JP2511071B2 - Driving method for color display device - Google Patents

Description

The present invention relates to a driving method of a color display device which is a means for transmitting visual information. More specifically, it relates to a driving method of a color display device using a Fabry-Perot type variable interference device as a variable color selection means.

<Prior Art> Color display is very effective as a means for transmitting character information or image information from a machine to a human, and various color display devices are widely used in various information processing fields and others. There is. To give a simple example, there is a color pilot lamp that displays the operating state of machinery such as green when it is normal and red when it is abnormal. Examples of complex ones are color CRT displays and color liquid crystal displays that display images or the output of computer-based equipment.

Most of such various color display devices have a structure in which light sources of fixed colors, that is, red, green, and blue, light-emitting bodies, or display bodies such as filters are combined. With such a configuration, it is impossible to directly display colors other than the fixed color emitted by the display body, and thus various colors are displayed by the following method. That is, each display body is arranged closer than a distance that can be separated by the spatial resolution at the time of visual observation of the color display device, and the light intensity of each display body is set according to the displayed color. It was

In a conventional color display device using a fixed color display body, three types of display bodies (red, green and blue) are required to display one pixel emitting any color. for that reason,
It had the following problems.

One is that the number of display units is three times the number of pixels, so
This means that the entire color display device is inevitably complicated and expensive as compared with the case of the pixel 1 display body. Among them, for a color liquid crystal display that requires wiring for each display body, the number of wirings is three times the number of pixels, and the configuration is further complicated.

The second problem is that when the viewer approaches the conventional color display device, the fixed color of the display body is visible in addition to the color to be displayed. For example, a viewer is considerably close to a color display device used as a computer output terminal in order to read characters and the like. Therefore, if a white fine vertical line is displayed on the color display device, a phenomenon occurs that the left side of the line is reddish and the right side is bluish due to the fixed color display body. , The colors that should be displayed are not displayed correctly.

<Problems to be Solved by the Invention> In order to solve these problems, the present invention proposed a color display device using a Fabry-Perot type variable interference device (Japanese Patent Application No. 62-34911). This is basically the light emitted from the light source is incident on the Fabry-Perot type variable interference device,
Therefore, by selectively transmitting only light of a specific color, various primary colors, namely purple, blue, blue green, green, yellow, orange,
It displays red or the like. Since such a new color display device has one pixel using one variable color filter, that is, a Fabry-Perot type variable interference device, the configuration is simple as compared with the conventional color display device.
It has an advantage that high quality color display without color bleeding can be realized.

This color display device can display only the hue among the three elements of color, that is, the hue, the saturation, and the lightness, by the normal static driving method. The driving method of the above device for enabling display of any color with respect to hue and saturation is that primary colors that can be represented by the above device, for example, three colors of blue, green, and red are determined from the color discrimination limit time of the visible person. The basic principle is to display a color having an arbitrary hue and saturation as a mixture of the primary colors by repeatedly switching and changing at a fast cycle.

However, the driving method of the color display device described above cannot display the brightness. Therefore, the present invention makes it possible to display any brightness in a color display device using a Fabry-Perot type variable interference device.
The aim is to display the full three elements of color.

<Means for Solving the Problem> In the method for driving a color display device of the present invention, two reflective films formed by superimposing a light-semitransmissive reflective film on a transparent body are arranged such that the reflective films face each other. , A Fabry-Perot type variable interferometer comprising a color conversion mechanism for changing the distance between the reflection films or the refractive index between the reflection films according to an applied electric signal, and a light source having an emission spectrum in the visible region,
A driving method for a color display device, comprising: a drive circuit for the color conversion mechanism, wherein the light from the light source is color-displayed through the Fabry-Perot type variable interference device. The drive circuit drives the color conversion mechanism so as to repeatedly switch between a case where the wavelength having the maximum reflectance is included in the visible region and a case where the wavelength is not included in the visible region in a time cycle shorter than the color identification time of the viewer. It is characterized by

In addition, the variable interference device has three types of black, red, green and blue.
Display any color by temporal mixing of the primary colors.

