JP4833566B2 - Optical scanning device 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. 17 is a block diagram showing a configuration example of a conventional polygon mirror type optical scanning apparatus. In FIG. 17, reference numeral 1751 denotes a light source, which is composed of a four-beam semiconductor laser that emits four beams. 1752 is a collimator lens, 1753 is a stop, 1732 is a cylindrical lens, 1702 is a polygon mirror as an optical deflector, 1722 is a spherical lens (first scanning lens), 1726 is a toric lens (second scanning lens), and 1755. 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 1730 (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 on the photosensitive drum (photosensitive member) 1727 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. 18 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 any 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 1808, approximately the same number of signal electrodes 1809 as the number of dots of the organic EL are arranged. Each signal electrode 1809 is electrically connected to the transparent electrode 1811 through a first contact hole 1810 made of an insulating film. The transparent electrode 1811 is opposed to the electron injection electrode 1815 in the second contact hole 1812 of the insulating film with the hole transport layer 1813 and the light emitting layer 1814 interposed therebetween.

  Since the second contact holes 1812 of this insulating film correspond to the light emitting region, they are arranged on a straight line at equal intervals. The electron injection electrode 1815 is electrically connected to the common electrode 1818 in the first contact hole 1816 of the protective film. The protective film second contact hole 1817 is necessary to electrically connect the signal electrode 1809 and the transparent electrode 1811 because the protective film is formed between the signal electrode 1809 and the transparent electrode 1811.

  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. 19 is a block diagram showing a configuration example of an optical scanning device using the large wavelength dispersion characteristic of a conventional photonic crystal. This optical scanning device periodically inserts cylindrical silicon 19132 in a silicon oxide film 19131. Using the photonic crystal 19130 and the wavelength tunable laser 19110 arranged in the above, the current flowing through the wavelength controller of the wavelength tunable laser 19110 is changed, and the wavelength is changed from 650 nm to 660 nm, whereby the light beam in the photonic crystal 19130 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. 18), long ones can be manufactured in a lump, so there is no mounting process and low cost. 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 drive unit, generates no 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.

  To achieve the above object, according to the present invention, a light source, a scanning unit that scans light from the light source, a scanning range expanding unit that expands a scanning range of light by the scanning unit, and a scan emitted by the scanning range expanding unit. The optical scanning device is constituted by re-scanning range expanding means for emitting light by entering and expanding the scanning range. It should be noted that two or more rescanning range enlarging means may be provided so that the scanning light emitted from the preceding rescanning range enlarging means is sequentially incident and the scanning range is enlarged and emitted. For example, as a scanning unit, a polarizing device that deflects and scans light from a light source by controlling a voltage applied to a photonic crystal formed of a ferroelectric material, and expands a scanning range and a rescanning range. The means uses two types of photonic crystals to form an interface having a deflection angle of 90 °, and determines the incident angle of the scanning light from the scanning means, the scanning range expanding means, or the preceding rescanning range expanding means to the interface. By making the angle larger than 45 °, the scanning range is sequentially enlarged.

  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 addressing the above-described problems of the conventional technique.

  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 light source, the scanning means for scanning the light from the light source, the scanning range expanding means for expanding the scanning range of the light by the scanning means, and the scanning range expanding means are provided. An optical scanning device is constituted by re-scanning range expansion means for entering the emitted scanning light and expanding and outputting the scanning range. It should be noted that two or more rescanning range enlarging means may be provided so that the scanning light emitted from the preceding rescanning range enlarging means is sequentially incident and the scanning range is enlarged and emitted. For example, as scanning means, polarized light 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 (lead lanthanum zirconate titanate crystal). The scanning range enlarging means and the rescanning range enlarging means use two types of photonic crystals to form an interface with a deflection angle of 90 °, and the scanning means, the scanning range enlarging means, or the previous rescanning range enlarging By making the incident angle of the scanning light from the means to the interface larger than 45 °, the scanning range is sequentially expanded, and the structure different from the technique described in Japanese Patent Application No. 2005-011526 is used. The scanning system is downsized.

