JP4240986B2 - Optical print head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical print head using a shutter for recording an image on a photosensitive recording medium by exposure / non-exposure.
[0002]
[Prior art]
For example, FIG. 25 and FIG. 26 are explanatory views showing the configuration of a conventional optical print head disclosed in Japanese Patent Laid-Open No. 8-300731. FIG. 25 is an explanatory view of the conventional optical print head viewed from the side, and FIG. 26 is an explanatory view of the conventional optical print head viewed from above. This conventional optical print head surrounds a light source lamp 101 having a wide exposure amount in the visible light region and the periphery thereof, and a slit 103 for passing only necessary exposure light toward an off-axis parabolic mirror 102, and the periphery thereof. Is formed of a cylindrical rotating color filter 104 located at the center. The rotating color filter 104 includes a red color filter 104r that transmits red light, a green color filter 104g that transmits green light, and a blue color filter that transmits blue light (not shown), and the periphery of the light source lamp 101 and the slit 103 is driven by a motor or the like. It is configured to rotate.
[0003]
The off-axis parabolic mirror 102 creates parallel light in the vertical and horizontal directions, the plane reflecting mirror 105 has a vertical incident angle to the monochrome liquid crystal shutter array 106, and the incident light quantity in the main scanning direction to the monochrome liquid crystal shutter array 106 is It is adjusted to be roughly uniform. Here, as the liquid crystal cell of the monochrome liquid crystal shutter array 106, a super twisted nematic type, a twist angle of 240 °, and a cell gap of 5 μm are used. The light that has passed through the monochrome liquid crystal shutter array 106 that is opened and closed according to the image data passes through a prism or diffraction grating that changes the emission angle for each color, which is not shown in the figure, but reaches the condenser lens 107 and is collected. The light is imaged on the photosensitive recording medium 108.
[0004]
However, the conventional optical print head disclosed in Japanese Patent Laid-Open No. 8-300731 generates parallel light by the off-axis parabolic mirror 102 and reflects the parallel light by the plane reflecting mirror 105. Therefore, there is a problem that the optical system becomes large and the optical print head becomes inevitably large. In addition, since the light from the light source lamp 101 is converted into red, green, and blue light by the rotating color filter 104, a rotating unit for the rotating color filter 104 is required, which increases the size and cost of the apparatus. there were.
[0005]
In order to solve the above problems, for example, an optical print head disclosed in Japanese Patent Application Laid-Open No. 7-256869 has been proposed. FIG. 27 is a perspective view showing the configuration of a conventional optical print head disclosed in Japanese Patent Laid-Open No. 7-2566928. In FIG. 27, white light from the halogen lamp point light source 201 is separated into red, green, and blue light by the color liquid crystal shutter 202 and is continuously irradiated onto the end face of the acrylic rod 203 at different times. The acrylic rod 203 is covered with a reflective foil deposited with aluminum or the like except for the light exit surface, and has a function of efficiently converting light incident from the end surface of the rod into linear light. Accordingly, the black and white liquid crystal shutter array 205 is continuously irradiated with red, green, and blue linear light at different times.
[0006]
At this time, there are three pixel columns corresponding to red, green, and blue in the monochrome liquid crystal shutter array 205, but each is driven so that only designated color light can be transmitted. For example, when red linear light is irradiated, only one pixel column corresponding to red can be transmitted, and the other two pixel columns are kept in a dark state. The red, green, and blue linear lights modulated by the monochrome liquid crystal shutter array 205 are imaged on the photosensitive recording medium 206 by the converging lens array 204. At this time, the photosensitive recording medium 206 is moved relative to the black-and-white liquid crystal shutter array 205, so that the red, green, and blue linear lights are sequentially exposed at the same place on the photosensitive recording medium 206. No recorded image is obtained.
[0007]
According to the conventional optical print head disclosed in Japanese Patent Application Laid-Open No. 7-256828, the red light is placed between the halogen lamp point light source 201 and the acrylic rod 203 that converts the point light source into linear light. A small color liquid crystal shutter 202 with green and blue filters attached, and a halogen lamp point for forming a line image formed on the converging lens array 204 on a photosensitive recording medium 206. It is possible to reduce the size and cost of an optical system that emits color light from the light source 201 onto the photosensitive recording medium 206.
[0008]
However, the conventional optical print head disclosed in Japanese Patent Application Laid-Open No. 7-256928 has a problem that the exposure amount difference of each pixel in the main scanning direction is large. That is, there is a problem that the closer to the halogen lamp point light source 201, the higher the light intensity, and the larger the exposure amount, and the farther the light intensity is weak, the lower the exposure amount, so that the difference is too large. In addition, since the light emitted from the acrylic rod 203 is diffused, the light incident on the black and white liquid crystal shutter array 205 includes a large amount of oblique light components. Further, since the color liquid crystal shutter 202 is used, there is a problem that the optical print head is expensive.
