JPH09216417A - Photo element and image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use energy of incident light flux for image recording to reduce the probability of causing a trouble. SOLUTION: A PLZT element 48 includes a flat plate-like base 50 made of PLZT, and a protrusion 52 that is made of PLZT, protrudes a specified height from the base 50 and continuously runs parallel to a side 50A. A rectangular solid part stretching from the upside of the protrusion 52 to the bottom of the base 50 serves as a light transmission part where laser light rays pass through. A common electrode 54 is provided on one side of the light transmission part and a large number of electrodes 56 are provided along the length of the protrusion 52 on the other side of the light transmission part. A voltage applied across the electrodes 56 and the common electrode 54 can be individually controlled by a driver. After the laser light passes through places located between the electrode 54 and the common electrode 52 across which a voltage is applied, its polarization direction is rotated and the laser light is used for image recording. However, the laser light that passes through places that lie and do not lie between the electrodes 56 and 54 across which a voltage is not applied is also used partly for image recording.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element and an image recording apparatus, and more particularly to an optical element which selectively changes the polarization direction of an incident light beam by utilizing the electro-optical effect of an electro-optical material such as PLZT, and The present invention relates to an image recording device that records an image on a recording medium using the optical element.

[0002]

2. Description of the Related Art In an image recording apparatus for recording an image on a recording medium, improvement in image recording speed is always demanded.
In an image recording apparatus configured to record an image in pixel (dot) units by scanning a light spot on a recording medium such as a photosensitive material, a plurality of light spots are simultaneously irradiated onto the recording medium to simultaneously record a plurality of dots. It is effective to improve the recording speed of the image.

In connection with the above, Japanese Patent Laid-Open No. 2-254472 uses a halogen lamp as a light source, guides light emitted from the halogen lamp to a rod lens by an optical fiber guide, and records the light through the rod lens. A solid scanning type print head has been proposed in which a plurality of dots are simultaneously exposed and recorded on a recording medium by irradiating the medium.

However, the above print head is effective when a recording medium having a high sensitivity to light is used, such as a photosensitive drum for recording an image by electrophotography or a silver salt photosensitive material. However, for example, as described in Japanese Patent Application No. 6-275183, a color material sheet on which a photoelectric conversion layer, a color material layer, and the like are formed, and an image receiving sheet on which an image receiving layer is formed, are configured to be stacked. , The irradiated light is converted into heat energy by the photoelectric conversion layer, and when the converted heat energy causes the temperature of the color material layer to reach a threshold value or more, the color material layer is pressed against the image receiving layer by ablation to form an image on the image receiving layer. The amount of light was insufficient to record an image on a recording medium having low sensitivity to light, such as a recording material on which is formed.

Also, an optical element (so-called optical shutter array) comprising a plurality of prismatic shutters made of PLZT and arranged at regular intervals along a predetermined direction is used.
A light beam emitted from one or a plurality of laser light sources is shaped into a wide light beam along the predetermined direction by an optical system arranged between the light source and the optical shutter array, and a beam waist of the light beam is formed. The polarization direction of the light transmitted through each shutter section is selectively changed by the optical shutter array arranged at the position, and only the light with the predetermined polarization direction among the light transmitted through each shutter section of the optical shutter array is recorded on the recording medium. An optical head has also been proposed in which a plurality of dots are simultaneously exposed and recorded by irradiation (Japanese Patent Laid-Open No. 4-3038).
(See Japanese Patent Laid-Open No. 17-306620, etc.).

When a plurality of light sources are used in the above optical head, a laser light source array in which laser light sources are formed in an array at regular intervals can be used as a light source, and in this case, a plurality of lasers are used. The optical system between the laser light source and the optical shutter array is designed so that the light beams emitted from the light sources are overlapped and are incident on the optical shutter array as a wide light beam along a predetermined direction. The positional alignment between the optical shutter array and the plurality of laser light source arrays in (1) is completed by aligning only a single laser light source, and the manufacturing is easy.

Further, in the above optical head, a plurality of prismatic shutter portions are formed by forming grooves in a portion corresponding to the gap of the shutter portion by cutting in the block made of PLZT. (For example, Japanese Patent Laid-Open No. 4-
(See FIGS. 7 and 8 of JP 303817), the top portion of the shutter portion through which light is transmitted is polished, whereas the groove is only cut and not polished, and the surface roughness is large.

Therefore, the light emitted between the shutter portions of the optical shutter array is reflected, absorbed or scattered by the surface of the groove, so that the light is substantially transmitted between the shutter portions (the groove portion). The non-transmissive portions are not adjacent to each other, and the light emitted to the non-transmissive portions does not pass through the optical shutter array, is not emitted to the recording medium, and the shutter portions are structurally independent, so that they are adjacent to each other. A small amount of light (so-called leakage light) that leaks between the two light fluxes that pass through the shutter portion and are recorded on the recording medium as adjacent dots is provided, and a recorded image with high contrast can be obtained.

[0009]

However, in the above-mentioned optical shutter array, the light irradiating the portion other than the shutter portion, that is, the non-transmissive portion and other portions does not pass through the optical shutter array and is reflected, absorbed or Since the light is scattered, the energy of the light radiated to the non-transmissive part and other parts is converted into heat energy and the temperature of the optical shutter array becomes high, and the wire connecting the electrode of the optical shutter array and the drive circuit is connected. There have been cases where the connection portion of the bonding has a poor connection or the operation of the drive circuit has failed.

Further, in the above-mentioned optical shutter array, the gap of the shutter portion is cut and processed. However, due to this cutting work or polishing of the top portion of the shutter portion, a part of the top portion of the shutter portion may be cut off, and this top portion is cut off. For the purpose of suppressing variations in the characteristics of each shutter portion due to chipping, in reality, as shown in FIGS. 1 and 4 of Japanese Patent Laid-Open No. 4-306620, chamfering of the top portion of the shutter portion is performed. There is a need. Therefore, in the above optical shutter array, the light emitted to the non-transmissive portion and the light emitted to the chamfered portion of the shutter portion are not emitted to the recording medium side, so the energy of the light emitted from the light source is effective for image recording. Is not used for
There is also a problem that image recording takes time as compared with the energy of light emitted from the light source.