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

  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 is a first scanning range in FIG. FIG. 4 is an explanatory diagram showing a configuration example of the first photonic crystal constituting the enlarging means and the second scanning range enlarging means, FIG. 4 is a photonic band diagram of the TE mode of the first photonic crystal in FIG. 5 is an explanatory view showing a dispersion surface of the TE mode second band of the first photonic crystal in FIG. 3, and FIG. 6 shows the first scanning range expanding means and the second scanning range expanding means in FIG. FIG. 7 is a diagram illustrating a configuration example of the second photonic crystal, FIG. 7 is a photonic band diagram of the TE mode of the second photonic crystal in FIG. 6, and FIG. 8 is a photonic band diagram in FIG. Fig. 9 is an enlarged view of Fig. 1. FIG. 10 is an explanatory diagram showing a configuration example of the first scanning range expanding means in FIG. 1, and FIG. 11 is a first scanning range in FIG. FIG. 12 is an explanatory diagram illustrating an example of the configuration of the enlarging unit and the second scanning range enlarging unit, and FIG. 12 is an explanatory diagram illustrating an example of deflection characteristics by the first scanning range enlarging unit and the second scanning range enlarging unit in FIG. 13 is a block diagram showing a second configuration example of the optical scanning device 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. The first scanning range expanding means 15 as the scanning range expanding means of the present invention, the second scanning range expanding means 5 as the rescanning range expanding means of the present invention, and the optical scanning position detector (photodiode) 2 , 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 first and second scanning range expanding means 15 and 5 are formed of the first photonic crystals 15a and 5a formed of a dielectric (TiO ₂ : titanium oxide) and the same dielectric (TiO ₂ ). Second photonic crystals 15b and 5b, and have photonic crystal interfaces 14 and 4 between the first photonic crystals 15a and 5a and the second photonic crystals 15b and 5b. As described above, the first and second photonic crystals 15a, 5a, 15b, and 5b formed of TiO ₂ are also provided with holes (elliptical hole 13a and rectangular hole 13b) in the TiO ₂ flat plate as shown in FIG. Are periodically formed, and 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 device of this example shown in FIGS. 1 and 2, the first and second photonic crystals 15a, 15b, 5a constituting the first and second scanning range expanding means 15, 5 are made of TiO _2. , 5b, and the photonic crystal 12 constituting the scanning means 11 is formed by PLZT.

  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 first incident on the first and second photonic crystals 15a and 15b of the first scanning range expanding unit 15 to expand the scanning range. Next, the scanning light expanded by the first scanning range expansion unit 15 is incident on the first and second photonic crystals 5a and 5b of the second scanning range expansion unit 5 to further increase the scanning range. By enlarging, 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 crystals 15a and 5a constituting the first and second scanning range expanding means 15 and 5 are elliptical holes (elliptical holes) in a TiO ₂ flat plate. 13a) are arranged two-dimensionally, and the direction of each period (x direction = first period direction, y direction = second period direction) is 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.

  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, the second photonic crystals 15b and 5b constituting the first and second scanning range expanding means 5 have rectangular holes (rectangular holes 13b) in the TiO ₂ flat plate as shown in FIG. It is arranged two-dimensionally. Similar to the first photonic crystals 15a and 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. The same as the crystal 5a. 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, light does not propagate through the second photonic crystals 15b and 5b.

  The structural conditions of the first photonic crystals 15a, 5a and the second photonic crystals 15b, 5b will be specifically described. When the light source is red (wavelength 660 nm), the first photonic crystals 15a, 5a The hole arrangement period (lattice constant) in the x direction of the second photonic crystals 15b and 5b is 203.9 nm, and the hole arrangement period (lattice constant) in the y direction is 254.9 nm. Further, the length of the elliptical holes of the first photonic crystals 15a and 5a is 102.0 nm, the length of the y direction is 153.0 nm, and the rectangular holes of the second photonic crystals 15b and 5b are formed. The length in the x direction 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 crystals 15a and 5a and the second photonic crystals 15b and 5b is set to 164.4 nm. The arrangement period (lattice constant) of holes in the y direction is set to 205.5 nm. The length of the elliptical holes of the first photonic crystals 15a and 5a is 82.2 nm, the length of the y direction is 123.3 nm, and the rectangular holes of the second photonic crystals 15b and 5b are formed. The length in the x direction is 111.8 nm, and the length in the y direction is 164.4 nm.