[0009]
[Patent Document 1]
JP-A-8-300731
[Patent Document 2]
Japanese Patent Laid-Open No. 7-256828
[0010]
[Problems to be solved by the invention]
As described above, the conventional optical print head has a problem that the apparatus size becomes large when the amount of light transmitted through the liquid crystal shutter is uniform. Further, when the apparatus size is reduced, there is a problem in that the intensity of light incident on the liquid crystal shutter varies, the exposure amount difference in the main scanning direction increases, and an image having a uniform density cannot be obtained. In addition, since a rotating color filter and a color liquid crystal shutter are used for color separation of the light source light, there is a problem that the optical print head is expensive.
[0011]
The present invention has been made to solve the above-described problems, and provides an optical print head that is small, inexpensive, has a small difference in exposure amount at each position in the main scanning direction, and can form an image having a uniform density. For the purpose.
[0012]
[Means for Solving the Problems]
An optical print head according to the present invention includes a shutter that opens and closes according to image information, a transparent light guide whose longitudinal direction is the main scanning direction, a light source provided at a longitudinal end of the light guide, And a cover that covers the light guide, and the light guide has a cross-sectional shape that is convex, and a light diffusion region is formed on the surface of the light guide on the long side of the convex cross-section. The light guide surface on the short side of the convex cross section is the light exit surface.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is an exploded view showing the configuration of the optical print head according to the first embodiment. FIG. 2 is a perspective view showing a configuration of a transparent rod portion of the optical print head. FIG. 3 is a side sectional view of the optical print head, and the direction perpendicular to the paper surface is the main scanning direction.
[0014]
In FIG. 1, reference numeral 7 denotes a light source unit on which three-color LEDs, a red LED 8a, a green LED 8b, and a blue LED 8c are mounted so as to be in contact with the end portion of the transparent rod 9 made of glass or acrylic whose longitudinal direction is the main scanning direction. Be placed. Further, 1 selectively transmits / shields the light emitted from the light exit surface 13 of the transparent rod 9 based on the image data, and exposes / not exposes the photosensitive recording medium 2 via the converging lens array 14. This is a monochrome liquid crystal shutter mounted with a driver IC 1b for exposure. In the first embodiment, twisted nematic (TN) liquid crystal is used as the liquid crystal cell. The monochrome liquid crystal shutter 1 is disposed so as to be in close contact with the light exit surface 13 of the transparent rod 9, the central axis of the light exit surface 13 in the sub-scanning direction width W, and the aperture element of the monochrome liquid crystal shutter 1. Arranged so that the central axes of the length L in the sub-scanning direction 1a coincide. Reference numeral 10 denotes a cover that covers the surface of the transparent rod 9 other than the light exit surface 13 and is made of a member that increases the reflectivity of the inner surface, such as white resin, aluminum, and stainless steel. The positional relationship between the light exit surface 13 and the bottom surface of the cover 10 is configured such that the light exit surface 13 protrudes about 0 to 0.1 mm from the bottom surface of the cover 10.
[0015]
In FIG. 2, the transparent rod 9 has a convex cross section in the sub-scanning direction. A light diffusing layer 12 corresponding to a light diffusing region printed with a reflective paint for diffusing light, for example, white paint, is formed on the light diffusing surface 11 having the long side of the convex cross-sectional shape. Light is emitted from a light emitting surface 13 facing the surface 11. When the structure of the transparent rod 9 is viewed from a cross section, the transparent rod 9 is divided into a portion A including the light diffusion surface 11 and a portion B including the light exit surface 13. The LEDs 8a, 8b, and 8c are connected to the end surface 16− of the transparent rod 9. 1 is mounted on the light source unit 7 so as to be in contact with the A portion on the top.
[0016]
In FIG. 2, the light diffusing layer 12 is formed so that the light emitted from the light emitting surface 13 which is a surface facing the light diffusing surface 11 is substantially uniform at each position in the transparent rod 9. ing. Here, the light diffusion layer 12 is formed in a triangular shape that increases in the direction farther from the light source unit 7 because the light intensity becomes weaker as the distance from the light source unit 7 increases.
[0017]
Although the optical print head casing is omitted in FIG. 1, as shown in FIG. 3, the monochrome liquid crystal shutter 1, the converging lens array 14, the light source unit 7, the transparent rod 9, and the like are included in the casing 15. The one housed inside is called an optical print head.
The optical print head is configured to be movable relative to the photosensitive recording medium 2 by a driving means (not shown).
[0018]
Next, the operation will be described.
When the optical print head comes to a predetermined position (printing start position) with respect to the photosensitive recording medium 2, first, the red LED 8a is turned on, and the red light emitted from the red LED 8a enters the transparent rod 9. The behavior of light entering the transparent rod 9 at this time will be described with reference to FIGS.
