JP3474122B2 - Flat panel display - Google Patents

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 medical flat panel display for monochrome display.

[0002]

2. Description of the Related Art Conventionally, in the medical field, various diagnostic image acquisition devices using X-rays have been used.
An X-ray imaging device, a CR (Computed Radiography) device, and the like are put into practical use.

The 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 to obtain a visible image. Presence or absence of lesions or injuries in the medical field by being electronically displayed on a soft copy device such as a CRT display device or recorded on a photographic light-sensitive material (film) by an LP (laser printer) and observed on a Schaukasten. , Is used for diagnosis such as grasping the contents. A CRT display device has been conventionally used as a soft copy device, but today, a flat panel display using a liquid crystal panel, an organic EL panel, or the like is also widely used. Compared with CRT, it is considered that it will be more and more popular in the medical field in the future due to advantages such as space saving, light weight and low power consumption.

The "CR (Computed Radiography) apparatus" means that a part of radiation energy is accumulated by irradiation of radiation, and then excitation light such as visible light or infrared light is irradiated. Stimulable phosphor (stimulable phosphor) that exhibits stimulated emission according to the radiation energy stored by
A radiation image recording / reading device for recording radiation image information of a subject such as a human body, and photoelectrically reading stimulated emission light generated by scanning the stimulable phosphor with excitation light to obtain an image signal. This means that it has become widespread in recent years and has been put to practical use (JP-A-62-18536, etc.).

[0005]

By the way, in the case of recording a medical image on a film and observing with a Schaukasten as described above, when a blue-based film is used, the display color tone is also a blue-based monochrome image and is observed. To be done. In medical practice, since X-ray films have been blue-based for a long time, doctors and radiologists are accustomed to making diagnoses with blue-based images. Under these circumstances, even when a medical image is displayed on a softcopy device, it is desired to display the medical image as a blue-based monochrome image in the same manner as when recording the medical image on a film and observing it on a Schaukasten. There is.

However, some flat panel displays such as liquid crystals can display in a predetermined color tone, but they display green-based or amber-based monochrome images. In this case, blue-based monochrome images are displayed. Can not be displayed. Therefore, if an attempt is made to display a blue-based monochrome image on the soft copy device, for example, R (red), G (green), B
There has been no choice but to adjust the level of each signal on a display device using a display device for color display corresponding to each (blue) signal input to display a blue-based monochrome image of a desired color tone.

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

Therefore, in the display device using the display device for color display as described above, if the levels of R and G are lowered in order to display the blue base of the blue color tone, the overall brightness is lowered and the film is recorded on the film. And usually 5000 to 6000 when observed on Schaukasten
Compared with displaying up to cd / m ² , there is a significant difference.

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

In other words, since the expression range corresponding to the film density of 1 is often observed for medical use, the maximum brightness is required in order to obtain the best brightness / darkness discrimination ability of 50 to 500 cd / m ^2. Range is 500-5000 cd /
It is preferably m ² .

Furthermore, since each RGB image signal is generally an 8-bit signal, if the signals are mixed to produce a gradation representation in monochrome, 256 gradations are displayed, resulting in a medical problem. The number of display gradation steps is insufficient for an image display device.

The present invention has been made in view of the above circumstances, and even when a blue-based medical image is displayed by a soft copy device, it can be displayed with sufficient brightness from the viewpoint of light-dark discrimination and visual acuity. Makes it possible to record on a blue-based film and display it with the same brightness as when observing with Schaukasten,
An object of the present invention is 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 applications.

[0013]

A flat panel display according to the present invention is a display using a flat display device, and the display color of the display device is a coordinate point (x, y),
Each coordinate (0.174, 0), (0.4, 0.4),
It is characterized in that it is a device for monochromatic display that outputs so as to be within the area surrounded by (α, 0.4). Here, α is a coordinate value in the x-axis direction represented by an intersection of the spectrum locus and a straight line having a coordinate value in the y-axis direction of 0.4.

In order to make the display color of the display device within the above-mentioned region a monochromatic display device, 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, a diffusion device. It is preferable that at least one member of a film, a collimating film, a prism film, and a polarizing film is provided, and at least one of these members is colored with a predetermined color.

Here, the "predetermined color" may be any color that results in the display color of the display device being within the above-mentioned area. The display color being in the above-mentioned area means that it is a blue-based display of a blue color tone. Generally, it is preferable that the member is also colored in a bluish color tone, but it is not always blue. The coloring is not limited to the color tone of the system.

The face plate is a plate which is arranged on the display surface of a flat display device, and is generally provided with a protective film for preventing reflection or scratches.

