JP2001324731A - Variable grating spacing diffraction grating, optical deflection device and display device using the same - Google Patents

Abstract

(57) [Problem] To provide an optical deflecting device that is small, has low power consumption, has good responsiveness, and does not easily generate noise. A wavelength-modulated light generator for generating a wavelength-modulated light having a wavelength modulated by a control signal, an optical interference light generator for generating an interference light for causing interference with the wavelength-modulated light. An interference fringe 14 caused by interference between the wavelength-modulated light 12 and the interference light 13 is arranged on the surface, and an optical refractive index distribution pattern 15 corresponding to the interference fringe 14 corresponds to the wavelength of the wavelength-modulated light 12. It has a diffraction grating section 3 for forming a diffraction grating having a variable grating interval D, and a readout light irradiating section 4 for irradiating the diffraction grating section 3 with readout light 16. The modulation deflects the diffracted light 18 read by the read light 16 from the diffraction grating section 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffraction grating having a variable grating interval, an optical deflection device and a display device using the same.

[0002]

2. Description of the Related Art A diffraction grating is often used as an optical element for decomposing light having various wavelength components such as white light for each wavelength component (spectral decomposition). For example, in wavelength division multiplexing optical communication, optical signals having different wavelengths, which are independent modes, are multiplexed and transmitted by a single optical transmission path composed of optical fibers, and the wavelength division multiplexed optical signal is finally transmitted for each wavelength. In this case, a diffraction grating is used as a device for decomposing a wavelength-division multiplexed optical signal for each wavelength.

[0003] A typical diffraction grating is one in which a large number of grooves are formed in a mirror or glass substrate to form a pattern of reflectance and refractive index distribution. In such a diffraction grating, since the grating interval cannot be adjusted so that light is diffracted in a desired angle direction, the interval between the diffraction gratings changes due to thermal expansion and contraction of the substrate due to a temperature change or the like. . For this reason, it is not suitable for use in which a wavelength division multiplexed optical signal is accurately decomposed for each wavelength so as to be incident on a desired optical transmission path.

On the other hand, a system for deflecting laser light one-dimensionally or two-dimensionally is used in various communication devices and image input / output devices. For example, in optical communication, a laser beam is deflected when a communication path of an optical signal is changed. In an image input device such as a scanner, a laser beam is used as spot illumination light and is deflected to illuminate a document surface. In an image output device such as a printer, a laser beam is used, for example, to expose a photoconductor, and is deflected to form a two-dimensional electrostatic latent image.

Conventionally, as a light deflecting device used for such an application, a rotating polygon mirror system, a rotating holography system, a galvanometer mirror system, an acousto-optic device (AO)
M) system or the like is used. The rotating polygon mirror system deflects laser light by rotating a polygon mirror. The rotation holography method is a method in which each surface is radially equally divided, and a hologram plate in which the same hologram is recorded on each divided surface is rotated to deflect emitted diffracted light. The galvanomirror method deflects reflected light by rotating a single total reflection mirror left and right at a fixed angle about an axis parallel to the mirror surface.

In each of these three systems, a relatively large mirror or hologram plate is mechanically driven to rotate by a drive unit including a motor, so a motor with a large torque is required, and the shape of the drive unit becomes large. However, there is a problem that power consumption is large.

The AOM system is described in, for example, Adrian Korpel, Acou
As described in sto-Optics. Marcel Dekker, New York (1997), utilizing the properties of an acousto-optic element that changes the local density of a material and changes the optical refractive index distribution when a standing acoustic wave is applied. Then, a sound wave whose energy is controlled passes through an acousto-optic element, and a diffraction grating is formed by a local change of the resulting optical refractive index, and a diffraction angle of diffracted light emitted from the diffraction grating is controlled. In this method, deflection is performed.

Accordingly, this method does not require a mechanical drive unit, but requires a large device for generating a sound wave, and an acousto-optic device generates a distribution of refractive index due to a change in physical density of a material. A large volume is required, and the entire device becomes large. Furthermore, since the diffraction angle is controlled by physically displacing the acousto-optic element, there is a problem that the power consumption is large, the response speed is slow, and noise tends to be generated in the generation of the stationary sound wave.

[0009]

As described above, the conventional diffraction grating has a problem that it is difficult to adjust the grating interval and is susceptible to thermal expansion and contraction of the grating interval due to a temperature change.

