JP4231583B2 - Optical print head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical print head that records an image or the like on a recording medium using a plurality of light emitting elements.
[0002]
[Prior art]
FIG. 5 is a diagram schematically illustrating an example of the structure of the optical print head 101 using a fluorescent light-emitting tube as a light source. The optical print head 101 is provided inside a housing (not shown) as a writing head of a fluorescent printer. A silver salt sheet 20 (silver salt paper or silver salt photographic paper) is arranged inside the housing so as to face the optical print head 101. The silver salt sheet 20 and the optical print head 101 are arranged in the sub-scanning direction (left and right in the figure). It is configured to be relatively movable along (direction).
[0003]
The optical print head 101 has three fluorescent light emitting tubes 100R, 100G, and 100B. Each fluorescent light-emitting tube irradiates dot-shaped light of each color of red (R), green (G), and blue (B) from each anode. Each anode 30 (R, G, B) is a large number of light emitting dots arranged in a line or staggered at predetermined intervals along a direction perpendicular to the paper surface in FIG. Each fluorescent light emitting tube 100 has the light emitting dot arrangement direction as the main scanning direction, and the three fluorescent light emitting tubes 100R, 100G, and 100B are arranged along the sub-scanning direction of the silver salt sheet 20. Outside each fluorescent light emitting tube 100, an equal magnification imaging element 40 and color filters 50R, 50G, and 50B corresponding to the respective colors are provided for each fluorescent light emitting tube. The light emitted from the light emitting dots of the fluorescent light emitting tubes 100R, 100G, and 100B passes through the equal magnification imaging element 40 and the color filters 50R, 50G, and 50B, and is irradiated onto the silver salt sheet 20.
[0004]
The color image is color-separated into red (R), green (G), and blue (B) data, and the fluorescent tubes 100R, 100G, and 100B are driven with the corresponding color data. In synchronization with this, the optical print head 101 and the silver salt sheet 20 are relatively moved along the sub-scanning direction (left-right direction in FIG. 5), and dot-shaped light of each color is emitted from each fluorescent light emitting tube 100R, 100G, 100B. Is irradiated on the silver salt sheet 20. When the latent image formed thereby is developed, the original color image is reproduced on the silver salt sheet 20.
[0005]
[Problems to be solved by the invention]
The optical print head described above requires a large space for moving with respect to the photographic paper and is difficult to reduce in size.
[0006]
In addition, it is necessary to accurately align the three-color dot-shaped light coming from each fluorescent light emitting tube on the photographic paper. However, as the resolution increases and the length increases, it is affected by the optical distortion of the equal magnification imaging element. , It becomes difficult to match the same over the entire width. That is, the equal-magnification imaging element is an element in which a large number of rod-shaped lenses are integrated, but the linearity and total pitch of the light emission pattern differ due to the disorder of the arrangement of the lenses, and there are individual differences.
[0007]
Since there are individual differences in the equal-magnification imaging elements provided for each fluorescent light emitting tube, the light emitting dots (anodes 30R, 30G, 30B) of each fluorescent light emitting tube are uniformly distributed with a predetermined accuracy as shown in FIG. Even if they are arranged side by side, the positions of the respective light emitting dots that pass through this and form an image on the photographic paper (silver salt sheet 20) are not as expected. Therefore, even if an attempt is made to reproduce the original image by driving the fluorescent light-emitting tubes of the respective colors at a predetermined timing by the color-separated image signal and superimposing the dot-shaped lights of the respective colors on the photographic paper, as shown in FIG. Each light dot is difficult to match on the photographic paper.
[0008]
In addition, in the conventional optical print head, the overlapping of the optical dots is shifted due to speed unevenness when the optical print head and the photographic paper are moved relative to each other, color shift occurs, and the dots are blurred without being sharp. There was also a problem.
[0009]
The present invention relates to an optical print head that forms an image by forming images of light from a plurality of light sources on a recording medium, and accurately superimposes the light from each light source on the recording medium without causing color shift or blur. An object of the present invention is to provide an optical print head capable of forming an image.