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

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

Coloring the diffusion film means coloring at least one of the diffusion part of the diffusion film and the base film of the diffusion film. Coloring the collimating film means coloring at least one of the collimating portion of the collimating film and the base film of the collimating film. Coloring the prism film means coloring 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 is composed of 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 turning on / off the input signals, time modulation means for independently time-divisionally driving each cell of the display device, and input signal levels to each cell independently. At least one of the intensity modulating means for controlling is provided, and the maximum brightness range per pixel is 10
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 gradation by changing the display period per unit time, and is known as pulse width gradation control which is well known as a liquid crystal driving method.
Frame thinning control or frame rate control (Frame
A typical example is Rate Control (FRC). For example, F
In the RC method, a signal of 6-bit gradation is converted into 8-bit or
A device that can display 10-bit gradation has been proposed.

A liquid crystal panel or an organic EL panel is preferably used as the display device of the flat panel display.

[0023]

According to the flat panel display of the present invention, the display device is a monochromatic display device exhibiting a bluish color whose display color tone is within the area surrounded by the aforementioned coordinates on the CIE chromaticity diagram. Therefore, it becomes possible to display a blue-based monochrome image.

In order to make the display color of the display device fall within the above-mentioned area, at least one of the constituent members of the display device such as the substrate, face plate, or diffusion plate is used.
It suffices to color one with a predetermined color, and it is easy to manufacture.

Further, if the color filter is a monochromatic filter which is colored in a predetermined color, or the other constituent members are colored in a predetermined color, the matching with the black and white display device is considered unlike the color display device. Display brightness can be increased and a bright blue-based monochrome image can be displayed.

Further, 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 the gradation corresponding to the 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 it is 2} or more and 5000 cd / m ² or less, it is possible to increase the number of gradations that can be expressed by time modulation or intensity modulation to the number of gradations that is the number of cells multiplied by the number of gradations, and at the same time, a blue-based film similar brightness to the case of observing by the recording to a light-box, ie can also be displayed in the range of 50~500cd / m ² which is excellent in brightness discrimination and vision. The maximum brightness range per pixel can be increased in this way because the maximum brightness per pixel can be set to be a multiple of the maximum brightness per cell. Therefore, when the flat panel display according to the present invention is used as a medical image display device used in, for example, a CR device, it is possible to provide a display device having a sufficient number of display gradation steps and brightness for medical image applications. Like

Further, if the display device is a liquid crystal panel, the same liquid crystal panel as that in which the color filter of the color liquid crystal panel is replaced with the above-mentioned monochromatic filter can be used. That is, in the manufacturing process of a liquid crystal panel for color display, if the above-mentioned monochromatic filter is formed on each cell using a current color filter mask, a blue-based liquid crystal panel in which one pixel is composed of three cells Therefore, the liquid crystal panel used in the present invention, without causing a special cost burden such as new development of the mask,
It can be manufactured very easily. Also,
A liquid crystal driver (controller) that controls the gradation of a liquid crystal panel can also control the gradation of a monochrome image using an existing color liquid crystal driver.

When the display device is an organic EL panel, it is not necessary to form a monochromatic filter on each cell like a liquid crystal panel, and a panel formed by arranging a large number of organic ELs emitting the same color is formed. be able to.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION 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 a color filter of a color liquid crystal panel is replaced with a single color filter so that one pixel of a monochrome image can be represented by three cells. There is. 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, pixel number 4
Each pixel such as 1, 42, 43, and 44 is configured so that it can be represented by three cells (for example, 41a, 41b, 41c for pixel number 41).

The liquid crystal panel 40, including a backlight (not shown) using, for example, a high-intensity halogen lamp, has a display color indicated by coordinate points (x, y) on the CIE chromaticity diagram of FIG. Then, each coordinate (0.174, 0), (0.4,
0.4) and (α, 0.4), a monochromatic color filter is formed on all cells so as to be within the area shown by the shaded area. Where the coordinates (0.174,0)
Is the coordinate indicating the short wavelength end of the spectrum locus, which is the curved line portion in the figure, and α is the coordinate in the x-axis direction represented by the intersection of the spectrum locus and the straight line whose coordinate value in the y-axis direction is 0.4. It is a value. The shaded area surrounded by these coordinates is blue.

As the monochromatic filter, it is preferable to use a monochromatic filter colored blue. Since it is not necessary to determine the display brightness of each cell in consideration of color display and the transmittance can be freely determined, for example, a bluish monochromatic filter having high transmittance can be used. Therefore, the liquid crystal panel 40 has a maximum luminance range of 100 to 100 per pixel including a backlight.
50 to 500c, which is excellent in light-dark discrimination ability and visual acuity by performing various modulations described later so as to be 10000 cd / m ^2.
Monochrome display is possible within the range of d / m ² .

