JPH05210126A - Optical scanner - Google Patents

Abstract

PURPOSE:To execute nonmechanical scanning with light by small-sized constitution. CONSTITUTION:The space optical modulating element 10 is constituted of an electrooptical crystal 11 which changes the polarization direction of light by a voltage, a voltage impressing part 12 for impressing the voltage for controlling the rotatory polarization characteristic of the crystal 11 and a diffraction grating 13 of reflection type disposed behind the crystal. The space optical modulating elements 10a, 10b, 10c... are disposed in N layers in series and the state of impressing the energy to the respective space optical modulating elements is controlled according to scanning speeds, by which the optical routes for two directions are provided for one layer. The max. 2N pieces of the scanning points are thus scanned with the light on an image plane 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device, and more particularly to an optical scanning device for performing optical scanning without using a mechanical mechanism such as a rotary mirror.

[0002]

2. Description of the Related Art In a laser printer or a facsimile machine equipped with a laser printer, a laser beam is used to scan a photosensitive member and the laser beam is turned on during scanning.
Turn off and record exposure (form an electrostatic latent image) on the surface of the photoconductor,
Then, the toner image is recorded on a sheet by the steps of forming, transferring and fixing. A mechanical scanning optical system that scans a laser beam by rotating a polygon mirror is widely used in a scanning / exposure device such as a laser printer.
According to this scanning optical system, the beam diameter of a laser beam (which is a divergent beam) emitted from a semiconductor laser or the like is narrowed down through a collimating lens or the like and converted into parallel light. Then
Thereafter, the rotary polygon mirror is irradiated and deflected, and the scanning speed of the deflected laser beam is corrected by an fθ lens or an arcsin θ lens and the light is condensed on the photoconductor.

However, the method using the polygon mirror requires a large number of optical parts such as a collimating lens, an fθ lens, and a tilt correction optical system, and since it is a mechanical scanning system, the exposure apparatus can be downsized and the cost can be reduced. Has become a factor that prevents the reduction of

For this reason, light emitting elements such as LEDs are arranged in a line at a predetermined density (for example, 16 dots / mm) so as to face the photoconductor drum, and the photoconductor drum is rotated and at the same time, depending on the image to be recorded. Then, a non-mechanical scanning / exposure device has been developed in which a predetermined light emitting element is sequentially emitted to form an electrostatic latent image by dots on a photosensitive drum, and thereafter recording is performed on plain paper by an electrophotographic process.

FIG. 7 is a schematic configuration diagram of such an LED array type electrophotographic printer, in which 1 is a photosensitive drum and 2 is an LE.
D array head, 3 is a light modulation signal generator, LED
From each LED of the array head 2, a light modulation signal generator 3
A light beam which is on / off-modulated according to the output of is emitted and is condensed on the photosensitive drum 1. The photoconductor drum 1 is L
Since the ED array head 2 rotates in the direction of the arrow Y perpendicular to the longitudinal direction (main scanning direction), an electrostatic latent image by dots is formed on the photosensitive drum 1 and recorded on plain paper by an electrophotographic process.

[0006]

In the LED array type non-mechanical scanner, it is necessary to arrange at least two LED elements in series in the main scanning direction for 2 ^N scanning points. As the number of points increases, there is a problem that the depth direction of the device becomes longer and the device becomes larger.

In view of the above, an object of the present invention is to provide an optical scanning device which can scan light non-mechanically and with simple control and which can be miniaturized.

[0008]

FIG. 1 illustrates the principle of the present invention. 10, 10a, 10b, 10c, 10d ... are spatial light modulators, 11, 11a, 11b, 11c, 11d
.. is a crystal that changes the polarization direction of light by external energy such as electricity, for example, a transmissive electro-optic crystal such as liquid crystal,
Reference numeral 12 is a voltage application section for controlling the polarization property of the electro-optic crystal, 1
, 13a, 13b, 13c, 13dc ··· are arranged behind the electro-optic crystal with respect to the incident light, and the intensity of either the diffracted and reflected light or the reflected light (0th order light) is increased depending on the polarization direction of the light. A reflection type diffraction grating, and 21 is an image plane.

