JP2006142541A - Optical line head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical line head which adjusts an imaging position at a face to be irradiated, by an optical element. <P>SOLUTION: The optical line head images an emitted light from array light sources 72 and 73 of a line shape aligned in two or more arrays in a sub scanning direction of a substrate 62, at the face to be irradiated by using an optical system of an erect equal magnification. The optical element of a prism shape with inclined faces 2a and 2b formed thereat is disposed to each array of the array light sources arranged in the two or more arrays. An angle of a light exit face to a horizontal face 62a is different from that of a light incidence face in a cross section in the sub scanning direction at the optical element. The optical element is set so that an interval in the sub scanning direction of spots formed when the light radiated from the array light source of each array is imaged on the face to be irradiated becomes smaller than an interval of the array light sources. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical line head that forms an image on an irradiated surface with an optical element at an interval narrower than a sub-scan interval of a light source.

  In an image forming apparatus that performs optical writing, a method of providing a scanning optical system as an exposure device and an optical line head method using a light emitting element array are known. For example, Patent Document 1 describes a method using an optical line head in an exposure apparatus. In this example, staggered LEDs are used as the light source, and a gradient index rod lens array (trade name Selfoc lens array, hereinafter abbreviated as SLA) is provided between the light source and the photoconductor. Yes.

  A certain amount of light source area (diameter D) is required to secure the optical power of each light emitting portion of the line light source. Therefore, the light sources cannot be arranged in one row, and the arrangement is staggered. In particular, in a light-emitting element having a small optical power per unit area such as an organic EL element, a staggered arrangement is indispensable in order to obtain a large optical power in order to cope with a higher speed.

  A gradient index rod lens array (trade name: SELFOC lens array [SLA], manufactured by Nippon Sheet Glass Co., Ltd.) is used to form an image of a line light source on an irradiated surface. Since this lens array is an equal-magnification and upright optical system, the arrangement of the light-emitting elements is projected directly onto the surface to be scanned. An image forming apparatus that performs optical writing on a photoconductor using a line head in which such light sources are arranged in a staggered manner is configured.

  In FIG. 12, light emitting elements 23 a and 23 b of light sources connected to lead wires 21 and 22 are arranged in a staggered manner in the optical line head 20. D is the diameter of the light source, and P is the distance between the light emitting element lines. In this example, light emitting element lines are arranged at intervals of 2P in the sub-scanning direction. In order to secure the optical power required for exposure of each light emitting element of the light source arranged in a line, a certain area of the light source (that is, the diameter D of each light emitting element) is required.

  If the area of the light source is expanded, that is, if the diameter of the light emitting element is increased and the light sources are arranged in a line in the main scanning direction, they interfere with the adjacent light emitting element. For this reason, a plurality of light emitting element lines in which a plurality of light emitting elements are arranged in the main scanning direction are provided in a plurality of rows in the sub scanning direction, and the light emitting elements of each light emitting element line are arranged in a staggered manner to avoid interference between adjacent light emitting elements. be able to.

  As shown in FIG. 12, when the two light emitting element lines are spaced apart by 2P, the image forming points are spaced apart by 2P on the irradiated surface of the image carrier in the process advancing direction. If the image forming points are arranged in a line in the main scanning direction and the horizontal lines are exposed, the light emission timing is determined in accordance with the position of each light emitting element line in order to align the image forming points in a line. Need to change.

  In FIG. 12, P is a pixel pitch in the image forming apparatus. In the page printer, 600 pixels per inch, that is, P = 42.33 μm. In the above example, there is a shift of two lines between the odd and even pixels, so when data of a line with an odd dot is output, the even dot needs to output data two lines ahead. .

  This point will be described with reference to FIG. In FIG. 15, reference numeral 40 denotes an irradiated surface such as an image carrier, 62 denotes a glass substrate, 72 denotes an odd number of light emitting element lines (L1), 73 denotes an even number of light emitting element lines (L2), and 65 denotes SLA. . Each light emitting element line 72, 73 is formed as an array light source. In this case, the image of the odd-numbered light emitting element lines (L1) is formed at the position 41 on the optical axis of the irradiated surface, and the image of the even-numbered light emitting element lines (L2) is irradiated. An image is formed at a position 42 on the optical axis of the surface. For this reason, in order to superimpose the L2 image on the L1 image, it is necessary to perform data processing for outputting data of two lines ahead. Also, when setting the interval in the sub-scanning direction of the spots formed by imaging the light emitted from the array light sources in each row on the irradiated surface to be smaller than the interval between the array light sources. , Complicated data processing is required.