FIG. 4 is an explanatory diagram showing the behavior of light in the cross section in the main scanning direction of the light source unit 7 and the transparent rod 9 of the optical print head, and the arrow line indicates the traveling direction of the light. In FIG. 4, the direction perpendicular to the paper surface is the sub-scanning direction. FIG. 5 is an explanatory view showing the behavior of light in the sub-scanning direction cross section of the transparent rod 9 of the optical print head, and the arrow line indicates the traveling direction of the light. In FIG. 5, the direction perpendicular to the paper surface is the main scanning direction.
[0019]
First, it demonstrates using FIG. Since the light source unit 7 and the transparent rod 9 are only in contact with each other, an air layer is interposed between the light source unit 7 and the transparent rod 9. The incident angle of light incident on the transparent rod 9 from the red LED 8a is θ ₀ (Not shown), the refraction angle is θ ₁ When the refractive index of the transparent rod 9 is n, the following formula (1) is established from Snell's law.
sinθ ₁ = Sinθ ₀ / N (1)
Here, if the refractive index n of the transparent rod 9 is 1.5, the refraction angle θ of the light incident on the transparent rod 9 ₁ Is about 41.8 ° at the maximum. Since the cover 10 is only covered so as to be in contact with the transparent rod 9, an air layer is interposed between the cover 10 and the transparent rod 9, and the interface between the transparent rod 9 and the air layer at this time The critical angle θc of total reflection in the light beam is also about 41.8 °, and most of the light reaching the interface between the transparent rod 9 and the air layer after entering the transparent rod 9 is totally reflected and transparent. The light propagates in the opposite direction to the light source unit 7 in the rod 9 and spreads in the main scanning direction. Light having an incident angle exceeding θc is emitted outside the transparent rod 9, but is reflected by the cover 10 and returns to the transparent rod 9 again.
[0020]
Of the light propagating through the transparent rod 9, the light hitting the light diffusing layer 12 provided on the light diffusing surface 11 is diffusely reflected, and the light emission provided on the surface facing the light diffusing surface 11. Of the light reaching the surface 13, light having an incident angle equal to or smaller than the critical angle θc is emitted from the light exit surface 13 and is incident on the aperture element 1 a of the monochrome liquid crystal shutter 1. Light whose incident angle to the light exit surface 13 exceeds the critical angle θc is returned into the transparent rod 9 by total reflection. Of the light striking the light diffusing layer 12, the light incident on a surface other than the light exit surface 13 in the transparent rod 9, the light having an incident angle exceeding the critical angle θc is totally reflected, and is less than the critical angle θc. Light is emitted outside the transparent rod 9. The light emitted from a surface other than the light emitting surface 13 in the transparent rod 9, for example, the light emitted from the transparent rod end surface 16-2 facing the light incident surface from the light source unit 7 of the transparent rod 9, And is incident on the transparent rod 9 again.
[0021]
Next, the behavior of light incident on the aperture element 1a of the monochrome liquid crystal shutter 1 will be described with reference to FIG. The transparent rod 9 has a convex cross section, and in FIG. 5, the cross section of the transparent rod 9 is divided into a portion A including the light diffusion surface 11 and a B portion including the light exit surface 13. The light striking the light diffusing layer 12 on the light diffusing surface 11 is diffused, and the diffused light is divided into light traveling into the A portion including the light diffusing surface 11 and light traveling into the B portion including the light emitting surface 13. It is done. Here, as described above, the light traveling toward the portion A is totally reflected at the interface with the cover 10 as the incident angle is larger than the critical angle θc, and has an incident angle smaller than the critical angle θc. The light is emitted from the transparent rod 9, but is reflected by the cover 10 and returned into the transparent rod 9.
[0022]
On the other hand, since the cross-sectional shape of the transparent rod 9 has a convex shape, the light path width into the portion B is narrower than that in the portion A. Among them, most of the light hitting the side surface c and d surface of the B part is totally reflected and proceeds to the light exit surface 13. Therefore, as compared with the case where a conventional rectangular transparent rod is used, the density (light flux) of light emitted from the light exit surface 13 is increased, and the light emitted from the light exit surface 13 is directed in the sub-scanning direction. The degree of diffusion becomes smaller. Further, of the light impinging on the side surface c and d surface of the B part, light that is not totally reflected is emitted from the transparent rod 9, but is reflected by the cover 10 and returned to the transparent rod 9.
[0023]
The red light emitted from the light exit surface 13 of the transparent rod 9 is transmitted from the aperture element 1 a to the pixel position to be exposed according to the image data by the monochrome liquid crystal shutter 1, and the transmitted red light is transmitted by the converging lens array 14. After being condensed, it is exposed on the photosensitive recording medium 2, and an image corresponding to the image data is formed. For this reason, as described above, as the density of light emitted from the light exit surface 13 of the transparent rod 9 is increased, the amount of light incident on the aperture element 1a of the black-and-white liquid crystal shutter 1 increases and the loss of light intensity is small. An optical print head can be obtained.