The display device is not limited to the liquid crystal panel, and 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 brightness range is 100 to 10,000 cd /
In order to obtain m ² , each organic EL that composes the cell
Drive current may be increased, and higher brightness may be achieved by developing materials.

The flat panel display 1 displays the image signal as shown in detail in FIG.
The intensity modulating means 10 for controlling the voltage applied to each of the cells 41a, 41b, 41c based on S0 and the output of the intensity modulating means 10 are F
The time modulation means 20 for controlling the gradation for each cell according to the RC system, the area modulation means 30 for controlling the input to each cell by independently turning on and off the output of the time modulation means 20, and the image signal S0 Based on the above, the controller 50 controls the intensity modulating means 10, the time modulating means 20, and the area modulating means 30 so that the density unevenness in one pixel does not occur. As a result, the area modulation, the time modulation, and the intensity modulation are combined to increase the number of steps of display gradation and the maximum brightness per pixel. By controlling the printing voltage applied to each cell by the intensity modulating means 10, the display density, that is, the display gradation can be changed.
Bits, that is, 256 stages are controlled.

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

In this example, the time modulating means 20 changes the unit time by 4
The signal is input from the intensity modulating means 10 on a divided basis in each divided period, and time-division driving is performed to control the signal. The output signal of the area modulating means 30 corresponds to each cell.
To enter. Therefore, for example, if only one division period is turned on, gradation 1 can be expressed, and if two division periods are turned on, gradation 2 can be expressed, and finally four gradations (gradation level 0 (Except)) can express the gradation of the level.

The area modulating means 30 independently controls the output signals from the time modulating means 20 to turn them on and off and input them 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, finally the number of display gradations of one pixel is 256 × Four
× 3 stages, that is, 3072 stages. Further, the display brightness of one pixel is the maximum brightness per one cell times the number of cells, that is, three times. If one pixel is represented by N cells and the number of display gradations by the intensity modulation and time modulation of each cell is L and N, respectively, the final number of display gradations is L × M × N.
In addition, the display brightness of one pixel can be N times the maximum brightness per cell.

In this way, the flat panel display 1 of the present invention combines the area modulation, the time modulation and the intensity modulation to increase the number of display gradation steps, and
Maximum brightness range per pixel is 100 to 10,000 cd
/ M ² and then, 50~500c excellent in brightness discrimination ability and vision
Monochrome display is possible within the range of d / m ² .
Therefore, by using the flat panel display 1 as a medical image display device such as a CR device, a display device having sufficient performance for medical image use can be configured.

As described above, the flat panel display 1 having the above-described structure is designed to increase the display gradation by increasing the display gradation by distributing the density of one pixel of a monochrome image to a plurality of cells. As for the distribution of the densities to the cells, the densities are not evenly distributed to the cells, and the densities are evenly distributed to the cells forming one pixel so that the density unevenness in one pixel does not occur. Preferably. FIG. 5 illustrates this density distribution method. FIG. 5 (A) shows the case where the density is 3, and it is preferable that the density distributions of the three cells are equally distributed to "1, 1, 1" instead of "3, 0, 0". . Similarly, although FIG. 5B shows the case where the density is 4, the values are not “4,0,0” but “2,1,1”, “1,2,1” or “4,0,0”, respectively. 1,
1, 2 ”is preferably distributed as evenly as possible.
This is done 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 so that the density distribution of each cell becomes even.

The flat panel display 1 described above is one in which area modulation, time modulation and intensity modulation are combined to increase the number of display gradation steps and the maximum luminance per pixel. Is not limited to this, and any one of area modulation, time modulation, and intensity modulation
You need to have at least one. For example, a combination of area modulation and time modulation, or a combination of area modulation and intensity modulation can be used. Even in this case, the number of display gradation steps and the maximum luminance per pixel can be increased by the number of cells, respectively, as compared with the case of only time modulation or intensity modulation.

By the way, as described above, the flat panel display of the present invention uses the liquid crystal panel 40 in which the color filter of the color liquid crystal panel is replaced with a single color filter so that one pixel of a monochrome image is represented by three cells. However, this point will be described below. A color display liquid crystal panel generally has R (red), G (green), and B (blue) color filters formed on each cell to represent one pixel. RGB
If all of the filters are B filters, a blue-based monochrome liquid crystal panel capable of representing 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, the RG
If the B filter forming step is the B filter forming step, it is a manufacturing process of a blue-based monochrome liquid crystal panel. Therefore, it is much easier and cheaper than adding the B filter forming step to the manufacturing process of the monochrome liquid crystal panel. A base monochrome liquid crystal panel can be manufactured.
Further, in the liquid crystal panels commercially available in recent years, the color liquid crystal panel is cheaper than the monochrome liquid crystal panel, and this is also an extremely effective manufacturing method.