[0011]
[Means for Solving the Problems]
  Claim1Is an optical print head that forms an image by imaging light from a plurality of light sources (fluorescent tubes 1, 2, 13) on a recording medium, and irradiates light in a predetermined direction. Orthogonal to the first light source (fluorescent light emitting tube 1), the second light source (fluorescent light emitting tube 2) that irradiates light in a direction opposite to the first light source, and the first and second light sources. Selected from the group consisting of a third light source (fluorescent tube 13) that irradiates light in the directionAt least twoA light source and one common magnification imaging element (12) used in common;It has a triangular prism shape, and its two surfaces are dichroic mirrors that selectively reflect light of a specific wavelength from the at least two light sources and transmit light of other wavelengths, and each light from the at least two light sources A dichroic optical element (10) that is arranged so that the optical path lengths are not the same inside, and that introduces each light from the at least two light sources into the equal-magnification imaging element with the optical axes aligned,
  A triangular prism-shaped optical member provided in the vicinity of the dichroic mirror of the dichroic optical element, wherein each light from the at least two light sources passes through the dichroic optical element and the optical member, respectively. An optical member (11) having a refractive index and a dimension determined so that they are substantially the same;And each of the light beams from the plurality of light sources is imaged by being superimposed at substantially the same position on the recording medium.
[0014]
  Claim2The optical printhead described in claim1In the above-described optical print head, the light sources (fluorescent light-emitting tubes 1, 2, 13)DichroicSo as to absorb light other than light introduced into the optical element (10).DichroicA light absorbing member (light absorbing film 20) is disposed in the vicinity of the optical element.
[0015]
  Claim3The optical printhead described in claim1The mounted optical print head is characterized in that at least one of the plurality of light sources (fluorescent light emitting tubes 1, 2, 13) is a combination with an optical filter (filters R, G, B).
[0016]
  Claim4The optical printhead described in claim1In the above-described optical print head, each light source is a monochromatic light source composed of a combination of an optical filter (filters R, G, B) that transmits light of a specific wavelength and a fluorescent light emitting tube (fluorescent light emitting tube 1, 2, 13). It is characterized by being.
[0019]
  Claim5The optical printhead described in claim1In the above-described optical print head, each of the light sources has a different emission color.
[0020]
  Claim6The optical printhead described in claim1In the above-described optical print head, each of the light sources includes at least one different emission color.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The optical print head of the present invention uses a plurality of light sources, but a single magnification lens array (selfoc lens array) for forming an image on a recording medium is common to each light source. (1 set) only. Then, using special optical elements, light from each light source is introduced into this equal-magnification imaging lens array in a state where the optical axes coincide with each other, and is exposed at the same position on the recording medium to synthesize an image. To do. In the following two examples, a case where a plurality of light sources have different emission colors and a dichroic optical element (mirror, filter, etc.) is used as an optical element is shown. The number of light sources is two to three.
[0022]
The optical print head of the first example shown in FIG. 1 faces a first fluorescent light-emitting tube 1 as a first light source that irradiates light in a predetermined direction, the first fluorescent light-emitting tube 1, and the first fluorescent light-emitting head 1. A second fluorescent light emitting tube 2 is provided as a second light source that irradiates light in the opposite direction parallel to the light from the light emitting tube 1.
[0023]
The fluorescent light-emitting tubes 1 and 2 of this example include an envelope 5 formed by sealing a box-shaped container portion 4 to a glass anode substrate 3. A light-transmitting anode conductor and an anode 6 (R, G, B) made of a phosphor deposited on the anode conductor are formed on the anode substrate 3 in the envelope 5. The anode 6 is a large number of light emitting dots arranged in a line or a staggered pattern (a line in the figure) at a predetermined interval along a direction perpendicular to the paper surface in FIG. Each fluorescent light emitting tube 1, 2 has the light emitting dot arrangement direction as the main scanning direction, and the two fluorescent light emitting tubes 1, 2 are arranged along the sub-scanning direction of the recording medium 7.
[0024]
The first fluorescent light-emitting tube 1 uses a ZnO: Zn phosphor, which is a zinc oxide-based phosphor having a wide emission spectrum and an emission color in the blue to red region. The green filter 8 is used to obtain a green emission color. If the filter is blue, a blue emission color can be obtained.