[0024]
Next, the red LED 8a is turned off and the green LED 8b is turned on. At the same time, the monochrome liquid crystal shutter 1 is transmitted / shielded according to the image data. Similarly, green light is exposed on the photosensitive recording medium 2 and imaged. Subsequently, similarly, exposure by the blue LED 8c is performed and an image is formed.
[0025]
FIG. 6 is a cross-sectional view of a transparent rod formed into a convex shape, a light diffusion layer is provided on a light diffusion surface having a long side of the convex cross-sectional shape, and a surface facing the light diffusion surface is defined as a light emission surface. It is explanatory drawing which made the result of the light intensity measurement experiment of the main scanning direction of the optical print head in this Embodiment 1 and the conventional optical print head whose transparent rod cross-sectional shape is a rectangle a graph. In FIG. 6, the vertical axis indicates the relative light intensity, the horizontal axis indicates the distance from the light source unit in the main scanning direction, and the solid line indicates the main scanning of the optical print head according to the first embodiment in which the transparent rod has a convex cross-sectional shape. The broken line shows the result of measuring the light intensity in the main scanning direction of a conventional optical print head having a square cross section of the transparent rod.
[0026]
In the measurement results shown in FIG. 6, the only difference in the experimental conditions is in the transparent rod cross-sectional shape, the length L in the sub-scanning direction of the aperture element 1a of the monochrome liquid crystal shutter 1 is 0.1 mm, and the critical angle θc is about 41.8. °. The optical head having a convex cross section of the transparent rod has a portion A height of 1.5 mm, a portion B height of 2 mm, and a light exit surface width W of 1 mm shown in FIG. All other experimental conditions are the same.
[0027]
As a result of the experiment, the relative variation (variation) based on the average of the light intensity measurement values in the main scanning direction in the conventional optical print head having a square cross section of the transparent rod is about 19%, and the cross section of the transparent rod is also convex. The optical print head according to the first embodiment formed in the mold is about 7%, and the optical print head according to the first embodiment in which the transparent rod has a convex sectional shape has a light intensity in the main scanning direction. It can be seen that the uniformity is excellent. Further, regarding the light intensity, the optical print head according to the first embodiment in which the transparent rod cross-sectional shape is convex with respect to the average light intensity in the main scanning direction of the conventional optical print head having a square transparent rod cross-sectional shape. As a result, the average light intensity in the main scanning direction was about 33% higher.
[0028]
Here, the relationship between the sub scanning direction length L of the aperture element 1a of the monochrome liquid crystal shutter 1, the width W of the light exit surface 13 of the transparent rod 9, and the height t of the light exit surface 13 will be described. When the critical angle θc of total reflection at the interface between the transparent rod 9 and the air layer is used, the following equation (2) is established.
t> (W−L) / 2 tan θc (2)
FIG. 7 is an explanatory diagram showing the behavior of light incident on the aperture element 1 a of the monochrome liquid crystal shutter 1. In order to make more light incident on the aperture element 1a of the monochrome liquid crystal shutter 1, if the light totally reflected on the side surface c and d surface of the B portion of the transparent rod 9 is incident on the aperture element 1a. Good. As a condition at this time, the incident angle θ of the reflected light at the end of the aperture element 1a _λ Is less than the critical angle θc of the interface on the light exit surface 13 of the transparent rod 9, and the height of the portion ((W−L) / 2) other than the aperture element 1a on the light exit surface 13 and the B portion. The ratio to t is tanθ _λ Need to be. Equation (2) satisfies this condition.
[0029]
As described above, the cross-sectional shape of the transparent rod 9 is formed in a convex shape, the light diffusion layer 12 is provided on the light diffusion surface 11 having the long side of the convex cross-sectional shape, and the surface facing the light diffusion surface 11 The light exit surface 13 can increase the density (light flux) of the light emitted from the light exit surface 13 and can also diffuse the light emitted from the light exit surface 13 in the sub-scanning direction. Since the degree can be reduced, an optical print head having high light intensity and excellent light intensity uniformity in the main scanning direction can be obtained. As a result, a high-quality printed image with little density unevenness can be obtained.
[0030]
Further, the light emitting surface 13 is configured to protrude about 0 to 0.1 mm from the bottom surface of the cover 10 covering the surface other than the light emitting surface 13 of the transparent rod 9, and the light emitting surface 13 is an opening of the monochrome liquid crystal shutter 1. By being configured to be in close contact with the element portion 1a, no extra air layer is interposed between the light exit surface 13 and the monochrome liquid crystal shutter 1, so that the light emitted from the light exit surface 13 is diffused by the air layer. In other words, the loss of light intensity of light incident on the aperture element portion 1a of the monochrome liquid crystal shutter 1 can be reduced.
[0031]
Further, since a color LED lamp is used without using a relatively expensive color liquid crystal shutter, a further inexpensive optical print head can be obtained.