  Furthermore, 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 crystals 15a and 5a and the second photonic crystals 15b and 5b is set to 141.2 nm. The arrangement period (lattice constant) of holes in the y direction is 176.5 nm. In addition, the length of the elliptical holes of the first photonic crystals 15a and 5a is set to 70.6 nm, the length of the y direction is set to 105.9 nm, and the rectangular holes of the second photonic crystals 15b and 5b are formed. The length in the x direction is 96.0 nm, and the length in the y direction is 141.2 nm.

In this example, an angle θ (FIGS. 9 and 10) formed by the interfaces 14 and 4 between the first photonic crystals 15a and 5a and the second photonic crystals 15b and 5b and the x direction (Γ-X direction). Reference) is the arc tangent of “2 · ay / ax”, “tan- ¹ (2 · ay / ax) = 68.2 °”.

  Further, the x direction (Γ-X direction) of the first photonic crystal 15a of the first scanning range expanding means 15 and the x direction (Γ of the first photonic crystal 5a of the second scanning range expanding means 5 are shown. -X direction), as shown in FIG.

  In such a configuration, the laser beam 8 deflected and scanned by the scanning unit 11 including the photonic crystal 12 formed of the dielectric (PLZT) in FIG. 1 constitutes the first scanning range expansion unit 15. The first photonic crystal 15a enters from a cutting plane parallel to the x direction (Γ-X direction), and the incident light propagates along the first photonic crystal 15a along the y direction. The light is deflected by 90 ° at the interface 14 between the photonic crystal 15a and the second photonic crystal 15b. At this time, the incident angle to the interface 14 between the first photonic crystal 15a and the second photonic crystal 15b is 68.2 °.

  Then, the light deflected by 90 ° at the interface 14 propagates along the x direction in the first photonic crystal 15a and is a cut surface parallel to the y direction (Γ-X ′ direction) of the first photonic crystal 15a. It is emitted from.

  The scanning light emitted from the first scanning range enlarging unit 15 in this way is then incident on the second scanning range enlarging unit 5. As in the case of the first scanning range expansion unit 15, this scanning light is cut parallel to the x direction (Γ-X direction) of the first photonic crystal 5 a constituting the second scanning range expansion unit 5. The incident light enters the surface, propagates along the y direction in the first photonic crystal 5a, 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. 12 shows the incident positions of the first and second scanning range expanding means 15 and 5 composed of the first photonic crystals 15a and 5a and the second photonic crystals 15b and 5b in this example. It is the figure which showed the relationship with the radiation | emission position, and the radiation | emission position is scanned 0-210mm by scanning 0-33.6mm of incident positions, and a scanning range can be expanded 6.25 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 first and second scanning range enlarging means 15 and 5 shown in this example, light to the interface between the first photonic crystals 15a and 5a and the second photonic crystals 15b and 5b. Even if the incident angle is 68.2 °, which is larger than 45 °, 90 ° can be deflected at the interface, so that the scanning range can be expanded.

  As described above with reference to FIGS. 1 to 12, in the optical scanning device of this example, the photonic crystal 12 formed of ferroelectric (PLZT) and the upper and lower surfaces of the photonic crystal 12 are formed. The scanning means 11 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) according to an external signal, and the light is 2 The interfaces 14 and 4 between the first photonic crystals 15a and 5a and the second photonic crystals 15b and 5b of the first and second scanning range expanding means 15 and 5 made of different types of photonic crystals, and the interface 14 , 4 is deflected at 90 ° in spite of 68.2 °, which is larger than 45 °, the scanning range is expanded, and thus the scanning optical system can be made smaller.

  The optical scanning device of the present invention is not limited to the example described with reference to FIGS. 1 to 12, and various modifications can be made without departing from the scope of the invention. For example, in this example, in the first photonic crystals 15a and 5a and the second photonic crystals 15b and 5b, the elliptic hole arrangement period in the x direction and the elliptic hole arrangement period in the y direction are different periods, In addition, the ratio of the size of the elliptical holes 13a to the elliptical array period is also different in the x direction and the y direction, but only one of them may be different. In short, the first and second photonic crystals 15a, 5a, 15b and 5b are arranged with a dielectric constant of one or more of the two or more dielectrics constituting the crystal or a dielectric. It is only necessary that one or more of the ratios of the respective dielectrics in the period of the periodicity or the ratio of the dielectrics having the different dielectric constants arranged periodically are different. Further, the shape of the periodically arranged holes is not elliptical, but may be other shapes such as a rectangle.