Further, among the conventional optical deflecting devices of the type which mechanically drives a mirror or a hologram plate, there is a problem that the driving section becomes large and the power consumption is large. In addition to the increase in size, there is a problem that power consumption is large, responsiveness is poor, and noise is easy to ride.

The present invention provides a variable grating spacing diffraction grating suitable for realizing an optical deflection device which is small, has low power consumption, has good responsiveness, and is difficult to generate noise, and an optical deflection device and a display device using the same. The purpose is to do.

[0012]

In order to solve the above-mentioned problems, a variable grating spacing diffraction grating according to the present invention comprises: a wavelength-modulated light generating section for generating a wavelength-modulated light whose wavelength is modulated by a control signal; An optical interference light generation unit that generates interference light for causing interference with the modulated light, and an optical interference light that is arranged so that interference fringes due to interference between the wavelength-modulated light and the interference light are formed on the surface; A diffraction grating portion that forms a diffraction grating that exhibits a refractive index distribution and changes the grating interval according to the wavelength of the wavelength-modulated light.

The light deflecting device according to the present invention has, in addition to the above-mentioned variable grating spacing diffraction grating, a reading light irradiating section for irradiating the diffraction grating section with reading light for reading the diffracted light from the diffraction grating section. Then, by modulating the wavelength of the wavelength-modulated light with the control signal, the diffracted light read by the read light from the diffraction grating portion is deflected.

In the variable grating spacing diffraction grating and the optical deflecting device configured as described above, the driving unit only needs to drive an electrostatic actuator that controls the size of a laser cavity used in, for example, a wavelength modulation light generating unit. No need to drive large mirrors and holograms with large torque or physical displacement of the acousto-optic element, so it is small, consumes low power, has good responsiveness, and may use noise because it does not use sound waves. Nor.

Further, the display device according to the present invention is a display device for displaying an image by irradiating light onto the retina, and comprising a wavelength-modulated light generator for generating a wavelength-modulated light whose wavelength is modulated by a control signal. And an optical interference light generation unit that generates interference light for causing interference with the wavelength modulated light, and an interference fringe is arranged so that interference fringes are formed on the surface by interference between the wavelength modulated light and the interference light. A diffraction grating part that forms a diffraction grating whose grating interval changes according to the wavelength of the wavelength-modulated light by exhibiting a modified optical refractive index distribution, and is modulated according to an image signal to read out the diffracted light from the diffraction grating part A readout light irradiating section for irradiating the readout light to the diffraction grating section, and modulating the wavelength of the wavelength modulated light by a control signal, thereby diffracting the readout light by the readout light from the diffraction grating. And direction, the diffracted light which is the deflected and irradiating on the retina. With such a configuration, a small-sized and low-power-consumption retinal display device suitable as wearable can be realized.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows the configuration of a variable grating spacing diffraction grating according to a first embodiment of the present invention. This diffraction grating is a diffraction grating whose grating interval is variable by external control, and includes a wavelength modulated light generation unit 1, an interference light generation unit 2, and a diffraction grating unit 3.

The wavelength-modulated light generator 1 has a wavelength-modulated light 1 whose wavelength has been modulated according to a control signal 10 given from the outside.
1 is generated. The wavelength-modulated light 11 enters the interference light generator 2, where an interference light 13 for causing interference with the wavelength-modulated light 12 that has passed through the interference light generator 2 is generated. The direction and the optical path length of each of the wavelength-modulated light 12 and the interference light 13 are adjusted so that the wavelength-modulated light 12 and the interference light 13 intersect each other inside the diffraction grating 3 to form interference fringes 14 on the surface of the diffraction grating 3. I have. The wavelengths of the wavelength-modulated light 12 and the interference light 13 are usually
Equally chosen.

The diffraction grating generator 3 is formed of, for example, a photorefractive material, and forms a diffraction grating by exhibiting an optical refractive index distribution corresponding to the interference fringes 14 formed on the surface. In other words, the diffraction grating unit 3
Has the function of converting the interference fringes, which are the light energy distribution, into the optical refractive index distribution pattern 15 (diffraction grating).

