JP4662244B2 - Optical scanning device and optical scanning system, and image forming apparatus and printer using the same - Google Patents

Description

  The present invention relates to an optical scanning technique used in an image forming apparatus including a copying machine, a printer, a laser exposure apparatus, a display apparatus, and the like, and more particularly, downsizing and high performance of an optical scanning system and an image forming apparatus using the optical scanning system. The present invention relates to an optical scanning technique suitable for realizing a low cost.

  In an image forming apparatus including a copying machine, a printer, a laser exposure device, a display device, and the like, an optical scanning device that deflects and scans light is used.

  For example, a polygon mirror type optical scanning device disclosed in Patent Document 1 is an optical scanning device that is most frequently used in current copying machines, electrophotographic printers, and the like. In this polygon mirror system, light can be scanned by rotating a polygon mirror having a plurality of reflecting surfaces at high speed and applying light to the reflecting surfaces.

  FIG. 15 is a block diagram showing a configuration example of a conventional polygon mirror type optical scanning device. In FIG. 15, reference numeral 1551 denotes a light source, which is composed of a four-beam semiconductor laser that emits four beams. 1552 is a collimator lens, 1553 is a stop, 1532 is a cylindrical lens, 1502 is a polygon mirror as an optical deflector, 1522 is a spherical lens (first scanning lens), 1526 is a toric lens (second scanning lens), and 1555. Is a parallel plate glass as an optical member (interval adjustment member), and in the sub-scanning direction according to the amount detected by the photodetector 1530 (position shift information in the sub-scanning direction of a plurality of beams scanned on the photosensitive drum). Thus, the drawing position (scanning start position) in the sub-scanning direction of a plurality of beams that scan the photosensitive drum (photosensitive member) 1527 is adjusted.

  As another method of the conventional optical scanning device, for example, there is an optical scanning device disclosed in Patent Document 2 in which light emitting elements such as LEDs and organic ELs are arranged in an array.

  FIG. 16 is a block diagram showing a configuration example of a conventional optical scanning device in which light emitting elements are arranged in an array. This optical scanning device has a configuration in which organic EL elements are arranged in an array, and an arbitrary organic It is possible to scan the light by controlling and lighting the EL element.

  In the optical scanning device shown in the figure, on the glass substrate 1608, approximately the same number of signal electrodes 1609 as the number of dots of the organic EL are arranged. Each signal electrode 1609 is electrically connected to the transparent electrode 1611 through a first contact hole 1610 made of an insulating film. The transparent electrode 1611 is opposed to the electron injection electrode 1615 in the second contact hole 1612 of the insulating film with the hole transport layer 1613 and the light emitting layer 1614 interposed therebetween.

  Since the second contact holes 1612 of the insulating film correspond to the light emitting region, they are arranged on a straight line at equal intervals. The electron injection electrode 1615 is electrically connected to the common electrode 1618 in the first contact hole 1616 of the protective film. The protective film second contact hole 1617 is necessary to electrically connect the signal electrode 1609 and the transparent electrode 1611 because the protective film is formed between the signal electrode 1609 and the transparent electrode 1611.

  Further, as a conventional optical scanning device, for example, there is an optical scanning device using a large wavelength dispersion characteristic of a photonic crystal, which is proposed in Patent Document 3 and the like.

  FIG. 17 is a block diagram showing a configuration example of an optical scanning device using a large wavelength dispersion characteristic of a conventional photonic crystal. This optical scanning device periodically inserts cylindrical silicon 17132 in a silicon oxide film 17131. Using the photonic crystal 17130 and the wavelength tunable laser 17110 arranged in the same manner, the current flowing through the wavelength controller of the wavelength tunable laser 17110 is changed, and the wavelength is changed from 650 nm to 660 nm, whereby the light beam in the photonic crystal 17130 is changed. The traveling direction is changed, thereby changing the deflection direction of the light beam greatly to perform optical scanning.

  However, the above-described polygon mirror method requires a mechanical drive unit that mechanically rotates the mirror, which causes a problem in terms of reliability that mechanical wear occurs, and noise is generated. There is a problem. Furthermore, there is a problem in that it occupies a relatively large space, and the size of a printer or the like using the space increases.

  On the other hand, an optical scanning device in which light emitting elements such as LEDs and organic ELs are arranged in an array forms a light emitting element and turns on an arbitrary light emitting element. It does not occur, and the occupied space is relatively small, and the printer device can be downsized.

  However, in an optical scanning device in which LEDs are arranged in an array as light emitting elements, it is very difficult to produce a very long LED array chip, so it is necessary to mount a plurality of LED array chips side by side. Since accuracy greatly affects the print quality, it is necessary to implement with high accuracy, leading to an increase in cost.

  Further, the LED array has a problem of light emission variation that greatly affects the print quality. Although there is a technique for adjusting the light emission variation for each bit by cutting a part of the electrode with a laser beam as in Patent Document 4, the number of processes increases, leading to an increase in cost.

  In an optical scanning device in which organic EL elements are arranged in an array as a light emitting element, as shown in Patent Document 2 (see FIG. 16), since a long one can be manufactured in a lump, there is no mounting process and the cost is low. In addition, there is relatively little variation in light emission. However, the organic EL element has a problem that the lifetime is shorter than that of the LED, and the luminance gradually decreases as the cumulative lighting time becomes longer.

  To solve this problem, the light emission intensity per unit area is lowered due to the structure as in the technique described in Patent Document 5, or the lifetime is increased. Alternatively, as in the technique described in Patent Document 6, organic EL is used. It is possible to arrange multiple lines in an array, and when the line in use reaches the end of its life, it is possible to switch to another line to substantially extend the life. However, the structure becomes complicated, and the organic EL low cost and small size. There is a problem in that the advantage of conversion is impaired. Furthermore, the organic EL array has a short lifetime and is not a fundamental solution to the problem of gradually decreasing brightness.

