JPS6248815B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color light modulation device used in color printers, color facsimiles, color display devices, and the like. More specifically, the present invention uses a multi-wavelength light source such as a white light source, and transmits the light from the multi-wavelength light source through an optical filter that can change the wavelength range through which it passes by controlling the applied voltage. The present invention relates to a color light modulation device capable of illuminating a photosensitive device to obtain a color image on a photosensitive device.

An object of the present invention is to realize a color light modulation device that has a simple overall configuration and can be constructed at low cost.

A color light modulation device according to the present invention includes a multi-wavelength light source, an electro-optic material substrate through which light from the light source passes, electrodes provided between the electro-optic material substrate,
A drive circuit including a variable power supply that applies a voltage to the electro-optic material substrate through this electrode, a color photosensitive means that is irradiated with light emitted from the electro-optic material substrate, and drives the voltage applied to the electro-optic material substrate. It is characterized in that a color image (including a positive image and a negative latent image) is obtained on the color photosensitive means by controlling the voltage to a predetermined voltage according to a color designation signal applied to the circuit.

FIG. 1 is a block diagram showing one embodiment of the present invention, and here an example of a color printer is shown. In the figure, 1 is a multi-wavelength light source such as a white light source, 2 is a mirror that converts the light from light source 1 into parallel light, and 31 is a filter that passes light in a specific wavelength range, and is used in combination with light source 1. However, depending on the type of light source, it may not necessarily be necessary. 32 is a lens, and 4 is an optical filter, into which a multi-wavelength light beam condensed by the lens 32 is incident. Reference numeral 5 designates a drive circuit for this optical filter 4, to which a color designation signal and a brightness signal (brightness/darkness) are applied via a control circuit 6, and a predetermined voltage corresponding to the color designation signal and a pulse corresponding to the brightness designation signal. Contains a variable power supply that outputs a wide signal. 71 and 73 are lenses, and 72 is an aperture disposed between each lens 71 and 72. These serve to convert the light emitted from the optical filter 4 into a point light source and then into parallel light, so that the light emitted from the optical filter 4
This is not necessarily necessary depending on the configuration of the exit surface.
Reference numeral 8 denotes a light scanning means, which here includes a mirror 81 and a mirror driving means 82 for swinging this mirror at a constant period.
and an fθ lens 83 that allows the reflected light from the mirror 81 to pass through and corrects scanning distortion at the scanning center and both ends. Note that instead of installing the fθ lens 83, scanning distortion may be eliminated by, for example, moving the lens 73 in the optical axis direction in synchronization with the mirror 81. 9
is a color photosensitive means to which the light beam from the optical scanning means 8 is irradiated, and for example, color photographic paper (positive type, negative type), color photosensitive drum, color display surface, etc. are used. Note that 60 is a temperature detection means for detecting the temperature of the optical filter 4, which is provided to eliminate the influence of the temperature of the optical filter 4, and its output signal is applied to the control circuit 6 to control the drive voltage. There is. This temperature detection means is not necessarily necessary. Alternatively, a part of the output light of the optical filter may be detected by a photodiode, and the temperature may be corrected by feedback control using the control circuit 6.

FIG. 2 is a perspective view showing an example of the optical filter 4 used in the device shown in FIG. In the figure, 41 is a plate-shaped electro-optic material substrate having an electro-optic effect such as the Kerr effect. This material substrate includes PLZT, LiNbO ₃ ,
BSO etc. can be used, but PLZT has a larger electro-optic constant than other materials, requires a lower driving voltage, and has a transmission wavelength range of 0.4 μm to 8 μm.
It is the most suitable because it operates not only in visible light but also in the far infrared region. 42 and 43 are Cr provided on the surface of the electro-optic material substrate 41 so as to sandwich it;
The electrode is made of Au or the like and is formed on the substrate 41 using a technique such as vapor deposition or sputtering.
The drive circuit 5 is connected to electrodes 42 and 43, and applies electricity to the electro-optic material substrate 41 via these electrodes.
A voltage of a predetermined magnitude corresponding to the color designation signal is applied for a time (pulse width) corresponding to the luminance signal.
45 and 46 are polarizers that sandwich the electro-optic material substrate 41 and are arranged in the path of light passing through the optical material substrate 41, including a polarizer 45 on the side where the light enters and a polarizer on the side where the light exits. Here, the polarization planes of 46 form an angle of 45° with the electric field direction (perpendicular to the electrode surface) in the optical material substrate 41, and an example is shown in which they are arranged orthogonally to each other (an example of orthogonal polarizers). . Note that the polarization planes of the polarizers 45 and 46 may be arranged parallel to each other (parallel polarizers), and depending on the shape of the electro-optic material substrate, these polarizers 4
5 and 46 are not necessarily required.