In the thus constructed variable grating spacing diffraction grating, the grating spacing D of the diffraction grating section 3 can be changed by modulating the wavelength λ of the wavelength modulated light 11 with the control signal 10. Since the grating interval D is determined by the interference fringes 14, it is hardly affected by the thermal expansion of the device, and is variable and can be finely adjusted. AOM can also perform spectral decomposition, but AOM requires a standing wave of acoustic waves as described above, and furthermore, because it generates a diffraction grating with physical density, it is easy for noise to ride, and it is not possible to generate a high-speed response or a high-frequency diffraction pattern. On the other hand, in the present invention, since the diffraction pattern is generated by the interference fringes 14, there is an advantage that a stable and high-frequency diffraction pattern can be generated and the response is fast.

Next, how the grating interval D changes in accordance with the wavelength of the wavelength-modulated light 12 will be described in detail with reference to FIG. As described above, the interference fringe 14 is composed of the wavelength modulated light 12 and the interference light 13.
The spacing (grating spacing) D is a function of the wavelength λ of the wavelength-modulated light 12 and the interference light 13, and D = λ / sin θ ₀ (1). Here, θ ₀ is the intersection angle between the wavelength modulated light 12 and the interference light 13. Normally, the wavelength modulated light 12 and the interference light 13 need to be coherent with each other, and therefore both have the same wavelength. The interference fringe 14 becomes an optical refractive index distribution pattern 15, that is, a diffraction grating as it is, from the characteristics of the diffraction grating section 3. In this manner, a diffraction grating in which the grating interval D changes according to the wavelength λ of the wavelength-modulated light 12 can be realized.

(Second Embodiment) In the variable grating spacing diffraction grating described in the first embodiment, when laser light is incident on the diffraction grating section 3, diffracted light is emitted. in this case,
By controlling the grating interval D of the diffraction grating section 3, it is possible to change the diffraction angle of the higher-order diffracted light, that is, deflect the light emitted from the diffraction grating section 3.

FIG. 3 shows a second embodiment of the present invention.
FIG. 1 shows a configuration diagram of an optical deflection device to which this principle is applied. This light deflector has a wavelength modulated light generating unit 1, an interference light generating unit 2, a diffraction grating unit 3, and a readout light irradiating unit 4; 4 is added.

The readout light irradiating section 4 is, for example, a known laser diode, and the readout light 1 is a laser beam.
6 is generated and irradiated to the diffraction grating section 3. That is, the readout light 16 is incident on the optical refractive index distribution pattern 15 which is a diffraction grating formed in the diffraction grating portion 3 and is diffracted. Is emitted.

The deflection angle θ of the higher-order diffracted light 18 is a function of the grating interval D of the diffraction grating, and θ = tan ⁻¹ (λ ₁ / 2D) (2) Here, λ ₁ is the wavelength of the reading light 16.
From Expressions (1) and (2), θ is further expressed as θ = tan ⁻¹ (sin θ ₀ × λ ₁ / 2λ) (3).

As described above, by modulating the wavelength of the wavelength-modulated light 12, the grating interval D of the diffraction grating 15 can be changed, and as a result, the diffraction angle (deflection angle) θ of the higher-order diffracted light 18 is controlled. be able to. For example, as shown in FIG. 4, the wavelengths of the wavelength modulated light 12 and the interference light 13 are λ (solid line).
In this case, the optical refractive index distribution pattern 14 on the diffraction grating portion 3 is as shown by a solid line, and the high-order diffracted light 18 is diffracted in the direction of the deflection angle θ. When the wavelength is λ ′ (broken line), the optical refractive index distribution pattern 14 is as shown by a broken line, and the high-order diffracted light 19 is diffracted in the direction of the deflection angle θ ′. Next, a specific configuration of each unit will be described. [Regarding Wavelength Modulated Light Generating Unit 1] FIG. 5 shows a configuration example of the wavelength modulated light generating unit 1. The wavelength modulated light generation unit 1 of this example is a known wavelength tunable laser,
2 with the reflection mirror 101 and the exit side mirror 103 interposed therebetween.
Are arranged, and the wavelength of the wavelength-modulated light 12 is changed by the displacement of the reflection mirror 101 in the direction perpendicular to the optical axis. The reflection mirror 101 has mirror support arms 106 and 1 having one end (the upper end in the figure) fixed.
07. Mirror support arm 106,1
07, electrostatic actuators 104 and 105 made of, for example, laminated piezoelectric elements are respectively installed.
05 is displaced, so that the mirror support arms 106 and 107 are displaced.
Expands and contracts. The reflection mirror 101 is made of a thin film, and the center of the mirror surface moves up and down depending on the length of the mirror support arms 106 and 107. Thereby, the distance between the reflection mirror 101 and the emission side mirror 102 constituting the laser resonator changes, and as a result, the natural frequency of the laser resonator changes, so that the wavelength of the wavelength modulated light 12 changes. . Such tunable lasers are characterized by their small size,
By using this in the wavelength-modulated light generator 1, it is possible to contribute to further downsizing of the optical deflecting device.