<Operation> According to the driving method of the color display device of the present invention, the wavelength that is selectively transmitted or reflected by the Fabry-Perot type variable interference device is faster than the visible image distinguishable time between the visible region and the invisible region. By repeatedly switching and changing the period, it is possible to obtain an arbitrary brightness depending on the ratio of the time that the wavelength exists in the visible region.

<Examples> Hereinafter, the present invention will be described in detail based on Examples. First
FIG. 1 is a block diagram of a color display device used in the first embodiment of the present invention. Light source 1 having an emission spectrum in the entire visible region
The light output by the lens 2 becomes parallel rays by the lens 2,
The light is transmitted through the Fabry-Perot type variable interference device 3 that functions as a variable color filter, and diffused in various directions by the diffusion plate 4. The voltage V applied to the Fabry-Perot type variable interference device 3 is supplied from the drive circuit 5.

In FIG. 1, color display is performed by using the light transmitted through the variable interference device 3.
The light reflected after being incident on may be used, and color display is performed by using the transmitted scattered light of the diffuser plate 4. Regarding this, the reflected scattered light scattered when reflected by the variable interference device 3 is also used. You may use.

Here, as the light ray 1, an incandescent lamp, a halogen lamp,
A xenon lamp or a fluorescent lamp can be used. The shape of the light source 1 may be a dot shape, a linear shape, or a planar shape. The lens 2 is used to convert the light output from the light source 1 into parallel rays and make them incident on the variable interference device 3 at the same incident angle. The reason why parallel rays are incident on the variable interference device 3 is that the wavelength at which the spectral transmittance of the variable interference device 3 is maximum depends on the incident angle. As the lens 2, a glass lens, a plastic lens, a distributed index type lens, a Fresnel type lens, or the like can be used. Instead of the lens, a reflecting mirror such as a spherical mirror or a parabolic mirror may be installed on the back surface of the light source 1 (direction opposite to the variable interference device 3). Incident light to the variable interference device 3 can be made nearly parallel by separating the light source 1 from the variable interference device 3 without using the lens 2 or the reflecting mirror.

As the diffusion plate 4, a light-scattering object such as frosted glass or a micro prism array is used. This scatters the light emitted from the variable interference device 3 in various directions, and thus serves to widen the place where the viewer can see the color display device. If the position of the viewer can be regarded as constant, the diffuser plate 4 can be omitted.

The principle of the Fabry-Perot type variable interference device will be described below.

This interferometer utilizes interference due to repeated multiple reflection of light between opposing reflecting films, that is, Fabry-Perot interference. Due to this interference, the transmittance (or reflectance) of light is wavelength-dependent, and exhibits high transmittance at a specific wavelength and low transmittance at other wavelengths.

The wavelength at which the spectral transmittance of the interference device becomes maximum, that is, the central wavelength λp, is mainly determined by the distance d between the opposing reflecting films and the refractive index n of the medium between the reflecting films. In other words, the central wavelength λp is the optical path length nd (product of n and d) of the variable interference device.
Is proportional to Here, assuming that the center wavelength λp is the first-order Fabry-Perot interference peak, and ignoring the effect of the characteristics of the reflective film on the Fabry-Perot interference, the center wavelength λp is represented by the next color.

λp = 2nd Here, when the medium is air, nitrogen, or vacuum, the refractive index n = 1 can be set, and at this time, λp is 4000 to 7800.
If it is changed in the entire visible region of Å, the reflective film interval d needs to be changed in the range of 2000 to 3900Å (actually, since the above formula is an approximate formula ignoring the effect of the reflective film characteristics, d The range of change is slightly different from the one listed here). On the contrary, the center wavelength λp can be changed by keeping d constant and changing n. For example PLZT (Pb, La, Z
Fabry-Perot type, which is rich in high speed and easy to manufacture, by using a material that has a so-called electro-optical effect in which the refractive index changes according to the applied voltage, such as ceramics (compound of r, Ti, O) A variable interference device can be realized.

