the display surface of a flat display device and is generally provided with a protective film such as an anti-reflection or anti-scratch.

The diffusion plate is a plate for scattering light emitted from a light source disposed on the back surface or the surface of a flat display device, particularly a liquid crystal panel.

The diffusion film and the collimating film are members used for widening the viewing angle in a flat display device, especially in a liquid crystal panel. Also,
The prism film is a member used for improving luminance in a flat display device, particularly a liquid crystal panel.

Coloring the diffusion film means coloring at least one of the diffusion portion of the diffusion film and the base film of the diffusion film. To color the collimating film means to color at least one of the collimating portion of the collimating film and the base film of the collimating film. To color the prism film means to color at least one of the prism portion of the prism film and the base film of the prism film.

In the flat panel display according to the present invention, the display device includes a large number of cells, and one pixel of a monochrome image can be represented by a plurality of cells. Area modulation means for controlling the output luminance of one pixel by independently controlling on / off of the input signal, time modulation means for independently time-division driving each cell of the display device, and independently controlling the input signal level to each cell. And at least one of the intensity modulation means for controlling the intensity modulation means.
0 cd / m ² or more 10000 cd / m ² or less, more preferably it is desirable to 500 cd / m ² or more 5000 cd / m ² or less.

Here, the time modulation is to express a gradation by changing a display period per unit time, and a pulse width gradation control known as a liquid crystal driving method,
Frame thinning control or frame rate control (Frame rate control), which is a gradation display control realized by STN liquid crystal.
Rate Control (FRC) is a typical example. For example, F
In the RC system, a 6-bit grayscale signal is converted to 8 bits or
A device capable of displaying a 10-bit gradation has been proposed.

As a display device of the flat panel display, it is desirable to use a liquid crystal panel or an organic EL panel.

[0023]

According to the flat panel display of the present invention, the display device is a device of a monochromatic display exhibiting a bluish color in which the display color is in a region surrounded by the above-mentioned coordinates on the CIE chromaticity diagram. Therefore, a blue-based monochrome image can be displayed.

In order for the display color of the display device to be within the above-described region, at least one of the components of the display device such as a substrate, a face plate, or a diffusion plate is required.
One may be colored in a predetermined color, and manufacture is easy.

If the color filter is a single-color filter colored in a predetermined color or the other components are colored in a predetermined color, the matching with the monochrome display device is considered unlike the color display device. This eliminates the need to perform the operation, and can increase the display luminance and display a bright blue-based monochrome image.

Also, the display device is composed of a large number of cells, and one pixel of a monochrome image can be represented by a plurality of cells, and a gradation corresponding to a monochrome image signal is distributed to each cell. or, by its so that apportioned tone to time modulation or intensity modulation for each cell, a maximum brightness range 100 cd / m ² or more 10000 cd / m ² or less and more preferably per pixel 500 cd / m ^{If the number is 2} or more and 5000 cd / m ² or less, the number of tones that can be expressed by time modulation or intensity modulation can be increased to the number of tones obtained by multiplying the number of cells by the number of cells, and a blue-based film is used. And can be displayed in the same brightness as when observed with a Shakasten, that is, in the range of 50 to 500 cd / m ² , which is excellent in light / dark discrimination ability and visual acuity. Note that the maximum luminance range per pixel can be increased in this way because the maximum luminance per pixel can be multiplied by the number of cells of the maximum luminance per cell. Therefore, for example, if the flat panel display according to the present invention is used as a medical image display device used for a CR device or the like, a display device having a sufficient number of display gradations and brightness for medical image applications can be provided. Become like

If the display device is a liquid crystal panel, it is possible to use the same liquid crystal panel as that in which the color filters of the color liquid crystal panel are replaced with the above-described monochromatic filters. That is, in the process of manufacturing a liquid crystal panel for color display, if the above-described single-color filter is formed on each cell using the current color filter mask, a blue-based liquid crystal panel in which one pixel is composed of three cells Since the liquid crystal panel used in the present invention can be obtained, there is no particular cost burden such as new development of a mask.
It can be manufactured very easily. Also,
The liquid crystal driver (controller) for controlling the gradation of the liquid crystal panel can also control the gradation of the monochrome image using the existing color liquid crystal driver.