In addition to the tunable laser described above, the wavelength modulated light generator 1 may be a combination of a normal laser diode and a Fabry-Perot filter having a variable cavity size, or a normal laser diode and a harmonic generation crystal (SHG). Basically, any one can be used as long as the wavelength of the laser light can be continuously changed, such as a combination with the above.

[Regarding Interference Light Generation Unit 2] FIG. 6 shows a configuration example of the interference light generation unit 2. The interference light generator 2 includes a half mirror 201 and a mirror 202. The wavelength-modulated light 11 incident from the wavelength-modulated light generating unit 1 is split by the half mirror 201, one of which is straight as it is as the wavelength-modulated light 12 to the diffraction grating unit 3, and the other is a mirror 20.
The light is reflected by the light 4 and becomes the interference light 13.

As in the case of a surface emitting laser array, when laser light sources are arranged in an array, have coherence between the laser light sources, and each of them is wavelength tunable,
The light emitted from a certain laser light source can be used as the wavelength modulated light 12 and the light emitted from another laser light source can be used as the interference light 13. In this case, since not only the wavelength of the modulated light 12 but also the wavelength of the interference light 13 can be controlled, there is an advantage that the dynamic range of the diffraction grating interval D can be increased and the deflection angle θ can be increased.

(Diffraction Grating Section 3) As the diffraction grating section 3, a material whose refractive index changes by light irradiation, that is, a photorefractive material, particularly a photorefractive crystal, is suitably used. There are various types of photorefractive materials, such as ferroelectric oxides, cubic oxides, compound semiconductors, organic materials, and the like. In particular, GaAs in a compound semiconductor is effective from the viewpoints of the response near the infrared which can stably change the wavelength and the need for an applied voltage.

(Third Embodiment) As can be understood from Expression (1), the grating interval D is not only the wavelength λ of the wavelength modulated light 12 and the interference light 13 but also the wavelength modulated light 12 and the interference light 13. 13 is a function of the intersection angle θ ₀ of both beams. Therefore, as shown in FIG. 7, when the interference light 13 intersects with the wavelength modulated light 12 at an angle θ ₀ ′ different from the interference light 13 and is coherent with the wavelength modulated light 12, A grid with another grid spacing D ′ different from D is generated.

FIG. 8 shows a third embodiment of the present invention.
An example of a configuration of a variable grating spacing diffraction grating to which this principle is applied will be described. The difference from the variable grating spacing diffraction grating shown in FIG.
The interference light generator 2 generates and outputs a plurality of interference lights 20;
The point is that the interference light selection unit 5 selects one of the plurality of interference lights 20 as the interference light 13 and makes the interference light 13 enter the diffraction grating unit 3. According to the present embodiment, in addition to the wavelength of the wavelength-modulated light 12, the intersection angle between the wavelength-modulated light 12 and the interference light 13 can also be controlled, so that the dynamic range of the grating interval of the diffraction grating can be widened. is there.

In the interference light generation unit 2 in the present embodiment,
For example, a plurality of interference lights 20 can be generated by dividing one original interference light using a beam splitter. As the interference light selector 5, a known light modulation device such as a liquid crystal shutter can be used. In addition to such a combination of a beam splitter and a light modulation device, when a plurality of light sources are arranged in an array such as a surface emitting laser array and they are coherent, the light emitted from a certain light source is converted into a wavelength modulated light. Then, at least one outgoing light of the other light sources can be selected as the interference light.

(Fourth Embodiment) FIG. 9 shows a fourth embodiment of the present invention.
As an embodiment of the present invention, a configuration of an optical deflecting device using the grating pitch variable diffraction grating shown in FIG. 8 will be described. The difference from the light deflecting device shown in FIG.
Is generated and output, and the interference light selection unit 5 selects one of the plurality of interference lights 20 as the interference light 13 and causes the interference light 13 to enter the diffraction grating unit 3.

Although not shown, the wavelength-modulated light generator 1 is configured to emit a plurality of wavelength-modulated lights at different angles, and one of these wavelength-modulated lights is selected and the diffraction grating section 3 is selected. It is good also as a structure which makes it enter.