In the optical filter configured in this manner, a PLZT substrate is used as the electro-optic material substrate 41, and when a voltage is applied to the electro-optic material substrate 41 via the electrode, this is caused by the electric field generated in the material substrate. The operation will be explained based on the assumption that the property (Kerr effect) in which a phase difference occurs between the polarized light component perpendicular to the electric field and the light polarized light component parallel to the electric field is used.

Now, in FIG. 2, when non-monochromatic light (multi-wavelength light flux) is incident on the optical material substrate 41 from the polarizer 45 side, this incident light
Due to the Kerr effect, a phase difference occurs between the polarized light component perpendicular to the electric field and the light polarized light component parallel to the electric field, which passes through the polarizer 46 and becomes emitted light.

Here, the ratio (light transmittance) between the incident light Ii and the output light Io to the electro-optic material substrate that has passed through the polarizer is expressed by the following equation, assuming that there is no optical loss due to the optical material substrate 41. Can be done.

For orthogonal polarizers: Io/Ii=Sin ² (πn ³・R・L/2λD・V ₂ )
...(1) For parallel polarizer: Io/Ii=Cos ² (πn ³・R・L/2λD・V ₂ )
...(2) However, n: refractive index R: Kerr constant V: applied voltage λ: wavelength of light D: distance between electrodes L: optical path length in electro-optic material substrate FIG. 4 is a characteristic diagram in which the relationship between the voltage applied between 42 and 43 and the light transmittance Io/Ii was investigated with different wavelengths of incident light. Here n≒2.5, R=3.0x10 ^-16
m ² /V ² , D=380 μm, and L=5 mm. From this experimental result, when the applied voltage is 50V or less, each wavelength of light exhibits almost the same transmittance characteristics, but when the applied voltage exceeds 90V, each wavelength exhibits different transmittance characteristics. It has been recognized that it can last a long time.

FIG. 4 is a characteristic diagram showing the relationship between the wavelength of transmitted light and the light transmittance using the applied voltage as a parameter. Here, the applied voltage is 90V, 100V, 110V
The experimental results showed that by controlling the applied voltage, the wavelength region of light passing through could be changed. In other words, at an applied voltage of 90V, the wavelength is 440n.
With an applied voltage of 100 V, specific light with a wavelength of about 550 nm can be passed, and with an applied voltage of 110 V, specific light with a wavelength of about 650 nm can be passed. Therefore, in FIG. 2, by changing the value of the voltage V applied between the electrodes 42 and 43, the wavelength range of the light passing through can be arbitrarily set.

FIG. 5 is a characteristic diagram showing the voltage dependence of the hue of emitted light on a chromaticity diagram in the optical filter of FIG. 2. Here, the applied voltage V was gradually increased from 40 V to 160 V, and as is clear from this diagram, by setting the applied voltage V to an arbitrary value, the hue of the emitted light can be changed. can be set within a predetermined range.

Also, here, with a voltage of a predetermined magnitude,
By controlling the application time (pulse time width), the amount of light passing through a certain period of time changes, so the brightness (brightness) can be controlled without changing the hue.

Returning to FIG. 1, an example of the operation will now be described with reference to the waveform diagram of FIG. 6.

The drive circuit 5 includes, for example, a ROM (read only memory), in which the most appropriate voltage signals corresponding to each hue of light emitted from the optical filter 4 are stored in advance. this
Storage in the ROM is performed, for example, in accordance with a characteristic line showing voltage dependence expressed on a chromaticity diagram as shown in Fig. 5. Within the range of the moving point, a plurality of various hues can be arbitrarily set by using a predetermined voltage.

The drive circuit 5 is given a color designation signal from the control circuit 6, and applies a predetermined voltage to the optical filter 4 according to the color designation signal. In other words, when using an optical filter with voltage dependence as shown in Figure 5, in the case of white,
It outputs a voltage of 50V for T hours, and when it is red it outputs a voltage of 75V for T hours, and when it is green, it outputs a voltage of 75V for T hours.
A voltage of 125 V is output for a time T and is applied to the electro-optic material substrate 41 of the optical filter 4 as shown in FIG.

Further, a brightness signal is given to the drive circuit 5, and by controlling the time for applying the voltage of the predetermined magnitude according to the brightness signal, the transmittance of light is changed together with the color, and the brightness is changed. That's what I do. For example, if the color is blue and has a dark brightness, a voltage of 90 V is applied for t ₁ time (t ₁ <T) as shown in FIG.