If the display device is an organic EL panel, it is not necessary to form a single-color filter on each cell as in a liquid crystal panel, and a panel formed by arranging a large number of organic ELs emitting light of the same color. be able to.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings. The flat panel display 1 according to the present invention uses, as a display device, a liquid crystal panel 40 in which one pixel of a monochrome image can be represented by three cells by replacing a color filter of a color liquid crystal panel with a monochromatic filter. I have. FIG. 1 is a diagram showing an example of a pixel array of the liquid crystal panel 40. As shown in FIG. 1, the liquid crystal panel 40 has, for example, a pixel number 4
Each pixel such as 1, 42, 43, 44, etc., is configured to be represented by three cells (for example, 41a, 41b, 41c for the pixel number 41).

The display color of the liquid crystal panel 40 is indicated by coordinate points (x, y) on the CIE chromaticity diagram of FIG. Then, each coordinate (0.174,0), (0.4,
A single-color filter is formed on all the cells so as to be within a region shown by oblique lines surrounded by (0.4) and (α, 0.4). Here, the coordinates (0.174,0)
Is a coordinate indicating a short wavelength end of a spectrum locus which is a curved portion in the figure, and α is a coordinate in the x-axis direction represented by an intersection of the spectrum locus and a straight line having a coordinate value of 0.4 in the y-axis direction. Value. The shaded area surrounded by these coordinates has a blue color.

It is preferable to use a monochromatic filter colored in a bluish color. It is not necessary to determine the display luminance of each cell in consideration of color display, and the transmittance can be freely determined. For example, a blue-based monochromatic filter having a high transmittance can be used. Therefore, the liquid crystal panel 40 has a maximum luminance range per pixel including the backlight of 100 to 100.
It is adjusted to 10,000 cd / m ^2, and various modulations to be described later are performed, so that the brightness is 50 to 500 c which is excellent in light / dark discrimination ability and visual acuity.
Monochrome display can be performed in the range of d / m ² .

The display device is not limited to a liquid crystal panel. For example, an organic EL panel formed by arranging a large number of organic ELs emitting the same color so as to be within a predetermined range on the CIE chromaticity diagram as described above. Can also be used.
In this case, the maximum luminance range is 100 to 10000 cd /
In order to obtain m ² , each organic EL constituting the cell
In this case, the drive current may be increased, and the luminance may be increased by developing the material.

As shown in FIG. 3 in detail, the flat panel display 1 operates as shown in FIG.
An intensity modulating means 10 for controlling a voltage applied to each of the cells 41a, 41b, 41c based on S0;
A time modulating means 20 for gradation control for each cell according to the RC system, an area modulating means 30 for controlling the input to each cell by independently turning on and off the output of the time modulating means 20, and an image signal S0. A controller 50 for controlling the intensity modulating means 10, the time modulating means 20, and the area modulating means 30 so that density unevenness in one pixel does not occur. Thus, the number of display gradations and the maximum luminance per pixel can be increased by combining area modulation, time modulation, and intensity modulation. The display density, that is, the display gradation can be changed by controlling the imprint voltage to each cell by the intensity modulating means 10.
Bits, that is, 256 stages of control are performed.

FIG. 4 is a diagram for explaining the operation of the time modulation means 20. The time modulating means 20 is connected to each cell of the liquid crystal 40 via the area modulating means 20, respectively.

In this example, the time modulating means 20 sets the unit time to 4
It divides and performs time-division driving for ON / OFF control of a signal input from the intensity modulation means 10 for each divided period, and outputs the output signal to the area modulation means 30 corresponding to each cell.
To enter. Therefore, for example, if only one divided period is turned on, gradation 1 can be expressed, and if two divided periods are turned on, gradation 2 can be expressed, and finally four (gray level 0) can be expressed. ) Can be expressed.

The area modulating means 30 controls on / off of the output signal from the time modulating means 20 independently and inputs it to each cell of the liquid crystal panel 40. Therefore, the liquid crystal panel
Since each pixel of 40 is composed of three cells, if the number of display gradations of each cell by the intensity modulating means 10 is 256, the number of display gradations of one pixel finally becomes 256 × 4
× 3 steps, that is, 3072 steps. In addition, the display luminance of one pixel is three times as large as the maximum number of cells per cell. If one pixel is represented by N cells, and the number of display gradation steps by intensity modulation and time modulation of each cell is L and N, respectively, the final number of display gradation steps is L × M × N
And the display luminance of one pixel can be set to N times the maximum luminance per cell.