As described in the third embodiment, the variable grating spacing diffraction grating used in this embodiment has a wide dynamic range of the grating spacing, and thus has the advantage that the dynamic lens of the deflection angle of the diffracted light can be widened.

When a plurality of interference lights are made to enter the diffraction grating portion 3 at two-dimensionally different angles, not only the frequency of the diffraction grating but also the direction of the fringes can be controlled in accordance with the angle of incidence. At that time, by appropriately selecting the interference light, it is possible to deflect the beam two-dimensionally.

(Fifth Embodiment) Next, as a fifth embodiment of the present invention, a retinal display device to which the light deflecting device of the present invention is applied will be described. FIG. 10 shows the configuration of this retinal display device. The retinal display device is a display that transmits image information by using the retina 311 of the human eye 310 as an image forming screen and directly irradiating a laser beam on the retina to perform two-dimensional scanning. Such a retinal display device is wearable, does not require an image projection system other than the retina, and is promising as a compact image output device in the future. But,
Conventional retinal display devices are very heavy, very inconvenient to carry, consume large amounts of power, and have a noticeable noise, because a galvanomirror or an optical deflecting device using an acousto-optic element is used for scanning with laser light. was there.

On the other hand, in the retinal display device of the present embodiment, as shown by a broken line, a frame 301 similar to the frame of the eyeglasses is used as a support, and the light deflector 300 is installed at a position corresponding to the lens center of the eyeglasses. Have been. The base of the frame 301 is held around the ear 312. Further, a display control device 303 is provided, from which an image signal and various synchronization signals are transmitted to the optical deflecting device 300 via the cable 304, so that the optical deflecting device 300 is driven. The laser light (diffraction light) modulated by the image signal by the light deflector 300 and deflected in synchronization with the synchronization signal is irradiated onto the retina 311.

As described above, according to the present invention, the light deflecting device 300 can be made lighter, smaller, and lower in power consumption.
The above-described conventional retinal display device has the advantage that the difficulty can be solved and the burden on the user can be reduced, and an optimal retinal display device as a wearable display can be provided.

FIG. 11 shows a detailed configuration of the light deflecting device 300 in this embodiment. The configuration of the light deflecting device 300 is basically the same as that shown in FIG. 9, but includes a point that the readout light irradiation unit 4 has a plurality of light sources capable of outputting a plurality of readout lights 16, and a display control device 303. , An image signal 321, a sub-scanning synchronization signal (vertical synchronization signal) 322, and a main scanning synchronization signal (horizontal synchronization signal) 323.

The main scanning synchronizing signal 323 is input to the wavelength modulation light generator 1 and is subjected to horizontal synchronization. That is, the wavelength-modulated light generator 1 emits the wavelength-modulated light 11 whose wavelength sequentially changes in accordance with the control signal 10 (deflection control signal) every time the main scanning synchronization signal 323 is input, that is, the wavelength is continuously swept. I do. Image signal 321 and sub-scan synchronization signal 3
22 is input to the reading light irradiation unit 4. The read-out light irradiator 4 is constituted by a known one-dimensional laser array in which light sources are arranged in a line in the vertical direction,
2, one light source is sequentially selected from the laser array, and an image signal 321 is supplied to the selected light source.
The drive current flows according to. As a result, the reading light 16 generated by the reading light irradiation unit 4 moves in the sub-scanning direction while being intensity-modulated by the image signal 321.

As shown in FIG. 12, the beam-like read light 16 output from the read light irradiator 4 is
, The readout light 16 deflected in the horizontal direction by the diffraction grating section 3
On 11, a main scanning line is formed. Therefore, by selecting one beam corresponding to a desired main scanning line from the laser beams emitted from the laser array constituting the readout light irradiation unit 4 based on the sub-scanning synchronization signal 322, the scanning in the sub-scanning direction is performed. Becomes possible.

In addition to the present embodiment, as described in the third embodiment, for example, a plurality of
By making the light enter the diffraction grating portion 3 at different angles in a three-dimensional manner and appropriately selecting the interference light, the beam can be deflected in both the main scanning direction and the sub-scanning direction.

As described above, the diffracted light 18 emitted from the light deflector 300 is deflected in the main scanning direction and the sub-scanning direction, is intensity-modulated by the image signal 321, and scans the retina 311 with the diffracted light 18. By doing
Image display becomes possible.