  In order to perform such processing, (1) shift the odd dots and even dots when writing the image to be printed in the image memory, or (2) switch the address when calling from the image memory, Any one of the methods (3) or a method of changing the data transfer order by accessing the image memory as usual and inserting a buffer memory before reaching the write head can be considered.

  By the way, depending on the size of the light emitting portion, there are cases where it is necessary to arrange three light emitting element lines instead of arranging the light emitting element lines in two lines in the sub-scanning direction as shown in FIG. . FIG. 13 is an explanatory diagram of an example in which three light emitting element lines are arranged in the sub-scanning direction. In FIG. 13, light source elements 23 and 24 connected to lead wires 21 and 22 and light source elements 25 connected to lead wires 26 are arranged in a staggered pattern in the optical line head 20a. D is the diameter of the light source, and P is the distance between each light source. In this example, three rows of light emitting element lines are arranged at intervals of 2P in the sub-scanning direction.

  Further, there are cases where a plurality of light emitting elements are formed in a chip shape like an LED array, and a plurality of the chips are arranged. Even in such a configuration, when it is difficult to arrange the light emitting elements to the end of the chip, the chips may be arranged in a staggered pattern for each chip. FIG. 14 is an explanatory diagram showing an example of an optical line head having such a configuration. In FIG. 14, the optical line head 30 has chips 31, 33, 35... Arranged in a staggered pattern in the main scanning direction. Each chip 31, 33, 35 is provided with a light emitting element line 32, 34, 36, respectively.

  Even when chips in which a plurality of light emitting elements are integrated as shown in FIG. 14 are arranged in a staggered manner, there is a problem that the circuit configuration becomes complicated. Therefore, Patent Document 2 describes an example in which a plurality of lens arrays are used to solve such a problem. Patent Document 3 describes an example in which light from two rows of light sources having an angle of 90 ° is overlapped in one row using a half mirror as an optical element.

Japanese Patent Laid-Open No. 2-147259 Japanese Patent Application Laid-Open No. 10-211731 JP-A-56-28869

  In any of the methods (1) to (3), there is a problem that the circuit configuration becomes complicated and the cost is increased. Furthermore, in (1) and (2), image processing is complicated, and there is a problem that the contents of image processing must be changed every time the arrangement of the light emitting section of the head is changed. Is versatile but has the problem of requiring extra circuitry and memory. When the diameter D of the light emitting portions is larger than the pitch as shown in FIG. 12, it must be arranged in three rows. In this case, since 6 lines of memory are required, there is a problem that the cost becomes disadvantageous.

  The methods described in Patent Documents 2 and 3 also have a problem that the number of optical elements increases, the structure becomes complicated, and the line head becomes large. In some cases, it is necessary to adjust the optical system so that the imaging spots of the light from the two rows of light sources are exactly one row on the irradiated surface, and there is a problem that the operation becomes complicated.

  The present invention has been made in view of such problems of the prior art, and its purpose is to form an image on an irradiated surface without complicating the circuit configuration and requiring complicated adjustment of the optical system. An object of the present invention is to provide an optical line head whose position can be adjusted.

  In order to achieve the above object, an optical line head according to the present invention receives light emitted from a linear array light source arranged in two or more rows in the sub-scanning direction of a substrate using an erecting equal-magnification optical system. In the optical line head that forms an image on the irradiation surface, for each column of the array light source arranged in two or more columns, the angle of the light exit surface with respect to the horizontal plane in the cross section in the sub-scan direction is the light incident surface Different prism-shaped optical elements are arranged, and the interval in the sub-scanning direction of spots formed by imaging the light emitted from the array light sources in each row on the irradiated surface is larger than the interval between the array light sources. It is set so that it may become small. As described above, in the embodiment of the present invention, the interval in the sub-scanning direction of the spots formed by the light from the light sources on the irradiated surface (imaging surface) is reduced. For this reason, the amount of shifting the lighting timing of each light source can be reduced, and the capacity of the buffer memory for temporarily storing data can be reduced. In addition, the adjustment of making the interval in the sub-scanning direction of the spot image formation position on the irradiated surface narrower than the interval in the sub-scanning direction of the array light source can be performed by a fixed prismatic optical element. The configuration can be simplified.