As described above, the flat panel display 1 of the present invention increases the number of display gradation steps by combining area modulation, time modulation, and intensity modulation.
The maximum luminance range per pixel is 100 to 10000 cd
/ M ² , 50-500c with excellent light / dark discrimination ability and visual acuity
Monochrome display can be performed in the range of d / m ² .
Therefore, if the flat panel display 1 is used as a medical image display device such as a CR device, a display device having sufficient performance for medical image applications can be configured.

As described above, in the flat panel display 1 having the above structure, one pixel of a monochrome image is distributed in density to a plurality of cells to increase the display gradation and increase the display luminance of one pixel. Concerning the distribution of the density to each cell, the density is distributed as evenly as possible to each cell constituting one pixel so as not to cause a bias to each cell, and the density unevenness in one pixel does not occur. Is preferred. FIG. 5 explains this method of density distribution. FIG. 5A shows the case of the density 3, and it is preferable that the density distribution of the three cells is equally distributed to "1, 1, 1" instead of "3, 0, 0". . Similarly, FIG. 5B shows the case of density 4, but instead of “4,0,0”, respectively, “2,1,1”, “1,2,1” or “1,2” 1,
It is preferable to distribute as equally as possible to "1, 2".
This is performed by the controller 50 controlling the intensity modulating means 10, the time modulating means 20, and the area modulating means 30 based on the image signal S0 such that the density distribution of each cell becomes uniform.

In the flat panel display 1 described above, the number of display gradations and the maximum luminance per pixel are increased by combining area modulation, time modulation and intensity modulation. Is not limited to this, and any one of area modulation, time modulation, and intensity modulation
It is sufficient if at least one is provided. For example, a combination of area modulation and time modulation, or a combination of area modulation and intensity modulation may be used. Even in this case, the number of display gradations and the maximum luminance per pixel can be increased by multiplying the number of cells, respectively, as compared with the case of only time modulation or intensity modulation.

As described above, the flat panel display of the present invention uses the liquid crystal panel 40 in which one pixel of a monochrome image is represented by three cells by replacing the color filters of the color liquid crystal panel with monochromatic filters. This point will be described below. In general, a color display liquid crystal panel is configured such that R (red), G (green), and B (blue) color filters are formed on each cell to represent one pixel. RGB
If all the filters are B filters, a blue-based monochrome liquid crystal panel that can represent one pixel of a monochrome image as described above with three cells is obtained. Therefore, in the manufacturing process of the liquid crystal panel for color display, RG
If the B filter forming process is a B filter forming process, it becomes a manufacturing process of a blue-based monochrome liquid crystal panel. Therefore, it is extremely easy and inexpensive to add a blue filter to the manufacturing process of a monochrome liquid crystal panel. The base monochrome liquid crystal panel can be manufactured.
In addition, among liquid crystal panels commercially available in recent years, a liquid crystal panel for color is cheaper than a liquid crystal panel for monochrome, and this is an extremely effective manufacturing method from this point as well.

Further, the controller for controlling the gradation of the liquid crystal panel can control the gradation of the blue-based monochrome image easily by using the existing color liquid crystal driver and controlling the RGB input. become.

Although the preferred embodiment of the flat panel display according to the present invention has been described above, the present invention is not limited to the above-described embodiment, and the display device uses a CIE chromaticity diagram. The upper coordinate point (x,
y), each coordinate (0.174, 0), (0.
Any display device may be used as long as it is a device of a single-color display that outputs an image within the area surrounded by (4, 0.4) and (α, 0.4).

For example, in the above-described embodiment, a description has been given of an example in which a liquid crystal panel for displaying a monochrome image in which the color filters of the color liquid crystal panel are replaced with blue-based monochromatic filters is used as a display device. A display device in which the constituent members are colored in a predetermined color may be used.

FIG. 6 is a diagram schematically showing general components of a liquid crystal panel for color display. A light source 80 for a backlight is provided on the back surface of the liquid crystal panel 60 shown in FIG. The liquid crystal panel 60 includes two glass substrates 62 and 63 provided so as to sandwich a liquid crystal layer 61, a panel main portion 65 including an RGB color filter 64 laminated on the glass substrate 63, and both sides of the panel main portion 65. And polarizing films 70 and 71 disposed on the substrate. Further, a collimating film 72 is provided outside the polarizing film 70 of the liquid crystal panel 60, that is, on the light source 80 side,
A diffusion film 73 is provided outside the polarizing film 71, that is, on the display surface side. Furthermore, collimating film 72
On the light source 80 side, a diffusion plate 74 for scattering light emitted from the light source 80 is provided, and on the display surface side of the diffusion film 73, a face plate 75 provided with a protective film such as antireflection or scratch prevention is provided. Is provided. Although a detailed description of the actions of the diffusion film 73 and the collimating film 73 is omitted, they are both members used to increase the viewing angle of the liquid crystal panel 60. RGB color filter
Numeral 64 designates a color display of the liquid crystal panel 60. When a black and white display liquid crystal panel is used, the RGB color filter 64 is not attached.

