JPH0522888B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a color light valve device suitable as a light source for color displays, color printers, and the like. An example of a conventional optical modulator is disclosed in Japanese Patent Application Laid-Open No. 56-5523, but it requires the use of an optical crystal material to input polarized light. Furthermore, in order to improve the diffraction efficiency, restrictions are imposed on making the light incident on the electrode as parallel as possible. Further, a laser is often used as a light source for the light beam incident on such a modulation element. Alternatively, Japanese Patent Laid-Open No. 56-94377 discloses a light valve using liquid crystal, and like the above-mentioned Japanese Patent Laid-Open No. 56-5523, it is necessary to give predetermined polarization characteristics to the incident light beam. In this case, it is difficult to obtain a good erasure ratio. Therefore, forming a light source for obtaining a color image using the above-mentioned light modulation element has the disadvantage that the apparatus becomes complicated and the cost increases. SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks and provide a color light valve device that does not require a special light source such as a laser as a light source and can use a general white light source such as a halogen lamp. A further object of the present invention is to provide a color light valve device that does not require the light source to have polarization properties. A further object of the present invention is to provide a color light valve device that does not require any particular restriction on the direction of incidence of the light beam from the light source. The color light valve device according to the present invention includes a light modulation section that modulates light by creating a refractive index distribution in the medium by applying heat to the medium, a light source section that projects a light beam to the light modulation section, and a light source section that projects a light beam onto the light modulation section. A color filter is provided at a position through which the light beam that has undergone wavefront conversion in the modulation section passes, and by applying a predetermined amount of wavefront conversion to the incident light beam in the light modulation section, the modulated light beam passes through the predetermined color filter. It was designed to do so. Hereinafter, the present invention will be explained in detail using the drawings. FIG. 1A is a diagram showing an embodiment of a light modulation element using heat-induced refractive index change used in the present invention. In FIG. 1A, 1 is a transparent protective plate, 2 is a thin layer made of a thermal effect medium whose refractive index is easily changed by heat, 3 is a thermally conductive insulating layer, and 4 is 6
The heat generating resistor layer shown by a, 6b, 6c, 6d, . When the heating resistor generates heat, this heat is transmitted through the insulating layer 3 to the thin thermal effect medium layer 2, creating a temperature distribution within the thin liquid layer and forming a refractive index distribution. For example, as shown in FIG. 1, when the heat-generating resistor 6b is selected and generates heat, this heat is transmitted to the thin heat effect medium layer 2 via the insulating layer 3 adjacent to the resistor 6b, and the heat is transferred to the resistor 6b. The liquid in the opposing region of the thin thermal effect medium layer 2 is heated to form a refractive index distribution 7 in this region. This refractive index distribution 7
disappears after a predetermined period of time as the heat effect medium in this area cools. One cycle from the formation of this refractive index distribution to its disappearance is a very short time, and can be performed on the order of KHz. The heating resistors are formed on the support 5 using IC manufacturing technology, and the spacing between adjacent heating resistors is on the order of mμ. As the heat effect medium, water, alcohol, or any other liquid may be used. The refractive index temperature dependence ∂n/∂T of this liquid is −1.0×10 ⁻⁴ for water and −4.0×10 ⁻⁴ for ethyl alcohol. or,
As a solid material, a plastic material such as acrylic or polycarbonate, or a polymeric material such as an epoxy resin used as an adhesive is suitable. ∂n/∂T is approximately −1.0×10 ⁻⁴ for acrylic and approximately −1.3×10 ⁻⁴ for polycarbonate. FIG. 1B is a schematic perspective view showing the configuration of the light modulation element shown in FIG. 1A, and the numbered numbers 1 to 6 are the same as those shown in FIG. 1A. Reference numeral 8 denotes a conductive wire, which is connected to individual drive voltages so that the heating resistors 6a, 6b, . . . can be driven independently, while the other ends of the heating resistors are grounded or set to a common voltage. When a voltage signal is applied to each of the heating resistors 6a, 6b, . . . from the conductive wire 8, a refractive index distribution is generated in the thin layer of the thermal effect medium in the vicinity of each heating resistor.
When the voltage signal is reduced to zero, this refractive index distribution is cooled and returns to the original state without refractive index distribution. FIG. 2 is a diagram showing a transmission type light modulation element, and the structure of the light modulation element itself is the same as that shown in FIG.
6b', . . . and the insulating layer 3' are made of a transparent medium. In the above light modulation element, when the intensity of the voltage applied to the heating resistor is changed, the amount of heat generated by the heating resistor changes, and the refractive index distribution in the thermal effect medium in the vicinity of the heating resistor changes. The wavefront of the light flux also changes. FIG. 3 is a diagram explaining how the traveling direction of light changes, that is, is deflected, due to the above-mentioned refractive index distribution. Reference numerals 1 to 7 are the same members as explained in FIG. 1, and in this case, a light modulation element. It is assumed that all of the components are made of translucent materials as shown in FIG. In FIG. 3, when a white incident light ray 11 enters a part of the refractive index distribution 7 where the gradient of the refractive index change is particularly large, the direction of the light ray's emission changes, and the light ray is deflected and emitted as shown by 12. 10 is a filter 10a that passes red light, and a filter 10 that passes green light.
b, a color filter layer in which a filter 10c that passes blue light is disposed, and the emitted light beam 12 is
It passes through any one of the color filters 10a, 10b, 10c, and at that time, red,
It becomes monochromatic light, either green or blue. When the voltage applied to the heating resistor 6 is changed, the refractive index distribution 7 changes, and the refractive index gradient with respect to the incident light beam 11 also changes. Therefore, the direction of the outgoing light beam 12 also changes,