[0025]
The second fluorescent light-emitting tube 2 has a lack of energy in the red region in the ZnO: Zn phosphor in view of the sensitivity characteristics of the photosensitive layer (eg, cyan layer) that is sensitive to red in the silver salt sheet as the recording medium 7. (Zn, Cd) S phosphor (Zn_1-x, Cd_x) S: Ag, Cl phosphor is used. This phosphor is a phosphor widely used in fluorescent display tubes as a Reddish Orange color having an x value of 0.75 to 0.80 and a peak wavelength of around 650 to 660 nm. A red emission color is obtained by using an R filter 9.
[0026]
Between the two fluorescent light emitting tubes 1 and 2 (including the respective filters 8 and 9), there is an optical element 10 and an optical member 11, from which the optical axes overlap each other. The light is incident on a common equal magnification imaging element (selfoc lens array) 12. The optical element 10 of this example is formed of a dichroic optical element having a triangular prism shape (prism shape) and two surfaces being dichroic mirrors (filters). The equal-magnification imaging element 12 (Selfoc lens array) of this example is an optical system that forms a single continuous real-magnification image by arranging a plurality of gradient index lenses. That is, as the refractive index in the lens continuously changes, the light meanders with a constant period and acts like a spherical lens, and reproduces a high-resolution and accurate erecting real-size real image.
[0027]
As shown in FIG. 1, the green (or blue) dot-like light emitted from the first fluorescent light-emitting tube 1 is a first reflection surface of a dichroic optical element 10 having a selective reflection function and transmission function for each wavelength. The light path is reflected by 10a and the optical path is changed to 90 ° below. Color components other than green (or blue) emitted from the first fluorescent light-emitting tube 1 are separated by transmitting through the reflecting surface 10a.
[0028]
As shown in FIG. 1, the red dot-like light emitted from the second fluorescent light emitting tube 2 is reflected by the second reflecting surface 10b of the dichroic optical element 10 having a selective reflection function for each wavelength, and the lower 90 The optical path is changed to ° and the first reflecting surface 10a is transmitted. Light having a wavelength other than red is transmitted without being reflected by the second reflecting surface 10b. Since the second fluorescent light emitting tube 2 of this example emits red light by the red light emitting phosphor and the red filter 9, the second reflecting surface 10b may be a total reflection mirror.
[0029]
Then, the dot lights having different colors from the first and second fluorescent light emitting tubes 1 and 2 are incident on the common equal-magnification imaging element 12 with their optical axes aligned, and are superimposed on the recording medium 7. The image is formed at the same position. Therefore, the obtained image is clearer than before.
[0030]
As shown in FIG. 1, a triangular prism-shaped optical member 11 such as a prism is provided close to the first fluorescent light-emitting tube 1 side of the optical element 10. The light emitted from the first fluorescent light emitting tube 1 passes through the optical member 11, is reflected by the first reflecting surface 10 a of the dichroic optical element 10, passes through the optical member 11, and goes out. The light emitted from the second fluorescent light emitting tube 2 passes through the dichroic optical element 10 and then passes through the optical member 11 and exits. The distance that the light emitted from the fluorescent light emitting tubes 1 and 2 passes through the dichroic optical element 10 is different from the distance that the light passes through the optical member 11. However, in this example, since the refractive index and dimensions of the optical member 11 are appropriately determined, the optical path lengths of the light emitted from both fluorescent light emitting tubes are substantially the same. That is, the arrangement of the two fluorescent light-emitting tubes 1 and 2 with respect to the equal magnification imaging element 12 is not the same, but the optical path lengths of the two fluorescent light-emitting tubes 1 and 2 and the equal magnification imaging element 12 are the same. That is, the imaging positions (focal positions) of the light from both fluorescent light emitting tubes 1 and 2 are the same, and both can form dot images on the recording medium 7 in the same state.
[0031]
As described above, in order to set the focal positions of the two fluorescent light-emitting tubes 1 and 2 on the recording medium 7, after determining the position of one fluorescent light-emitting tube with respect to the optical element 10 and the optical member 11, The position of the other fluorescent light emitting tube may be moved back and forth, up and down, left and right along the optical path to find a position where the focal points overlap.
[0032]
The color image is separated into red (R) and green (G) (or blue) data, and each fluorescent light-emitting tube is driven with the corresponding color data. In synchronization with this, the optical print head and the recording medium 7 are relatively moved along the sub-scanning direction (left and right direction in FIG. 1), and the dot-shaped light of each color is emitted from each fluorescent light emitting tube at the same position on the recording medium. Irradiate. When the latent image formed thereby is developed, the original color image is reproduced on the recording medium.