[0032]
Moreover, the cross-sectional shape of the transparent rod 9 is formed in a convex shape, and is in contact with the upper surface portion A including the light diffusion surface 11 having the long side of the convex cross-sectional shape on the end surface 16-1 of the transparent rod 9. By arranging the plurality of color LEDs 8a, 8b, 8c, the height (thickness) of the transparent rod 9 can be reduced, so that a thin and small optical print head can be obtained.
[0033]
In the first embodiment, the light diffusion layer 12 is printed with a reflective paint (in this case, a white paint) that diffuses light. However, the light diffusion layer 12 is not limited to this as long as the light can be diffused. 11 may be formed with minute irregularities or sawtooth shapes. In this case, the same effect can be obtained by forming the shape of the region where the minute unevenness and the sawtooth shape are formed into a triangle that is large in the direction far from the light source unit 7. Furthermore, the shape of the light diffusion layer 12 is not limited to this as long as the light emitted from the light emitting surface 13 can be made substantially uniform, and a stepped shape, a curve, or the like may be used as shown in FIG. The same applies to the following embodiments.
[0034]
Further, in the first embodiment, the optical print head is configured to move relative to the photosensitive recording medium 2, but the photosensitive recording medium 2 is configured to move relative to the optical print head. Also good. The same applies to the following embodiments.
[0035]
In the first embodiment, an example in which an LED is used as a light source has been described. However, the present invention is not limited to this, and the same effect can be obtained by using, for example, an EL (Electro Luminescence) light emitting element. The same applies to the following embodiments.
[0036]
In the first embodiment, an example in which a red LED, a green LED, and a blue LED are used as a light source and a black and white liquid crystal shutter is used as a liquid crystal shutter is shown. The same effect can be obtained even if a color liquid crystal shutter is used as the liquid crystal shutter. The same applies to the following embodiments.
[0037]
In the first embodiment, an example in which a monochrome liquid crystal shutter is used in which one row (one color) of pixels is arranged in the main scanning direction is shown. For example, a conventional example (Japanese Patent Laid-Open No. 7-256828) is shown. The same effect can be obtained even when a pixel having three rows (three colors) of pixels similar to that in Japanese Patent Publication No. 1) is obtained, and an optical print head capable of printing at higher speed can be obtained. The same applies to the following embodiments.
[0038]
In the first embodiment, an example in which a converging lens array that collects light transmitted from a monochrome liquid crystal shutter is used has been described. For example, the distance between the monochrome liquid crystal shutter array and the photosensitive recording medium is shortened. By doing so, it is possible to prevent the light from diffusing and to eliminate the focusing lens array. The same applies to the following embodiments.
[0039]
Moreover, in this Embodiment 1, although the order which irradiates the light of LED was the order of red LED, green LED, and blue LED, the same effect is acquired regardless of what order. Can do. The same applies to the following embodiments.
[0040]
In the first embodiment, the monochrome liquid crystal shutter 1 is a TN liquid crystal shutter using a twisted nematic liquid crystal. However, the present invention is not limited to this as long as it has a shutter function. For example, an STN liquid crystal using a super twisted nematic liquid crystal is used. A shutter may be used, or a shutter that does not use liquid crystal. The same applies to the following embodiments.
[0041]
In the first embodiment, the case where the surfaces other than the light diffusion surface and the light emission surface of the transparent rod 9 are formed perpendicularly or horizontally to these surfaces has been described. If the intensity of light emitted from the light exit surface can be increased by narrowing, the surface is not limited to this, and a surface other than the light diffusion surface and the light exit surface is inclined, or a convex shape is formed by drawing a curve. Also good. The same applies to the following embodiments.
[0042]
Embodiment 2. FIG.
In the first embodiment, the case where the light source unit is provided on one end face of the transparent rod 9 has been described. In the second embodiment, the case where the light source unit is provided on both end faces of the transparent rod will be described.
[0043]
FIG. 9 is a cross-sectional view in the main scanning direction of the light source unit and the transparent rod of the optical print head in the second embodiment, and the direction perpendicular to the paper surface is the sub-scanning direction. FIG. 10 is a perspective view showing a configuration of a transparent rod of the optical print head.
[0044]
As shown in FIG. 9, the light source unit 7 is provided on both end faces 16-1a and 16-2a of the transparent rod 9a. Thereby, an optical print head with high light intensity can be obtained. In this case, as shown in FIG. 10, the shape of the light diffusing layer 12a on the light diffusing surface 11a is shaped so that the area of the light diffusing layer 12a increases as the distance from the both end faces of the transparent rod 9a increases. The light diffusing layer 12a is shaped so that the area of the light diffusing layer 12a is maximized at the center of the transparent rod 9a. Thereby, the light which inject | emits from the light emission surface 13a becomes substantially uniform in each position in the said transparent rod 9a.
Since other configurations and operations are the same as those in the first embodiment, description thereof is omitted.
[0045]
Therefore, the light source unit 7 is provided on both end faces 16-1a and 16-2a of the transparent rod 9, and the shape of the light diffusing layer 12a on the light diffusing face 11a is increased as the distance from the both end faces of the transparent rod 9a increases. By adopting a shape that increases the area of 12a, it is possible to obtain an optical print head having a large light intensity in addition to the same effects as those of the first embodiment. An optical print head capable of printing can be obtained.