  Further, in this example, the first photonic crystals 15a and 5a have the same structure in the first scanning range enlarging means 15 and the second scanning range enlarging means 5, but they may have different structures. Further, a scanning range enlarging unit for further enlarging the scanning light expanded and emitted by the second scanning range enlarging unit 5 is provided at the subsequent stage of the second scanning range enlarging unit 5, and further, the subsequent stage of the scanning range enlarging unit. Another scanning range enlarging means may be provided to sequentially expand the scanning range. At this time, the x direction (Γ-X direction) of the first photonic crystal of the preceding scanning range expanding means and the x direction (Γ-X direction) of the first photonic crystal of the succeeding scanning range expanding means They are arranged so as to be orthogonal to each other.

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),.

  In this example, the ratio of kx · ax to ky · ay is 2: 1 in the first scanning range enlarging unit 15 and the second scanning range enlarging unit 5, but the first The ratio of kx · ax and ky · ay of the scanning range expansion means 15 is 3: 1, and the ratio of kx · ax and ky · ay of the second scanning range expansion means 5 is 2: 1. Different ratios are possible.

The two-dimensional photonic crystal of TiO ₂ that is the first photonic crystal 15a, 5a and the second photonic crystal 15b, 5b constituting the first and second scanning range expanding means 15, 5 is TiO _2. After a metal mask is formed on the _two substrates by an EB lithography process, a metal film deposition process, and a lift-off process, it can be manufactured by a dry etching process using a fluorocarbon gas. In addition, the first photonic crystals 15a and 5a and the second photonic crystals 15b and 5b may be produced in separate steps and finally joined, or may be produced simultaneously on the same substrate.

  Further, the first scanning range expanding means 15 and the second scanning range expanding means 5 may be 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 a dielectric material for forming the first photonic crystals 15a and 5a and the second photonic crystals 15b and 5b constituting the first and second scanning range expanding means 15 and 5. However, other dielectric materials or ferroelectric materials may be used as long as they are transparent to the light source wavelength.

  Further, although PLZT is used as a 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 11 used in this example has no movable part, there is no problem of noise and reliability, and there is no large heat generation as in the acousto-optic element, so that the scanning means constituting the optical scanning device of the present invention. As best.

  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, a position detection sensor 1302 in which laser light emitted from the second photonic crystal 1305a is branched by a beam splitter 1301 and photodiodes are arranged in an array as shown in FIG. The position may always be detected and fed back to the voltage control unit 1310.

  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.

  FIG. 14 is a block diagram showing a first configuration example of a printer using the optical scanning device according to the present invention, and FIG. 15 is a second configuration example of a printer using the optical scanning device according to the present invention. FIG. 16 is a block diagram showing a third configuration example of a printer using the optical scanning device according to the present invention.

  In FIG. 14, an electrophotographic printer is shown as an example. This electrophotographic printer has light sources (semiconductor lasers) 9, 1309 and scanning means 11, similar to those shown in FIGS. 1 and 13. 1311, an optical scanning device 140 including first scanning range expanding means 15 and 1315, second scanning range expanding means 5 and 1305, optical scanning position detectors 2 and 3 and 1302, and an image carrier (photosensitive Drum) 141, charging device 140a, developing device 140b, transfer device 140c, fixing device 140e, and cleaner 140f.

  In the electrophotographic printer having such a configuration, first, the image carrier (photosensitive drum) 141 is charged by the charger 140a, and the charged image carrier (photosensitive drum) 141 is placed on the charged image carrier (photosensitive drum) 141 by the optical scanning device 140. The laser beam 148 whose intensity is modulated according to the image data is scanned. The area on the image carrier (photosensitive drum) 141 irradiated with the laser beam 148 has a reduced charge amount, and the charge amount is related to the reciprocal of the laser beam 148 dose. An electrostatic latent image is formed.

  Next, the toner is adsorbed to the charged portion on the image carrier (photosensitive drum) 141 by the developing device 140b, and the toner on the image carrier (photosensitive drum) 141 is transferred to the transfer paper 140d by the transfer device 140c. The image is formed on the paper surface by transferring and fixing the toner on the transfer paper 140d on the paper surface by the fixing device 140e. Further, the image carrier (photosensitive drum) 141 is cleaned by the cleaner 140f, and the same process is repeated again.