[0009]

The electro-optic crystal 11 changes the polarization direction of the incident linearly polarized light according to the presence / absence of voltage application. This is because when the voltage applied to the electro-optic crystal 11 changes, the crystal orientation changes, and the polarization direction (vertical polarization, horizontal polarization) of the transmitted light changes according to the change in the orientation. On the other hand, the reflection type diffraction grating 13 has a property that the diffraction efficiency varies depending on the polarization state, and the intensity of the diffracted light is small when vertical polarized light is incident. Therefore, the incident vertical polarized light is reflected as it is, and the 0th order light (reflected light ) Is emitted as. When the horizontally polarized light is incident, the intensity of the diffracted light is increased and the incident horizontally polarized light is deflected by a predetermined angle and emitted as diffracted reflected light. Therefore, a transmissive electro-optic crystal 11 that changes the polarization direction of light according to a voltage,
Voltage application unit 1 for applying a voltage for controlling the polarization of the crystal
2 and the reflection type diffraction grating 13 arranged at the rear of the crystal constitute a spatial light modulator, and the spatial light modulators 10a, 10b, 1
0c, 10d, ... Are arranged in N layers in series to form an optical scanning device.

According to this optical scanning device, by controlling the voltage application state to each spatial light modulation element according to the scanning speed, it is possible to realize a two-direction light reflection path for one layer. It is possible to perform light scanning on a maximum of 2 ^N scanning points on the image plane 21 with a non-mechanical and compact structure.

Further, the electro-optic crystal which changes the polarization direction of light by electric energy is of a reflection type, and the diffraction grating is of a transmission type and is arranged in front of the reflection-type electro-optic crystal to reflect from the reflection-type electro-optic crystal. By controlling the polarization direction of the emitted light by the polarization direction of the incident light, a two-way light reflection path is realized for each layer according to the voltage application state to the reflective electro-optic crystal of each layer. Therefore, the scanning of light is non-mechanical for up to 2 ^N scanning points.
Moreover, it can be performed with a small configuration.

Further, one transmissive electro-optical crystal of the uppermost layer, a reflective electro-optical crystal for (N-1) layers, and a voltage for applying a voltage to control the polarization of each electro-optical crystal. Reflection type diffraction that is incident on the reflection type electro-optic crystal of the next layer by controlling the deflection direction of the output light by the polarization direction of the light that is transmitted or reflected by the application part and the electro-optic crystal of one layer. If the optical scanning device is composed of the grating, it is possible to realize two-direction optical reflection paths in the reflection type diffraction grating for the incident light from the electro-optic crystal of each layer. Therefore, for a maximum of 2 ^N scanning points. It is possible to scan light with a non-mechanical and compact structure.

Further, a reflection type electro-optical crystal having N reflection areas and changing the polarization direction of light by electric energy for each reflection area, and the polarization property of each reflection area of the electro-optical crystal are controlled. In order to achieve this, a voltage application unit that applies a voltage to each reflection region, and a reflection type electro-optic crystal that controls the deflection direction of outgoing light by the polarization direction of light that is reflected by a predetermined reflection region of the reflection-type electro-optic crystal and incident If an optical scanning device is configured with N layers of reflection type diffraction gratings that are incident on adjacent reflection regions of, the light reflection paths in two directions can be realized in the reflection type diffraction grating of each layer. Therefore, a maximum of 2 ^N scanning points can be realized. On the other hand, it is possible to perform light scanning with a non-mechanical and compact structure.

[0014]

【Example】

(a) Overall Configuration of Spatial Light Modulator FIG. 2 is a configuration diagram of the spatial light modulator and an explanatory view of optical path control. 10 is a spatial light modulator, and 11 is a transmissive type that changes the polarization direction of light by voltage. An electro-optic crystal, for example, an electro-optic crystal such as a liquid crystal or PLZT, 12 is a voltage application unit that controls the polarization of the electro-optic crystal, and 13 is a reflection type diffraction grating arranged behind the electro-optic crystal with respect to incident light. And
This is a surface relief type hologram having a uniform unevenness (interference fringes) spatial frequency in the surface main scanning direction, and a reflecting film is formed on the hologram. The 0th order light is reflected and the diffracted light is reflected and diffracted. ing.