  In the optical line head of the present invention, the optical element has a light incident surface that is the same plane in the cross section in the sub-scanning direction and a plurality of light exit surfaces that have different angles with respect to the horizontal plane, and are integrated in a prism shape. It is characterized by being formed. This embodiment corresponds to the prism 2 shown in FIG. The prism 2 is integrally formed with a light incident surface 2c on the same plane and a plurality of light exit surfaces 2a and 2b having different angles with respect to the horizontal surface 62a (the surface of the glass substrate 62). According to this configuration, since the light emission surfaces 2a and 2b are only cut from a rectangular base material, the shape of the prism is simple and the manufacture is facilitated.

  The optical line head of the present invention has a planar light incident surface and a planar light exit surface in a cross section in the sub-scanning direction, and is arranged in a wedge-shaped shape so as to be separated into a plurality of prism-shaped optical elements. Is provided corresponding to each array light source arranged in a plurality of rows in the sub-scanning direction. This embodiment corresponds to the prism described in FIG. The prisms 3 and 4 are formed in a wedge shape. According to this configuration, by separating the prism into two, the emitted light from the plurality of light emitting element lines can be clearly separated, and crosstalk can be prevented.

  In the optical line head of the present invention, the array light source is formed in a line shape in the main scanning direction on the glass substrate, and an emitted light beam from the array light source is emitted through the glass substrate. It is characterized by. This embodiment corresponds to the prisms 5 and 6 described in FIGS. 6 and 7. According to this configuration, the surface on which the array light source of the glass substrate is provided is different from the surface on which the prism is provided. In FIG. 6, the prism and the glass substrate are integrated, and in FIG. 7, the prism and the glass substrate can be installed as close to the prism as possible. For this reason, when the prism is installed, it is possible to suppress the occurrence of light loss due to an increase in the distance between the prism and the glass substrate.

  In the optical line head of the present invention, the prism-like optical element is formed integrally with the glass substrate on a surface facing the array light source formed on the glass substrate. . This embodiment corresponds to the prism 5 described in FIG. According to this configuration, since the prism is formed by processing the glass substrate itself, it is not necessary to configure the prism with a separate member, the number of parts can be reduced, and the cost can be reduced.

  In the optical line head of the present invention, the prism-shaped optical element is bonded to the glass substrate with a groove. This embodiment corresponds to the prism 6 shown in FIG. According to this configuration, since the prism is directly fixed to the glass substrate, a member for fixing the prism is not necessary, and the configuration of the optical line head can be simplified. In addition, reflection of the incident surface of the prism can be prevented by selecting the refractive index of the adhesive and filling it between the light emitting portion and the incident surface of the prism.

  The optical line head of the present invention is characterized in that the array light sources are arranged in three or more rows in the sub-scanning direction. This embodiment corresponds to the configuration in which the light emitting element lines L1 to L3 shown in FIG. 8 are provided. According to this configuration, the optical power with respect to the irradiated surface can be increased.

  The optical line head of the present invention is characterized in that the array light sources are arranged in a staggered manner. This embodiment corresponds to the light emitting element lines 72 and 73 shown in FIG. According to this configuration, in the optical line head having a reduced length in the main scanning direction, the adjustment in which the interval in the sub-scanning direction of the spot image formation position on the irradiated surface is made smaller than the interval in the sub-scanning direction of the array light source. However, it can be performed by a fixed prism-like optical element.

  The optical line head of the present invention is characterized in that the array light sources are arranged in a grid pattern. This embodiment corresponds to a configuration in which the interval in the sub-scanning direction of the spot image formation position on the irradiated surface is made narrower than the interval in the sub-scanning direction of the array light source by the light emitting element lines 75 and 76 shown in FIG. . According to this configuration, when the array light sources are arranged in a grid, the interval in the sub-scanning direction of the spots formed by the light from each light source on the irradiated surface (imaging surface) is reduced. The amount of shifting the lighting timing of each light source can be reduced, and the capacity of the buffer memory for temporarily storing data can be reduced.