The color filters that the light passes through are different, and the color of the light rays finally emitted from the light modulation element also changes.
Therefore, by selecting the voltage input to the heating resistor 6, the emitted light 12 can be made to pass through a desired filter, and emitted light of a desired color can be obtained. FIG. 4 is a diagram showing another embodiment of the color light valve device according to the present invention. Numbers assigned to members shown in FIG. 4 that are the same as those in FIG. 3 represent the same members. In FIG. 4, the heating resistor 6
When no voltage is applied to , the incident light beam 11 enters the lens system 13 as an exit light beam 11' which undergoes no wavefront transformation. Thereafter, the light is blocked by a light blocking plate 14. On the other hand, when a voltage is applied to the heating resistor 6, the color filters 10a and 10b are
Alternatively, the color light passes through either of the light shielding plates 10c and reaches the observation surface 15 without being blocked by the light shielding plate 14. Therefore, flashing colored light is formed on the observation surface 15 by turning the applied voltage on and off. In the above embodiment, lens system 1
3 is not an essential requirement, and it is meaningful to separate modulated light and non-modulated light by the light shielding plate 13. FIG. 5 is a diagram showing another embodiment of the color light valve according to the present invention, in which the same numbers as those assigned to the embodiments described above indicate the same members. Fifth
In the figure, heating resistors 21, 22, and 23 are applied with predetermined voltages corresponding to different color video signals, and zero or a constant voltage is applied to each heating resistor. When no voltage is applied to each heating resistor, the passing light flux is blocked by the light shielding plate 14,
When a voltage is applied to any or all of the heating resistors 21, 22, and 23, the light beam incident on the refractive index distribution portion corresponding to each heating resistor is deflected,
The light passes through color filters 10a, 10b, and 10c, each of which has been installed at a predetermined position, and reaches the observation surface 15. This embodiment uses a predetermined constant voltage without changing the voltage applied to each heating resistor as in the previous embodiment, and
This improves the drawback of the previous embodiment that it is not possible to obtain a plurality of color lights at the same time. Therefore, in this embodiment, a plurality of color lights, that is, mixed color light, can be obtained at the same time. FIG. 6 is a diagram showing another embodiment of the color light valve device according to the present invention. In the drawings, the same numbers as in the previous embodiment represent the same members. 31,3
2 and 33 are heating resistors. When a predetermined voltage is applied to each heating resistor, a refractive index distribution is generated in the thermal effect medium 2 as described above, and the light beams deflected thereby are passed through the color filters 10a, 10a and 10a, respectively.
It passes through positions 10b and 10c. For example, a surface 15' containing the imaginary divergence origin of the light rays 16a and 17a passing through the color filter 10a.
By arranging a lens system 13 in which the observation surface 15 and the observation surface 15 are in a conjugate relationship, and by providing a light shielding plate 14 at the imaging point position of the incident light beam 11 by the lens 13, the light beam 1
6a and 17a reach the observation surface 15 without being deflected by the light shielding plate 14 and form an imaging spot 18. Imaging spots 19 and 20 are similarly formed for the other heating resistors. FIG. 7, FIG. 8, and FIG. 9 are diagrams showing other embodiments of the color light valve device according to the present invention,
Each figure shows changes in the direction of the emitted modulated light flux depending on how the heating resistor to which voltage is applied is selected. In addition, in the numbers attached to FIG. 7, FIG. 8, and FIG. 9, the same numbers as in the above embodiment indicate the same members. FIG. 7 is a diagram showing the state of emitted light when the voltages applied to the heating resistors 41 to 44 are applied for different times, that is, when voltages are not applied to two or more heating resistors at the same time. . As shown in FIG. 7, when a voltage is applied, the light beam that has passed through the refractive index distribution by the heating resistor 41 passes through the color filter 1.
Similarly, the light flux that has passed through the refractive index distribution of 42 passes through the color filter 10b, and the light flux that has passed through the refractive index distribution of 43 passes through the color filter 10.
c, the light flux that passes through the refractive index distribution by 44 is 1
A light modulation element is formed so that each light passes through 0c. Now, in FIG. 7, if voltage is applied to the adjacent heating resistors 41 and 42 at the same time, as shown in FIG. 8, there will be no independent refractive index distribution for each, and the two heating resistors will have one refractive index A distribution is formed. This can be realized by making the distance between the heating resistors 41 and 42 close. When the light beam 11 is incident on a portion of such a refractive index distribution, the light beam is deflected only at the end portions of the refractive index distribution, and the light beams 23 and 24 in the central portion thereof pass through without being deflected. In this case, the modulated light flux passes through the color filter 10a and the color filter 10b, and two types of light fluxes 21 and 22 having different colors are emitted. Next, when a voltage is applied to the heating resistors 42 and 43 at the same time, a refractive index distribution similar to that described above is created, and the emitted light is emitted in two types of colored light fluxes corresponding to the color filters 10b and 10c. Furthermore, heating resistor 4
When voltages 3 and 44 are applied at the same time, two types of colored light beams corresponding to the color filters 10c and 10d are emitted. Next, as shown in FIG. 9, when voltages are simultaneously applied to the heating resistors 41, 42, and 43, the refraction gradient increases only in the portions corresponding to both ends of the heating resistors 41 and 43, based on the same principle as described above. Only the light incident on the part is deflected, and the color filter 10a
and 10c. The light beam incident on the central portion is not deflected and is emitted as non-modulated light beams 25 and 26. For the embodiments shown in FIGS. 7 to 9, by using the same lens system 13 and light shielding plate 14 as shown in FIG. 6, any color or combination thereof can be formed on the observation surface 15. Observed. Now, assuming that the color filters 10a, 10b, 10c, and 10d are respectively red (R), green (G), blue (B), and white (W), the combinations of voltages applied to the heating resistors are shown in Table 1. You can get color combinations like this.