  In addition, the optical scanning device composed of the photonic crystal and the wavelength tunable laser does not have a mechanical driving unit, does not generate noise, and can downsize the printer device. However, it is necessary to use a special laser called a wavelength tunable laser, and there is a problem that the apparatus becomes expensive.

JP 2003-202510 A JP-A-9-226172 JP 2001-13439 A JP-A-11-70695 JP 2003-54030 A JP 2003-1864 A

  The problem to be solved is that, in the prior art, by using a photonic crystal and a wavelength tunable laser, there is no mechanical drive unit, no noise is generated, and the printer device can be downsized. It is necessary to use a special and expensive laser called a wavelength tunable laser.

  The object of the present invention is to solve these problems of the prior art, to provide an optical scanning device with low noise and high reliability at a very small size and at a low price, as well as enabling high-quality optical scanning. It is.

  In order to achieve the above object, in the present invention, an optical scanning device is constituted by a light source, a scanning unit that scans light from the light source, and a scanning range expansion unit that expands a scanning range of light by the scanning unit. For example, as a scanning unit, a polarizer that deflects and scans light from a light source by controlling a voltage applied to a photonic crystal formed of a ferroelectric material, and the scanning range expanding unit includes two types of photonic crystals. An interface having a deflection angle of 90 ° is formed using a crystal, and an incident angle of light scanned from the scanning unit to the interface is made larger than 45 °, so that a scanning range is expanded.

  According to the present invention, it is possible to increase the scanning range in a small space without using a special laser, and it is possible to scan with high quality light without variation in the amount of light.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

First, a technique described in Japanese Patent Application No. 2005-011526 proposed by the present inventor will be described as a technique for coping with the above-described problems of the prior art.

  In the optical scanning device described in Japanese Patent Application No. 2005-011526, a light source, a deflector in which a photonic crystal is formed of a ferroelectric, and controlled by a voltage applied to the photonic crystal formed of the ferroelectric, The deflection angle is set to 120 by forming the deflection angle of the deflected light made of a dielectric material or a photonic crystal made of a dielectric material and having only one band for the light from the light source. The optical scanning can be performed at an angle of more than 0 °, and the optical scanning system is downsized.

  On the other hand, in the optical scanning device according to the present invention, the optical scanning device is composed of a light source, a scanning unit that scans light from the light source, and a scanning range expansion unit that expands the scanning range of light by the scanning unit. ing. For example, as a scanning means, a polarizer that deflects and scans light from a light source by controlling a voltage applied to a photonic crystal formed of a ferroelectric material such as PLZT (lanthanum-doped lead zirconate titanate crystal). The scanning range expanding means uses two types of photonic crystals to form an interface having a deflection angle of 90 °, and makes the incident angle of the light scanned from the scanning means to the interface larger than 45 °. The optical scanning system is downsized with a configuration that enlarges the scanning range and is different from the technique described in Japanese Patent Application No. 2005-011526.

  Details of the optical scanning apparatus according to the present invention will be described below with reference to FIGS.

  FIG. 1 is a block diagram showing a first configuration example of an optical scanning device according to the present invention, FIG. 2 is a top view of the optical scanning device in FIG. 1, and FIG. 3 shows scanning range expansion means in FIG. FIG. 4 is an explanatory diagram showing a configuration example of the first photonic crystal, FIG. 4 is a photonic band diagram of a TE mode of the first photonic crystal in FIG. 3, and FIG. 5 is a first photonic crystal in FIG. FIG. 6 is an explanatory diagram showing a configuration example of a second photonic crystal constituting the scanning range expanding means in FIG. 1, and FIG. 7 is a diagram showing FIG. FIG. 8 is an enlarged view of the photonic band diagram in FIG. 7, and FIG. 9 is an explanatory view showing a configuration example of the scanning range expanding means in FIG. 10 is a scan in FIG. Explanatory view showing a deflection characteristic example of 囲拡 large unit, FIG. 11 is a block diagram showing a second configuration example of the optical scanning apparatus according to the present invention.

  As shown in FIG. 1, the optical scanning device of this example scans light on an image carrier (photosensitive drum) 1, and includes a light source (semiconductor laser) 9 that emits laser light 8, scanning means 11, and the like. , A scanning range expanding means 5 and optical scanning position detectors (photodiodes) 2 and 3.

  The scanning unit 11 includes a photonic crystal 12 formed of a ferroelectric material (PLTZ) and a voltage control unit 10. Electrodes 6 and 7 are formed on both upper and lower surfaces of the photonic crystal 12. The photonic crystal 12 is connected to the voltage control unit 10 and controlled to apply a voltage to deflect the laser beam 8 from the light source (semiconductor laser) 9 to scan. The nick crystal 12 and the voltage control unit 10 constitute a polarizer. As shown in FIG. 2, the photonic crystal 12 has a structure in which holes 13 are periodically formed in a PLZT flat plate, and PLZT and air having different dielectric constants are periodically arranged.

The scanning range expanding means is composed of a first photonic crystal 5a formed of a dielectric (TiO ₂ : titanium oxide) and a second photonic crystal 5b formed of a dielectric (TiO ₂ ). It has a photonic crystal interface 4 between the first photonic crystal 5a and the second photonic crystal 5b. As described above, the first and second photonic crystals 5a and 5b formed of TiO ₂ also have periodic holes (elliptical holes 13a and rectangular holes 13b) in the TiO ₂ flat plate as shown in FIG. The TiO ₂ and air having different dielectric constants are periodically arranged.