[0046]
Embodiment 3 FIG.
In the first embodiment, the case where the width in the sub-scanning direction of the portion A including the light diffusing surface 11 of the transparent rod 9 is uniform, but in the third embodiment, as the distance from the light source unit increases, The case where the width | variety of the said A part is made small is demonstrated.
[0047]
FIG. 11 is a perspective view showing the configuration of the transparent rod of the optical print head according to the third embodiment. FIG. 12 is a top sectional view of a portion A including the light diffusion surface of the transparent rod.
As shown in FIG. 11, the shape of the transparent rod 9b in the third embodiment is configured such that the cross-sectional width of the A portion of the transparent rod 9b becomes smaller as the distance from the light source unit 7 increases. For example, as shown in FIG. 12, when the portion A of the transparent rod 9b is viewed from the upper surface, it has a tapered shape with a taper angle α.
[0048]
The operation will be described below.
Since the lighting operation of the LEDs 8a, 8b, and 8c and the exposure operation for the photosensitive recording medium 2 are the same as those in the first embodiment, description thereof is omitted here. Here, the behavior of light in the transparent rod 9b will be described. The behavior of the light incident on the transparent rod 9b in the main scanning direction is the same as that in FIG. 4 with respect to the cross section direction in the main scanning direction in the transparent rod 9b, and between the transparent rod 9b and the cover 10. All the light reaching the interface of the air layer is totally reflected, propagates in the transparent rod 9b in the direction opposite to the light source unit 7, and spreads in the main scanning direction.
[0049]
The behavior of light that spreads in the sub-scanning direction among the light incident on the transparent rod 9b will be described with reference to FIG.
If the light spreading in the sub-scanning direction reaches the interface of the air layer between the transparent rod 9b and the cover 10 and the incident angle at the interface with the cover 10 is equal to or greater than the critical angle θc, total reflection is performed. Repeatedly propagates in the main scanning direction in the transparent rod 9b. Here, since the shape of the A portion of the transparent rod 9b in the sub-scanning direction is a shape that tapers in the main scanning direction having a taper angle α, the incident angle θn at the n-th incidence of the totally reflected light is When the first incident angle θo,
θn = θo−nα (3)
Thus, the light satisfying θn> θc is totally reflected, and the other light is reflected by the cover 10 and returned again into the transparent rod 9b. The light propagating in the main scanning direction repeats reflection and total reflection, and finally strikes and diffuses the light diffusion layer 12b. The diffused light exhibits the same behavior as in the first embodiment and is emitted from the light exit surface 13b.
Since other configurations and operations are the same as those in the first embodiment, description thereof is omitted.
[0050]
As described above, as the distance from the light source unit 7 increases, the cross-sectional area in the width direction of the portion A having the light diffusing surface 11b of the transparent rod 9b is reduced, so that even in a position far from the light source unit 7, Since the luminous flux (density) of the light increases, the light intensity emitted from the light exit surface 13b can be increased, and an optical print head having high light intensity and excellent light intensity uniformity in the main scanning direction is obtained. It is possible. As a result, it is possible to obtain a higher-quality printed image without density unevenness.
[0051]
Embodiment 4 FIG.
In the third embodiment, the case where the light source unit is provided on one end face of the transparent rod has been described. In the fourth embodiment, the case where the light source unit is provided on both end faces of the transparent rod will be described.
[0052]
FIG. 13 is a perspective view showing the configuration of the transparent rod of the optical print head according to the fourth embodiment.
[0053]
As shown in FIG. 13, the shape of the transparent rod 9c in the fourth embodiment is such that the width in the sub-scanning direction of the A portion including the light diffusion surface 11c is maximum at both end surfaces and minimum at the center portion. To form. Further, the shape of the light diffusion layer 12c on the light diffusion surface 11c is made such that the area thereof increases as the distance from the both end faces of the transparent rod 9c increases, and the area of the light diffusion layer 12c is the center of the transparent rod 9c. The shape is maximized at the part. And the light source unit 7 which is not shown in figure is provided in the both end surfaces 16-1c and 16-2c of the transparent rod 9c as shown in FIG. Thereby, the light intensity can be increased, and the light emitted from the light emitting surface 13c can be made substantially uniform at each position in the transparent rod 9c.
Other configurations and operations are the same as those in the third embodiment, and a description thereof will be omitted.
[0054]
Accordingly, the light source unit 7 is provided on both end faces 16-1c and 16-2c of the transparent rod 9c, and the width of the transparent rod 9c in the sub-scanning direction of the portion A including the light diffusion surface 11c is maximum at both end faces. The shape of the light diffusion layer 12c on the light diffusion surface 11c is such that the area of the light diffusion layer 12c increases as the distance from the both end surfaces of the transparent rod 9c increases. Thus, an optical print head that has the same effects as those of the third embodiment, can further increase the light intensity, has a short printing time, and can perform high-speed printing can be obtained.