The present invention has been made in consideration of the above facts, and the polarization of incident light can be controlled according to the image to be recorded so that the energy of the incident light can be effectively used for image recording. The purpose is to obtain an optical element with a low probability of failure.

Another object of the present invention is to obtain an image recording apparatus capable of recording an image on a recording medium at high speed.

[0013]

In order to achieve the above-mentioned object, an optical element according to the invention of claim 1 is made of an electro-optical material and has a substantially constant length along the traveling direction of an incident light beam, A light transmitting portion having a shape that is continuous along a predetermined direction that intersects the incident light flux, and a plurality of light transmitting portions that are arranged on both sides of the light transmitting portion with an optical path of the incident light flux interposed therebetween and that are spaced apart by a predetermined distance along the predetermined direction. And a pair of arranged electrodes.

In the invention described in claim 1, PLZT is preferable as the electro-optical material applicable as the light transmitting portion. However, PLNZT, PBLN, barium titanate (BaTiO ₃ ), potassium tantalate (KTaO) other than PLZT is preferable. ₃ ), lithium niobate (LiNbO ₃ ),
Examples thereof include materials having an electro-optical effect such as BNN (Ba ₂ NaNb ₅ O ₁₅ ).

According to the first aspect of the present invention, electrode pairs are provided on both sides of the light transmitting portion made of an electro-optical material with the optical path of the incident light flux interposed therebetween, and the electrode pairs are arranged in a predetermined direction intersecting the incident light flux. A plurality of them are arranged at predetermined intervals along the line. As a result, when a voltage is applied to a certain electrode pair, the polarization direction of the light flux transmitted through a predetermined portion of the light transmitting portion sandwiched by the electrode pair to which the voltage is applied changes due to the electro-optical effect. Therefore, by controlling the voltage application to each of the plurality of electrode pairs, the polarization direction of the light beam transmitted through each part of the light transmitting portion corresponding to each electrode pair can be controlled, and the incident light beam is recorded. The polarization can be controlled according to the image to be processed.

Here, in the invention of claim 1, the shape of the light transmitting portion is such that the length along the traveling direction of the incident light flux is substantially constant,
The shape is continuous along a predetermined direction intersecting the incident light flux. Therefore, according to the first aspect of the invention, the light transmitting portion is not processed such as cutting or chamfering in a portion corresponding to the gap between the electrode pairs, and it is not necessary to perform the processing. . Further, when a wide light flux along a predetermined direction is incident on the light transmissive portion over the entire portion where the electrode pair of the light transmissive portion is provided, among the light flux incident on the light transmissive portion, each of Light that has not been emitted to the recording medium side by the groove (non-transmissive portion) or the chamfered portion formed in a portion corresponding to the electrode pair is also emitted to the recording medium side.

As a result, the light which has been converted into heat energy in the non-transmissive portion or the like in the past is also transmitted through the light transmissive portion and emitted, so that the optical element can be prevented from reaching a high temperature and the wiring can be prevented. It is possible to reduce the probability that a failure such as a poor connection of the connection portion occurs.

Then, between the optical element according to the first aspect of the present invention and the recording medium, the removing means for removing most of the light having a predetermined polarization direction in the incident light beam to form recording light. By arranging (for example, a polarization beam splitter, a polarizer, etc.) and irradiating the recording medium with the recording light formed by the removing means, the chamfered portion can record the light which has not been conventionally used for image recording. Irradiates the medium and contributes to image recording, and also records light that has not been used for image recording in the past by non-transmissive parts (light that has transmitted through parts not sandwiched by the electrode pairs of the light transmissive parts). Since the medium can be used for recording an image by irradiating the medium, the energy of the incident light flux can be effectively used for image recording, and the image can be recorded at a higher speed.

By the way, in the invention of claim 1, when the width of the light transmitting portion along the direction orthogonal to the incident light beam and the predetermined direction is insufficient for transmitting the entire light beam of the incident light beam, or the like. Is irradiated with light also on a portion other than the light transmitting portion of the optical element according to the invention of claim 1 (for example, wiring provided on each of a plurality of electrode pairs), and this light energy is converted into heat energy. As a result, there is a possibility that a failure such as a poor connection at the connecting portion of the wiring may occur.

In view of the above, as described in claim 2, it is preferable to further provide a light reflecting portion for reflecting the light incident on the portion of the incident light beam other than the light transmitting portion. As a result, it is possible to prevent the energy of the light incident on the portion other than the light transmitting portion from being converted into thermal energy and to prevent the portion other than the light transmitting portion from reaching a high temperature. Even when the width of the transparent portion is small, it is possible to reduce the probability of failure such as connection failure of the wiring connection portion.

An image recording apparatus according to a third aspect of the present invention includes a first light source, an optical element according to the first or second aspect, and a light beam emitted from the first light source in the predetermined direction. Selected for each of the plurality of electrode pairs of the optical element according to the first optical system that is incident on the light transmitting portion of the optical element as a wide light flux along the line and the image to be recorded on the recording medium. Control means for selectively applying a voltage, and removing means for removing most of the light having a predetermined polarization direction out of the light beam transmitted through each part of the light transmitting part of the optical element to form recording light. And a second optical system for irradiating the recording medium with the recording light formed by the removing means.

According to a third aspect of the present invention, the optical element according to the first or second aspect is provided, and the control means controls a plurality of electrode pairs of the optical element according to an image to be recorded on the recording medium. Since the voltage is selectively applied to each of the light beams, the light beam emitted from the first light source and incident on the light transmitting portion of the optical element as a wide light beam along the predetermined direction by the first optical system is The polarization control is performed according to the image to be recorded, for each light beam having different transmission positions on the light transmitting portion of the optical element. Then, the light flux transmitted through the optical element is removed by the removing means of the second optical system to remove most of the light having a predetermined polarization direction to form recording light, and this recording light is applied to the recording medium. As a result, the image is recorded on the recording medium.