Incidentally, instead of the collimating film 72,
A prism film for improving luminance may be provided.

The light source 80 has a color temperature of 5700 ° K.
A 100 ° K daylight fluorescent lamp is used. The invention is not limited to this, and a lamp having another color temperature including a bluish wavelength can be used.

In the liquid crystal panel 60 having such a configuration,
When the display color is represented by a coordinate point (x, y) on the CIE chromaticity diagram, each coordinate (0.174, 0), (0.4, 0.
4) In order to make a device of a single color display that outputs within the area surrounded by (α, 0.4), the liquid crystal panel
Similarly to 40, the RGB color filters 64 are changed to blue-colored monochromatic filters, and the glass substrates 62, 63,
At least one of the polarizing films 70 and 71, the collimating portion 72a and the base film 72a of the collimating film 72, and the diffusing portion 73a and the base film 73a of the diffusing film 73, the diffusing plate 74, and the face plate 75 have a predetermined color, preferably. It is good to color blue.

When the components other than the color filter 64 are colored as described above, the RGB color filter 64 is removed in order to display a monochrome image. When a prism film is provided instead of the collimator film 72, the prism portion of the prism film and the base film may be colored.

As a colorant for coloring these components, for example, when the base film is polyethylene terephthalate (PET), an anthraquinone dye can be used to color the components blue.

It is to be noted that the present invention is not limited to the liquid crystal panel.
Even when the L panel is used, similarly to the above, by coloring constituent members such as a substrate and a face plate, a device of a single color display in which a display color is within the above-described region can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a pixel configuration of a liquid crystal panel used for a flat panel display according to an embodiment of the present invention.

FIG. 2 is a CIE chromaticity diagram showing a range of display colors of the liquid crystal panel.

FIG. 3 is a block diagram showing the configuration of the flat panel display for one pixel of a liquid crystal panel.

FIG. 4 is a diagram illustrating time modulation.

FIG. 5 is a view for explaining density distribution.

FIG. 6 is a diagram schematically illustrating components of a liquid crystal panel.

[Explanation of symbols]

 Reference Signs List 1 flat panel display 10 intensity modulation means 20 time modulation means 30 area modulation means 40 liquid crystal panel (display device) 50 controller 60 liquid crystal panel (display device) 61 liquid crystal layer 62, 63 glass substrate 64 RGB color filter 65 panel main part 70, 71 Polarizing film 72 Collimating film 73 Diffusion film 74 Diffusion plate 75 Face plate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/20 680 G09G 3/20 680W 3/30 3/30 K

Claims (6)

[Claims] 1. In a flat panel display using a flat display device, when the display color of the display device is represented by a coordinate point (x, y) on a CIE chromaticity diagram, each coordinate (0. 174,
0) A flat panel display, which is a device of a single-color display that outputs an image within an area surrounded by (0.4, 0.4) and (α, 0.4). (Where α is the coordinate value in the x-axis direction represented by the intersection of the spectrum locus and the straight line having the coordinate value of 0.4 in the y-axis direction) 2. The display device includes at least one member of a substrate, a face plate, a diffusion plate, a color filter, a diffusion film, a collimating film, a prism film, and a polarizing film, and at least one of the members is The flat panel display according to claim 1, wherein the flat panel display is colored in a predetermined color. 3. The display device is composed of a large number of cells, and one pixel of a monochrome image can be represented by a plurality of cells. On / off control of input signals to the plurality of cells is performed independently of each other. Area modulation means for controlling the output luminance of the one pixel, time modulation means for independently time-division driving each cell of the display device, and intensity modulation means for independently controlling the input signal level to each cell. The maximum luminance range per pixel is 100 cd / m ² or more.
3. The flat panel display according to claim 1, wherein the flat panel display is set to 0000 cd / m ² or less. 4. The maximum luminance range per pixel is 50.
0 cd / m ² or more 5000 cd / m ² flat panel display according to claim 3, wherein follows the thing. 5. The flat panel display according to claim 1, wherein the display device is a liquid crystal panel. 6. The flat panel display according to claim 1, wherein the display device is an organic EL panel.