  FIG. 15 shows a silver salt printer as an example, and this silver salt printer also includes three optical scanning devices 150a, 150b, and 150c having the same configuration as that shown in FIGS. , A transport roller 151b, a developing device 151c, and a fixing device 151d. In the three optical scanning devices 150a, 150b, and 150c, the wavelengths of the laser beams (G) 158a, (B) 158b, and (R) 158c from the respective light sources are different from each other, and green (G), blue (B), and red (R). The three optical scanning devices 150a, 150b, and 150c 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 in accordance with image data by the three optical scanning devices 150a, 150b, and 150c are applied to the silver salt paper 151a. The silver salt paper 151a is exposed by sequentially scanning. Thereafter, development is performed by the developing device 151c, and then fixing is performed by the fixing device 151d, followed by drying, so that printing can be performed on the silver salt paper 151a.

  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, full-color printing is possible by configuring with three or more optical scanning devices 150a, 150b, and 150c having different light source wavelengths as in this example. 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 151a, but it is also possible to print on a color film or other color recording medium in the same manner.

  In FIG. 16, 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 160a and 160b having the same configuration as that shown in FIG. 1 and FIG. , 160c, a conveyance roller 161b, and an ultraviolet light source (ultraviolet lamp) 161c. In the three optical scanning devices 160a, 160b, and 160c, the wavelengths of the laser beams (G) 168a, (B) 168b, and (R) 168c from the respective light sources are different, and green (G), blue (B), and red (R). The three optical scanning devices 160a, 160b, and 160c 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. 16 having such a configuration, first, a rewritable paper (described as “photochromic paper” in the figure) 161a made of a photochromic material is irradiated with ultraviolet light by an ultraviolet lamp 161c, and the rewritable paper 161a is already exposed. Erase the image formed on. Next, the rewritable paper 161a from which the image has been erased is sequentially scanned with light of three colors intensity-modulated according to the image data by the three optical scanning devices 160a, 160b, and 160c, and the image on the rewritable paper 161a. Is printed.

  In this example, three light scanning devices 160a, 160b, and 160c each using RGB as a light source are used. However, as in the example shown in FIG. 15, 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 160a, 160b and 160c 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 16, in the optical scanning device of this example, the light source, the scanning means for scanning (deflecting) the light from the light source, and the scanning light scanned by this scanning means are used. A first scanning range enlarging unit that enters and expands and emits a scanning range, and a second scanning range that energizes and emits the scanning light emitted by the first scanning range enlarging unit and emits the scanning range Since it is composed of the magnifying means, it is possible to easily manufacture an optical scanning device that does not vary in light quantity, is very small, and does not require a special laser.

  In particular, in this example, the scanning means 11 and 1311 are composed of 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. The scanning range expansion means 15 and 1315 and the second scanning range expansion means 5 and 1305 of at least the first photonic crystals 15a, 5a, 1315a and 1305a and the second photonic crystals 15b, 5b, 1315b and 1305b. By providing an interface having a deflection angle of 90 ° formed of two or more types of photonic crystals, and 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, The scanning range of the scanning light is further expanded to reduce the size of the optical scanning system.

  More specifically, the first photonic crystals 15a, 5a, 1315a, and 1305a among the two or more types of photonic crystals constituting the first and second scanning range enlarging means 15, 5, 1315, and 1305 are: A two-dimensional photonic crystal having periodicity in two different directions, or a three-dimensional photonic crystal having periodicity in three different directions, wherein at least two periodic directions are orthogonal, The period in the periodic direction is ax, the period in the second periodic direction is ay, the magnitude of the wave vector in the first periodic direction is kx for the light from the light source, and the wave vector in the second periodic direction is When the magnitude is ky, the ratio between the wave vector magnitude and period kx · ax in the first period direction and the wave vector magnitude and period product ky · ay in the second period direction is n : 1 (n is The second photonic crystals 15b, 5b, 1315b, 1305b have a photonic band gap with respect to the light from the light source (laser beams 8, 1308), and the first photonic crystals 15b, 5b, 1315b, 1305b have a photonic band gap. The angle formed by the interfaces 4, 14, 1304, 1314 with the photonic crystals 15a, 5a, 1315a, 1305a and the first periodic direction is an arc tangent of n · ay / ax. .