In the invention of claim 3, the optical element of claim 1 or 2 is used to control the polarization of the light beam. Therefore, like the invention of claim 1, the light is emitted from the first light source. The energy of the luminous flux can be effectively used for image recording, and an image can be recorded on the recording medium at high speed. Also, instead of increasing the image recording speed,
It is also possible to reduce the cost required for the first light source by setting the light amount (energy) of the light flux emitted from the light source of 1.

In the optical element according to claim 1 or 2, the light transmitting portions are not structurally independent (continuous along a predetermined direction), and accordingly, structurally. Since so-called leakage light increases as compared with a conventional optical shutter array having a plurality of independent prismatic shutter sections, a section where transfer or color development or density change on a recording medium is not desired during image recording. The amount of light radiated on the object increases.
For this reason, it is conceivable that the contrast of the recorded image will be reduced if a photosensitive drum or a silver salt photosensitive material having high sensitivity to light is applied as the recording medium.

However, as the recording medium, when the temperature of the irradiated light exceeds a threshold value, the recording medium changes in transfer or color development or density, or when the amount of the irradiated light exceeds the threshold value. When a so-called binary recording medium such as a recording medium whose transfer, color development or density changes, is used, recording of the recording medium does not cause transfer, color development or density change only by irradiation of leak light. The contrast of the image does not decrease, and conversely, the leaked light is irradiated to a predetermined portion on the recording medium where it is actually desired to cause the transfer, the color development, or the change in the density, and the surrounding area, so that the light emission is relatively short. This is preferable because the transfer of the predetermined portion, color development and density change occur.

According to a fourth aspect of the present invention, in the invention of the third aspect, the recording medium is transferred to a predetermined portion when the temperature of the predetermined portion exceeds a threshold value by the light irradiated to the predetermined portion. Alternatively, the recording medium is a recording medium in which color development or a change in density occurs, the recording medium includes a second light source, and the light flux emitted from the second light source at the same time as or before the recording light is irradiated to the recording medium. It is characterized in that an irradiating means for irradiating the recording medium is further provided.

According to a fourth aspect of the present invention, there is provided irradiation means for irradiating the recording medium with the light beam emitted from the second light source, at the same time as or before the recording light is irradiated onto the recording medium. Therefore, the temperature of the portion of the recording medium irradiated with the light flux emitted from the first light source is raised by the light flux emitted from the first light source and the light flux emitted from the second light source, and the temperature is shorter. Then, the temperature rises above the threshold value, and transfer or color development or density change occurs. Therefore, it is possible to record an image at a higher speed on a recording medium in which transfer or coloring or change in density of a predetermined portion occurs when the temperature of the predetermined portion exceeds a threshold value by the light irradiated to the predetermined portion. it can.

It should be noted that, in order that the temperature of each part of the recording medium does not exceed a threshold value only with the light beam irradiated by the irradiation means, the light amount of the light beam irradiated by the irradiation means onto the recording medium or each part of the recording medium is If the irradiation time of the light flux or the width of the light flux is adjusted, transfer, color development, or density change does not occur at a portion of the recording medium that is not irradiated with the recording light.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. In the following, description will be made using numerical values that do not hinder the present invention, but the present invention is not limited to the numerical values described below.

FIG. 1 shows an image recording apparatus 1 according to this embodiment.
0 is shown. The image recording device 10 includes a bracket 1
The drum 14 is rotatably supported by the drum 14. The drum 14 is driven at a constant speed in the direction of arrow A in FIG. 1 by a driving means (not shown) (for example, the peripheral speed is about 0.5 to 15 m / s).
Rotated by Further, on the peripheral surface of the drum 14, the recording medium according to the present invention (more specifically, the recording medium according to claim 4).
The recording member 16 is wound around and is held on the peripheral surface of the drum 14 by being attracted by a negative pressure.

As shown in FIG. 2, the recording member 16 is constructed by stacking a color material sheet 18 and an image receiving sheet 20 on each other. The color material sheet 18 includes a photothermal conversion layer 24, an intermediate layer 26, and a color material layer 28 on the surface of the base 22 on the image receiving sheet 20 side.
Are sequentially formed and configured. Also, the image receiving sheet 2
0 is the image receiving layer 32 on the surface of the base 30 on the color material sheet 18 side.
Is formed. An image is recorded on the recording member 16 by using a laser beam having a wavelength that matches the wavelength sensitivity characteristic of the recording member 16.

That is, the color material sheet 18 of the recording member 16
When the laser light is irradiated from the side, the laser light passes through the base 22 and reaches the photothermal conversion layer 24, and the optical energy of the irradiated laser light is converted into thermal energy by the photothermal conversion layer 24. Is transmitted to the color material layer 28 via the intermediate layer 26. In the color material layer 28, the temperature rises at the portion where the heat energy is transferred, and only the portion where the temperature becomes equal to or higher than the threshold value is ablated to the image receiving sheet 20.
Of the image receiving layer 32. After that, color material sheet 1
When the image receiving sheet 20 and the image receiving sheet 20 are separated from each other, the color material layer 28 is formed on the image receiving layer 3 of the image receiving sheet 20 only in the portion irradiated with the laser beam.
2 and the image is formed on the image receiving layer 32 of the image receiving sheet 20.

As is clear from the above, the recording member 16
Is held on the peripheral surface of the drum 14 such that the color material sheet 18 side is on the outer peripheral side of the drum 14. Meanwhile, the drum 14
A pair of guide rails 34 that are parallel to the axial direction of the drum 14 are disposed on the sides of the guide rails. A moving block 36 that is slidably movable along the guide rail 34 is attached to the guide rail 34, and the moving block 36 is along the guide rail 34 (that is, parallel to the axial direction of the drum 14) by a driving unit (not shown). Be moved).