In this way, the hue and brightness of the light from the multi-wavelength light source that passes through the optical filter 4 is controlled by the magnitude and application time of the applied voltage, and this light passes through the lenses 71 and 72. The color photosensitive means 9 is linearly scanned by the optical scanning means 8 . The color photosensitive means 9 is extended in the direction of the arrow b perpendicular to the scanning direction of the light beam (arrow a), and it is possible to obtain a color image or color latent image formed by a collection of dots on the color photosensitive means 9. can.

FIG. 7 is a block diagram showing another embodiment of the apparatus according to the present invention, showing an example of a color printer.

In this embodiment, the optical filter 4 has a plurality of (two examples are shown here) electro-optic material substrates 41a and 41b arranged in the direction of propagation of light, and the space between each optical material substrate and the light Polarizer 4 so that the plane of polarization is parallel to the incident plane and the output plane, respectively.
5, 46, and 47 are arranged.
Then, electrodes 42a, 43a and electrodes 42 provided on each optical material substrate 41a, 41b are provided.
Predetermined voltages Va and Vb, which change in accordance with the color designation signal, are applied via the terminals b and 43b. Here, each electro-optic material substrate 41a,
The ratio of the predetermined voltages Va and Vb applied to 41b (Va/
Vb) is maintained at a constant ratio as described below. Further, in this embodiment, the optical scanning means 8
For example, a color photosensitive paper 9 is installed on an inner wall surface, and a rotating drum 80 that rotates and moves at a constant speed in the direction of the arrow b, and a color photosensitive paper 9 that is installed inside the rotating drum 80, which receives light from a lens 73. The structure includes a mirror 85 and a lens 86 for guiding. Further, in this embodiment, an optical modulator 40 that modulates (brightness modulates) the light from the optical filter 4 is arranged on the output surface side of the optical filter 4. Here, the optical filter 4 and
Brightness (brightness) is controlled by a light modulator 40.

The operation of the apparatus configured as described above will be explained below, focusing mainly on the operation of the optical filter 4.

Figure 8 shows an optical filter with a parallel polarizer configuration consisting of one electro-optic material substrate, with the voltage applied to the electro-optic material substrate being 106V (solid line),
It is a characteristic diagram examining the relationship between the wavelength of passing light and light transmittance when the voltage is 150V (broken line). When two optical filters with such characteristics are arranged one on top of the other, the overall optical characteristics will be the product of the two characteristics.

The optical filter 4 used in the device shown in FIG.
106V), the second electro-optic material substrate 41b has a voltage
When Vb (for example, 150V) is applied, the overall optical characteristics of this optical filter 4 are as shown in FIG.
The band width becomes narrower and the separation characteristics are improved. In this characteristic diagram, each voltage Va,
When Vb is changed, in the characteristic diagram in Figure 9,
By moving the center wavelength of the bandwidth in parallel and controlling the voltage, the hue of the light emitted from the optical filter 4 can be arbitrarily set without causing color shift.

This driving method uses an applied voltage that matches the transmission characteristics of each of the two optical filters with the desired wavelength (bandpass filter), but as another example of driving, one optical filter can be moved to the desired wavelength band. A pass filter may be used, and another optical filter may be operated as a band reject filter that removes side bands of the band pass filter. In this case, the applied voltages Va and Vb corresponding to each hue are stored in the ROM of the drive circuit 5 and are read out sequentially.

Returning to FIG. 7, the optical filter 4 and the optical modulator 4
The brightness-modulated color light with a predetermined color passing through 0 becomes parallel light beams by lenses 71 and 73 and an aperture 72, and is converted into parallel light beams by a mirror 85 and a lens 8.
6 onto color photosensitive paper 9. Note that the optical modulator 40 is driven by the drive circuit 5, and its light transmittance changes in accordance with the luminance signal. The color photosensitive paper 9 is rotated by a drum 80 and moved in the direction of arrow b, and the light irradiated thereon is scanned to create a color image.

The device configured in this way includes an optical filter 4
It emits color light with no color shift, making it possible to obtain clear color images. In the apparatus shown in FIG. 7, the optical modulator 40 may be omitted and the brightness modulation may be performed by changing the pulse width (time width) of the voltages Va and Vb applied to the optical filter 4. good. Also lens 71
The light converged by the lens 86 may be guided to the lens 86 using an optical fiber. In addition, as an optical scanning means, a seventh
A mirror like the one used in the figure or a polyhedral polygon mirror may also be used.

FIG. 10 is a perspective view showing still another embodiment of the device according to the present invention.

In this embodiment, the optical filter 4 has a plurality of optical paths arranged in a direction perpendicular to the direction in which the light travels, so that color light beams can be emitted from a plurality of locations arranged in a direction perpendicular to the direction in which the light travels. In this embodiment, an optical filter array structure is used, and the optical scanning means is omitted. That is, in FIG. 10, 1 is a rod-shaped multi-wavelength light source, and 2 is a parabolic mirror, from which a sheet-shaped light beam is incident on the optical filter array 4.