【table】

[Table] ○: Voltage application The heating resistors 41 to 44 in the above embodiment are used as color signal sources for one screen, and by arranging them periodically, one-dimensional multiple pixels or two-dimensional multiple pixels can be generated. A color signal source can be realized. FIG. 10 is a diagram showing an example of a one-dimensional array of multiple pixels, 101 to 104, 201 to 204,
301 to 304, . . . are the heating resistors 41 to 44, each serving as a color signal source for one pixel in the above embodiment, arranged periodically;
00 is an electrode connected to the voltage applying means, 5
00 is a ground electrode. The spacing between the heating resistors is such that when voltage is applied to adjacent heating resistors at the same time, the refractive index distribution will be the same as that explained in Fig. 8 or 9. , are arranged close to the heating resistor. FIG. 11 shows color filters corresponding to the heating resistor shown in FIG. 10, and R, G, B, and W are color filters of red, green, blue, and white, respectively, which are arranged periodically. Further, in the above-described embodiment of the present invention, a transmissive light modulation element has been described as an example, but for example, in the light modulation element in FIG. 7, 4 is an insulating layer and 3 is a light reflective layer. It is also possible to use a reflective light modulation element, and the same effect can be obtained as compared to a transmissive light modulation element. As described above, the color light valve device according to the present invention is different from conventional devices in that (1) the medium for deflecting light is a liquid such as water or alcohol, or an inexpensive material such as a polymeric material such as acrylic; (2) There are no restrictions on the angle of incidence of the light flux that enters the light modulation element, and the arrangement can be freely selected. (3) The light flux that enters the light modulation element can be left as natural light. (4) IC manufacturing technology allows It is possible to increase the density of the arrangement of the heating resistors or the electrode pattern around them. (5) Excellent effects such as a good extinction ratio can be obtained.

[Brief explanation of the drawing]

1A, B, 2 and 3 are diagrams for explaining the light modulation element used in the apparatus of the present invention, and 4.
5, 6, 7, 8, and 9 each show a color light valve device according to the present invention, and FIG. 10 shows a heat generating resistor array of the device according to the present invention. FIG. 11 is a diagram showing an embodiment of the color filter of the apparatus according to the present invention. 1... Transparent protective plate, 2... Thermal effect medium, 3...
Insulating layer, 4... Heat generating resistor layer, 5... Support, 6
...Heating resistor, 7...Refractive index distribution, 10...Color filter layer, 10a, 10b, 10c...
Color filter, 11... Incident light beam, 12...
Emission light beam, 13... Lens system, 14... Light shielding plate,
15...Observation surface.

Claims (1)

[Scope of Claims] 1. A medium whose refractive index changes depending on temperature, a heating means that applies heat to the medium and generates a refractive index distribution in accordance with the temperature distribution within the medium, and the refraction of the medium. irradiation means for irradiating a light beam to a location where the refractive index distribution occurs so as to be deflected by the refractive index distribution;
A color light valve device comprising: a color filter provided at a position through which a light beam deflected by the refractive index distribution of the medium passes. 2. A medium whose refractive index changes depending on temperature, a heating means that applies heat to the medium to generate a refractive index distribution in accordance with the temperature distribution, and a location of the medium where the refractive index distribution occurs. , irradiation means for irradiating a luminous flux so as to be deflected by the refractive index distribution;
control means for controlling the amount of heat given to the medium by the heat generating means, and selectively generating mutually different first and second refractive index distributions in the medium;
a color filter for forming first colored light provided at a position through which the light beam deflected by the first refractive index distribution of the medium passes; and a color filter that forms a first colored light beam deflected by the second refractive index distribution of the medium A color light valve device comprising: a color filter that is provided at a position through which a light beam passes and forms a second colored light having a different color from the first colored light.