The moving block 36 has an optical head 3 on the upper side.
8 is integrally attached. The optical head 38 emits a large number (for example, 128) of laser beams arranged along the direction parallel to the axial direction of the drum 14 toward the peripheral surface of the drum 14. A large number of laser lights emitted from the optical head 38 are simultaneously applied to the recording member 16 held on the peripheral surface of the drum 14, and the irradiation position of each laser light on the recording member 16 is the rotation of the drum 14. Thus, the recording member 16 is moved along the rotation direction of the drum 14 (main scanning).

Since the multiple laser beams emitted from the optical head 38 are arranged in a direction parallel to the axial direction of the drum 14, that is, in the sub-scanning direction orthogonal to the main scanning direction, the drum 14 makes one revolution. In (one main scan), many lines of an image are recorded at the same time. The sub-scanning is performed by moving the moving block 36 (and the optical head 38) along the guide rail 34.

Next, the structure of the optical head 38 will be described. As shown in FIG. 3, the optical head 38 has a recording semiconductor laser 40 as the first light source of the present invention.
As the semiconductor laser 40, for example, a linear array type in which a plurality of light emitting surfaces (or light emitting points) are arranged in a line along a predetermined direction as shown in FIG. 4 can be applied, and the semiconductor laser 40 emits light. A plurality of laser lights are emitted along the arrangement direction of the surfaces. In FIG. 3B, 3 out of the plurality of laser beams emitted from the semiconductor laser 40 are shown.
Although only a laser beam of a book is shown as a representative, for example, FIG.
As shown in, the number of light emitting surfaces is 24 and the shape of the light emitting surface is 200μ.
The rectangular shape of m × 1 μm and the arrangement pitch of the light emitting surfaces can be 390 μm. Further, for example, the wavelength of the laser light emitted from the semiconductor laser 40 can be 0.83 μm, and the power of the laser light can be 20 W.

The wavelength of the laser beam is not limited to the above numerical values, and may be any value that matches the wavelength sensitivity characteristic of the recording member. The power of the laser light varies depending on the sensitivity of the recording member and the image recording time of the image recording apparatus, but may be within a practical range. It is also possible to apply a semiconductor laser other than the linear array type, for example, a normal type semiconductor laser having a single light emitting surface (or a light emitting surface). In addition to the semiconductor laser, it is also possible to use a solid-state laser such as YAG or YFL, or a gas laser such as argon or carbon dioxide gas.

On the other hand, a cylindrical lens 42 is arranged on the laser light emitting side of the semiconductor laser 40. The cylindrical lens 42 has a focal length f ₁ (for example, 3 from the light emitting surface of the semiconductor laser 40).
mm) are arranged so that the direction having the lens power is orthogonal to the arrangement direction of the plurality of laser beams emitted from the semiconductor laser 40. In the following description, for convenience, the arrangement direction of a plurality of laser beams emitted from the semiconductor laser 40 (the direction perpendicular to the paper surface in FIG. 3A) is the lateral direction, and the direction orthogonal to the arrangement direction (FIG. 3). The direction perpendicular to the paper surface in (B) is referred to as the vertical direction. With this cylindrical lens 42, the plurality of laser beams emitted from the semiconductor laser 40 and incident on the cylindrical lens 42 are converted from divergent light into parallel light only in the vertical direction.

On the laser light emitting side of the cylindrical lens 42, a rotationally symmetrical first lens 44 having a positive lens power is arranged. The first lens 44 is arranged at a position separated from the light emitting surface of the semiconductor laser 40 by the focal length f ₂ (for example, 50 mm) of the first lens 44. The plurality of laser lights emitted from the cylindrical lens 42 and incident on the first lens 44 by the first lens 44 are changed from parallel light to focused light in the vertical direction and from divergent light to parallel light in the horizontal direction. The light beams are emitted in the form of a wide light beam in the lateral direction near the focal position of the first lens 44, and the optical axes are aligned at the focal position of the first lens 44.

A polarizing element 46 is arranged on the laser light emitting side of the first lens 44. The polarization direction of the laser light emitted from the semiconductor laser 40 is a direction perpendicular to the paper surface of FIG. 3A (hereinafter, the polarization direction is based on this direction (= 0.
However, the polarization element 46 is
The polarization direction of the laser light emitted from the lens 44 is rotated by 45 ° so that the laser light is inclined by 45 ° with respect to the vertical direction and the horizontal direction. When the polarization direction of the laser light is rotated by 45 °, for example, a ½ wavelength plate can be used as the polarization element 46. The polarization direction of the laser light may be rotated by 135 ° by the polarization element 46. The cylindrical lens 42, the first lens 44, and the polarization element 46 described above correspond to the first optical system of the present invention.

A PLZT element 48 as an optical element according to the present invention is arranged on the laser light emitting side of the polarizing element 46. Although only a part of the PLZT element 48 is shown in FIGS. 5A to 5C, the PLZT element 48 is formed of PLZT and has a substantially flat plate-like base portion 50 and a position spaced apart from a predetermined side 50A of the base portion 50 by a predetermined distance. In addition, the protrusion 52 formed of PLZT is provided so as to protrude from the upper surface of the base 50 by a certain height and is continuous along a direction parallel to the predetermined side 50A.
And It should be noted that the bottom surface of the base portion 50 (the projection portion 52 through the top surface of the projection portion 52 and the projection portion 52 and the base portion 50).
The rectangular parallelepiped portion extending to the surface opposite to the surface on which (1) is provided corresponds to the light transmitting portion.

In the PLZT element 48, the bottom surface of the base portion 50 faces the first lens 44 side, the lengthwise direction of the protrusion 52 coincides with the lateral direction, and the tip end of the protrusion 52 is the first lens 44.
The laser light that is coincident with the focal position of the first lens 44 and is emitted from the first lens 44 is incident on the light transmitting portion along the height direction of the protruding portion 52, is transmitted through the light transmitting portion, and is emitted from the tip of the protruding portion 52. It is arranged to be done. In this embodiment, PL
The width of the light flux along the vertical direction of the laser light when passing through the ZT element 48 is about 30 μm, and the thickness dimension d of the protrusion 52 (that is, the dimension along the vertical direction of the light transmitting portion)).
Is large enough (for example, 60 μm) to transmit most of the laser light.