Further, the controller for controlling the gradation of the liquid crystal panel also uses the existing color liquid crystal driver, and if the RGB inputs are controlled, the gradation of the blue-based monochrome image can be easily controlled. 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 embodiment, and the display color of the display device is a CIE chromaticity diagram. Upper coordinate point (x,
y), each coordinate (0.174, 0), (0.
4, 0.4), (α, 0.4), any display device may be used as long as it is a device for monochromatic display that outputs within a region.

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

FIG. 6 is a diagram showing an outline of general constituent members of a liquid crystal panel for color display. A light source 80 for a backlight is arranged 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 the liquid crystal layer 61, a panel main portion 65 including RGB color filters 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. 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 the 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 for preventing reflection or scratches. Is provided. Although detailed description of the functions of the diffusing film 73 and the collimating film 73 is omitted, they are both members used for widening the viewing angle of the liquid crystal panel 60. RGB color filter
Reference numeral 64 enables the liquid crystal panel 60 to display in color, and when using a liquid crystal panel for monochrome display, the RGB color filter 64 is not attached.

Instead of the collimating film 72,
A prism film may be provided to improve the brightness.

The light source 80 has a color temperature of 5700 ° K to 7
A 100 ° K daylight fluorescent lamp is used. However, the present invention is not limited to this, and it is also possible to use a lamp having another color temperature including a bluish wavelength.

In the liquid crystal panel 60 having such a structure,
When the display color is indicated by the coordinate point (x, y) on the CIE chromaticity diagram, each coordinate (0.174, 0), (0.4, 0.
4), the liquid crystal panel described above is used as a device for monochromatic display in which the output is made within the area surrounded by (α, 0.4).
Similar to 40, except that the RGB color filter 64 is a monochromatic filter colored blue, 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, the diffusing portion 73a of the diffusing film 73, the base film 73a, the diffusing plate 74, and the face plate 75 has a predetermined color, preferably It is good to color it in a bluish color.

When the components other than the color filter 64 are colored in this way, the RGB color filter 64 is removed for monochrome display. When a prism film is provided instead of the collimate film 72, the prism portion of the prism film and the base film may be colored.

As a coloring agent for coloring these constituent members, for example, when the base film is polyethylene terephthalate (PET), anthraquinone dye can be used to give a bluish color.

Not only the liquid crystal panel but also organic E
Even in the case of using the L panel, it is possible to obtain a monochromatic display device in which the display color is within the above-mentioned region by coloring the constituent members such as the substrate and the face plate in the same manner as described above.

[Brief description of drawings]

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

FIG. 2 is a CIE chromaticity diagram showing a display color range 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 diagram illustrating density distribution.

FIG. 6 is a diagram for explaining an outline of constituent members of a liquid crystal panel.

[Explanation of symbols]

1 flat panel display 10 intensity modulation means 20 time modulation means 30 Area modulation means 40 LCD panel (display device) 50 controller 60 LCD 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 Diffuser 75 face plate

Continuation of the front page (51) Int.Cl. ⁷ identification code FI G09G 3/20 680 G09G 3/20 680W 3/30 3/30 K (58) Fields investigated (Int.Cl. ⁷ , DB name) A61B 6 / 00-6/14 A61B 8/00-8/14 G09G 3/00-5/40 G09F 9/00-9/46

Claims (4)

(57) [Claims] 1. A flat panel display using a flat panel display device, wherein 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), (0.4, 0.4), (α, 0.4) is a device for monochromatic display that outputs within the area surrounded by
In addition, it consists of many cells and is a monochrome image.
A pixel can be represented by a plurality of the cells, and input signals to the plurality of cells are independently turned on / off.
Area for controlling the output brightness for one pixel by
Modulation means, time modulation for independently driving each cell in time division
Means, and the input signal level to each cell is independently controlled.
At least one of the intensity modulating means
For example, the maximum luminance range per the pixel 100 cd / m @ 2 or less
A flat panel display characterized by having a top of 10,000 cd / m 2 or less . (However, α is the spectral locus and the coordinate value in the y-axis direction is 0.
(Coordinate value in the x-axis direction represented by the intersection with the straight line that is 4) 2. The maximum luminance range per pixel is 50
0 cd / ^{m 2} or more 5000 cd / ^{m 2} flat panel display of claim 1, wherein follows the thing. Wherein the display device, according to claim 1 or 2 display as claimed characterized in that it is a liquid crystal panel. Wherein said display device, according to claim 1 or 2 flat panel display, wherein the organic EL panel.