[0033]
In this example, the coordinates of the luminous dot arrangement of both fluorescent luminous tubes are common. Even if the dot arrangement of each fluorescent light emitting tube is staggered, the arrangement pattern can be shared by the two tubes.
[0034]
A second example of the embodiment of the present invention will be described with reference to FIG.
The optical print head of the second example shown in FIG. 2 faces the first fluorescent light-emitting tube 1 as a first light source that irradiates light in a predetermined direction, the first fluorescent light-emitting tube 1, and the first fluorescent light-emitting head 1. A second fluorescent light emitting tube 2 as a second light source that irradiates light in the opposite direction parallel to the light from the light emitting tube 1, and light in a direction orthogonal to the light from the first and second fluorescent light emitting tubes. And a third fluorescent light-emitting tube 13 as a third light source for irradiating.
[0035]
The first fluorescent light-emitting tube 1 has a ZnO: Zn phosphor and a blue (B) filter 14 and irradiates blue light-emitting dots. The second fluorescent light emitting tube 2 has a ZnO: Zn phosphor and a green (G) filter 8 and irradiates green light emitting dots. The third fluorescent light emitting tube 13 has a (Zn, Cd) S phosphor and a red (R) filter 9 and irradiates red light emitting dots. The structure as a fluorescent light emitting tube is the same as in the first example.
[0036]
Between the three fluorescent light emitting tubes 1, 2, 13 (including each filter), there is one optical element 10 and two optical members 11a, 11b, through which the optical axes are overlapped 3 Light from the two fluorescent light-emitting tubes 1, 2, and 13 is incident on a common 1 × imaging element 12 (selfoc lens array). The equal-magnification imaging element 12, the optical element 10, and the optical member 11 of the present example are substantially the first example except for design matters to be applied to the three fluorescent light-emitting tubes 1, 2, and 13. It exhibits the same functions and effects.
[0037]
As shown in FIG. 2, after the blue dot-like light emitted from the first fluorescent light emitting tube 1 is transmitted through the first optical member 11a, the dichroic optics having a selective reflection function and transmission function for each wavelength. Reflected by the first reflecting surface 10a of the element 10, the optical path is changed to 90 ° downward. Light having a wavelength other than blue passes through the first reflecting surface 10a without being reflected.
[0038]
As shown in FIG. 2, the green dot-like light emitted from the second fluorescent light emitting tube 2 is reflected by the second reflecting surface 10 b of the dichroic optical element 10 having a selective reflection function for each wavelength, and the lower 90 The optical path is changed to 0 °, the light is emitted from the first reflecting surface 10a, and is transmitted through the first optical member 11a. Light having a wavelength other than green is transmitted without being reflected by the second reflecting surface 10b.
[0039]
As shown in FIG. 2, the red dot-like light emitted from the third fluorescent light-emitting tube 13 is transmitted through the second optical member 11b, transmitted through the second reflecting surface 10b of the dichroic optical element 10, and first reflected. The light passes through the surface 10a and further passes through the first optical member 11a.
[0040]
Then, the blue, green, and red dot light from the first, second, and third fluorescent light-emitting tubes 1, 2, and 13 enter the common equal magnification imaging element 12 with the optical axes aligned. Then, the images are formed at the same position on the recording medium 7 in the overlapped state.
[0041]
FIG. 8 shows an image formed on the photographic paper through which the R, G, B light passes through the lens.
The state of the image (image formation) formed on the photographic paper is
(1) is an image formation example at the time of image formation when three light sources in one row are used.
(2) is an example of image formation when three light sources in a staggered array are combined.
(3) is an example of image formation when a single row of light sources and a staggered array of light sources are combined.
It becomes.
Matching the optical axis (X) means aligning the lens center of the SELFOC lens array in parallel with the light emission pattern center.
In addition, overlapping at the same position means that the same RGB pattern overlaps as in (1) and (2), and in (3), the X coordinate of the RGB pattern is the same and the coordinate in the Y direction is almost the same. It is in agreement (at least the same pattern is touched in the vicinity of the optical axis, or overlaps with a predetermined light emission pattern area arranged in a staggered manner, or exists in the area).
In the figure, RGB is a floating figure, but the image is formed in the same plane (on the photographic paper) for easy understanding of the overlapping state of RGB.