The PLZT element 48 has a predetermined side 50.
A common electrode 54 is formed over the entire surface on the side surface of the protrusion 52 on the side closer to A and on the upper surface of the base 50 between the protrusion 52 and the predetermined side 50A. The common electrode 54 has a protrusion 5
2 is continuous along the length direction (predetermined direction according to claim 1) and corresponds to one electrode of each of the plurality of electrode pairs according to claim 1.

Further, the base portion 50 between the side surface of the protruding portion 52 opposite to the side surface on which the common electrode 54 is formed, and the side (not shown) facing the predetermined side 50A of the base portion 50 and the protruding portion 52. A large number (for example, 128) of electrodes 56 are formed on the upper surface of the. Each of the electrodes 56 has a constant width dimension along the length direction of the protrusion 52, and from the same height position as the tip of the protrusion 52 on the side surface of the protrusion 52,
It is continuous to the side facing the side 50A through the side surface and the upper surface, and is spaced at a predetermined pitch (for example, about 6 μm) along the length direction of the protrusion 52 at a constant pitch (for example, 63.5 mm).
(μm).

As described above, the common electrodes 54 are provided on both sides of the light transmitting portion with the optical axis of the laser light passing through the light transmitting portion interposed therebetween.
A large number of pairs of electrodes including the electrodes 56 are formed along the length direction of the protrusion 52. Thus, the multiple electrodes 56 correspond to the other electrode of each of the plurality of electrode pairs of claim 1. Each of the common electrode 54 and the multiple electrodes 56 is connected to a driver 86 (see FIG. 6) via a wiring (not shown), and the driver 86 causes a voltage between each of the multiple electrodes 56 and the common electrode 54. Is independently controlled.

As described above, the polarization direction of the laser light incident on the PLZT element 48 is 45 by the polarization element 46.
It is rotated by ° (or 135 °) and inclined by 45 ° with respect to the vertical and horizontal directions. Therefore, a certain electrode 5
The laser light transmitted through a predetermined portion of the light transmitting portion sandwiched by 6 and the common electrode 54 has its polarization direction rotated when a voltage is not applied between the electrode 56 and the common electrode 54. None (remains 45 °) PLZT element 4
8 is emitted from the electrode 56 by the driver 86.
A voltage is applied between the common electrode 54 and the common electrode 54, and when the electric field is applied to the predetermined portion by the application of this voltage, the polarization direction of the laser light is rotated by 90 ° (for example, the incident laser light). If the polarization direction is 45 °, the polarization direction is rotated 90 ° to 135 °) PLZ
It is emitted from the T element 48.

For this reason, the laser light emitted from the PLZT element 48 after passing through the respective portions of the light transmitting portion corresponding to the large number of electrodes 56 of the PLZT element 48 is disposed at the electrodes 56 corresponding to the transmitting portions. The polarization direction is selectively rotated by 90 ° depending on whether or not a voltage is applied between the common electrode 54 and the common electrode 54. It should be noted that the laser light incident on the portion of the light transmitting portion which is not sandwiched by the electrode 56 and the common electrode 54 is also transmitted through the light transmitting portion and emitted from the PLZT element 48.

Further, in the PLZT element 48, the high reflection film 58 having a very high light reflectance is formed by vapor-depositing aluminum, for example, over the entire surface of the bottom surface of the base 50 except the portion corresponding to the light transmitting portion. And the like. The high reflection film 58 corresponds to the light reflecting portion of the second aspect.

On the laser light emitting side of the PLZT element 48,
A polarization beam splitter 60 as a removing means of the present invention,
The second lens 62 is arranged in order. As described above, the PLZT element 48 emits laser light whose polarization direction is still 45 ° and laser light whose polarization direction is rotated by 90 ° to 135 °, but the polarization beam splitter 60 Since the laser light emitted from the PLZT element 48 is rotated by 135 ° with respect to the optical axis, the laser light whose polarization direction is 135 ° is theoretically transmitted through the polarization beam splitter 60 for recording. The laser light that is emitted to the second lens 62 side as the laser light for use and has the polarization direction of 45 ° is reflected by the reflection surface of the polarization beam splitter 60,
It is removed from the recording laser light by being emitted in a direction different from the lens 62 side.

However, in reality, the tolerance of the assembly accuracy at the time of manufacture,
Alternatively, due to the deviation of the tilt angle of the polarization beam splitter 60 due to the positional deviation of the polarization beam splitter 60 after manufacturing, or the manufacturing error at the time of manufacturing the polarization beam splitter 60, the laser light (light transmission Light transmitted through a portion sandwiched between the electrode 56 to which no voltage is applied and the common electrode 54, and PLZT
The laser light that has transmitted through a portion of the element 48 that is not sandwiched by the electrode 56 and the common electrode 54 of the light transmission portion of the element 48 also passes through the polarization beam splitter 60, though slightly.

On the other hand, the second lens 62 has a rotationally symmetrical shape having a positive lens power, and the first lens 4
4 from the focal length f ₂ of the first lens 44 and the second lens 6
They are arranged at positions separated by a distance corresponding to the sum of the two focal lengths f ₃ (for example, 70 mm). This second lens 62
Thus, the laser light transmitted through the polarization beam splitter 60 and emitted to the second lens 62 is converted from divergent light into parallel light in the vertical direction, and converted into focused light from the parallel light in the horizontal direction and emitted. It

On the laser light emitting side of the second lens 62, a third lens 64 having a positive lens power and having a rotationally symmetrical shape is arranged. The third lens 64 from the second lens 62 is disposed a distance apart locations corresponding to the sum of the focal length f ₃ of the second lens 62 focal length f ₄ of the third lens 64 (e.g., 10 mm) . The laser light emitted from the second lens 62 and incident on the third lens 64 by the third lens 64 is changed from parallel light to focused light in the vertical direction and from divergent light to parallel light in the horizontal direction. Is ejected.