(Sixth Embodiment) Next, as a sixth embodiment of the present invention, an optical connection device to which the variable grating spacing diffraction grating of the present invention is applied will be described with reference to FIG. An optical connection device is used as a device for changing a transmission path of an optical signal in the field of optical communication.

The optical connection device of the present embodiment is configured by using a variable grating spacing diffraction grating 400, and the path of an optical signal is selected by a control signal (path selection signal) 10 input thereto. The configuration of the grating pitch variable diffraction grating 400 is substantially the same as that of FIG. An input optical signal transmitted by an input optical transmission line 401 made of an optical fiber is incident on a diffraction grating 400 with a variable grating interval and is diffracted, and a plurality of output optical transmissions made of an optical fiber are performed according to the diffraction angle. It is passed to one of the roads 402. At this time, the diffraction angle (deflection angle) is changed by controlling the grating interval of the grating interval variable diffraction grating 400 by the control signal 10, so that the output side optical transmission path 402 through which the optical signal is transmitted, that is, the output light The output path of the signal is determined.

In this embodiment, the input-side optical transmission path 40
1 and the plurality of output optical transmission lines 40
2 are detected by the photodetectors 411 and 412, and the intensity ratio measuring unit 413 determines the intensity ratio between the two. From this intensity ratio, the accuracy of selecting an output path by the grating spacing variable diffraction grating 400 is known. For example, when the diffraction angle is slightly deviated, the traveling direction of the diffracted light emitted from the diffraction grating 400 deviates from the original output path of the output-side optical transmission path 402, and the optical signal intensity on the output path decreases. . Therefore, the intensity ratio information obtained by the intensity ratio measurement unit 413 is fed back to the control circuit 414, and the control signal 10 is adjusted so that the intensity ratio becomes maximum, and the diffraction angle is controlled. The optical signal intensity can be increased.

(Seventh Embodiment) Next, as a seventh embodiment of the present invention, an image forming apparatus using the light deflecting device of the present invention will be described with reference to FIG. This image forming apparatus is applied to a printer, and is configured to form a full-color image in the present embodiment.

In FIG. 14, a photosensitive drum 501 as an electrostatic latent image carrier is formed by providing an organic or amorphous silicon photosensitive layer on a cylindrical conductive substrate, and is driven by a motor (not shown) in the direction of the arrow. While passing through the charging / exposure / development stations arranged at four positions on the photosensitive drum 501 separated in the rotational movement direction (sub-scanning direction) of the photosensitive drum 501 as described below. .

The photosensitive drum 501 is first charged with a first charger 502 composed of a corona charger or a scorotron charger.
-1, after the photosensitive layer is uniformly charged,
The first exposure laser beam 503-1 modulated in accordance with the first color image information (for example, yellow image data) is irradiated forward in the sub-scanning direction of -1 to expose the photosensitive layer surface with the first static laser beam 503-1. An electrostatic latent image is formed. Thereafter, the electrostatic latent image formed by the first exposure laser beam 503-1 is developed by the first developing device 504-1 containing a first color (for example, yellow) liquid developer,
A first color visible image composed of a liquid developer or toner attached to the electrostatic latent image is formed.

The visible image of the first color by the liquid developer or the toner thus adhered to the electrostatic latent image may be transferred to the recording paper 509 by the transfer device 505. Move on. That is, the photosensitive drum 501 is continuously uniformly charged by the second charger 502-2, and is further charged by the second exposure laser beam 503-2 modulated by the second color image information (for example, magenta image data). After the second electrostatic latent image is formed at the same position as the position where the first electrostatic latent image is formed, a second developer different from the liquid developer stored in the first developing unit 504-1 is formed.
It is developed by a second developing unit 504-2 containing a liquid developer of a color (for example, magenta), and a visible image of the second color is formed. Therefore, after this development, the photosensitive drum 50
A visible image of a first color and a visible image of a second color are superimposed on each other.

Similarly, the third exposure laser beam 503-modulated by the third charging device 502-3 and the third color image information (for example, cyan image data).
3, a third electrostatic latent image is formed by the third developing device 504-3, and a visible image of a third color (for example, cyan) is sequentially formed by the third developing device 504-3. 4
Formation of a fourth electrostatic latent image by the fourth exposure laser beam 503-4 modulated by the color image information (for example, black image data) of the fourth color (for example, black) by the fourth developing device 504-4. Formation of a visible image is sequentially performed.