Optical Properties of Electro-Optical Crystal The electro-optical crystal 11 such as liquid crystal or PLZT has a refractive index anisotropy and has a property of changing the polarization direction of incident linearly polarized light according to the voltage applied to the electro-optical crystal. Have That is, when the voltage applied to the electro-optic crystal 11 is changed, the orientation of the crystal molecules is changed, and the polarization direction of the transmitted light is changed accordingly. For example, in a twisted nematic liquid crystal, linearly polarized light (vertical polarized light) that enters vertically when no voltage is applied is
The light is rotated ⁰ and emitted as horizontal polarized light, and when voltage is applied, it is not rotated inside the crystal and is emitted as vertically polarized light.

Optical Properties of Reflective Diffraction Grating The diffraction grating has a property that the diffraction efficiency varies depending on the polarization state (vertical polarization or horizontal polarization) of the incident light even if the wavelength and the incident angle of the incident light are constant. When incident, the diffracted light intensity is low and the 0th-order light intensity is high. Therefore, in the case of a transmissive diffraction grating, the incident vertically polarized light is transmitted as 0th order light (transmitted light). Further, when the horizontally polarized light is incident, the intensity of the diffracted light increases, and the incident horizontally polarized light is deflected by a predetermined angle and is emitted as diffracted light. On the other hand, the reflection type diffraction grating 13 is formed by forming a reflection film on the transmission type diffraction grating, and the 0th order light in the transmission type diffraction grating is reflected and the diffracted light is reflected and diffracted.

Optical path control Therefore, a transmission type electro-optic crystal 11, a voltage application section 12 for controlling the polarization of the crystal, and a voltage-applying section 12 disposed behind the crystal are provided. If the spatial light modulator 10 is configured by the reflection type diffraction grating 13 that increases the intensity of either light) or diffracted reflection light, the reflection type diffraction grating 13 is controlled by controlling the voltage application to the electro-optic crystal 11. The path of the light reflected from can be controlled in two directions.

For example, when a voltage V ₁ is applied to the transmissive electro-optic crystal 11, the electro-optic crystal 11 directly emits the incident vertically polarized light as shown in FIG. The incident vertically polarized light is reflected in the first direction as 0th order light (reflected light). On the other hand, when the electro-optic crystal 11 applies a voltage V _2, the electro-optic crystal 11, as shown in FIG. 2 (c), is emitted as the horizontal polarized light by 90 ⁰ optical rotation of the vertically polarized light incident internally reflective diffraction The grating 13 deflects the incident horizontal polarized light by a predetermined angle and reflects it in the second direction as diffracted reflected light.

(B) Embodiment of Optical Scanning Device FIG. 3 shows an embodiment of the present invention in which the spatial light modulators of FIG. 2 are arranged in N layers in series and light scanning is performed non-mechanically at a maximum of 2 ^N scanning points. FIG. 3 is a configuration diagram of an embodiment of the optical scanning device of FIG. Incidentally, FIG.
(a) shows the schematic arrangement of each spatial light modulator as viewed from the front, and (b) shows the schematic arrangement as viewed from the side.

Reference numerals 10a, 10b, 10c, 10d, ... Are spatial light modulators, and 11a, 11b, 11c, 11d.
.. is a transmission type electro-optic crystal such as liquid crystal, 13a, 13b,
13c, 13d ... is a reflection type diffraction grating, 21 is an image plane, 1
Reference numeral 2 denotes a voltage application unit, which is used to control the light path in each layer (each spatial light modulator) and is used as a transmission electro-optic crystal 11
a for controlling the voltage applied to a, 11b, 11c, 11d, ..., 23 for a semiconductor laser (light source) that generates laser light, and 24 for converging incident laser light for image plane 21 is a lens for focusing the laser beam, and 25 is a semiconductor laser 23.
Is a control unit that controls the voltage application unit 12 to start scanning as well as performing on / off control.