  Also, the first photonic crystals 15a and 1315a of the first scanning range expanding means 15 and 1315 and the first photonic crystals of the second scanning range expanding means 5 and 1305 are in the x direction (Γ-X direction). 5a and 1305a are arranged so as to be orthogonal to the x direction (Γ-X direction).

  In this example, the first photonic crystals 15a, 5a, 1315a, 1305a and the second photonic crystals 15b, 5b, 1315b, 1305b are one or more of two or more dielectrics constituting each of them. The dielectric constant of each of the dielectrics, or the period in which the dielectrics are arranged, or the periodically occupied dielectrics having different dielectric constants, at least one of the proportions of the respective dielectrics being different, To do.

  Further, in this example, the first photonic crystals 15a, 5a, 1315a, 1305a are periods in which dielectrics having different dielectric constants are arranged in the first periodic direction and the second periodic direction which are orthogonal to each other. Alternatively, the dielectrics having different dielectric constants arranged periodically are configured so that one or more of the proportions of the respective dielectrics are different.

  In this example, the scanning position detected by the detectors 2, 3 and 1302 for detecting the scanning position is 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. 1-16, and can be variously changed in the range which does not deviate from the summary. 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 1st scanning range expansion means and the 2nd 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 1st scanning range expansion means and the 2nd 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 2nd scanning range expansion means in FIG. It is explanatory drawing which shows the structural example of the 1st scanning range expansion means in FIG. It is explanatory drawing which shows the structural example of the 1st scanning range expansion means and the 2nd scanning range expansion means in FIG. It is explanatory drawing which shows the example of a deflection characteristic by the 1st scanning range expansion means and the 2nd 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, 141: image carrier (photosensitive drum), 2, 3, 153, 1302: optical scanning position detector, 4, 14, 1304, 1314: photonic crystal interface, 5, 1305: second scanning range expanding means 5a, 15a, 1305a, 1315a: first photonic crystal, 5b, 15b, 1305b, 1315b: second photonic crystal, 6, 7, 1306, 1307: electrode, 8, 1308: laser light, 9. 1309: Light source (semiconductor laser) 10, 1310: Voltage controller 11, 1311: Scanning means 12, 1312: Ferroelectric (PLZT) photonic crystal, 13: hole, 13a: elliptical hole, 13b: rectangular Holes, 151315: first scanning range expanding means, 1301: beam splitter, 140a: charger, 140b, 151c: developer, 140c: 140 d: transfer paper, 140 e, 151 d: fixing device, 140 f: cleaner, 148: laser light, 151 a: silver salt paper, 151 b, 161 b: transport roller, 150 a, 160 a: optical scanning device (G), 150 b, 160b: optical scanning device (B), 150c, 160c: optical scanning device (R), 158a, 168a: laser light (G), 158b, 168b: laser light (B), 158c, 168c: laser light (R), 161a: photochromic paper, 161c: ultraviolet light source (ultraviolet lamp), 1702: polygon mirror, 1722: spherical lens (first scanning lens), 1726: toric lens (second scanning lens), 1727: photosensitive drum (photosensitive) Body), 1730: photodetector, 1732: cylindrical lens, 1751: light source means 1752: Collimator lens, 1753: Aperture, 1755: Parallel flat glass, 1808: Glass substrate, 1809: Signal electrode, 1810: First contact hole of insulating film, 1811: Transparent electrode, 1812: Second contact hole of insulating film 1813: hole transport layer, 1814: light emitting layer, 1815: electron injection electrode, 1816: first contact hole of protective film, 1817: second contact hole of protective film, 1818: common electrode, 19110: wavelength tunable laser, 19130: Photonic crystal, 19131: Silicon oxide film, 19132: Cylindrical silicon.