  The optical line head of the present invention is characterized in that a plurality of chips on which array light sources are arranged are arranged in the main scanning direction. This embodiment corresponds to a configuration in which a plurality of chips 31, 33, and 35 are arranged in the main scanning direction as shown in FIG. According to this configuration, when a chip-shaped light source is used, the adjustment of making the interval in the sub-scanning direction of the spot image formation position on the irradiated surface narrower than the interval in the sub-scanning direction of the array light source is fixed. The prism-shaped optical element can be used.

  The optical line head of the present invention is characterized in that the chips are arranged in a staggered manner. This embodiment corresponds to a configuration in which chips 31, 33 and 35 are arranged in a staggered manner as shown in FIG. According to this configuration, in the optical line head in which the light source is composed of a chip and the length in the main scanning direction is shortened, the sub-portion of the spot formed by the light from each light source is imaged on the irradiated surface (imaging surface). Since the interval in the scanning direction is reduced, the amount of shifting the lighting timing of each light source can be reduced, and the capacity of the buffer memory for temporarily storing data can be reduced.

  In the optical line head of the present invention, the light emitting element of the light source is an organic EL element. This embodiment corresponds to the configuration in FIGS. 1 to 14 that uses an organic EL element as the light source of the light emitting element line. According to this configuration, it becomes possible to combine the driver formed on the glass substrate by the TFT process and the organic EL light emitting element, and the driver and the light emitting portion can be integrally formed on the glass substrate.

  In the optical line head of the present invention, the light emitting element of the array light source is an LED. This embodiment corresponds to the configuration using FIGS. 1 to 14 in which LEDs are used as the light sources of the light emitting element lines. According to this configuration, in the optical line head using LEDs, the interval in the sub-scanning direction between spots formed by the light from each light source on the irradiated surface (imaging surface) is reduced. For this reason, the amount of shifting the lighting timing of each light source can be reduced, and the capacity of the buffer memory for temporarily storing data can be reduced. In addition, the adjustment of making the interval in the sub-scanning direction of the spot image formation position on the irradiated surface narrower than the interval in the sub-scanning direction of the array light source can be performed by a fixed prismatic optical element. The configuration can be simplified.

  The optical line head of the present invention is characterized in that a groove is formed in a holder to mount the optical system element, and the glass substrate is provided on a surface of the holder facing the incident surface of the optical system element. To do. This embodiment corresponds to the configuration of FIG. According to this configuration, since the optical substrate and the glass substrate on which the light emitting element lines are formed are attached to the holder, a compact configuration can be achieved.

  In the present invention, since the interval between spots formed by the light from each light source being imaged on the irradiated surface (imaging surface) is reduced, the amount of shifting the lighting timing of each light source can be reduced, and data can be temporarily stored. There is an advantage that the buffer memory for storing the memory can be small. In addition, the adjustment of making the interval of the spot image formation position of the irradiated surface in the sub-scanning direction narrower than the interval of the array light source in the sub-scanning direction can be performed by a fixed optical element, so the configuration of the control unit is simplified. Can be

  The present invention will be described below with reference to the drawings. FIG. 10 is an enlarged perspective view schematically showing the optical line head 50 according to the embodiment of the present invention. Four optical line heads 50 are installed for each color when used in a full-color image forming apparatus. In FIG. 10, the organic EL element array 61 is held in a long housing 60. The positioning pins 69 provided at both ends of the long housing 60 are fitted into the opposing positioning holes of the case (not shown), and the fixing screws are inserted into the case through the screw insertion holes 68 provided at both ends of the long housing 60. Each optical line head 50 is fixed at a predetermined position by being screwed into the screw hole and fixed.

  The optical line head 50 mounts, for example, a plurality of rows of light emitting portions 63 of the organic EL element array 61 on the glass substrate 62 in the sub-scanning direction, and is driven by TFTs 71 formed on the same glass substrate 62. An SLA (refractive index distribution type rod lens array) 65 constitutes an imaging optical system and is arranged by stacking rod lenses on the front surface of the light emitting unit 63. Reference numeral 60 denotes a housing, 66 denotes a cover, and 67 denotes a fixed leaf spring. In the present invention, the arrangement of the light emitting element lines is expressed as “column” in the sub-scanning direction and “line (row)” in the main scanning direction.