  Here, a photonic crystal is a structure in which transparent materials having different refractive indexes are periodically arranged in a multidimensional manner, and is known to have characteristics such as photonic band gap, anisotropy, and high dispersibility. Yes.

  It has been reported that the high dispersibility of photonic crystals is a property that the refraction angle changes greatly only by slightly changing the wavelength of light, and that the refraction angle can be changed greatly even if the incident angle is changed slightly. (See H. Kosaka et al., Rhys. Rev. B 58, R10096 (1998)).

  On the other hand, in the case of a photonic crystal formed of a ferroelectric material such as PLZT, the refraction angle is greatly changed by changing the voltage applied to the photonic crystal even if the wavelength and incident angle of light are fixed. It has been reported (see D. Scrimgeour, N. Malkova, S. Kim and V. Gopalan, Appl. Phys. Lett., 82, 3176 (2003)).

In the optical scanning apparatus of this example shown in FIGS. 1 and 2, the first and second photonic crystals 5a and 5b constituting the scanning range expanding means are formed by TiO ₂ , and the scanning means 11 is formed by PLZT. The photonic crystal 12 to be formed is formed.

  In the scanning means 11 of this example, since the voltage control unit 10 is connected to the electrodes 6 and 7 formed on the upper and lower surfaces of the photonic crystal 12, the laser emitted from the semiconductor laser 9 and incident on the photonic crystal 12. The light 8 can be scanned by deflecting it in an arbitrary direction by controlling the voltage applied to the photonic crystal 12.

  In this example, the laser beam 8 deflected and scanned by the scanning unit 11 is further incident on the first and second photonic crystals 5a and 5b of the scanning range expanding unit to expand the scanning range, and the laser beam 8 can be scanned over the image carrier 1 over a wide range.

  Although the photonic crystal has high wavelength dispersion as described above, the optical scanning position detectors 2 and 3 detect the scanning start position and the scanning end position, and feed back the signals to the voltage controller 10. Thus, even if the emission wavelength of the semiconductor laser 9 slightly varies due to a change in environmental temperature or the like, the laser beam 8 can be normally scanned on the image carrier 1.

In this example, as shown in FIG. 3, the first photonic crystal 5a constituting the scanning range expanding means 5 has an elliptical hole (elliptical hole 13a) arranged two-dimensionally on a TiO ₂ flat plate. The directions of the respective periods (x direction = first period direction, y direction = second period direction) are orthogonal to each other.

The elliptic hole arrangement period (lattice constant) in the x direction (Γ-X direction of the first Brillouin zone) is ax, and the elliptic hole arrangement period (lattice constant) in the y direction (Γ-X ′ direction of the first Brillouin zone) In the present example, ay = 1.25 · ax, that is, ay is 1.25 times ax. The length of the elliptical hole 13a in the x direction is 0.5 times ax, and the length in the y direction is 0.6 times ay. The photonic band diagram at this time is as shown in FIG. As described in paragraphs 0032 and 0033, the photonic crystal can change the refraction angle depending on the characteristics of the photonic crystal.

  Under such a structural condition, when the normalized frequency (ωa / 2πc) is “0.309”, the dispersion surface of the second band is as shown in FIG. 5, and the wave in the x direction (Γ−X direction) The product of the vector size kx (the magnitude of the wave vector at point A in FIG. 5) and the elliptical hole arrangement period ax is kx · ax = 0.528π, and the wave in the y direction (Γ−X ′ direction). The product of the vector magnitude ky (the magnitude of the wave vector at point B in FIG. 5) and the elliptical hole arrangement period ay is ky · ay = 0.264π, and “kx · ax” and “ky · The ratio to “ay” is 2: 1.

On the other hand, as shown in FIG. 6, the second photonic crystal 5b constituting the scanning range expanding means 5 has rectangular holes (rectangular holes 13b) arranged two-dimensionally on a TiO ₂ flat plate. . Similar to the first photonic crystal 5a, the directions of the respective periods are orthogonal to each other, and the rectangular hole arrangement period in the x direction and the rectangular arrangement period in the y direction are also the first photonic crystal 5a. Same as. The length of the rectangular hole in the x direction is 0.68 times that of ax, and the length in the y direction is 0.8 times that of ay. The photonic band diagram at that time is as shown in FIG.

  FIG. 8 is an expansion of the normalized frequency on the vertical axis of the photonic band diagram in FIG. 7. When the normalized frequency is “0.309”, no band exists, and in this light the photonic band gap Thus, the light does not propagate through the second photonic crystal 5b.

  The structural conditions of the first photonic crystal 5a and the second photonic crystal 5b will be specifically described. When the light source is red (wavelength 660 nm), the first photonic crystal 5a and the second photonic crystal 5a. The arrangement period (lattice constant) of the holes in the x direction of the crystal 5b is 203.9 nm, and the arrangement period (lattice constant) of the holes in the y direction is 254.9 nm. Further, the length of the elliptical hole of the first photonic crystal 5a in the x direction is 102.0 nm, the length of the y direction is 153.0 nm, and the length of the rectangular hole of the second photonic crystal 5b in the x direction is set. The length is 138.7 nm, and the length in the y direction is 203.9 nm.

  When the light source is green (wavelength 532 nm), the arrangement period (lattice constant) of the holes in the x direction of the first photonic crystal 5a and the second photonic crystal 5b is 164.4 nm, and the holes in the y direction The arrangement period (lattice constant) is set to 205.5 nm. The length of the elliptical hole of the first photonic crystal 5a in the x direction is 82.2 nm, the length of the y direction is 123.3 nm, and the rectangular hole of the second photonic crystal 5b is in the x direction. The length is 111.8 nm, and the length in the y direction is 164.4 nm.