Next, the structure and optical characteristics of the Fabry-Perot type variable interference device 3 used in this embodiment will be described. In this method, the center wavelength λp is made variable by making the reflection film interval d variable, and as a method therefor, a method using an electrostrictive effect and a method using an electrostatic attractive force were examined.

FIG. 2A is a sectional view of a variable interference device utilizing the electrostrictive effect. The principle of this variable interference device is disclosed in Japanese Patent Application Laid-Open No. 58-17.
It is already known from No. 3439. Semi-transmissive reflective films 13a and 13b are vapor-deposited on the central portions of the flat glass plate 11 and the glass plate 12 having a step around the periphery. As the reflection films 13a and 13b, metal films such as silver and aluminum, TiO ₂ , SiO ₂ , ZnS, Mg
A dielectric film such as F ₂ or a multilayer film thereof can be used. The glass plates 11 and 12 are connected via a spacer 14 so that the reflection films 13a and 13b face each other. The spacer 14 is made of an electrostrictive material, and when a voltage is applied via a lead wire from the drive circuit 5 associated with each variable interference device between the electrodes 15a and 15b on both ends of the spacer 14, the spacer 14 responds to the voltage. To expand and contract. By the expansion and contraction of the spacer 14, the distance between the glass substrates 11 and 12 and the opposing reflecting films 13a and 13b 2
Changes. Here, PZ is used as the electrostrictive material of the spacer 14.
Many materials such as T (compound of Pb, Zr, Ti, O) PVDF (polyvinylidene fluoride) ZnO can be used.

FIG. 2 (b) is a cross-sectional view of a Fabry-Perot type variable interferometer utilizing electrostatic attraction applied in Japanese Patent Application No. 61-102989. Metal films 23a and 23b such as silver are vapor-deposited on the relatively thick glass plate 21 and the relatively thin glass plate 22, respectively, and the two glass plates 21 and 22 are bonded to each other via a spacer 24. The metal films 23a and 23b also serve as semi-transmissive reflection films and electrodes for applying electrostatic force. Drive circuit 5 to metal film 23
When a voltage V is applied between a and 23b, the electrostatic attraction F bends the central portion of the glass substrate 22 and the metal films 23a and 23b.
The interval of is reduced. Not only the electrostatic method shown here, but also the cavity type Fabry-Perot interferometer that changes the distance between the opposing reflecting films by supporting both ends with fixed length spacers and applying a force to the central part Can be used for.

FIG. 3 shows the following spectral transmittances when the voltages V ₀ , V ₁ , V ₂ , V ₃ and V ₄ were applied to the Fabry-Perot type variable interference device having the above structure. For reference, the luminosity curve is shown by a chain line in FIG. From this figure, it can be read that the Fabry-Perot type variable interference device transmits blue, green and red lights respectively when voltages V ₁ , V ₂ and V ₃ are applied.
Further, when the voltage V ₀ is applied, the center wavelength is in the ultraviolet region, so that the color becomes slightly purplish black. When the voltage V ₄ is applied, the two central wavelengths are in the ultraviolet region and the infrared region, respectively, and the color thereof is slightly reddish purplish black. Therefore, either V ₀ or V ₄ can be used to display black.

The method of driving the variable interference device according to the present invention will be described below with reference to FIG. 4 (a), (b),
In (c), the horizontal axis represents time and the vertical axis represents the voltage applied to the variable interference device. FIG. 4 (a) shows a case where the voltages V ₀ , V ₁ , V ₂ and V ₃ are applied for a certain period of time between the surroundings T ₁ and repeated. Here, the cycle T ₁ is set to 1/60 seconds so that the time can be shorter than the color distinguishable time of the viewer. This color display device displays black, blue, green, and red at each application time of the voltages V ₀ , V ₁ , V ₂ , and V ₃ , and the
You will be able to see colors that are a mixture of the colors according to their display time. In the example of FIG. 4 (a), since the blue display time is longer than the green and red display times, bluish white (light blue) is displayed, and the brightness is about half of the display time. Since it is, it has an intermediate brightness. Fourth
In the diagram (b), the order of voltage application during one cycle T ₁ is V ₀ , V ₁ ,
V ₀ , V ₂ , V ₀ , V ₃ but the total display time of V ₀ and V ₁ ,
The display time of V ₂ , V ₃ is V ₀ ,
Since it is equal to the display time of V ₁ , V ₂ and V ₃ , the display color is the same as in FIG. 4 (a). There is also a method of continuously scanning the applied voltage as shown in FIG. 4 (c). Any method can be used to display an arbitrary color.