The beam emitted from the lens 24 is reflected by the first spatial modulation element 10a in one of two optical paths based on the voltage application state, and then by the second spatial modulation element 10b. The light is reflected in one direction of the two light paths according to the voltage application state, and thereafter, similarly, is sequentially reflected in the predetermined light path direction by the third, fourth ... Spatial modulation elements 10c, 10d. 21 predetermined scanning points P ₁ , P ₂ , P ₃ , ...
.. Image on Pn.

When applied to a laser printer, the control unit 25 controls the semiconductor laser 23 to be turned on / off in accordance with the image data, instructs the voltage application unit 12 to start scanning, and also controls the barcode reader. In the case of applying to a feeder or the like, the arrival of an article is detected, the laser diode 23 is turned on / off, and the scanning start is instructed to the voltage application section 12.

When instructed to start scanning, the voltage applying section 12 scans points P ₁ , P ₂ , P ₃ , ... On the image plane 21.
The voltage application state to the electro-optical crystals 11a, 11b, 11c and 11d of each layer is controlled so that Pn is sequentially scanned according to the scanning speed.

For example, in order to form an image of the laser beam at the scanning point P ₁ , a voltage V ₂ is applied to the electro-optic crystal 11a of the first layer to diffract and reflect the incident light and to generate electricity of the other layers. A voltage V ₁ is applied to the optical crystals 11b, 11c, 11d to reflect the incident light, and the laser beam is imaged at the scanning point P ₁ .

Next, in order to position the laser beam to the scanning point P ₂ , a voltage V ₂ is applied to the electro-optic crystal 11a of the first layer to diffract and reflect the incident light, and the electro-optic crystal 11b, A voltage V ₁ is applied to 11c to reflect the incident light, and a voltage V ₂ is applied to the electro-optic crystal 11d to diffract and reflect the incident light to form a laser beam at the scanning point P ₂ .

Thereafter, if the voltage applied to each electro-optic crystal is controlled in the same manner, the laser beam scans light on a maximum of 2 ^N (N layer) scanning points on the image plane 21. It can be done non-mechanically. And in this case, the lens 2
Since the distance from 4 to the image plane 21 can be made constant at all scanning points, a uniform beam diameter can be obtained in all scanning areas.

(C) Second Embodiment of Optical Scanning Device In the configuration shown in FIG. 3, the electro-optic crystal is a transmission type and the diffraction grating is a reflection type. However, the electro-optic crystal is a reflection type and the diffraction grating is a transmission type. It can also be configured to. FIG. 4 is a configuration diagram of such an optical scanning device, and the same parts as those in FIG. 3 are denoted by the same reference numerals. Incidentally, FIG. 4A shows a schematic arrangement of each spatial light modulator as viewed from the front, and FIG. 4B shows a schematic arrangement as viewed from the side.

In the figure, 10a ', 10b', 10c ', 1
0d '... are spatial light modulators, and 11a', 11
b ', 11c', 11d '... are reflective electro-optic crystals,
13a ', 13b', 13c ', 13d' ... are transmission type diffraction gratings arranged in front of the reflection type electro-optic crystal with respect to incident light, 21 is an image plane, 12 is a voltage applying section, and each layer ( Transmission type electro-optic crystals 11a ', 11b', 11c ', 1 for controlling the light path in each spatial light modulator)
Controlling the voltage applied to 1d '...
A semiconductor laser (light source) that generates laser light, 24 is a lens that collects incident laser light and forms a laser beam on the image plane 21, and 25 is a semiconductor laser 23 that is turned on. The control unit performs off control and instructs the voltage application unit 12 to start scanning. The scanning control operation is substantially the same as that shown in FIG.