  Further, when the light source is blue (wavelength 457 nm), the arrangement period (lattice constant) of the holes in the x direction of the first photonic crystal 5a and the second photonic crystal 5b is 141.2 nm, and the holes in the y direction The arrangement period (lattice constant) is set to 176.5 nm. The length of the elliptical hole of the first photonic crystal 5a in the x direction is 70.6 nm, the length in the y direction is 105.9 nm, and the length of the rectangular hole of the second photonic crystal 5b in the x direction is set. The length is 96.0 nm, and the length in the y direction is 141.2 nm.

In this example, an angle θ (see FIG. 9) formed by the interface 4 between the first photonic crystal 5a and the second photonic crystal 5b and the x direction (Γ-X direction) is expressed as “2 · ay / ax”. Is a tangent tangent of “tan- ¹ (2 · ay / ax) = 68.2 °”, and the scanning means 11 is composed of the photonic crystal 12 formed of the dielectric (PLZT) in FIG. The laser beam 8 deflected and scanned is incident from a cut surface parallel to the x direction (Γ-X direction) of the first photonic crystal 5a constituting the scanning range expanding means 5, and the incident light is the first light. The photonic crystal 5a propagates along the y direction and is deflected by 90 ° at the interface 4 between the first photonic crystal 5a and the second photonic crystal 5b. At this time, the incident angle to the interface 4 between the first photonic crystal 5a and the second photonic crystal 5b is 68.2 °.

  The light deflected by 90 ° at the interface 4 propagates along the x direction in the first photonic crystal 5a, and is a cut surface parallel to the y direction (Γ-X ′ direction) of the first photonic crystal 5a. It is emitted from.

  FIG. 10 is a diagram showing the relationship between the incident position and the outgoing position in the scanning range enlarging means 5 constituted by the first photonic crystal 5a and the second photonic crystal 5b of this example, By scanning the incident position from 0 to 84 mm, the emission position is scanned from 0 to 210 mm, and the scanning range can be enlarged by 2.5 times.

  When light is deflected using a general mirror, the incident angle to the mirror is equal to the reflection angle at the mirror. Therefore, if the light is to be deflected by 90 °, it is necessary to enter the mirror at 45 °. The scanning range is not enlarged.

  On the other hand, in the scanning range enlarging means 5 shown in this example, the incident angle of light to the interface between the first photonic crystal 5a and the second photonic crystal 5b is 68.2 °, which is larger than 45 °. However, since 90 ° deflection can be performed at the interface, the scanning range can be expanded.

As described above with reference to FIGS. 1 to 10, in the optical scanning device of this example, the photonic crystal 12 formed of a ferroelectric (PLZT) and the upper and lower surfaces of the photonic crystal 12 are formed. The scanning means including the electrodes 6 and 7 and the voltage control unit 10 connected to the electrodes 6 and 7 deflects and scans light (laser light 8) in accordance with a signal from the outside. In the interface 4 between the first photonic crystal 5a and the second photonic crystal 5b of the scanning range expanding means 5 made of a photonic crystal, the incident angle to the interface 4 is 68.2 ° which is larger than 45 °. Regardless, it is deflected at 90 ° . In other words, the optical scanning device of this example includes a scanning range expanding unit 5 that parallelizes each light deflected and scanned by the scanning unit and expands the scanning range. A first photonic crystal 5a that enters each deflected scanning light and propagates each scanning light in a straight line in a direction perpendicular to the incident surface (that is, the y direction in FIG. 9), and the first photonic crystal 5a. The first photonic crystal 5a is joined to the first photonic crystal 5a so as to form an interface greater than 45 ° and less than 90 ° with respect to the incident surface. The second photonic crystal 5b bends each scanning light propagating straight in parallel at a right angle. Each deflected scanning light from the scanning means is incident on the first photonic crystal 5a, and each scanning light is sent to the first photonic crystal 5a. photo Each of the scanning lights propagating in a straight line in a direction perpendicular to the incident surface of the nick crystal 5a is incident on the interface at an incident angle greater than 45 ° and less than 90 °, and then bent and emitted at a right angle. . Thereby , the scanning range is expanded, and therefore the scanning optical system can be made small.
For example, the first photonic crystal 5a is a two-dimensional photonic crystal having periodicity in two different directions or a three-dimensional photonic crystal having periodicity in three different directions, and at least the first periodic direction and The product ax · kx of the period ax in the first period direction and the magnitude kx of the wave vector for the light from the light source in the first period direction is orthogonal to the second period direction, and The ratio of the product ay · ky of the period ay in the two periodic directions and the magnitude ky of the wave vector to the light from the light source in the second periodic direction is n: 1 (n is an integer of 2 or more) In addition, the second photonic crystal 5b has a photonic band gap with respect to the light from the light source, and an angle formed between the interface with the first photonic crystal 5a and the first periodic direction. Is the inverse tangent of n · ay / ax and Furthermore, the first photonic crystal 5a has a period in which dielectrics having different dielectric constants are arranged in a first periodic direction and a second periodic direction orthogonal to each other, or periodically Any one or more of the proportions of the dielectrics having different dielectric constants are different.
By adopting such a configuration, the scanning range enlarging means 5 makes each deflected scanning light from the scanning means incident on the first photonic crystal 5a, and each scanning light enters the incident surface of the first photonic crystal 5a. Further, the scanning light propagating straightly in parallel with the second photonic crystal is incident on the interface with the second photonic crystal 5b at an incident angle greater than 45 ° and less than 90 ° and bent at a right angle. And exit.