[0055]
Embodiment 5 FIG.
In the first embodiment, the case where the thickness of the portion A including the light diffusing surface 11 of the transparent rod 9 is uniform has been described. However, in the fifth embodiment, as the distance from the light source unit increases, the portion A A case where the thickness of the substrate is reduced will be described.
[0056]
FIG. 14 is a perspective view showing the configuration of the transparent rod of the optical print head in the fifth embodiment. FIG. 15 is a cross-sectional view in the main scanning direction of the transparent rod covered with a cover.
[0057]
As shown in FIG. 14, the shape of the transparent rod 9d in the fifth embodiment is configured such that the thickness of the A portion of the transparent rod 9d becomes thinner as the distance from the light source unit 7 increases. For example, as shown in FIG. 15, when the portion A of the transparent rod 9 d is viewed in the cross section in the main scanning direction, the thickness decreases as the distance from the light source unit 7 increases. Thereby, since the transparent rod 9d has a cross-sectional area in the thickness direction of the portion A having the light diffusing surface 11d as the distance from the light source unit 7 becomes smaller, similarly to the transparent rod 9b shown in the third embodiment, the light source Even at a position far from the unit 7, the light flux (density) of the light in the transparent rod 9d increases. In the first embodiment, the light that does not directly hit the light diffusing layer 12d is also distant from the light source unit 7 in the optical print head in the fifth embodiment, as indicated by the broken line in FIG. It directly hits the light diffusion layer 12d. As a result, the light reflected on the cover in the first embodiment is diffused by the light diffusion layer 12d with less loss in the fifth embodiment, so that the loss is less than that in the first embodiment. Become.
Since other configurations and operations are the same as those in the first embodiment, description thereof is omitted.
[0058]
Accordingly, as the shape of the transparent rod 9d becomes farther from the light source unit 7, the cross-sectional area in the thickness direction of the portion A of the transparent rod 9d is reduced, so that the inside of the transparent rod 9d is also located at a position far from the light source unit 7. Since the light flux (density) of the light increases, the light intensity emitted from the light exit surface 13d can be increased, and an optical print head having high light intensity and more excellent light intensity uniformity in the main scanning direction can be obtained. It is possible to obtain. As a result, it is possible to obtain a higher-quality printed image without density unevenness.
[0059]
Embodiment 6 FIG.
Although the case where the light source unit is provided on one side surface of the transparent rod has been described in the fifth embodiment, the case where the light source unit is provided on both end surfaces of the transparent rod will be described in the sixth embodiment.
[0060]
FIG. 16 is a perspective view showing the configuration of the transparent rod of the optical print head according to the sixth embodiment.
[0061]
As shown in FIG. 16, the shape of the transparent rod 9e in the sixth embodiment is formed so that the thickness of the A portion including the light diffusion surface 11e is maximum at both end surfaces and minimum at the center portion. . Further, the shape of the light diffusion layer 12e on the light diffusion surface 11e is made such that the area thereof increases as the distance from the both end faces of the transparent rod 9e increases, and the area of the light diffusion layer 12e is the center of the transparent rod 9e. The shape is maximized at the part. And the light source unit 7 which is not shown in figure is provided in the both end surfaces 16-1e and 16-2e of the transparent rod 9e as shown in FIG. As a result, the light intensity can be increased, and the light emitted from the light exit surface 13e can be made substantially uniform at each position in the transparent rod 9e.
Other configurations and operations are the same as those in the fifth embodiment, and a description thereof will be omitted.
[0062]
Therefore, the light source unit 7 is provided on both end surfaces 16-1e and 16-2e of the transparent rod 9e, and the shape of the transparent rod 9e in the sixth embodiment is the same as the thickness of the A portion including the light diffusion surface 11e. The surface is formed to be the largest and the smallest at the center, and the shape of the light diffusing layer 12e on the light diffusing surface 11e is such that the area increases as the distance from the both end faces of the transparent rod 9e increases. In addition, the shape in which the area of the light diffusion layer 12e is maximized at the central portion of the transparent rod 9e has the same effect as that of the fifth embodiment, and in addition to that, the light intensity is further increased. Therefore, an optical print head capable of high-speed printing with a short printing time can be obtained.
[0063]
Embodiment 7 FIG.
In the first embodiment, the case where both the width and the thickness in the sub-scanning direction of the portion A including the light diffusion surface 11 of the transparent rod 9 are uniform has been described. However, in the seventh embodiment, the light source unit A case will be described in which the width of the portion A is reduced and the thickness is reduced as the distance from the distance increases.
[0064]
FIG. 17 is a perspective view showing the configuration of the transparent rod of the optical print head according to the seventh embodiment. FIG. 18 is a side view of the transparent rod 9f as viewed from the end face 16-2f side.