(D) Third Embodiment of Optical Scanning Device FIG. 5 is a block diagram of a third embodiment of the optical scanning device of the present invention. FIG. 5 (a) shows a schematic frontal arrangement of each element. , (B) shows a schematic side view layout.

Reference numeral 31 is a transmission type electro-optic crystal of the uppermost layer, which changes the polarization direction of light by applying a voltage, 32, 33, 3
4,35 ... Reflective electro-optic crystal for (N-1) layers, which changes the polarization direction of light by electric energy, 41 is light that is transmitted through or reflected by the electro-optic crystal of a certain layer Is a reflection type diffraction grating which controls the deflection direction of emitted light according to the polarization direction and enters the reflection type electro-optic crystal of the next layer.

Further, 21 is an image plane on the same plane as the reflection type diffraction grating 41, and 12 is electro-optic crystals 31 to 35 in each layer.
.. The voltage application unit for controlling the voltage applied to
A semiconductor laser (light source) that generates laser light, 24 is a lens that collects incident laser light and forms a laser beam on the image plane 21, and 25 is a semiconductor laser 23 that is turned on. The control unit performs off control and instructs the voltage application unit 12 to start scanning.

The beam emitted from the lens 24 is incident on the reflection type diffraction grating 41, the polarization direction of which is controlled by the transmission type electro-optic crystal 31 of the first layer based on the voltage application state. The reflection type diffraction grating 41 reflects in one direction of two light paths depending on the polarization state of the incident light and enters the reflection type electro-optic crystal 32 of the second layer.

The reflective electro-optic crystal 32 of the second layer controls the polarization direction of the incident light on the basis of the voltage application state and reflects it on the reflective diffraction grating 41. The reflection type diffraction grating 41 reflects in one direction of the two optical paths ′ and ′ depending on the polarization state of the incident light and enters the reflection type electro-optic crystal 33 of the third layer. Thereafter, similarly, the third and fourth reflective electro-optic crystals 33,
At 34 ..., It is sequentially reflected in a predetermined optical path direction and finally an image is formed at a predetermined scanning point on the image plane 21.

When applied to a laser printer, the control unit 25 controls the semiconductor laser 23 to be turned on / off in accordance with the image data, instructs the voltage application unit 12 to start scanning, and also controls the barcode reader. In the case of applying to a feeder or the like, the arrival of an article is detected, the laser diode 23 is turned on / off, and the scanning start is instructed to the voltage application section 12.

When the control unit 25 instructs the voltage application unit 12 to start scanning, the voltage application unit 12 scans the scanning points P ₁ ,
The voltage application state to the electro-optic crystals 31 to 35 of each layer is controlled so that P ₂ , P ₃ , ... Pn are sequentially scanned according to the scanning speed.

For example, in order to form an image of the laser beam at the scanning point P ₁ , a voltage V is applied to the transmission type electro-optic crystal 31 of the first layer.
₂ is applied to diffract and reflect the incident light by the reflective diffraction grating 41, and the voltage V ₁ is applied to the reflective electro-optic crystals 32 to 35 of the other layers to reflect the incident light by the reflective diffraction grating 41. Then, the laser beam is imaged at the scanning point P ₁ .

Then, in order to position the laser beam to the scanning point P ₂ , the voltage V is applied to the transmission type electro-optic crystal 31 of the first layer.
₂ is applied to diffract and reflect the incident light by the reflection type diffraction grating 41, and a voltage V ₁ is applied to the electro-optic crystals 32 to 34 to reflect the incident light by the reflection type diffraction grating 41, and the reflection of the lowermost layer. A voltage V ₂ is applied to the electro-optical crystal 35 to diffract and reflect incident light by the reflection type diffraction grating 41, and a laser beam is generated.
The image is formed on the scanning point P ₂ .

After that, if the voltage applied to each electro-optic crystal is controlled in the same manner, the laser beam scans light at a maximum of 2 ^N (N layer) scanning points on the image plane 21. It can be done non-mechanically. Also in this case, since the distance from the lens 24 to the image plane 21 can be made constant at all scanning points, a uniform beam diameter can be obtained in all scanning areas.