  The optical scanning device of the present invention is not limited to the example described with reference to FIGS. 1 to 10 and can be variously modified without departing from the gist thereof. For example, in this example, in the first photonic crystal 5a and the second photonic crystal 5b, the elliptical hole arrangement period in the x direction and the elliptical hole arrangement period in the y direction have different periods, and the elliptical shape The ratio of the size of the elliptical holes 13a to the arrangement period is also different in the x direction and the y direction, but only one of them needs to be different. In short, the first and second photonic crystals 5a and 5b have a dielectric constant of one or more of the two or more dielectrics constituting the crystal, or a period in which the dielectrics are arranged, or It is sufficient that one or more of the proportions of the dielectrics having different dielectric constants periodically arranged are different. Further, the shape of the periodically arranged holes is not elliptical, but may be other shapes such as a rectangle.

In this example, the ratio of kx · ax to ky · ay is 2: 1, but may be 3: 1, 4: 1,..., N: 1 (n is an integer of 2 or more),. In this case, in accordance with the ratio (n: 1), the value of the angle θ formed by the interface between the first photonic crystal 5a and the second photonic crystal 5b and the x direction (Γ-X direction). Also, tan- ¹ (3 · ay / ax), tan- ¹ (4 · ay / ax),..., Tan- ¹ (n · ay / ax),.

Further, the two-dimensional photonic crystal of TiO ₂ which is the first photonic crystal 5a and the second photonic crystal 5b constituting the scanning range expanding means 5 is formed on the TiO ₂ substrate by an EB lithography process and a metal film deposition process. After the metal mask is formed by the lift-off process, it can be manufactured by a dry etching process using a chlorofluorocarbon gas. In addition, the first photonic crystal 5a and the second photonic crystal 5b may be formed in separate steps and may be joined at the end, or may be simultaneously formed on the same substrate.

  The PLZT two-dimensional photonic crystal, which is the photonic crystal 12 constituting the scanning means 11, is a pattern exposure of the gel-like photosensitive PLZT film with ultraviolet light, and dissolves the unirradiated portion of the ultraviolet light with an acidic aqueous solution. Then, it can be produced by baking at 400 ° C.

In this example, TiO ₂ is used as the dielectric material for forming the first photonic crystal 5a and the second photonic crystal 5b constituting the scanning range expanding means 5, but is transparent to the light source wavelength. Any other dielectric material or ferroelectric material may be used.

  Further, although PLZT is used as the ferroelectric material for forming the photonic crystal 12 constituting the scanning means 11, any ferroelectric material that is transparent to the light source wavelength may be used. However, PLZT is transparent in the visible light region and has very excellent electro-optical characteristics, and is optimal as a photonic crystal material constituting the optical scanning device of the present invention. Also, the structure of the photonic crystal is a two-dimensional structure in this example, but may be a three-dimensional structure.

  In this example, as means for deflecting and scanning light, electrodes 6 and 7 are formed on the upper and lower surfaces of the photonic crystal 12 formed of PLZT, and the voltage applied to the photonic crystal is controlled by the voltage control unit 10. Although the scanning means is used, a scanning means using a polygon mirror or a silicon micromirror, or a scanning means using an acousto-optic device may be used. However, since the scanning means used in this example has no movable part, there is no problem of noise and reliability, and there is no large heat generation like an acousto-optic element, so that the scanning means constituting the optical scanning device of the present invention is used. Is optimal.

  In this example, the scanning start position and the scanning end position are detected by the optical scanning position detection sensors 2 and 3 and fed back to the voltage control unit 10. However, the optical scanning position is detected at the scanning start position and the scanning position. For example, as shown in the configuration of FIG. 11, the laser beam emitted from the photonic crystal 115a is branched by the beam splitter 112, and the position detection sensor 113 in which the photodiodes are arranged in an array is always used for the position. May be detected and fed back to the voltage controller 110.

  Further, a plurality of the optical scanning devices of this example may be arranged in the main scanning direction or the sub-scanning direction, and an effective scanning speed can be increased with a configuration in which a plurality of optical scanning devices are arranged.

  Such an optical scanning device is used in an image forming apparatus including a copying machine, a printer, a laser exposure device, a display device, and the like. Hereinafter, a printer using the optical scanning device of this example will be described with reference to FIGS. Will be described.

  There are various types of printers that are currently popular, and one of them is an optical writing method that performs optical writing. Typical examples of the optical writing method include an electrophotographic method and a silver salt method.

  The silver salt method is a light writing method and is a typical self-luminous type. In this silver salt method, light is directly written on the photographic paper and the light irradiated is the color of the light irradiated after development. A color is developed, and full-color printing can be performed by writing using light of three colors of red (R), green (G), and blue (B).

  In addition, a self-coloring type that has recently attracted attention is one that uses a photochromic material. A photochromic material is a material whose color changes reversibly by light, and the part irradiated with light changes to the color of the light. Since it can be returned, it is expected to be a full-color rewritable paper that can be repeatedly written and erased by light.

  12 is a block diagram showing a first configuration example of a printer using the optical scanning device according to the present invention. FIG. 13 is a second configuration example of a printer using the optical scanning device according to the present invention. FIG. 14 is a block diagram showing a third configuration example of a printer using the optical scanning device according to the present invention.

  In FIG. 12, an electrophotographic printer is shown as an example. This electrophotographic printer has light sources (semiconductor lasers) 9, 119 and scanning means 11, similar to those shown in FIGS. 111, an optical scanning device 120 including scanning range expanding means 5, 115, optical scanning position detectors 2, 3, 113, and the like, an image carrier (photosensitive drum) 121, a charger 120a, a developing device 120b, and a transfer device. 120c, a fixing device 120e, and a cleaner 120f.

  In the electrophotographic printer having such a configuration, first, the image carrier (photosensitive drum) 121 is charged by the charger 120a, and the charged image carrier (photosensitive drum) 121 is placed on the charged image carrier (photosensitive drum) 121 by the optical scanning device 120. The laser beam 128 whose intensity is modulated according to the image data is scanned. The area on the image carrier (photosensitive drum) 121 irradiated with the laser beam 128 has a reduced charge amount, and the charge amount is related to the reciprocal of the irradiation amount of the laser beam 128. An electrostatic latent image is formed.