In this manner, on the photosensitive drum 501,
For example, visible images of four colors of yellow (Y), magenta (M), cyan (C), and black (K) are superimposed,
A full-color image is formed. This photosensitive drum 501
The upper color image is transferred by a transfer device 505 onto a recording sheet 509 which is a material to be transferred. Transfer device 505
Is composed of a drum-shaped intermediate transfer medium 506 provided in contact with the photosensitive drum 501 in this example. The transfer from the photosensitive drum 501 to the intermediate transfer medium 506 and the transfer from the intermediate transfer medium 506 to the recording paper 509 are all performed by electric field transfer or pressure (and heat).
Of the liquid developer can be used, but many liquid developers can generally be fixed on recording paper at room temperature.
The fixing roller 507 is heated by heating the pressure roller 507 contacted through the fixing roller 9. The above color image forming process is described, for example, in US Pat. No. 5,570,1.
No. 73, etc.

The surface of the photosensitive drum 501 is exposed to exposure laser beams 503-1 to 503 for forming an electrostatic latent image.
Accordingly, scanning is performed in a direction (main scanning direction) orthogonal to the rotation direction of the photosensitive drum 501. These exposure laser beams 503-1 to 503-4 are light beams emitted from the independent light deflecting device 510 according to the present invention, and are reflected by the folding mirror groups 512-1 to 512-8 on the surface of the photosensitive drum 501. The light is distributed to the specified positions. A control signal, an image signal, a main scanning synchronizing signal, and a sub-scanning synchronizing signal are input to the light deflecting device 510 from the control device 511 as in FIG.
An electrostatic latent image is formed on the photosensitive drum 501 by modulating (blinking control) 1 to 503-4 according to the image signal of each color.

In this type of color image forming apparatus, a polygon mirror is conventionally used to deflect the laser beam. However, since the polygon mirror is normally driven to rotate at a constant speed, the surface of the photosensitive drum 501 is scanned as it is. Sometimes, the scanning speed is not constant in the axial direction of the photosensitive drum 501. For this reason, it is necessary to pass the laser beam deflected by the polygon mirror through the fθ lens to keep the scanning speed on the photosensitive drum 501 constant, which complicates the configuration of the scanning system. On the other hand, in the present invention, the light deflector 5
By appropriately performing the wavelength modulation of the wavelength-modulated light by the control signal 10 given to the laser beams 503-1 to 503,
The change in the diffraction angle of the diffracted light of -4 can be easily controlled so that the scanning speed is constant. Although the color image forming apparatus has been described in the present embodiment, the light deflecting device according to the present invention can be applied to a monochrome image forming apparatus.

As described above, according to the present embodiment, the photosensitive member and the electrostatic latent image forming means for forming a latent image by scanning the photosensitive member with a plurality of light beams modulated by image information. Developing means for developing the electrostatic latent image to form a visible image using a toner or the like on a photoreceptor; and transfer means for transferring the visible image onto a recording medium such as recording paper. It is possible to provide an image forming apparatus that forms an electrostatic latent image by scanning the surface of a photoreceptor with a light beam deflected by the light deflecting device according to the present invention.

[0057]

As described above, according to the present invention, a variable grating spacing diffraction grating suitable for realizing an optical deflecting device which is small, has low power consumption, has good responsiveness, and does not easily generate noise is used. And a display device.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a variable grating spacing diffraction grating according to a first embodiment of the present invention.

FIG. 2 is a view for explaining the principle that the lattice spacing changes according to the wavelength of the wavelength-modulated light in the embodiment.

FIG. 3 is a diagram showing a configuration of a light deflecting device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a state in which the deflection angle of the emitted light changes according to the wavelength of the wavelength modulated light in the embodiment.

FIG. 5 is a diagram showing a configuration example of a wavelength-modulated light generation unit used in a variable grating spacing diffraction grating and an optical deflector according to the present invention.

FIG. 6 is a diagram showing a configuration example of an interference light generation unit used in the variable grating spacing diffraction grating and the optical deflector of the present invention.

FIG. 7 is a view for explaining a diffraction grating portion used in the grating interval variable diffraction grating and the optical deflector of the present invention.

FIG. 8 is a diagram showing a configuration of a variable grating spacing diffraction grating according to a third embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a light deflecting device according to a fourth embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a retinal display device according to a fifth embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of a light deflecting device in the embodiment.