Next, a second embodiment of the present invention will be described. FIG. 5 is a block diagram of the color display device used in the second embodiment.
In this embodiment, 64 variable interference devices are arranged in 8 rows and 8 columns to display various characters. The light emitted by the light source 1 and collimated by the lens 2 passes through the variable interferometer matrix 30 and is diffused by the diffuser plate 4. Here, the light source 1 and the lens 2 may be arranged in a total of 64 corresponding to each variable interference device. By doing so, the depth of the color display device can be reduced and the light of the color display portion can be reduced. It is easy to suppress unevenness in strength.

On the variable interference device matrix 30, 64 driving circuits associated with each variable interference device are installed. Each variable interferometer is connected to each drive circuit, for example, as shown in FIG.
Alternatively, a time division signal for displaying black, red, green and blue is sent as shown in (b). Wirings from the color signal transmission circuit 51 and the vertical scanning circuit 56 are connected to each driving circuit. FIG. 6 is an explanatory diagram for explaining this drive circuit system. Focusing on the variable interference device T ₂₁ in this figure, it operates by receiving a signal from the drive circuit D ₂₁ . This drive circuit D ₂₁ corresponds to the drive circuit 5 in the first embodiment. The color signal transmission circuit 51 sends the data about the color to be displayed to the drive circuit D ₂₁ through the wiring X ₂ . However, this data is not sent continuously. When the vertical scanning circuit 56 gives a read signal to the wiring Y ₁ , the gate element G ₂₁ is turned on, and the wiring X ₂ and the driving circuit D ₂₁ are turned on.
And are connected. At that time, the data is the color signal transmission circuit
Applied to circuit D ₂₁ from 51. The applied signal is held inside the drive circuit D ₂₁ until the gate element G ₂₁ turns off and then turns on again. When a read signal is applied to the wiring Y ₁ , the gates G ₁₁ , G ₂₁ , G ₃₁ ... Are all turned on, and data is given to the drive circuits D ₁₁ , D ₂₁ ,. At this time, no read signal is given to the wirings Y ₂ , Y ₃ . Next, when a read signal is applied to the wiring Y ₂ , 2
Data is given to the drive circuits D ₂₁ , D ₂₂ ... In the row. An image of one frame (one pixel) is given to each drive circuit Dij (i = 1,2, ... 8, j = 1,2, ... 8) every time the above scanning is completed. Here, although each gate Gij and each drive circuit Dij may be configured by individual circuit components, it is more advantageous in terms of cost, miniaturization, etc. to configure by a TFT (thin film transistor).

By making the number of variable interference devices, that is, the number of pixels, of this color display device even larger, for example, 640 × 400, it is possible to obtain a high-definition color display device, which is particularly suitable for computer application equipment. .

Next, a color numeral display device used in the third embodiment of the present invention will be described. When the number to be displayed is limited to numbers and letters, by devising the shape and arrangement of the display, it is possible to display numbers and letters with a smaller number of displays than the matrix arrangement. Become. Seventh
The figure is an external view of a color number display device used in this embodiment. In this display device, eight variable interference devices are used for each digit. Seven of them have an elongated display shape and are combined in the shape of a "day", and "0"
Up to "9" can be displayed. The remaining one variable buffer displays a dot representing the decimal point.