FIG. 11 is a perspective view showing an example of the optical filter array 4. As shown in FIG. This optical filter array 4 consists of one flat electro-optic material substrate 41.
A common electrode 43 is provided on one surface, and a plurality of strip-shaped electrodes 42 are provided on the other surface, arranged parallel to each other in the longitudinal direction (direction perpendicular to the direction in which light travels). The space between each strip-shaped electrode 42 and the common electrode 43 constitutes an optical path of each optical filter. The optical paths of these optical filters are arranged parallel to a direction (longitudinal direction) perpendicular to the direction in which light travels.

Returning to FIG. 10, each optical filter of the optical filter array 4 is supplied with a signal of a predetermined voltage and a predetermined pulse width from the drive circuit 5, respectively, and the light from there is transmitted to the rod lens array 70.
The light is irradiated onto the color photosensitive drum 9 via. The rod lens array 70 is the optical filter array 4
The function is to focus the light emitted from the beam into a beam, and this is not necessarily necessary. The color photosensitive drum 9 rotates at a constant speed, and a color image or color latent image is obtained here. Note that color photosensitive paper or a color display surface may be installed here.

In this embodiment, the optical filter array 4 may have a structure in which a plurality of electro-optic material substrates are arranged in the direction of propagation of light, as shown in FIG. Further, a light intensity adjustment array may be provided separately for modulating the brightness of light.

In each of the above embodiments, the drive circuit 5 and the control circuit 6 are conceptually shown as separate blocks, and the control circuit 6 provides a color designation signal and a brightness designation signal to the drive circuit 5; The circuit may be composed of, for example, a microprocessor including a memory circuit, and in this case, these can be represented by one block.

Conventionally, when trying to obtain a color image, it was common to separate a given hue into the three primary colors of red, green, and black and mix these color lights to obtain the desired color. , at least three systems of optical signal processing means are required, making the configuration complicated. The device according to the present invention includes an optical filter in which the hue and brightness are controlled by the magnitude of voltage and application time, and in which light travels through a portion sandwiched between electrodes, and color light from the optical filter is irradiated. The color light modulation device has a simple overall configuration, can be constructed at low cost, has high resolution, and can control brightness without causing color shift.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
The figure is a structural perspective view showing an example of the optical filter used in the device shown in Fig. 1, and Figs. Figure 4 is a diagram showing the relationship between applied voltage and light transmittance; Figure 4 is a diagram showing the relationship between wavelength of passing light and light transmittance using applied voltage as a parameter;
The figure is a line diagram showing the voltage dependence of the hue of the emitted light on a chromaticity diagram, FIG. 6 is a waveform diagram for explaining the operation of the device shown in FIG. 1, and FIG. 7 is a diagram showing other devices according to the present invention. 8 and 9 are characteristic diagrams for explaining the operation of the optical filter used in the device shown in FIG. 7, and FIG. 8 shows the relationship between applied voltage and light transmittance. A diagram showing the relationship, Figure 9 shows the voltage relationship shown in Figure 8 for the optical filter in Figure 7.
A diagram showing the relationship between the wavelength of passing light and light transmittance when Va and Vb are applied, FIG. 10 is a perspective view of the configuration of yet another embodiment of the device according to the present invention, and FIG. 11 is the diagram shown in FIG. FIG. 2 is a perspective view showing an example of an optical filter array used in the device. DESCRIPTION OF SYMBOLS 1...Multi-wavelength light source, 2...Mirror, 4...Optical filter, 5...Drive circuit, 8...Light scanning means,
9...Color photosensitive means.

Claims (1)

[Scope of Claims] 1. A multi-wavelength light source, an electro-optic material substrate through which light from the multi-wavelength light source passes, and electrodes provided on the electro-optic material substrate so as to be sandwiched therebetween in the thickness direction perpendicular to the traveling direction of the light. an optical filter that changes the hue of light according to a voltage applied to the electro-optic material substrate through this electrode, a color designation signal and a brightness signal are given, and a predetermined color designation signal is applied to the electro-optic material substrate. A color light modulation device comprising: a drive circuit that applies a voltage of a magnitude to an electrode of the optical filter for a time corresponding to the luminance signal; and a color photosensitive means to which color light emitted from the optical filter is irradiated. 2. The optical filter is constructed by arranging a plurality of electro-optic material substrates in the direction of propagation of light, and a voltage having a predetermined relationship is applied to each electro-optic material substrate in accordance with the luminance signal. 2. The color light modulation device according to claim 1, wherein the light is applied for only a certain period of time.