  Next, the developing device 120b causes the toner to be adsorbed to the charged portion on the image carrier (photosensitive drum) 121, and the transfer device 120c causes the toner on the image carrier (photosensitive drum) 121 to be transferred to the transfer paper 120d. The image is formed on the paper surface by transferring and fixing the toner on the transfer paper 120d on the paper surface by the fixing device 120e. Further, the image carrier (photosensitive drum) 121 is cleaned by the cleaner 120f, and the same process is repeated again.

  FIG. 13 shows a silver salt printer as an example. In this silver salt printer, three optical scanning devices 130a, 130b, and 130c having the same configuration as those shown in FIGS. , A conveying roller 131b, a developing device 131c, and a fixing device 131d. In the three optical scanning devices 130a, 130b, and 130c, the wavelengths of the laser beams (G) 138a, (B) 138b, and (R) 138c from the respective light sources are different, and green (G), blue (B), and red (R). The three optical scanning devices 130a, 130b, and 130c are arranged in the sub-scanning direction.

  In the silver salt printer of this example having such a configuration, first, three colors of light whose intensity is modulated according to image data by the three optical scanning devices 130a, 130b, and 130c are applied to the silver salt paper 131a. The silver salt paper 131a is exposed by sequentially scanning. Thereafter, the image is developed by the developing device 131c, then fixed by the fixing device 131d, and dried to be printed on the silver salt paper 131a.

  In this example, three optical scanning devices each having RGB (red, green, and blue) as light sources are used. However, by using two or more optical scanning devices, multicolor printing can be performed. Become. However, as in the present example, full-color printing is possible by using three or more optical scanning devices 130a, 130b, and 130c having different light source wavelengths. At that time, it is necessary to select a wavelength suitable for full-color printing such as RGB. In addition, the structure of the photonic crystal needs to be changed according to the wavelength of the light source.

  In this example, printing is performed on the silver salt paper 131a. However, it is also possible to print on a color film or other color recording medium in the same manner.

  In FIG. 14, a rewritable printer using a rewritable paper made of a photochromic material is shown as an example, and this printer has three optical scanning devices 140a and 140b having the same configuration as that shown in FIG. 1 and FIG. 140c, a conveying roller 141b, and an ultraviolet light source (ultraviolet lamp) 141c. In the three optical scanning devices 140a, 140b, and 140c, the wavelengths of the laser beams (G) 148a, (B) 148b, and (R) 148c from the light sources are different, and green (G), blue (B), and red are different. (R). The three optical scanning devices 140a, 140b, 140c are arranged in the sub-scanning direction.

  The photochromic material is a material that develops color by irradiation with ultraviolet light and decolors by irradiation with visible light absorbed by the colored material. Three types of photochromic materials were mixed: a yellow material having an absorption spectrum peak near a wavelength of 460 nm, a magenta material having an absorption spectrum peak near a wavelength of 530 nm, and a cyan material having an absorption spectrum peak near a wavelength of 630 nm. For the material coated on the white film, after all materials are colored by UV irradiation, the cyan material is decolored and red when irradiated with red light, and the magenta material is decolored when irradiated with green light. Thus, the green color is displayed, and the portion irradiated with the blue light is decolored by the yellow material to display blue, and a full color image can be displayed.

  In addition, when irradiated again with ultraviolet light, all the materials are colored and the image can be erased, so that it can be used as a rewritable paper that can be rewritten repeatedly (Ikue Kawashima, Hiroyuki Takahashi, Narunobu Hirano, Optics 32, No. 12, 707 (2003)).

  In this way, when a photochromic material is irradiated with light of a certain color, the irradiated portion becomes the color of the irradiated light, and when irradiated with ultraviolet light, it can be erased, so that it can be repeatedly rewritten as a rewritable paper. Can be used.

  In the printer shown in FIG. 14 having such a configuration, first, a rewritable paper made of a photochromic material (described as “photochromic paper” in the figure) 141a is irradiated with ultraviolet light by an ultraviolet lamp 141c, and already on the rewritable paper 141a. Erase the image formed on. Next, the rewritable paper 141a from which the image has been erased is sequentially scanned with light of three colors intensity-modulated in accordance with image data by the three optical scanning devices 140a, 140b, and 140c, and the image on the rewritable paper 141a. Print.

  In this example, the three light scanning devices 140a, 140b, and 140c each using RGB as a light source are configured. However, similarly to the example shown in FIG. 13, two or more light scanning devices are used. Multi-color printing is possible, and full-color printing is possible by comprising three or more optical scanning devices 140a, 140b, 140c having different light source wavelengths. At this time, it is necessary to select a wavelength suitable for full color printing such as RGB. In addition, the structure of the photonic crystal needs to be changed according to the wavelength of the light source.

  As described above with reference to FIGS. 1 to 14, in the optical scanning device of this example, the light source, the scanning unit that scans (deflects) the light from the light source, and the scanning in which the light is scanned by the scanning unit. Since it is composed of the scanning range expanding means for expanding the range, it is possible to easily manufacture an optical scanning device that does not vary in the amount of light, is very small, and does not require a special laser.

  In particular, in this example, the scanning means 11 and 111 are constituted by a ferroelectric photonic crystal made of PLZT or the like and a deflector made up of a voltage control unit for controlling the voltage applied to the photonic crystal, and the scanning range. The enlargement means 5 and 115 are formed of at least two types of photonic crystals, ie, the first photonic crystals 5a and 115a and the second photonic crystals 5b and 115b, and an interface having a deflection angle of 90 ° is provided. The scanning light from the scanning means is incident on the interface at an incident angle of 45 ° or more and deflected by 90 ° at the interface, so that the scanning range of the scanning light is expanded to reduce the size of the optical scanning system.

