JPS6234118A - Optical modulating device - Google Patents

Abstract

PURPOSE:To modulate with a large number of gradations by providing an element where numbers of oscillatory mirrors deflecting luminous flux from a light source in at least two directions are arrayed, a filter device for modulating luminous flux deflected by said element with different characteristics corresponding to the deflection directions, and a means which converges the deflected luminous flux. CONSTITUTION:The light from the light source 21 is passed through a convex lens 22, a slit plate 23, and a convex lens 24 and reflected by bending mirrors 25 and 26 to strike a defomable mirror device (DMD)27. At this time, the illumination luminous flux is stopped down by a slit plate 23 to reach only the DMD27. The DMD27 reacts the the signal electromechanically and a mirror oscillatory part oscillates. The light A emitted by the light 21 lights the mirror array part of the DMD27 in a slit shape and when individual mirror oscillatory parts for the mirror array on the DMD27 is off, the light A travels in the direction of reflected C from the mirror and is cut off a light shield plate 31, so it does not reach a photosensitive body 32. When the mirror oscillatory part is on, the light is reflected according to an applied voltage and enters the filter device 29.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light modulation device, and particularly to a light modulation device that uses an electromechanical transducer having a large number of fine swinging mirrors to generate an image based on image information such as an electrical signal. The present invention relates to a light modulation device suitable for forming a light pattern corresponding to information.

[Conventional technology]

An example of an electromechanical transducer having a minute oscillating mirror is a DMD (Deformable Mirror).
Device) is known.

Regarding DVD, IEEE Tran3action
on FJelectronDevice Vol.
It is described in ED-30A3544 (1983), and the optical system is also disclosed in Japanese Patent Application Laid-Open No. 59-17525.

The general mechanism of the DMD will be explained below based on the drawings.

FIG. 5(,) shows an enlarged sectional view of the DMD. Reference numeral 1 denotes a mirror structure, which is made of a material such as At or Ag, and serves to reflect incident light. 2 is a substrate that supports the mirror structure of 1 and is made of Au or the like. 3 and 4 are support members for 1 and 2, 3 is called a mirror contact, and in particular is used to receive a crest that performs electromechanical operation, and 4 is an insulating material of polyoxide St. 5 is a polysilicon gate MO
Type 8 FET transformer shows the role of the sostarter. 6
is an air gap, which has an air gap of 0.6 to several microns. 7
is floating, field plate, 8's N+7
Turning the transistor on and off from the 0-ting source
According to the information, a voltage is applied to the field plate at 70-ting of 7. 9 indicates an N+ drain. This is a MOS
Type FET) plays the role of Lannostar configuration.

10 is y-toxide, and 11 is a P-type silicon substrate.

FIG. 5(b) is an enlarged front view from the direction A of FIG. 5(,), in which 12 is an air gap, 13 is an electromechanically oscillating mirror swinging portion, and 14 is a base portion.

Reference numeral 15 indicates a mirror surface other than the mirror portion 13 on the DMD surface. A DMD is manufactured using a process similar to that of an IC or LSI.

FIG. 5(c) shows an electrical equivalent diagram of the DMD. 16 is 1
．． 2 shows the voltage vM applied to the mirror and support member of No. 2. 1
7 indicates the voltage V applied to 8. 18 shows the transistor configuration, 9 D (drain) signal, 5 G (
The voltage of vF becomes 8 due to the ON and OFF of the dirt) signal.
It is turned ON and OFF. At this time, the voltage vM is present between 1 and 2, and the potential difference between 1, 2 and 8 is ON, OF
It will be increased or decreased by the F' signal.

At this time, a force F according to the following formula is generated between 6 and 7 depending on the potential difference, and FctsuKVc' (K: incorporation V: potential Mα; constant F: bending force) Mirrors 1 and 2 are It is swung by the hinge part 14.

The left diagram in FIG. 5(a) shows the case where there is a large voltage difference between 1, 2, and 8, and the mirror swinging part 13 is bent from the hinge part 14, and due to this action, the incident light is transmitted to the mirror swinging part. It is reflected at an angle twice the deflection angle of 13.

On the other hand, when the voltage difference is small, as shown in the right diagram of FIG. Therefore, the incident light is a mirror shake!
41I will be reflected without touching 13.

The DMD electrically turns ON and OFF the mirror swing unit 13.
The oscillation is converted into ON and OFF states, and further converted into the deflection angle of light.

FIG. 6 is a partial cross-sectional view of the DMD 270, and 13 is a mirror swinging section. In the DMD 27, the arrangement of the mirror swinging parts 13 is such that two mirror swinging parts are arranged in one direction with the same length as the length of each mirror swinging part in that direction, as shown in FIG. A staggered pattern is formed in which two mirror oscillating part rows do not overlap in a direction perpendicular to the arrangement direction. The number of mirror swinging units 13 in the DMD 27 is, for example, about several dozen. Incidentally, the size of the mirror swinging section 13 is, for example, 10 μm×
It is about 10 μm.