  The housing 60 covers the periphery of the glass substrate 62 and the side facing the image carrier 20 is open. The light emitting unit 63 is driven to emit light from the fiber surface 70 of the SLA toward the image carrier on the irradiated surface (not shown). A light-absorbing member (paint) for absorbing unnecessary light is provided on the surface of the housing 60 that faces the end surface of the glass substrate 62.

  FIG. 11 is a schematic exploded perspective view showing an example of attachment of the SLA 65 and the glass substrate 62. A groove portion 54 is formed in the holder 51 having the flange portion 52. The SLA 65 is accommodated in the groove 54 and fixed by an appropriate means such as an adhesive. The glass substrate 62 on which the light emitting unit 63 is formed is attached to the bottom surface 53 of the holder 51. The groove 54 of the holder 51 is formed with an opening, and the output light of the light emitting unit 63 enters the fiber surface of the SLA 65 and forms an image on the image carrier. In the example of FIG. 11, since the optical element (SLA 65) and the glass substrate 62 on which the light emitting element lines are formed are mounted on the holder 51, the optical line head can be made compact. In FIG. 10 and FIG. 11, for the sake of simplicity, the prism-like optical element that is a feature of the present invention is not shown.

  FIG. 1 is an explanatory view showing an example of an optical line head 1 of the present invention. The same components as those in the conventional configuration described in FIG. 15 are denoted by the same reference numerals, and detailed description thereof is omitted. In the example of FIG. 1, the valley-shaped prism 2 is arranged close to the surface of the light emitting element. By arranging such a valley-shaped prism 2, images of the light emitting element lines L 1 and L 2 are formed so as to overlap with 43 positions on the irradiated surface 40.

  In the configuration of FIG. 1, in order to form the image of the light emitting element lines L1 and L2 so as to overlap the 43 position on the irradiated surface 40, the center position of the prism 2 and the centers of the two light emitting element lines L1 and L2 are formed. The line positions need to match. The angle θ of the prism is determined from the thickness of the prism 2 and the distance between the two light emitting element lines L1 and L2.

  The prism 2 shown in FIG. 1 is based on a horizontal plane 62a (the surface of the glass substrate 62), and a light incident surface 2c on the same plane and a plurality of light exit surfaces 2a, 2b having different angles from the light incident surface 2c. And are integrally formed. In the example of FIG. 1, the light emission surfaces 2a and 2b are formed in a valley shape. However, according to this configuration, the light emission surfaces 2a and 2b can be cut into a predetermined shape from a rectangular base material. A prism is obtained, and the shape of the prism is simple, which makes it easy to manufacture. The light emitting element lines 72 and 73 can be formed on a substrate of another form such as a translucent substrate instead of being formed on the transparent glass substrate 62.

  In the example of FIG. 1, it is desirable that δ is 0, that is, the intersection point P of the optical axes of the beams emitted from the prism 2 and the height of the light emitting unit coincide. If the heights do not match, the focus position on the surface to be scanned of the image carrier and the position where the two images (L1, L2) overlap will be displaced. However, by using the prism 2, even when the two-line images are not formed on the same line, the interval between the L1 and L2 images in the sub-scanning direction can be made smaller than the interval between the light sources.

  Further, when the angle θ of the prism 2 is decreased (a large angle with respect to parallelism), the emitted light that has reached the critical angle is totally reflected by the prism 2 and cannot be extracted outside. Thus, when the directivity characteristic (radiation angle characteristic) of the light radiated from the light emitting unit is wide, the loss of the emitted light is large.

  If the thickness of the prism 2 is thick, the light from the light emitting element of one light emitting element line will also pick up the light from the light emitting part of the other light emitting element line, and the image of the light emitting element of the two lines is clear. It cannot be separated (crosstalk). In such a case, as described below, the prism may be separated into two to prevent crosstalk.

  FIG. 2 is an explanatory diagram showing an example of a configuration for preventing the above-described crosstalk. In FIG. 2, the prism is separated into two prisms 3 and 4. Each of the prisms 3 and 4 has a planar light incident surface and a planar light exit surface in a cross section in the sub-scanning direction, and is formed in a wedge shape and separated into a plurality. By separating the prism into two in this way, the light emitted from the light emitting element lines L1 and L2 can be clearly separated, and crosstalk is prevented. In addition, even when it is difficult to process the valley-shaped prism as shown in FIG. 1, two wedge-shaped prisms as shown in FIG. 2 may be combined.