  More specifically, among the two or more types of photonic crystals constituting the scanning range expanding means 5 and 115, the first photonic crystals 5a and 115a are two-dimensional photonics having periodicity in two different directions. A crystal or a three-dimensional photonic crystal having periodicity in three different directions, wherein at least two periodic directions are orthogonal, the period of the first periodic direction is ax, and the period of the second periodic direction is When the period is ay, the magnitude of the wave vector in the first period direction is kx, and the magnitude of the wave vector in the second period direction is ky for the light from the light source, the first period direction The ratio of the wave vector magnitude and period product kx · ax to the second period direction wave vector magnitude and period product ky · ay is n: 1 (n is an integer of 2 or more), and Second photonic crystal 5 , 115b have a photonic band gap with respect to the light from the light source (laser beams 8, 118), the interfaces 4, 114 with the first photonic crystals 5a, 115a, and the first periodic direction. And the angle formed by the arc tangent of n · ay / ax.

  Further, in this example, the first photonic crystals 5a and 115a and the second photonic crystals 5b and 115b each have a dielectric constant of one or more of the two or more dielectrics constituting each of them, or Any one or more of the periods in which the dielectrics are arranged or the proportions of the dielectrics in the periodically arranged dielectrics having different dielectric constants are different.

  In the present example, the first photonic crystals 5a and 115a have a period in which dielectrics having different dielectric constants are arranged in the first periodic direction and the second periodic direction orthogonal to each other, or the period The dielectrics having different dielectric constants are arranged so that one or more of the proportions of the respective dielectrics are different.

  In this example, the scanning positions detected by the detectors 2, 3 and 113 that detect the scanning position are fed back to the control unit of the deflector to control the deflection / scanning of the light.

  In this example, by arranging two or more of such optical scanning devices in the main scanning direction or the sub-scanning direction, the scanning speed can be effectively increased and high-speed scanning is possible. In particular, by arranging two or more optical scanning devices having different light source wavelengths in the sub-scanning direction, the optical scanning device can be used in a multi-color printer, and more than three types of optical scanning devices having different light source wavelengths can be used. By arranging three or more in the scanning direction, it can be used in a full-color printer.

  Further, in this example, by using such an optical scanning device for a printer, an electrophotographic printer, a silver salt color printer, and a rewritable, which are very small, inexpensive, low noise, and highly reliable. A paper color printer can be easily realized.

  In addition, this invention is not limited to the example demonstrated using FIGS. 1-14, In the range which does not deviate from the summary, various changes are possible. For example, in this example, an example in which the optical scanning apparatus according to the present invention is used in a printer apparatus is shown. However, the optical scanning apparatus is used in an image forming mechanism such as an electronic copying machine, a display apparatus, or a laser exposure apparatus. These devices can be reduced in size and performance.

It is a block diagram which shows the 1st structural example of the optical scanning device concerning this invention. FIG. 2 is a top view of the optical scanning device in FIG. 1. It is explanatory drawing which shows the structural example of the 1st photonic crystal which comprises the scanning range expansion means in FIG. FIG. 4 is a photonic band diagram of a TE mode of the first photonic crystal in FIG. 3. It is explanatory drawing which shows the dispersion surface of the 2nd band of TE mode of the 1st photonic crystal in FIG. It is explanatory drawing which shows the structural example of the 2nd photonic crystal which comprises the scanning range expansion means in FIG. FIG. 7 is a photonic band diagram of a TE mode of the second photonic crystal in FIG. 6. It is an enlarged view of the photonic band diagram in FIG. It is explanatory drawing which shows the structural example of the scanning range expansion means in FIG. It is explanatory drawing which shows the example of a deflection characteristic of the scanning range expansion means in FIG. It is a block diagram which shows the 2nd structural example of the optical scanning device concerning this invention. 1 is a block diagram illustrating a first configuration example of a printer using an optical scanning device according to the present invention. It is a block diagram which shows the 2nd structural example of the printer using the optical scanning device concerning this invention. It is a block diagram which shows the 3rd structural example of the printer using the optical scanning device concerning this invention. It is a block diagram which shows the structural example of the conventional optical scanning apparatus of a polygon mirror system. It is a block diagram which shows the structural example of the optical scanning device which arranged the conventional light emitting element in the array form. It is a block diagram which shows the structural example of the optical scanning apparatus using the big chromatic dispersion characteristic of the conventional photonic crystal.

Explanation of symbols

  1, 121: image carrier (photosensitive drum), 2, 3, 113, 123, 133, 143: optical scanning position detector, 4, 114: photonic crystal interface, 5, 115: scanning range expanding means, 5a, 115a: first photonic crystal, 5b, 115b: second photonic crystal, 6, 7, 116, 117: electrode, 8, 118, 128: laser light, 9,119: light source (semiconductor laser), 10 110: Voltage control unit 11, 111: Scanning means 12, 112: Ferroelectric (PLZT) photonic crystal, 13: hole, 13a: elliptical hole, 13b: rectangular hole, 100: beam splitter, 120, 130a, 130b, 130c, 140a, 140b, 140c: optical scanning device, 120a: charger, 120b, 131c: developing device, 120c: transfer device, 120d: for transfer , 120e, 131d: fixing device, 120f: cleaner, 131a: silver salt paper, 131b, 141b: transport roller, 138a, 148a: laser beam (G), 138b, 148b: laser beam (B), 138c, 148c: laser Light (R), 141a: photochromic paper, 141c: ultraviolet light source (ultraviolet lamp), 1502: polygon mirror, 1522: spherical lens (first scanning lens), 1526: toric lens (second scanning lens), 1527 : Photosensitive drum (photoconductor), 1530: photodetector, 1532: cylindrical lens, 1551: light source means, 1552: collimator lens, 1553: aperture, 1555: parallel plate glass, 1608: glass substrate, 1609: signal electrode, 1610: the first contact hole of the insulating film, 611: Transparent electrode, 1612: Second contact hole of insulating film, 1613: Hole transport layer, 1614: Light emitting layer, 1615: Electron injection electrode, 1616: First contact hole of protective film, 1617: Second of protective film Contact hole, 1618: common electrode, 17110: tunable laser, 17130: photonic crystal, 17131: silicon oxide film, 17132: cylindrical silicon.