As described above, a light modulation device is configured using an MD, and the light modulation device modulates light from a light source according to an input image information signal, and thus projects the modulated light onto a display panel to display an image. Alternatively, it has been put into practical use to record an image by projecting the modulated light onto a photoreceptor.

By the way, in the optical modulation device using MD as described above, the input signal which is image information is usually a digital signal. That is, as explained with reference to FIG. 5 above, for example, when the input signals for both systems are ON, the DMD
When the mirror swinging unit 13 of I″i moves by a certain angle and the input signal related to the pixel is OFF, the mirror swinging unit 13 of I″i does not move.Therefore, the mirror swinging unit 13 is turned ON.
By projecting only the light reflected by the mirror swinging portion onto the display panel or photoreceptor, an image corresponding to the digital input signal can be formed.

[Problem that the invention seeks to solve]

However, it is not possible to realize fine density expression of an image by digital light modulation as described above.

Therefore, in order to realize detailed density expression in the optical modulation device using MD as described above, an analog signal is used as an input signal and the intensity of the light generated based on the change in the deflection angle of the mirror swinging section 13 is used. Although it is conceivable to perform density expression, a light modulation device using a DMD that can perform sufficient density expression has not yet been realized.

[Failure to solve the problem]

According to the present invention, in order to solve the problems of the prior art as described above, there is provided an element including a large number of swinging mirrors arranged to deflect a light beam from a light source in at least two directions, A light modulation device is provided, comprising: a filter device for modulating a light beam deflected in each direction with different characteristics depending on the polarization direction; and a means for converging the light beam deflected in each of the directions. Ru.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a first embodiment of the device of the present invention.

In the figure, 21 is a light source, 22 and 24 are convex lenses constituting the Koehler illumination optical system, 23 is a slit plate in the illumination optical system, and 25 and 26 are near bending mirrors in the illumination optical system. Yes, 27 is the above 5th ~
This is the DMD described with reference to FIG. DMD 27 is illuminated by Kohler illumination optics.゛Also, 28 is the D
This is a circuit that drives the MD, and 29 is a DIliiD
27 is a filter device disposed on the optical path of the reflected light; 30 is a convex cylindrical lens for focusing the light that has passed through the IIM and forming an image; and 31 is a light shielding plate. Furthermore, 32 is a photoreceptor.

In FIG. 1, light emitted from a light source 21 passes through a convex lens 22, a slit plate 23, and a convex lens 24, is reflected by bending mirrors 25 and 26, and is reflected by a DMD.
27. At this time, the illumination light beam is narrowed down by the slit plate 23 so that it does not reach anything other than the DMD 27. The DMD 27 operates according to the signal in FIG.
It reacts electromechanically according to the operating principle shown in c), and the mirror swinging portion 1:3 swings.

Light A of the illumination system emitted from the light source 21 is transmitted to the illumination optical system 22.
, 2: 3.24, 25.26, and illuminates the mirror array section of the DMD 27 in a grid pattern.

When the status of the individual mirror swinging parts of the mirror array on the DMD 27 is OFF, the irradiated light A heads in the direction of the reflected light C by the mirror and is blocked by the light shielding plate 31, and the light is not reflected on the photoreceptor 32. The light doesn't reach. In the case of ON, B1. The light is reflected in the B2 or B3 direction and enters the filter device 29.

FIG. 2 is a graph showing an example of the relationship between the voltage applied to the spacer 6 of the DMD 27 shown in FIG. 5 and the deflection angle of the mirror swinging section 13. From this graph, mirror swing part 1
It can be seen that the deflection angle of No. 3 can be easily changed by changing the applied voltage.

If the DMD has the characteristics shown in Figure 2,
For example, assuming that the directions C, B, , B2, and B correspond to the deflection angles θ°, 2°, 3°, and 4° of the mirror swinging unit 13, respectively, in order to obtain these deflection angles, the DMD
The voltages applied to the 27 holes 6 are OV and 2, respectively.
The voltages may be set to 1.3V, 23.7V and 25V.

The filter group [29] is a filter having a density distribution, and the density gradually increases from the right side to the left side in the figure. The lights reflected in the directions B2 and B will have different intensities after passing through the filter device 29.

The light that has passed through the filter device 29 enters the imaging lens 3° and is reflected by the mirror with an intensity corresponding to the oscillating portion of the mirror. A turn is tied onto the photoreceptor 32. This imaging position is DMD 27
The direction of the reflected light from B1 is the same regardless of whether it is B or B.

Next, details of the drive circuit 28 shown in FIG. 1 will be explained.

FIG. 3 is a schematic configuration diagram of the drive circuit 28. In the figure, 41 is an input signal amplifier that turns on and off! Pressure is output. Since the signals are normally input in series, they are converted by a serial-to-parallel converter 42 into parallel signals corresponding to the number of oscillating mirrors of the DMD, and stored in a register 43.

The signal is simultaneously extracted for one column Dt by a synchronization signal, and a drive voltage is supplied to the DMD 45 via the driver 44. Further, 46 is a drive voltage switching circuit;
7 is a switch.