[0042]
Also in this example, as in the first example, the first and second optical members 11a and 11b having appropriate optical functions are employed, so that the three fluorescent light emitting tubes 1, 2, 13 and the like are used. The optical path length to the double imaging element 12 is substantially the same. That is, the arrangement of the three fluorescent light-emitting tubes 1, 2 and 13 with respect to the equal magnification imaging element 12 is not the same, but the imaging positions (focal positions) of the light from the respective fluorescent light-emitting tubes 1, 2 and 13 are the same. Thus, any fluorescent light emitting tube can image dot light at the same position on the recording medium 7 in the same state.
[0043]
The optical members 10, 11a, 11b are made of borosilicate crown glass (BK7: German Schottglass Berke registered trademark), and have a general refractive index of 1.52, soda glass used in fluorescent tubes. (When an optical member and a fluorescent light emitting tube are joined, if the refractive index is the same, refraction at the joining surface hardly occurs and attenuation of light or the like can be prevented). FIG. 7 shows an optical path of each light emitting element. A solid line indicates an optical path when the optical members 10 and 11a and 11b are mounted, and a broken line indicates an optical path when the optical members 11a and 11b are not mounted. If the optical members 11a and 11b are not mounted on the optical path of the fluorescent light emitting tube 13, the distances through which the left and right optical paths pass through the optical member 10 are different, and the focal position is set at a position different from A and B due to the influence of the refractive index. I can't make an image accurately.
[0044]
Similarly, in the optical path of the fluorescent light emitting tube 2, if there is no optical member 11a, the focal position is at a position different from D and C. Therefore, the optical members 11a and 11b have a function of focusing any light passing on the optical path at the same position.
[0045]
A light absorption film 20 is formed on portions of the optical members 10, 11 a, and 11 b except for the light path incident portion from the fluorescent light emitting tube and the light path portion from which the synthesized light is emitted. This film is formed of an acrylic black paint, but any material that absorbs light may be used.
For example, the light absorbing film 20 absorbs the G light reflected by 10b out of the light from the fluorescent light emitting tube 13 of FIG. Without this light absorbing film 20, the G light is reflected by the inner surface of 11b and lowers the contrast.
[0046]
In the figure, the dichroic element 10 selectively reflects and transmits RGB wavelengths, so basically no color filter (optical filter) is required, but leakage of wavelengths other than the selected wavelength is also observed, so the purity of the photosensitive color Color filters are effective when you want to increase For example, when exposing to photographic paper, as an example, the RGB photosensitive areas of a certain photographic paper are R: 580 to 750 nm, G: 500 to 580 nm, B: 350 to 500 nm, and the boundary wavelengths of each color are around 500 nm and 580 nm. The color filter is effective when performing spectroscopic analysis. R: SC42, G: BPM53, B: BPN45 (all of which are model numbers) are sold by Fuji Photo Film as effective color filters capable of performing spectroscopy at the above wavelengths.
[0047]
As described above, in order to set the positions where the focal points of the three fluorescent light-emitting tubes 1, 2 and 13 overlap on the recording medium 7, one fluorescent light-emitting tube for the optical element 10 and the optical members 11a and 11b is used. After determining the position, the position of the remaining fluorescent light emitting tube is moved back and forth, up and down, left and right along the optical path to find the position where the focal points overlap.
[0048]
In this example, the color image is color-separated into data of three colors of red (R), green (G), and blue (B), and each fluorescent light emitting tube is driven with data of the corresponding color. In synchronization with this, the optical print head and the recording medium 7 are moved relatively along the sub-scanning direction (left-right direction in FIG. 2), and the dot-shaped light of each color is recorded from each of the fluorescent light-emitting tubes 1, 2, and 13. Irradiate the same position on the medium 7. When the latent image formed thereby is developed, the original full-color image (latent image) is formed on the recording medium.
[0049]
According to this example, as shown in FIG. 4, light emission of R, G, and B colors emitted from three fluorescent light emitting tubes using an optical element 10 (10a, 10b) such as a dichroic mirror or a half mirror. It is possible to form an image on the recording medium 7 by making the dots coincide with the optical axis and enter the common equal-magnification imaging element 12. Therefore, even if there is an individual difference in the equal magnification imaging element 12, as shown in FIG. 4, the position of each light emitting dot imaged on the recording medium 7 is constant including the individual difference. For this reason, problems such as color misregistration do not occur.