  As shown in FIG. 2, when the light is separated into two prisms 3 and 4, if light is reflected on the surface (F surface) where the two prisms 3 and 4 are in contact with each other, a different path from the original light is taken. Then, an image is formed at a position different from the spot position of the main body. That is, a ghost image is generated on the irradiated surface. Therefore, this boundary surface F forms a satin surface or the like in order to suppress unnecessary reflection. Moreover, the effect of scattered light can be further reduced by painting the pear ground black.

FIG. 3 is an explanatory diagram for explaining an example of setting the angle and dimensions of the prism.
In FIG. 3, when the refractive index of the prism 4 is n, n · sin θ1 = sin θ2 (note that the refractive index of air in the atmosphere is 1) according to Snell's law of refraction. Therefore, the apparent movement amount d of the light emitting point is represented by d = H · tan (θ2−θ1).

  For example, when a typical optical material BK7 (model number of Schott) is used for the prism 4, n = 1.5168 (at the d-line wavelength), so when θ1 is 30 °, θ2 is 49.32 °. . When the thickness H of the prism is 120 μm, the amount of movement d of the apparent position of the light emitting portion is about 42 μm. Therefore, when the light emitting portions of the two light emitting element lines are separated by 2P, that is, twice as large as 42.33 μm, since the two light emitting portions are apparently overlapped, the spots to be imaged also overlap. become.

  FIG. 4 is an explanatory view showing an embodiment of the present invention. In FIG. 4, 72 and 73 are two light emitting element lines. In this case, by using the prism 2, 3, or 4 as described in FIGS. 1 to 3, an image is formed on the irradiated surface as 44 and 45. The interval between the image formations 44 and 45 in the sub scanning direction is narrower than the interval between the light sources in the sub scanning direction.

  As shown in FIG. 4, in the embodiment of the present invention, the two-line light source images are narrowed in the sub-scanning direction by the prism. That is, the image of the light emitting element line 72 is formed at the position 44 on the irradiated surface moved in the sub-scanning direction as indicated by the arrow Xa. Further, the image of the light emitting element line 73 is formed at the position of 45 on the irradiated surface moved in the sub-scanning direction as indicated by the arrow Xb.

  As described above, in the embodiment of FIG. 4, the image of the two-line light source is formed with the interval narrowed in the sub-scanning direction, so that the amount of shifting the timing for turning on the two-line light source can be reduced. it can. For this reason, the capacity of the buffer memory for temporarily holding data can be reduced, and the cost of the control unit can be reduced.

  FIG. 5 is an explanatory view showing another embodiment of the present invention. The interval in the sub-scanning direction of the image formed on the irradiated surface by the light emitting element lines 72 and 73 is originally two lines. In the example of FIG. 5, the imaging 46 formed on the irradiated surface by using the prism is set to overlap one line. That is, the image of the light emitting element line 72 is formed at the position 46 of the irradiated surface moved in the sub-scanning direction as indicated by the arrow Ya.

  Further, the image of the light emitting element line 73 is formed at the same position of the irradiated surface 46 moved in the sub-scanning direction as indicated by the arrow Yb. Thus, in the example of FIG. 5, the image of the light source of 2 lines is set so that it may overlap with 1 line, and it has the structure of the best mode.

  In an embodiment of the present invention, the fixation of the prism used for narrowing the interval in the sub-scanning direction of the image formation on the irradiated surface to be smaller than the interval in the sub-scanning direction of the light source or overlapping one line is mechanical. It may be fixed or an adhesive for optical use may be used. By carefully selecting the refractive index of the adhesive and filling it between the light emitting portion and the incident surface of the prism, reflection of the incident surface of the prism can be prevented.

  FIG. 6 is an explanatory view showing another embodiment of the present invention. In the example of FIG. 6, the prism 5 is formed integrally with the glass substrate 62 in an element that emits light from the light emitting element lines 72 and 73 formed on the glass substrate 62 to the back side, that is, the irradiated surface through the glass substrate 62. To do. The prism 5 forms an inclined surface on the glass substrate 62 on the back side of the light emitting element lines 72 and 73. According to the configuration of FIG. 6, since the prism 5 is formed by processing the glass substrate 62 itself, it is not necessary to configure the prism with a separate member, the number of parts can be reduced, and the cost can be reduced.