In this drive circuit, the voltage supplied to the DMD 45 is switched stepwise into three stages. That is, the switches 47 are sequentially switched in synchronization with the input signals of each column, and three drive voltages (vBlr, VB2r, VB,) can be supplied. For example, as shown above, B,,B! and B.

When the directions correspond to deflection angles of 2°, 3°, and 4° of the mirror swinging portion 13, respectively, and if the bias voltage vM shown in FIG. 5(c) is OV, then VB is 21
, 3 V, V, is 23.7 V, Vg'&2
It should be 5■.

In this embodiment, the image information input to the drive circuit 28 is a signal whose intensity is divided into three for the same pixel. That is, first, the DMD 27 is driven with the drive voltage V, based on a signal corresponding to the drive voltage VB, and thereby the filter device 2 passes through the optical path in the direction of B1.
The light that has passed through the predetermined density portion of 9 forms a light dot pattern of a predetermined intensity on the photoreceptor 32. Next, photoreceptor 3
Drive voltage vB without moving 2! The DMD 27 is driven with the drive voltage VB based on the signal corresponding to the signal corresponding to the signal, and the light that passes through the predetermined concentration portion of the filter device 29 along the optical path of 1 h towards B2 is transmitted onto the photoreceptor 32 with a predetermined intensity. Form a door pattern. Subsequently, in the same manner, the DMD 27 is driven with the drive voltage VB,
As a result, a light dot pattern of a predetermined intensity is formed on the photoreceptor 32.

Thus, the same dot on the photoreceptor 32 is exposed three times with different intensities.

Next, the photoreceptor 2 is moved by an appropriate distance in the same direction as the arrow X in FIG. The area can be exposed to image information.

According to this embodiment, it is possible to output image information of 8 gradations by combining ON and OFF exposures three times.

In the above embodiment, the drive voltage was switched in three stages, but by increasing the number of switching stages of the drive voltage, it is possible to output image information with a higher number of gradations, and it is possible to output image information with a higher number of gradations. Close modulation is achieved.

FIG. 4 is a schematic configuration diagram showing a second embodiment of the device of the present invention. This embodiment is only for outputting color image information.

In the figure, the same members as in FIG. 1 are given the same reference numerals, and their explanation will be omitted here.

In this embodiment, the filter device 29 consists of three types of color filter parts: a red filter 32a, a green filter 32b, and a blue filter 32C. And DM
B reflected by D 27, ,B.

The light traveling in the directions of and B is passed through the red filter 3, respectively.
2a are selectively absorbed by the green filter 32b and the blue filter 32c, and only red light, green light, and evening light are transmitted, respectively.

DMD 27 (DI' live drive voltage v
B., Va.

and VB3, red dots, green dots, and blue dots can be formed on the photoreceptor 32, respectively.

In this embodiment, as the image information input to the drive circuit 28, signals obtained by color-separating each pixel into three colors of red, green, and blue are used, and DkiD is determined in the same manner as in the first embodiment. By driving, predetermined nine turns of red dots, a pattern of green dots, and a pattern of blue dots can be formed on the photoreceptor 32.

In this embodiment, a density distribution is attached to each color filter in the same manner as in the first embodiment, or even if a density distribution is not attached, the first By performing multiple exposures in the same manner as in the embodiment, color image information with a high number of gradations can be output.

In the above embodiment, the filter device 29 is the DMD 2
7 and the imaging lens 30; however, in the present invention, the filter device is disposed between the imaging lens 30 and the photoreceptor 32.
The imaging lens 30 can also be placed between the
It is also possible to incorporate the function of a filter device into itself.

〔Effect of the invention〕

According to the device of the present invention as described above, with a relatively simple configuration,
It becomes possible to perform modulation with a high number of gradations close to analog modulation. Further, by using a color separation filter as a filter device, it is also possible to perform color modulation.

[Brief explanation of drawings]

FIGS. 1 and 4 are configuration diagrams of the apparatus of the present invention. FIG. 2 is a graph showing the relationship between the deflection angle of the mirror swinging portion of the DMD and the applied voltage. FIG. 3 is a configuration diagram of a DMD drive circuit. FIGS. 5(,) to 5(C) are explanatory diagrams of the DMD. FIG. 6 is a partial plan view of the DMD. 13° mirror swinging part, 14: hinge part, 21: light source,
22.24: Convex lens, 23 Nislit plate, 25.26
: folding mirror, 27 : DMD. 28: drive circuit, 29: filter device, 30: imaging lens, 31: s original plate, 32: photoreceptor. Agent Patent Attorney Ms. Yamashita Figure 2 Figure 10 3°-fp 7ID electric wire (V) Figure 3 Figure 5 and Figure 6

Claims (3)

[Claims] (1) An element formed by arranging a large number of swinging mirrors that can deflect a light beam from a light source in at least two directions, and a filter that modulates the light beam deflected by the element with different characteristics depending on the direction of deflection. 1. A light modulation device comprising: a light modulation device; and means for converging the light beams deflected in each of the above directions. (2) The light modulation device according to claim 1, wherein the filter device has a concentration distribution. (3) The light modulation device according to claim 1, wherein the filter device has a color distribution.