[0050]
In this example, the shape and arrangement pattern of the light emitting dots of the first and second fluorescent light emitting tubes are common. Even if the dot arrangement of each fluorescent light emitting tube is staggered, the arrangement pattern can be shared by the two tubes. However, the light emitting dot pattern of the third fluorescent light emitting tube 13 has a mirror image relationship with the light emitting dot patterns of the first and second fluorescent light emitting tubes 1 and 2. Therefore, in this example, when the dot pattern of the anode of the fluorescent tube is a staggered arrangement or a plurality of arrangements, it is necessary to prepare two types of patterns, the first and second patterns and the third pattern. There is. Alternatively, all three have the same dot pattern, and either one set of fluorescent light-emitting tubes having the same structure (for first and second or third) is shifted by one dot in the longitudinal direction of the dot row, The dots may overlap so that the image data is shifted by one dot in accordance with the shifted direction.
[0051]
In this case, one light emitting dot is invalidated (that is, the effective image forming area is reduced by one light emitting dot), or common to each fluorescent light emitting tube provided with an extra light emitting dot by one light emitting dot in advance. A dot pattern is formed and the unnecessary light emitting dots are selectively used to eliminate invalid light emitting dots.
[0052]
As a modification of the second example, in the second example, any one of the first and second fluorescent light-emitting tubes 1 and 2 and the third fluorescent light-emitting tube 13 may be combined. The specific configuration is the same as in both the above embodiments.
[0053]
In each example described above, a prism-like element as shown in FIG. 3 (2) is used as the dichroic optical element, but a filter-like dichroic element (1) shown in FIG. 3 (1) is used. A dichroic filter) may be used.
[0054]
In each example of the present invention, a fluorescent light-emitting tube is used as a light source. However, other light-emitting elements (field emission display elements, light-emitting diodes, plasma display panels, inorganic and organic electroluminescence elements, liquid crystal shutters + backlight light sources) , PLZT shutter + backlight light source), or a composite light source in which the light-emitting elements are combined.
In each example of the present invention, the light source has a fluorescent emission tube having a wide emission spectrum and a blue to red region emission color, and a red light emission color. Although a fluorescent light emitting tube using a Zn, Cd) S-based phosphor is used, a monochromatic light source having each of blue, green, and red may be used. Moreover, you may use the light source which has two luminescent colors among blue, green, and red, the white light source which has three luminescent colors, and the light source which combined them.
[0055]
Furthermore, in each example of the present invention, the SELFOC lens array is used as the equal magnification imaging element, but a plastic lens array, a roof mirror lens array, or the like may be used.
[0056]
A dichroic filter is a kind of non-metal film interference filter that reflects light in a part of the wavelength range of visible light and transmits the rest.
Details are described in pages 783 to 860 of the Color Science Handbook (edited by the Japan Society for Color Science, University of Tokyo Press).
[0057]
In FIG. 3, (2) is the configuration of the optical element of Example 2. 10, 11a and 11b are formed of a material made of glass (BK7). 10 is formed with dichroic filters 10a and 10b. 11a and 11b are bonded to the surface on which 10 filters are formed by balsam (transparent adhesive).
In the filter 10a, light entering from above passes R and B light and reflects G light. Light incident from the right side reflects G light and transmits R and B light. In the filter 10b, light entering from above passes R and G light and reflects B light. Light incident from the left side reflects B light and transmits R and G light.
Accordingly, the R light passes through 10a and 10b and enters the lens. The G light is reflected by 10a, bends the optical path downward, passes through 10b, and enters the lens. The B light is reflected by 10b, bends the optical path downward, and enters the lens.
[0058]
In the case of Example 1, it may be considered that there is no 11b and there is no incidence from above. Moreover, although 10a is comprised with the dichroic filter, a total reflection mirror may be sufficient.
[0059]
In FIG. 3, (1) is the same as (2) in that an optical element is formed by forming a dichroic filter on flat glass. The configuration of the dichroic filter is the same as that of (2). In the filter 10a, light entering from above transmits R and B light and reflects G light. Light incident from the right side reflects G light and transmits R and B light. In the filter 10b, light entering from above passes R and G light and reflects B light. Light incident from the left side reflects B light and transmits R and G light.