Although the background portion of the display device, that is, the periphery of the variable interference device may have any color, it is black in this embodiment.
When set to black, when the color display is switched off,
This is convenient because the display bodies (variable interference device) 1a to 1h are almost invisible. When the numeral "1" is displayed in the first digit of the display device, the variable interference devices 1a to 1h in FIG. 7 are driven so that, for example, 1b and 1c are light blue, and the others are black. To be done. As shown in FIG. 4 (a) or (b), the drive signals of 1b and 1c are time-division signals of four kinds of voltages displaying black, red, green, and blue, and drive signals of other interference devices. Is a continuous voltage V ₀ .

Since the display device of this embodiment has a variable display color, some new display methods are conceivable.

One is a method of changing the display color according to the type of the displayed numbers. For example, in a multifunction clock, time, date,
Different display colors can be used for each function such as alarm set time. This makes it easy to understand the distinction between the functions.

The second method is to change the display color according to the size of the displayed numerical value. For example, with a thermometer attached to a certain device,
If the temperature of the device is above 80 ℃, you need to be careful,
If it is overheated at 0 ℃ or higher, the thermometer display color is green up to 80 ℃, yellow at 80-100 ℃, and red at 100 ℃ or higher. In this way, by changing the display color according to the size of the numerical value, the size of the numerical value can be easily grasped visually.

As described above, the color numeric display device is used as a color display device for input / output of various instruments such as a clock, a thermometer, a speedometer, a tachometer (tachometer), an ammeter-voltmeter, and a weight scale, or a terminal of a computer. Extremely useful.

<Advantages of the Invention> As described above, the present invention is a color display device in which a light source and a Fabry-Perot type variable interference device are combined, and an arbitrary hue, saturation, This ensures a driving method capable of displaying a color having lightness.

According to the present invention, an arbitrary color can be displayed by using one display member for one pixel, so that the number of display members is 1 / thicker than that of a conventional color display device using a fixed color display member. 3
become. Therefore, a color display device having a simple structure can be obtained.

Further, in the present invention, since the fixed color display body is not used, color blurring does not occur even if the viewer sufficiently approaches.
Therefore, higher quality color display can be performed as compared with the conventional color display device.

Since the color display device using the present invention has the advantages as described above, from the simple operation display of various devices to the display of various instruments to the display of characters and graphics of electronic devices, especially computer-applied devices in the future. Expected to be widely used.

[Brief description of drawings]

FIG. 1 is a block diagram of a color display device used in the first embodiment of the present invention. FIG. 2 is a sectional view of the Fabry-Perot type variable interference device shown in FIG. FIG. 3 shows the spectral transmittance of the Fabry-Perot type variable interference device shown in FIG. 1 using the applied voltage as a parameter. FIG. 4 is an explanatory diagram for explaining a driving method of the color display device which is one embodiment of the present invention. FIG. 5 is a block diagram of a color display device used in the second embodiment of the present invention. FIG. 6 is an explanatory diagram for explaining a drive circuit system in the second embodiment of the present invention. FIG. 7 is an external view of a color display device used in the third embodiment of the present invention. 1 ... Light source, 2 ... Lens, 3 ... Fabry-Perot variable interference device, 4 ... Diffuser, 5 ... Driving circuit

Claims (2)

(57) [Claims] 1. Two reflective films formed by superimposing a light-semitransmissive reflective film on a transparent body are arranged such that the reflective films face each other,
A Fabry-Perot type variable interferometer comprising a color conversion mechanism for changing the distance between reflecting films or the refractive index between reflecting films according to an applied electric signal; a light source having an emission spectrum in the visible region; A method of driving a color display device, comprising: a drive circuit of a color conversion mechanism, for performing color display of light from the light source through the Fabry-Perot type variable interference device. Driving the color conversion mechanism by the drive circuit so as to repeatedly switch between a case where the wavelength having the maximum rate is included in the visible region and a case where the wavelength is not included in the visible region in a time cycle shorter than the color identification time of the viewer. And a method for driving a color display device. 2. The method for driving a color display device according to claim 1, wherein the variable interference device displays an arbitrary color by temporally mixing three primary colors of black and red, green and blue.