  FIG. 7 is an explanatory view showing another embodiment of the present invention. In the example of FIG. 7, a rectangular groove 62a is formed in the glass substrate 62 on the back side where the light emitting element lines 72 and 73 are formed, as in FIG. The prism 6 is inserted into the groove 62 a and bonded, and fixed to the glass substrate 62. According to the configuration of FIG. 7, since the prism 6 is directly fixed to the glass substrate 62, a member for fixing the prism is unnecessary, and the configuration of the optical line head can be simplified.

  6 and 7, light-emitting element lines L1 and L2 (array light sources) formed in a line shape in the main scanning direction on the glass substrate 62 are provided, and the emitted light beam from the array light source is a glass substrate. Injected through 62. In this configuration, the surface on which the array light source of the glass substrate 62 is provided is different from the surface on which the prism is provided. In FIG. 6, the prism 5 and the glass substrate 62 are integrated, and in FIG. 7, the prism 6 can be installed at a position as close as possible to the glass substrate 62. For this reason, when a prism is installed in the optical line head, it is possible to suppress the occurrence of light loss due to an increase in the distance between the prism and the glass substrate.

  FIG. 8 is an explanatory view showing another embodiment of the present invention. In the example of FIG. 8, light sources are arranged in three rows in the sub-scanning direction with light emitting element lines 72, 73, and 74 as light sources. In this case, the prism 7 is formed by three portions 7 a to 7 c corresponding to the light emitting element lines 72, 73 and 74. Thus, the present invention can also be applied to a case where three or more rows of light sources are arranged in the sub-scanning direction.

  In the present invention, light from light emitting elements in the same column in the sub-scanning direction may be superimposed. FIG. 9 is an explanatory view showing such an embodiment of the present invention. In the configuration of FIG. 9, the light source composed of the light emitting element lines 75 and 76 is not in a staggered arrangement but in a lattice arrangement. The image of the light emitting element line 75 is formed at a position 47 moved in the direction of the arrow Za.

  The image of the light emitting element line 76 is also formed at the same 47 position moved in the direction of the arrow Zb. In such a light source arrangement as shown in FIG. 9, the resolution in the main scanning direction does not change, but the optical power from the two light emitting units can be superimposed on one line 47. This is effective when the optical power is insufficient.

  Also in this case, if the spot imaged on the irradiated surface overlaps one line, each of the two light sources is turned on at exactly the same timing in the sub-scanning direction even though the light source is two lines. / What is necessary is just to control light extinction. Therefore, two light emitting units can be connected to one driver, and the configuration of the control unit is simplified. In the example in which the light sources are arranged in a grid pattern as shown in FIG. 9, instead of superimposing the image of the irradiated surface on one line, two lines narrower than the interval of the light sources in the sub-scanning direction as described in FIG. An image can also be formed.

  In this case, in the example in which the light sources are arranged in a lattice shape, the interval in the sub-scanning direction of the spots formed by imaging the light of each light source on the irradiated surface (imaging surface) is reduced. For this reason, the amount of shifting the lighting timing of each light source can be reduced, and the capacity of the buffer memory for temporarily storing data can be reduced. In addition, the adjustment of making the interval in the sub-scanning direction of the spot image formation position on the irradiated surface narrower than the interval in the sub-scanning direction of the array light source can be performed by a fixed prismatic optical element. The configuration can be simplified.

  As described with reference to FIG. 14, even when the chips 31, 33, and 35 having a plurality of light emitting elements arranged in a row are arranged in a staggered manner, the same effect as in the example of FIG. 9 can be obtained. In this case, the configuration of the control unit is simplified by superimposing spots formed on the irradiated surface on one line by the emitted light from the light emitting elements of the chips 31, 33, and 35 arranged in a staggered pattern. Become.

  The embodiment of the present invention can also use an erecting equal-magnification lens array other than the gradient index rod lens array (SLA), for example, a roof mirror lens array. Furthermore, the present invention can be applied to a case where a projection optical system including a single lens system is used instead of the lens array.