The laser light emitted from the third lens 64 passes through an opening (not shown) provided in the housing of the optical head 38 and is emitted outside the housing. The recording member 16 held on the peripheral surface of the drum 14 described above is arranged at a position corresponding to the focal position of the third lens 64, and the recording member 16 is emitted from the third lens 64 and is the housing of the optical head 38. The laser light emitted to the recording member 16 is irradiated. As described above, the polarization beam splitter 60, the second lens 62, and the third lens 64 described above correspond to the second optical system of the present invention.

On the other hand, on the axis orthogonal to the optical axis of the laser beam from the semiconductor laser 40 to the polarization beam splitter 60 on the polarization beam splitter 60, the semiconductor lasers are sequentially arranged from the side distant from the polarization beam splitter 60. Four
A semiconductor laser 66 for heating having the same configuration as that of 0 (claim 4).
(Corresponding to the second light source described in 1), the cylindrical lens 4
A cylindrical lens 68 having the same configuration as that of No. 2, a fourth lens 70 having the same configuration as the first lens 44, and a polarizing element 72 having the same configuration as the polarizing element 46 are arranged (FIG. 3).
(A)).

As a result, the plurality of laser beams emitted from the semiconductor laser 66 are made into light beams having a wide width in the lateral direction near the focal position of the fourth lens 70 by the cylindrical lens 68 and the fourth lens 70. With the 4th
The optical axes are made to coincide with each other at the focal position of the lens 70, and the polarization direction is rotated by 45 ° by the polarization element 72 to be incident on the polarization beam splitter 60. The polarization direction is 45
The rotation of the laser beam incident on the polarization beam splitter 60 by the rotation is reflected by the reflective surface of the polarization beam splitter 60, emitted from the semiconductor laser 40 and transmitted through the polarization beam splitter 60 together with the recording laser beam.
The recording member 16 is irradiated with heating laser light through the second lens 62 and the third lens 64.

As described above, the semiconductor laser 66, the cylindrical lens 68, the fourth lens 70, and the polarization element 72 constitute a part of the irradiation means of the present invention, and the polarization beam splitter 60, the second lens 62, and the third lens 62. The lens 64 also has a function as the irradiation means.

As shown in FIG. 6, semiconductor lasers 40, 6
6 is a controller 84 via drivers 80 and 82, respectively.
It is connected to the. The controller 86 has a driver 86
And a signal line for inputting image data from the outside to the controller 84,
Image data representing an image to be recorded on the recording member 16 is input from the outside via the signal line. A frame memory 88 for storing image data is connected to the controller 84, and a drive unit for rotating the drum 14 and a drive unit for moving the moving block 36 (and the optical head 38) are also connected. (Not shown).

Next, the operation of this embodiment will be described. When recording an image on the recording member 16, image data is input to the controller 84 from the outside in advance. This image data is data representing the density of each pixel forming the image in binary (that is, the presence or absence of dot recording), and the controller 8
4 temporarily stores the input image data in the frame memory 88. When actually recording an image on the recording member 16, the controller 84 rotates the drum 14 at a constant speed, turns on the semiconductor lasers 40 and 66, and outputs the power of the laser light emitted from the semiconductor lasers 40 and 66. Are controlled so that each becomes a predetermined value, and the temperatures of the semiconductor lasers 40 and 66 are controlled so as to reach a predetermined temperature (for example, 25 ° C.).

In parallel with the above control, the controller 8
4 sequentially reads the image data stored in the frame memory 88 in the same pixel number as the number of the electrodes 56 provided in the PLZT element 48 according to the recording order of the image on the recording member 16 by the optical head 38. , PLZ according to the density value (binary) for each pixel represented by the read image data
For each of the multiple electrodes 56 of the T element 48, the driver 8
The voltage is selectively applied to the common electrode 54 via 6 repeatedly.

As a result, the recording laser light and the heating laser light are emitted from the optical head 38 and are irradiated onto the recording member 16, and as the drum 14 rotates, a large number of lines of an image are formed along the main scanning direction. Recording at the same time (optical head 3
The operation of 8 and the recording process of the image on the recording member 16 will be described later). When one main scan is completed, the controller 84 moves the moving block 36 and the optical head 38 along the guide rail 34 by a predetermined amount. As a result, sub-scanning of the recording laser beam and the heating laser beam is performed, and an image is recorded on the recording member 16 by repeating the above processing.

By the way, PL by the controller 84
More specifically, the voltage is applied to each of the plurality of electrodes 56 of the ZT element 48 with respect to the electrode 56 corresponding to the pixel of which density value is “high” (that is, with dot recording) in the read image data. Only, a constant voltage is applied to the common electrode 54. As a result, the PLZT element 48
In the light transmitting portion, the electric field is applied only to the portion sandwiched between the electrode 56 to which the voltage is applied and the common electrode 54.
A constant voltage is applied between the common electrode 54 and the electrode 56 corresponding to the pixel having the high density value, and the electrode 56 corresponding to the pixel having the low density value is applied. However, 0 V may be applied to the common electrode 54.

On the other hand, in the optical head 38, the semiconductor laser 4
A plurality of (for example, 24) laser beams emitted from 0 are transmitted through the cylindrical lens 42, the first lens 44, and the polarizing element 46 to be a light beam having a wide width in the lateral direction, and are superposed on each other. As shown in FIG. 7B, the beam profile along the lateral direction is a substantially trapezoidal light beam, and the polarization direction is 45 °.
The light is incident on the light transmitting portion of the T element 48.

The beam profile of the laser light incident on the PLZT element 48 along the vertical direction is shown in FIG.
As shown in (A), since the Gaussian distribution coincides with the Gaussian distribution, most of the laser light is transmitted through the light transmitting portion, but a part of the laser light corresponding to the skirt portion of the Gaussian distribution is transmitted through the light transmitting portion. Irradiation is applied to a part outside the corresponding part. But PL
Since the high reflection film 58 is formed on the entire surface of the ZT element 48 on the laser light incident side except for the portion corresponding to the light transmitting portion, it is irradiated to a portion outside the portion corresponding to the light transmitting portion. Most of the laser light is reflected by the high reflection film 58.
As a result, the temperature inside the PLZT element 48 does not rise, and it is possible to prevent the occurrence of a failure such as a connection failure at the wiring connection portion.