(E) Fourth Embodiment of Optical Scanning Device FIG. 6 is a configuration diagram of a fourth embodiment of the optical scanning device of the present invention, and FIG. 6 (a) shows a schematic frontal arrangement of each element. And the same figure
(b) shows a schematic side view layout.

Reference numeral 51 denotes N reflection areas 51a, 51b, 5
The reflective electro-optic crystal has 1c, 51d, ... And changes the polarization direction of light by a voltage for each reflection region. Incidentally, each reflection area is electrically insulated. 52
a and 52b are adjacent reflection regions 51b of the reflection-type electro-optic crystal 51 in which the deflection direction of the emitted light is changed according to the polarization direction of the light that is reflected by the two adjacent reflection regions 51a and 51b of the reflection-type electro-optic crystal 51. , The first incident on 51c
Reflection diffraction gratings 53 a and 53 b are reflection electro-optics by changing the deflection direction of the outgoing light according to the polarization direction of the light reflected by two adjacent reflection regions 51 c and 51 d of the reflection electro-optic crystal 51. It is the reflection diffraction grating of the second layer which is incident on the adjacent reflection region of the crystal 51. Although only the second layer is shown in FIG. 6, the third layer, the fourth layer, ... Are actually provided, and the light from the reflection type diffraction grating on the right side of the lowest layer is reflected on the image plane. The scanning is performed by sequentially forming images at a maximum of 2 ^N scanning points.

Reference numeral 21 is an image plane on the same plane as the reflection type diffraction grating 51, and 12 is a voltage application section for controlling the voltage applied to each reflection area 51a, 51b, 51c, 51d ... In the reflection type electro-optic crystal 51. , 23 is a semiconductor laser (light source) that generates laser light, 24 is a lens that collects incident laser light and forms a laser beam on the image plane 21, and 25 is a semiconductor laser. A control unit that controls the voltage application unit 12 to start scanning, while performing on / off control of the Za 23.

The beam emitted from the lens 24 has its polarization direction controlled based on the voltage application state to the first reflection region 51a of the reflection type electro-optic crystal 51, and the first reflection type diffraction grating 52a of the first layer. Incident on. The reflective diffraction grating 52a is
Depending on the polarization state of the incident light, one of two light paths
The light is reflected in the direction and enters the second reflective region 51b of the reflective electro-optic crystal 51.

The light incident on the reflective electro-optic crystal 51 is
The polarization direction is controlled based on the voltage application state to the second reflection region 51b, and the light is incident on the second reflection type diffraction grating 52b of the first layer. The reflection type diffraction grating 52b reflects in one direction of the two optical paths ',' depending on the polarization state of the incident light and enters the third reflection region 51c of the reflection type electro-optic crystal 51. Thereafter, similarly, the first and second reflective diffraction gratings 53a and 53b of the second layer, the first and second reflective diffraction gratings of the third layer,
・ Sequentially reflects in the direction of the predetermined optical path, and finally the image plane 21
An image is formed at a predetermined scanning point above.

When the control section 25 instructs the voltage application section 12 to start scanning, the scanning points P ₁ , P ₂ ,
Each of the reflection regions 51a, 51b of the reflection-type electro-optic crystal 51 so that P ₃ , ... Pn are sequentially scanned according to the scanning speed.
The voltage application state to 51c, ... Is controlled.

For example, in order to form an image of the laser beam on the scanning point P ₁ , the first reflection area 5 of the reflection type electro-optic crystal 51 is formed.
A voltage V ₂ is applied to 1a to diffract the incident light in a direction by the first reflection type diffraction grating 52a of the first layer, and the other reflection regions 51b, 51c, 5 of the reflection type electro-optic crystal 51.
A voltage V ₁ is applied to 1d to apply reflection type diffraction gratings 52b, 5b.
Incident light is reflected by 3a and 53b, and the laser beam is imaged at the scanning point P ₁ .