Accordingly, the R light passes through 10a and 10b and enters the lens. The G light is reflected by 10a, bends the optical path downward, passes through 10b, and enters the lens. The B light is reflected by 10b, bends the optical path downward, and enters the lens.
[0060]
Each example of the present invention described above can be applied to an optical print head using a fluorescent tube as a light source. This optical print head can be used as a writing head of a fluorescent printer such as a color printer.
[0061]
In each example of the present invention, dot light of different emission colors irradiated from a plurality of fluorescent light emission tubes is guided to a common equal magnification imaging element using a dichroic optical element, and the recording medium is in a state where the optical axes are aligned. The image is formed by exposing the image directly on the top. Moreover, the optical path lengths of the dot lights of the respective colors are substantially matched by using the optical member. For this reason, it is possible to form a clear image free from color shift and blur.
[0062]
【The invention's effect】
According to the present invention, the following effects can be obtained.
(1) By sharing a plurality of light sources with one optical element (lens), the entire apparatus can be reduced in size.
(2) Since the optical paths of a plurality of light sources are combined through the same optical path when they enter one optical element (lens), even if there is optical distortion in the optical element (lens), The problem of dot light alignment (dot light misalignment) does not occur, and the obtained image becomes clear.
(3) Since the light from a plurality of light sources is optically synthesized, the alignment of dot light is simplified, the number of optical elements (lenses) used is reduced, and the cost can be reduced.
(4) Since the light from a plurality of light sources is optically combined by an optical element (lens), it is possible to compactly combine light sources with different emission colors that were conventionally arranged spatially, The delay processing of the circuit and the moving space of the head could be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first example of an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a second example of the embodiment of the present invention.
FIG. 3 is a diagram showing an example of the structure of an optical element according to an embodiment of the present invention.
FIG. 4 is a perspective view showing an effect in the second example of the embodiment of the present invention.
FIG. 5 is a diagram schematically showing an example of the structure of a conventional optical print head.
FIG. 6 is a perspective view schematically showing a problem in a conventional optical print head.
FIG. 7 is a cross-sectional view showing an optical path of each light emitting element in a second example.
FIG. 8 is a diagram schematically showing a state in which R, G, B light is transmitted through a lens to form an image on a photographic paper in the embodiment of the present invention.
[Explanation of symbols]
1, 2, 13 Fluorescent tube as light source
10 Optical elements
11 Optical members
12-magnification imaging element
20 Light Absorbing Film as Light Absorbing Member

Claims (6)

In an optical print head that forms an image by imaging light from a plurality of light sources on a recording medium,
Irradiating light in a direction orthogonal to the first and second light sources, a first light source that irradiates light in a predetermined direction, a second light source that irradiates light in a direction opposite to the first light source, and At least two light sources selected from the group consisting of :
One common magnification imaging element used in common;
It has a triangular prism shape, and its two surfaces are dichroic mirrors that selectively reflect light of a specific wavelength from the at least two light sources and transmit light of other wavelengths, and each light from the at least two light sources A dichroic optical element which is arranged so that the optical path lengths are not the same inside, and introduces each light from the at least two light sources into the equal-magnification imaging element with the optical axes aligned,
A triangular prism-shaped optical member provided in the vicinity of the dichroic mirror of the dichroic optical element, wherein each light from the at least two light sources passes through the dichroic optical element and the optical member, respectively. An optical member having a refractive index and a dimension determined so that they are substantially the same,
Have
An optical print head characterized in that each light from the plurality of light sources forms an image by being superimposed at substantially the same position on a recording medium. The optical print head according to claim 1 Symbol mounting, characterized in that a light-absorbing member in the vicinity of the dichroic optical element to absorb light other than the light to be introduced into the dichroic optical element from the light sources. Wherein the plurality of light sources, according to claim 1 Symbol placement of the optical print head, wherein at least one light source is a combination of an optical filter. Wherein each light source, according to claim 1 Symbol placement of the optical print head, characterized in that a monochromatic light source comprising a combination of an optical filter and the fluorescent light emitting tube for transmitting light of a specific wavelength. Wherein each light source, according to claim 1 Symbol placement of the optical print head and having a different emission color, respectively. Wherein each light source, according to claim 1 Symbol placement of the optical print head, characterized in that it comprises at least one different light emission colors.

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