  In the embodiment of the present invention, an LED is used as a semiconductor light emitting element of a light source. However, as a light source, a fluorescent tube (FL), an EL light emitting element (organic or inorganic), or the like may be combined. Thus, the present invention can be widely applied to an optical line head regardless of the type of light source such as an LED or an organic EL element. For example, when a driver formed by a TFT process on a glass substrate and an organic EL light emitting element are combined, the driver and the light emitting portion can be integrally formed on the glass substrate.

  Although the optical line head of the present invention has been described based on some embodiments, the present invention is not limited to these embodiments and can be variously modified.

It is explanatory drawing of the optical line head of this invention. It is explanatory drawing concerning other embodiment of this invention. It is explanatory drawing of a prism. It is explanatory drawing concerning embodiment of this invention. It is explanatory drawing concerning other embodiment of this invention. It is explanatory drawing concerning other embodiment of this invention. It is explanatory drawing concerning other embodiment of this invention. It is explanatory drawing concerning other embodiment of this invention. It is explanatory drawing concerning other embodiment of this invention. It is a perspective view which shows the example of the optical line head of this invention. It is a disassembled perspective view of the optical line head of this invention. It is explanatory drawing which shows the example of zigzag arrangement. It is explanatory drawing which shows the example of 3 lines staggered arrangement | positioning. It is explanatory drawing which shows the example which has arrange | positioned the chip | tip in zigzag. It is explanatory drawing which shows the example of the image formation to a to-be-irradiated surface.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical line head, 2 ... Prism, 3, 4 ... Wedge-shaped prism separated into two, 5 ... Prism formed on glass substrate, 6 ... Groove of glass substrate 7... Prism corresponding to 7 light emitting element lines, 9... Cathode driver, 13... Anode control line, 40... Irradiated surface (image carrier) , 44 to 46 ... imaging spot position, 61 ... organic EL element array, 62 ... glass substrate, 63 ... light emitting part, 64 ... cover glass, 65 ... gradient index rod lens Array (SLA), 70 ... fiber, 72-76 ... light emitting element line

Claims (14)

In an optical line head for imaging light emitted from a line-shaped array light source arranged in two or more rows in the sub-scanning direction of the substrate on an irradiated surface using an erecting equal-magnification optical system, For each array of array light sources arranged in the cross section in the sub-scanning direction, a prism-shaped optical element having a light exit surface angle different from the light incident surface with respect to the horizontal plane is disposed, An optical line head characterized in that an interval in the sub-scanning direction of spots formed by imaging light emitted from array light sources in each column is set smaller than an interval between the array light sources. . The optical element has a light incident surface that is the same plane in a cross section in the sub-scanning direction and a plurality of light exit surfaces that have different angles with respect to a horizontal plane, and are integrally formed in a prism shape. The optical line head according to claim 1. In the cross section in the sub-scanning direction, a prismatic optical element having a flat light incident surface and a flat light emitting surface and arranged in a wedge shape and separated into a plurality of rows is arranged in a plurality of rows in the sub-scanning direction. The optical line head according to claim 1, wherein the optical line head is provided corresponding to each of the array light sources. The array light source is formed in a line shape in a main scanning direction on a glass substrate, and an outgoing light beam from the array light source is emitted through the glass substrate. Item 4. The optical line head according to Item 3. 5. The optical line head according to claim 4, wherein the prism-shaped optical element is formed integrally with the glass substrate on a surface facing the array light source formed on the glass substrate. . The optical line head according to claim 4, wherein the prism-like optical element is bonded to the glass substrate with a groove. The optical line head according to any one of claims 1 to 6, wherein the array light sources are arranged in three or more rows in the sub-scanning direction. The optical line head according to any one of claims 1 to 7, wherein the array light sources are arranged in a staggered manner. 8. The optical line head according to claim 1, wherein the array light sources are arranged in a grid pattern. 7. The optical line head according to claim 1, wherein a plurality of chips on which array light sources are arranged are arranged in the main scanning direction. The optical line head according to claim 10, wherein the chips are arranged in a staggered pattern. 12. The optical line head according to claim 1, wherein a light emitting element of the array light source is an organic EL element. 12. The optical line head according to claim 1, wherein a light emitting element of the array light source is an LED. 14. The optical system element is mounted by forming a groove in a holder, and the glass substrate is provided on a surface of the holder that faces the incident surface of the optical system element. The optical line head according to any one of the above.

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