Claims (19)

A light source;
Scanning means for scanning light from the light source;
A scanning range expanding means for entering the scanning light scanned by the scanning means and expanding and outputting the scanning range;
Re-scanning range expanding means for entering the scanning light emitted by the scanning range expanding means and expanding and outputting the scanning range;
Each of the scanning range expanding means and the rescanning range expanding means has at least a first photonic crystal and a second photonic crystal that bends light at a right angle at an interface between the first photonic crystal and the first photonic crystal. And
The scanning light is incident on the first photonic crystal and propagates straight,
An optical scanning device characterized in that the scanning light propagating in a straight line is incident on the interface at an incident angle greater than 45 ° and less than 90 ° and deflected by 90 °. A light source;
Scanning means for deflecting and scanning light from the light source;
A scanning range enlarging unit for making each light deflected and scanned by the scanning unit incident and parallel, and enlarging and emitting the scanning range;
Re-scanning range expanding means for entering the scanning light emitted by the scanning range expanding means and expanding and outputting the scanning range;
Each of the scanning range expanding means and the rescanning range expanding means is:
Comprising a first photonic crystal and a second photonic crystal that travel straight through the light incident on the incident surface;
The second 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;
The scanning range expanding means includes
Each deflected scanning light from the scanning means is incident on the first photonic crystal, and each scanning light is propagated straight in the first photonic crystal in a direction perpendicular to the incident surface. Each scanning light is bent at a right angle at the interface with the two photonic crystals and emitted from the first photonic crystal,
The rescanning range expanding means is
Each parallel scanning light emitted from the first photonic crystal of the scanning range expanding means is incident on the first photonic crystal of the rescanning range expanding means and propagates straight in parallel, and the rescanning is performed. Optical scanning characterized in that each scanning light is bent at a right angle at the interface with the second photonic crystal of the range expanding means and emitted from the first photonic crystal of the rescanning range expanding means. apparatus. The optical scanning device according to claim 1 , wherein:
The first photonic crystal and the second photonic crystal are:
The dielectric constant of one or more of the two or more dielectrics comprising each;
Alternatively, the period for arranging the dielectric,
Alternatively, the optical scanning device is characterized in that one or more of the proportions of the respective dielectrics differ among the periodically disposed dielectrics having different dielectric constants. The optical scanning device according to any one of claims 1 to 3,
The first photonic crystal 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 two periodic directions (first periodic direction, second periodicity) Direction) and the product ax · kx of the period ax in the first periodic direction and the magnitude kx of the wave vector for the light from the light source in the first periodic direction, and the second The ratio of the product ay · ky of the period ay in the periodic direction 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),
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 4,
The x direction (Γ-X direction) of the first photonic crystal of the scanning range expanding means and the x direction (Γ-X direction) of the first photonic crystal of the rescanning range expanding means are orthogonal to each other. An optical scanning device characterized by being arranged in the above. An optical scanning device according to any one of claims 1 to 5,
An optical scanning device comprising two or more rescanning range expanding means, sequentially entering the scanning light emitted from the preceding rescanning range expanding means and expanding the scanning range. The optical scanning device according to claim 6,
The x direction (Γ-X direction) of the first photonic crystal of the preceding rescanning range expanding means, and the x direction (Γ-X direction) of the first photonic crystal of the following rescanning range expanding means, Are arranged so as to be orthogonal to each other. The optical scanning device according to any one of claims 1 to 7,
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 8,
The scanning means includes a photonic crystal formed of a ferroelectric, and a voltage control means for controlling a voltage applied to the photonic crystal,
An optical scanning device characterized in that the voltage applied to the photonic crystal is controlled by the voltage control means to control the deflection of light incident on and emitted from the photonic crystal. The optical scanning device according to claim 9, wherein
An optical scanning device, wherein the photonic crystal is PLZT. The optical scanning device according to any one of claims 1 to 10,
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.   12. An optical scanning device comprising two or more optical scanning devices according to claim 1 arranged in the main scanning direction.   12. An optical scanning device comprising two or more optical scanning devices according to claim 1 arranged in the sub-scanning direction. The optical scanning device according to claim 13,
The optical scanning device characterized in that each of the two or more optical scanning devices arranged in the sub-scanning direction has a different light source wavelength.   12. An optical scanning device comprising at least three optical scanning devices according to claim 1 arranged in the sub-scanning direction and having different light source wavelengths. An optical scanning device according to any one of claims 1 to 15,
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 15,
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 device according to claim 15,
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. An optical scanning device according to any one of claims 1 to 15,
Exposure control means for controlling the output of light scanned by the optical scanning device in accordance with image data;
An ultraviolet light source that generates ultraviolet light for erasing an image formed on the rewritable paper by the light from the optical scanning device controlled by the exposure control means,
A rewritable printer, wherein a new image is formed on a rewritable paper from which an image has been erased by the ultraviolet light source.

Images