The laser light incident on the light transmitting portion of the PLZT element 48 is transmitted through each part of the light transmitting portion and is incident on the polarization beam splitter 60. However, the laser light is transmitted to the electrode 56 to which the voltage of the light transmitting portion is applied. Only the laser light transmitted through the portion sandwiched by the common electrode 54 is rotated by 90 ° in the polarization direction and is incident on the polarization beam splitter 60.

The recording laser light transmitted through the polarization beam splitter 60 is mainly rotated by 90 ° in the polarization direction.
Although the laser light is set to 0 °, as described above, the voltage of the light transmitting portion is applied due to the deviation of the inclination angle of the polarization beam splitter 60, the manufacturing error in manufacturing the polarization beam splitter 60, and the like. Most of the laser light transmitted through the portion sandwiched between the non-existing electrode 56 and the common electrode 54 is also reflected by the reflecting surface of the polarization beam splitter 60 and removed from the recording laser light, but a part of it is the polarization beam. The light passes through the splitter 60 (so-called leakage light) and is irradiated onto the recording member 16 as recording laser light.

In this embodiment, since the light transmitting portion of the PLZT element 48 is continuous along the direction parallel to the predetermined side 50A, the prismatic shutter portions are spaced at regular intervals along the predetermined direction. The light amount of the leaked light is larger than that in the case of using the conventional optical shutter array that is arranged. Further, the laser light transmitted through a portion not sandwiched by the electrode 56 and the common electrode 54 of the light transmitting portion also has a smaller amount of light than the leaked light, but part of the laser light passes through the polarization beam splitter 60. The recording member 16 is irradiated with recording laser light.

At the portion of the recording member 16 irradiated with the recording laser light, the light energy of the recording laser light is converted into thermal energy, but the recording member 16 is colored by the irradiated laser light. Transfer or coloration occurs due to ablation only at the site where the internal temperature exceeds the threshold value. On the other hand, in the recording laser light, the polarization beam splitter 6 is transmitted through a portion sandwiched between the electrode 56 to which the voltage of the light transmitting portion is not applied and the common electrode 54.
Laser light transmitted through 0 and laser light transmitted through the polarization beam splitter 60 (hereinafter, referred to as leaked laser light) that transmits through a portion of the light transmitting portion that is not sandwiched by the electrode 56 and the common electrode 54. Since the energy is relatively small, the temperature of the color material layer 28 at the portion of the recording member 16 irradiated with the laser light does not rise above the threshold value although it rises slightly. Does not cause transfer or color development.

On the other hand, of the recording laser light, it passes through a portion sandwiched between the electrode 56 to which the voltage of the light transmitting portion is applied and the common electrode 54, and the polarization beam splitter 6
Laser light transmitted through 0 (hereinafter referred to as main recording laser light)
Is large, and the temperature of the color material layer 28 at the portion of the recording member 16 irradiated with the main recording laser light is equal to or higher than a threshold value, and transfer or color development occurs. The leaked laser light is irradiated to the generated portion or a portion in the vicinity of the generated portion, and the temperature of the coloring material layer 28 is slightly raised by the leaked laser light, so that it is compared with the case where only the main recording laser light is irradiated. Then, the rate of temperature rise of the color material layer 28 in the portion irradiated with the main recording laser light increases, and transfer or color development occurs in a shorter time in the portion irradiated with the main recording laser light.

As a result, the irradiation time of the recording laser beam for recording the individual dots forming the image can be shortened, so that the image recording time on the recording member 16 can be shortened.

Further, this leaked laser light is recorded by the recording member 16
On the other hand, it is particularly effective when an image is recorded at a high recording density (small dot interval). That is, when an image is recorded at a high recording density, the PLZT element 48 is arranged so that the interval between dots recorded by the main recording laser beam with which the recording member 16 is irradiated is small (for example, at 3000 dpi, the dot interval is about 8 μm). It is necessary to design the subsequent optical system, and accordingly, the diameter of each beam of the main recording laser light becomes extremely small.

The recording member 16 used in the present embodiment has a relatively low sensitivity to light, while it is disclosed in Japanese Patent Laid-Open No. 4-303817.
The optical shutter array described in Japanese Patent Laid-Open Publication No. 2003-242242 does not use the light flux irradiated between the shutter portions for image recording, and thus it takes a very long time to record a single dot on the recording member 16. Alternatively, it is conceivable that visible dots are not recorded. On the other hand, in the above, the leakage laser light is irradiated to the part irradiated with the main recording laser light or the part close to the part, so that the visible dots are compared even when an image is recorded at a high recording density. It can be recorded in a very short time.

A plurality of laser beams emitted from the semiconductor laser 66 are transmitted through the cylindrical lens 68, the fourth lens 70, and the polarizing element 72 to be a light beam having a wide width in the lateral direction, and are superposed on each other. And PL
Similar to the laser beam incident on the ZT element 48, the beam profile along the horizontal direction is a substantially trapezoidal beam, and the polarization direction is 45 °, so that the polarization beam splitter 6
0, and is reflected by the reflection surface of the polarization beam splitter 60, so that the recording member 16 serves as heating laser light.
Is irradiated.

Here, in the present embodiment, the optical axis of the recording laser light and the optical axis of the heating laser light with which the peripheral surface of the drum 14 is irradiated are slightly deviated along the rotation direction of the drum 14, As shown in FIG. 8A, the heating laser light is applied to the upstream side in the rotating direction of the drum 14. This allows
The recording member 16 is preliminarily irradiated with the heating laser light before being irradiated with the recording laser light, so that the temperature of the color material layer 28 is entirely preliminarily raised.