Next, in order to position the laser beam to the scanning point P ₂ , the first reflection area 5 of the reflection type electro-optic crystal 51 is used.
1a to apply a voltage V ₂ to the first reflective diffraction grating 52a of the first layer to diffract and reflect the incident light in a direction, and to the reflective regions 51b and 51c of the reflective electro-optic crystal 51, a voltage V ₂ is applied.
₁ is applied to reflect the incident light on the reflection type diffraction gratings 52b and 53a, and a voltage V ₂ is applied to the reflection area 51d to diffract and reflect the incident light on the second reflection type diffraction grating 52d in the lowermost layer. Image the beam at the scanning point P ₂ .

After that, if the voltage applied to each reflection region of the reflection type electro-optic crystal 51 is controlled in the same manner, the laser beam scans light at a maximum of 2 ^N scanning points on the image plane 21. It can be done non-mechanically. Also in this case, since the distance from the lens 24 to the image plane 21 can be made constant at all scanning points, a uniform beam diameter can be obtained in all scanning areas.

In the fourth embodiment shown in FIG. 6, two reflection diffraction gratings, the first and second reflection diffraction gratings, are provided for each layer, but one reflection diffraction grating is provided for each layer (N layers). 2 ^N
It may be configured to scan individual scanning points. Although the present invention has been described above with reference to the embodiments, the present invention can be variously modified according to the gist of the present invention described in the claims,
The present invention does not exclude these.

[0049]

As described above, according to the present invention, an electro-optic crystal that changes the polarization direction of light according to a voltage, a voltage application section that applies a voltage that controls the polarization of the crystal, and a reflection element that is arranged behind the crystal. Since the spatial light modulation element is configured by the diffraction grating and the spatial light modulation elements are arranged in N layers in series to configure the optical scanning device, the voltage application state to each spatial light modulation element depends on the scanning speed. It is possible to realize a light reflection path in two directions for one layer by controlling the above-mentioned control.
It is possible to perform light scanning on ^N scanning points with a non-mechanical and compact structure.

Further, according to the present invention, the electro-optic crystal is of the reflection type, and the diffraction gratings are of the transmission type and are arranged in front of the reflection-type electro-optic crystals, and reflected from the reflection-type electro-optic crystal to enter. Since the configuration is such that the polarization direction of the emitted light is controlled by the polarization direction of the emitted light, a two-direction light reflection path can be realized for each layer according to the voltage application state to the reflective electro-optic crystal of each layer, For this reason, it is possible to perform light scanning on a maximum of 2 ^N scanning points with a non-mechanical and compact structure.

Further, according to the present invention, one transmission type electro-optical crystal of the uppermost layer, the reflection type electro-optical crystal of the (N-1) layer, and the polarization property of each electro-optical crystal are controlled. A voltage application unit that applies a voltage to the electro-optical crystal of one layer and a reflection-type electro-optical crystal of the next layer by controlling the deflection direction of outgoing light by the polarization direction of light that is transmitted through or reflected by the electro-optical crystal of a layer. because I constitute an optical scanning device by the reflection type diffraction grating is incident on, it can be realized in two directions of the optical reflection path in a reflective diffraction grating for incident light from each layer of the electro-optic crystal, Therefore, the maximum ^the 2 ^N It is possible to perform non-mechanical scanning of the light with respect to the scanning point of 1 with a small configuration.

Further, according to the present invention, the reflection type electro-optical crystal having N reflection areas and changing the polarization direction of light by the voltage for each reflection area, and the predetermined reflection area of the reflection type electro-optical crystal. Since the deflection direction of the outgoing light is controlled by the polarization direction of the light reflected by the incident light and the incident light is incident on the adjacent reflection region of the reflective electro-optic crystal, the optical scanning device is configured by the N-layer reflective diffraction grating. In the reflection type diffraction grating, light reflection paths in two directions can be realized, and therefore, it is possible to perform light scanning on a maximum of 2 ^N scanning points with a non-mechanical and compact structure.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a configuration diagram of a spatial light modulator of the present invention and an explanatory diagram of optical path control.