Claims (14)

A light source;
Scanning means for deflecting and scanning the light from the light source having a photonic crystal formed of a ferroelectric and voltage control means for controlling a voltage applied to the photonic crystal ;
Scanning range expanding means for collimating each light deflected and scanned by the scanning means and expanding the scanning range;
The scanning range expanding means includes
A first photonic crystal in parallel to the rectilinear propagation respectively perpendicular way towards the entrance surface of each scanning light incident to the deflection scanning light from said scanning means,
The first photonic crystal is bonded to the first photonic crystal so as to form an interface of greater than 45 ° and less than 90 ° with respect to the incident surface of the first photonic crystal, and the interface with the first photonic crystal A second photonic crystal that bends each scanning light propagating straight in parallel at a right angle;
Each deflected scanning light from the scanning means is incident on the first photonic crystal, and each scanning light is propagated straight in a direction perpendicular to the incident surface of the first photonic crystal ,
Straight advancing the propagated each scanning light scanning apparatus which is characterized in that y de bent at right angles at an incident angle greater than 90 ° from 45 ° in the interface. The optical scanning device according to claim 1 ,
The first photonic crystal is
A three-dimensional photonic crystal having a two-dimensional photonic crystal or three different directions periodicity having periodicity in two different directions, less a first periodic direction and a second period Direction are orthogonal also And the product ax · kx of the period ax in the first period direction and the magnitude kx of the wave vector for the light from the light source in the first period direction, and the period in the second period direction the ratio of the product ay · ky to the magnitude of the wave vector ky for the light from the light source in the second periodic direction is n: 1 (n is an integer of 2 or more);
The second photonic crystal is
It has a photonic band gap with respect to light from the light source, and an angle formed between the interface with the first photonic crystal and the first periodic direction is an arctangent of n · ay / ax. An optical scanning device characterized by comprising: The optical scanning device according to claim 2 ,
The first photonic crystal has a period in which dielectrics having different dielectric constants are arranged in a first periodic direction and a second periodic direction that are orthogonal to each other, or a dielectric constant that is periodically arranged. Any one or more of the proportions of the different dielectrics are different from each other. The optical scanning device according to any one of claims 1 to 3 ,
The first photonic crystal has elliptical holes periodically arranged so as to be orthogonal to the x direction and the y direction,
The second photonic crystal has rectangular holes periodically arranged to be orthogonal to the x direction and the y direction,
The arrangement period in the x direction of the elliptical hole of the first photonic crystal is the same as the arrangement period of the rectangular hole in the second photonic crystal in the x direction,
An optical scanning device characterized in that the arrangement period in the y direction of the elliptical hole of the first photonic crystal is the same as the arrangement period of the rectangular hole in the second photonic crystal in the y direction. The optical scanning device according to any one of claims 1 to 4 ,
Said scanning means, optical scanning apparatus which is characterized in that the deflection control of the light emitted is incident on by controlling the voltage applied to the photonic crystal said photonic crystal by the voltage control means. The optical scanning device according to claim 5 ,
An optical scanning device, wherein the photonic crystal is PLZT. The optical scanning device according to any one of claims 1 to 6 ,
Having a detector for detecting the scanning position of the light;
An optical scanning device characterized in that a scanning position detected by the detector is fed back to deflection control of the scanning means. An optical scanning system, characterized in that the optical scanning device, arranged two or more in the main scanning direction as claimed in any one of claims 7. The optical scanning device as claimed in any one of claims 7, an optical scanning system, characterized in that arranged two or more in the sub-scanning direction. The optical scanning system according to claim 9 ,
An optical scanning system characterized in that the light source wavelengths of the two or more optical scanning devices arranged in the sub-scanning direction are different. The optical scanning device as claimed in any one of claims 7, made by arranging at least three in the sub-scanning direction, and an optical scanning system, characterized in that each of the light sources of different wavelengths. An optical scanning device according to any one of claims 1 to 7 ,
Exposure control means for controlling the intensity of light scanned by the optical scanning device according to image data;
An image forming apparatus comprising: an image generating unit configured to receive light from the optical scanning device controlled by the exposure control unit on a light receiving medium and generate the image pattern. An optical scanning device according to any one of claims 1 to 7 ,
Exposure control means for controlling the intensity of light scanned by the optical scanning device according to image data;
An image carrier on which an electrostatic latent image is formed by light from the optical scanning device controlled by the exposure control means;
A developing device for developing an electrostatic latent image on the image carrier;
A transfer unit for transferring an image developed by the developing unit to transfer paper;
An image forming apparatus comprising: a fixing device that fixes an image transferred onto the transfer paper. An optical scanning system according to claim 11 ;
Exposure control means for controlling the intensity of light scanned by the optical scanning device according to image data;
A developing unit that develops an image formed on the silver salt paper by light from the optical scanning device controlled by the exposure control unit; and a fixing unit that fixes the image developed by the developing unit. Characteristic silver salt color printer.

Images