Accordingly, FIG. 8C showing the temperature of the coloring material layer 28 when the heating laser light is not irradiated, and the diagram showing the temperature of the coloring material layer 28 when the heating laser light is irradiated. 8 (D), it is clear that when the heating laser light is previously irradiated, the temperature of the color material layer 28 does not transfer or develop color at the portion irradiated with the main recording laser light. Since the threshold value is greatly exceeded, transfer or color development occurs in a shorter time in the area irradiated with the main recording laser light. Therefore, the irradiation time of the recording laser light for recording the individual dots forming the image can be further shortened, and the image recording time on the recording member 16 can be further shortened.

In the above description, each part of the recording member 16 is previously irradiated with the heating laser light before being irradiated with the heating laser light. However, the present invention is not limited to this, and FIG. As shown in (B), the same portion on the recording member 16 may be simultaneously irradiated with the recording laser light and the heating laser light. Also in this case, the recording member 16
An image can be recorded on the recording member 16 at high speed, as in the case where the heating laser beam is previously irradiated.

Although the polarization beam splitter 60 is used as the removing means in the above description, it may be any optical element capable of removing most of the incident light having a predetermined polarization direction, such as a polarizer. It is also possible to apply other optical elements.

The PL as the optical element according to the present invention
The shape of the ZT element is not limited to the shape shown in FIG. The optical element according to the present invention is provided with at least a light transmitting portion having a substantially constant length along the traveling direction of the incident light flux and being continuous along a predetermined direction intersecting the incident light flux. Any shape may be adopted as the shape of the portion other than the light transmitting portion. Further, in the above description, one electrode of each of the plurality of electrode pairs of the present invention is integrally formed as the common electrode 54, but the present invention is not limited to this, and the same number as the electrodes 56 is used instead of the common electrode, for example. Multiple electrodes may be provided.

[0078]

As described above, the optical element according to the first aspect of the present invention includes the light transmitting portion made of an electro-optical material,
Since the length of the incident light flux along the traveling direction is substantially constant and the shape is continuous along a predetermined direction intersecting with the incident light flux, the energy of the incident light flux is incident so as to be effectively used for image recording. The polarization of the light flux can be controlled according to the image to be recorded, and the probability of failure or the like can be reduced, which is an excellent effect.

According to a second aspect of the invention, in the first aspect of the invention, since the light reflecting portion for reflecting the light incident on the portion other than the light transmitting portion is provided, in addition to the above effect, the width of the incident light flux is increased. Even when the width of the light transmitting portion is small, the probability of failure or the like can be reduced.

An image recording apparatus according to a third aspect of the invention is selective for each of the plurality of electrode pairs of the optical element according to the first or second aspect, depending on the image to be recorded on the recording medium. A voltage is applied to the recording medium to irradiate the recording medium with the recording light formed by removing most of the light having a predetermined polarization direction out of the light beam transmitted through the light transmitting portions of the optical element. Thus, there is an excellent effect that an image can be recorded on the recording medium at high speed.

According to a fourth aspect of the present invention, in the third aspect of the invention, the light flux emitted from the second light source is applied to the recording medium at the same time as or before the recording light is applied to the recording medium. In addition to the above effect, in addition to the above effect, in the recording medium in which the transfer or color development or the density change of the predetermined part occurs when the temperature of the predetermined part becomes equal to or higher than the threshold value by the light irradiated to the predetermined part. On the other hand, there is an effect that an image can be recorded at a higher speed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an image recording apparatus according to this embodiment.

FIG. 2 is a schematic cross-sectional view showing the configuration of a recording member used in this embodiment.

3A and 3B are schematic diagrams showing a configuration of an optical system of an optical head.

FIG. 4 is a schematic diagram showing an example of the configuration of a semiconductor laser.

FIG. 5 (A) of the PLZT element (part) is a top view,
(B) is a perspective view and (C) is a sectional view.

FIG. 6 is a block diagram showing a schematic configuration around a controller.

FIG. 7 (A) of laser light incident on a PLZT element
3B is a schematic view showing a beam profile along the vertical direction, and FIG.

FIG. 8A shows a case where a recording laser beam and a heating laser beam are irradiated onto a recording member with a slight shift along the rotation direction of the drum, and FIG. 8B shows recording laser beam and heating laser beam. Schematic diagram showing the case of irradiating the same portion of the member,
(C) shows the case where the recording member is not irradiated with the heating laser beam,
(D) is a diagram showing the temperature of the color material layer when irradiated with a heating laser beam.

[Explanation of symbols]

 10 Image Recording Device 16 Recording Member 38 Optical Head 40 Semiconductor Laser 48 PLZT Element 54 Common Electrode 56 Electrode 58 High Reflection Film 60 Polarizing Beam Splitter 66 Semiconductor Laser

Claims (4)

[Claims] 1. A light transmitting portion made of an electro-optical material, having a substantially constant length along a traveling direction of an incident light beam, and having a shape continuous along a predetermined direction intersecting the incident light beam; An optical element comprising: a plurality of electrode pairs, which are arranged on both sides of the light transmitting portion with an optical path of a light flux therebetween and are arranged at predetermined intervals along the predetermined direction. 2. The optical element according to claim 1, further comprising a light reflecting portion that reflects light incident on a portion of the incident light flux other than the light transmitting portion. 3. A first light source, an optical element according to claim 1 or 2, and a light beam emitted from the first light source as a light beam having a wide width along the predetermined direction. A first optical system which is incident on the light transmitting portion of the optical element, and a control unit which selectively applies a voltage to each of the plurality of electrode pairs of the optical element according to an image to be recorded on a recording medium, The recording light formed by the removing unit is provided with a removing unit that removes most of the light whose polarization direction is a predetermined direction from the light flux transmitted through each part of the light transmitting portion of the optical element. And a second optical system for irradiating a recording medium with the image recording apparatus. 4. The recording medium is a recording medium in which transfer or color development or change in density of a predetermined portion occurs when the temperature of the predetermined portion becomes equal to or higher than a threshold value by light irradiated to the predetermined portion, An irradiation unit is further provided, which is provided with a second light source, and irradiates the recording medium with the light flux emitted from the second light source at the same time as or before the recording light is irradiated to the recording medium. The image recording apparatus according to claim 3, wherein