FIG. 12 is a view for explaining the operation of a readout light irradiation unit in the embodiment.

FIG. 13 is a diagram showing a configuration of an optical connection device according to a sixth embodiment of the present invention.

FIG. 14 illustrates a configuration of an image forming apparatus according to a seventh embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Wavelength modulation light generation part 2 ... Interference light generation part 3 ... Diffraction grating part 4 ... Readout light irradiation part 5 ... Interference light selection part 10 ... Control signal 11 ... Wavelength modulation light 12 ... Wavelength modulation light 13 ... Interference light 14 ... Interference fringes 15 ... Optical refractive index distribution pattern (diffraction grating) 16 ... Reading light 17 ... 0th-order diffracted light 18 ... High-order diffracted light 19 ... High-order diffracted light 20 ... Interference light 101 ... Reflection mirror 102 ... Laser medium 103 ... Emission side mirror 104, 105 ... Electrostatic actuators 106,107 ... Mirror support arms 108,109 ... Guide part 201 ... Half mirror 202 ... Total reflection mirror 300 ... Light deflector 301 ... Frame 303 ... Display control device 304 ... Cable 310 ... Eye 311 ... Retina 321 image signal 322 sub-scanning synchronization signal 323 main scanning synchronization signal 400 grating variable grating 401 Input side optical transmission line 402 ... Output side optical transmission line 411, 412 ... Photodetector 413 ... Intensity ratio measuring unit 414 ... Control circuit 501 ... Photoconductor drum 502 ... Charger 503 ... Laser beam 504 ... Developing device 505 ... Transfer device 506 intermediate transfer medium 507 pressure roller 508 cleaner 509 recording paper 510 light deflecting device 511 control device 512 folding mirror group

Claims (6)

[Claims] A wavelength-modulated light generation unit that generates wavelength-modulated light whose wavelength is modulated by a control signal; an optical interference light generation unit that generates interference light for causing interference with the wavelength-modulated light; Arranged such that interference fringes due to interference between the light and the interference light are formed on the surface, and exhibiting an optical refractive index distribution corresponding to the interference fringes, thereby changing the grating interval according to the wavelength of the wavelength-modulated light. And a diffraction grating section for forming a diffraction grating. 2. The diffraction grating according to claim 1, wherein said diffraction grating portion is formed of a photorefractive material. 3. The grating according to claim 1, wherein the interference light generation section generates at least one interference light selected by an interference light selection signal from a plurality of interference lights having different emission directions. Variable spacing grating. 4. The wavelength-modulated light generating section generates at least one wavelength-modulated light selected by a wavelength-modulated light selection signal from a plurality of wavelength-modulated lights having different wavelengths. A grating spacing variable diffraction grating as described in the above. 5. A wavelength-modulated light generator for generating a wavelength-modulated light having a wavelength modulated by a control signal; an optical interference light generator for generating an interference light for causing interference with the wavelength-modulated light; Arranged such that interference fringes due to interference between the light and the interference light are formed on the surface, and exhibiting an optical refractive index distribution corresponding to the interference fringes, thereby changing the grating interval according to the wavelength of the wavelength-modulated light. A diffraction grating portion that forms a diffraction grating to perform, and a readout light irradiation portion that irradiates the diffraction grating portion with readout light for reading out the diffracted light from the diffraction grating portion, and the wavelength modulated light according to the control signal. An optical deflector that deflects the diffracted light read by the read light from the diffraction grating section by modulating the wavelength of the light. 6. A display device for displaying an image by irradiating light on a retina, a wavelength-modulated light generating section for generating a wavelength-modulated light having a wavelength modulated by a control signal, and for causing interference with the wavelength-modulated light. A light interference light generation unit that generates interference light, and arranged so that interference fringes are formed on the surface by interference between the wavelength-modulated light and the interference light, and an optical refractive index distribution corresponding to the interference fringes. A diffraction grating portion that forms a diffraction grating whose grating interval changes according to the wavelength of the wavelength-modulated light by presenting the read light modulated according to an image signal to read the diffracted light from the diffraction grating portion. A readout light irradiating unit for irradiating the diffraction grating unit, and modulating the wavelength of the wavelength-modulated light by the control signal, so that the diffracted light read out by the readout light from the diffraction grating is provided. Direction, and a display device in which diffracted light the deflection and irradiating on the retina.