FIG. 3 is a configuration diagram of an embodiment of an optical scanning device of the present invention.

FIG. 4 is a configuration diagram of a second embodiment of the optical scanning device of the present invention.

FIG. 5 is a configuration diagram of a third embodiment of the optical scanning device of the present invention.

FIG. 6 is a configuration diagram of a fourth embodiment of the optical scanning device of the present invention.

FIG. 7 is a schematic explanatory view of an LED array type electrophotographic printer.

[Explanation of symbols] 10, 10a, 10b, 10c, 10d ··· spatial light modulator 11, 11a, 11b, 11c, 11d · · transmissive electro-optic crystal 12 · · voltage applying unit 13, 13a, 13b, 13c , 13d ・ ・ Reflective diffraction grating 21 ・ ・ Image plane

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location G06K 15/14 H04N 1/04 104 Z 7251-5C (72) Inventor Mamoru Hokari Nakahara, Kawasaki City, Kanagawa Prefecture 1015 Kamiodanaka, Ku Ward, within Fujitsu Limited (72) Inventor Shigeo Kayashima 1015 Kamikodanaka, Nakahara Ward, Kawasaki City, Kanagawa Within Fujitsu Limited

Claims (4)

[Claims] 1. A transmissive electro-optic crystal that changes the polarization direction of light by electric energy, a voltage application section that applies a voltage to control the polarization of the electro-optic crystal, and a rear part disposed behind the electro-optic crystal. A spatial light that has a reflective diffraction grating that controls the polarization direction of outgoing light according to the polarization direction of incident light, and that controls the deflection direction of outgoing light from the reflective diffraction grating according to the voltage application state to the electro-optic crystal. An optical scanning device characterized in that modulation elements are arranged in N layers in series, and the voltage application state of each spatial modulation element is controlled to perform scanning for a maximum of 2 ^N scanning points. 2. A reflective electro-optic crystal that changes the polarization direction of light by electric energy, a voltage application section that applies a voltage to control the polarization property of the electro-optic crystal, and a front part of the electro-optic crystal. The transmission type diffraction grating is disposed and controls the deflection direction of the emitted light by the polarization direction of the light reflected from the reflection type electro-optical crystal and incident, and the transmission type diffraction grating is provided according to the voltage application state to the electro-optical crystal. The spatial light modulators for controlling the direction of deflection of the light emitted from are arranged in N layers in series, and the voltage application state of each spatial modulator is controlled to a maximum of 2
An optical scanning device characterized by performing scanning on ^N scanning points. 3. A transmissive electro-optic crystal of the uppermost layer which changes the polarization direction of light by electric energy, and a reflection type (N-1) layer which changes the polarization direction of light by electric energy. Electro-optical crystals, a voltage application unit that applies a voltage to control the polarization of each electro-optical crystal, and outgoing light depending on the polarization direction of light that is transmitted through or reflected by the electro-optical crystal of a certain layer. It is equipped with a reflection type diffraction grating that controls the deflection direction of the incident light to enter the reflection type electro-optic crystal of the next layer, and the light from the reflection type electro-optic crystal of the lowermost layer can be used up to
An optical scanning device characterized by sequentially forming an image on ^N scanning points to perform scanning. 4. A reflection type electro-optic crystal having N reflection areas and changing the polarization direction of light by electric energy for each reflection area, and controlling the polarizability in each reflection area of the electro-optic crystal. In order to achieve this, a voltage application unit that applies a voltage to each reflection region, and a reflection type electro-optic crystal that controls the deflection direction of outgoing light by the polarization direction of light that is reflected by a predetermined reflection region of the reflection-type electro-optic crystal and incident Is equipped with a plurality of reflection type diffraction gratings that are incident on adjacent reflection regions of the above, and the light from the reflection type diffraction grating of the lowest layer is sequentially imaged at a maximum of 2 ^N scanning points on the image plane for scanning. Characteristic optical scanning device.