[0065]
As shown in FIG. 17, the shape of the transparent rod 9f in the seventh embodiment is such that the width in the sub-scanning direction of the portion A of the transparent rod 9f decreases as the distance from the light source unit 7 increases. The transparent rod 9f is configured so that the thickness of the portion A is reduced. Thereby, the cross-sectional area of the transparent rod 9f becomes smaller in both the width direction and the thickness direction of the portion A having the light diffusion surface 11f as the distance from the light source unit 7 becomes larger than the transparent rod shown in the third and fifth embodiments. Therefore, even at a position far from the light source unit 7, the light flux (density) of the light in the transparent rod 9f increases.
Since other configurations and operations are the same as those in the first embodiment, description thereof is omitted.
[0066]
Therefore, as the shape of the transparent rod 9f becomes farther from the light source unit 7, the cross-sectional area is reduced in both the width direction and the thickness direction of the A portion of the transparent rod 9f, so that the transparent rod 9f can be located at a position far from the light source unit 7. Since the light flux (density) of the light in the transparent rod 9f increases, the light intensity emitted from the light exit surface 13f can be increased, and the light intensity is large and the light intensity uniformity in the main scanning direction is more excellent. An optical print head can be obtained. As a result, it is possible to obtain a higher-quality printed image without density unevenness.
[0067]
Embodiment 8 FIG.
Although the case where the light source unit is provided on one side surface of the transparent rod has been described in the seventh embodiment, the case where the light source unit is provided on both end faces of the transparent rod will be described in the eighth embodiment.
[0068]
FIG. 19 is a perspective view showing the configuration of the transparent rod of the optical print head according to the eighth embodiment.
[0069]
As shown in FIG. 19, the shape of the transparent rod 9g in the eighth embodiment is such that the width shape in the sub-scanning direction of the A part including the light diffusing surface 11g is maximum at both end faces 16-1g and 16-2g, and The thickness of the portion A including the light diffusing surface 11g is minimized at the central portion, and is maximized at both end surfaces 16-1g and 16-2g and is minimized at the central portion. The shape of the light diffusing layer 12g on the light diffusing surface 11g is formed such that the area thereof increases as the distance from both end faces of the transparent rod 9g increases, and the area of the light diffusing layer 12g is the central portion of the transparent rod 9g. The maximum shape is obtained. And the light source unit 7 which is not shown in figure is provided in the both end surfaces 16-1g and 16-2g of the transparent rod 9g as shown in FIG. Thereby, the light intensity can be increased, and the light emitted from the light emitting surface 13g can be made substantially uniform at each position on the transparent rod 9g.
Other configurations and operations are the same as those in the seventh embodiment, and a description thereof will be omitted.
[0070]
Therefore, the light source unit 7 is provided on both end faces 16-1g and 16-2g of the transparent rod 9g, and the shape of the transparent rod 9g in the eighth embodiment is changed to the width in the sub-scanning direction of the A portion including the light diffusion surface 11g. The shape is maximum at both end faces 16-1g and 16-2g, and is minimum at the center, and further, the thickness of part A including the light diffusion surface 11g is maximum at both end faces 16-1g and 16-2g, and The light diffusing layer 12g on the light diffusing surface 11g is formed so as to be the smallest at the center, and the shape of the light diffusing layer 12g increases with increasing distance from both end faces of the transparent rod 9g. In addition to having the same effect as in the seventh embodiment, the light intensity can be increased and the printing time can be increased. Short , It is possible to obtain the optical print head capable of high-speed printing.
[0071]
Embodiment 9 FIG.
In the first embodiment, the case where the width of the portion B including the light emission surface 13 of the transparent rod 9 is uniform has been described. However, in the ninth embodiment, as the distance from the light source unit increases, A case where the width is increased will be described.
[0072]
FIG. 20 is a perspective view showing the configuration of the transparent rod of the optical print head according to the ninth embodiment. FIG. 21 is a configuration diagram of the transparent rod in a state covered with a cover as viewed from the light exit surface 13h side.
[0073]
As shown in FIGS. 20 and 21, the shape of the transparent rod 9h in the ninth embodiment is set so that the width of the B portion of the transparent rod 9h increases as the distance from the light source unit 7 increases. The area of the light exit surface 13h is configured to be wide. Thereby, even at a position far from the light source unit 7, the light flux emitted from the light exit surface 13h becomes relatively large.
Since other configurations and operations are the same as those in the first embodiment, description thereof is omitted.
[0074]
Accordingly, the shape of the transparent rod 9h is configured such that the area width of the light emission surface 13h increases as the distance from the light source unit 7 increases, so that the light emission can be achieved even at a position far from the light source unit 7. Since the amount of light emitted from the surface 13h is relatively large, the difference in the amount of light emitted from the transparent rod 9h in the main scanning direction can be reduced, and an optical print head capable of forming an image with a uniform density is obtained. Can do.
[0075]
Embodiment 10 FIG.
In the ninth embodiment, the case where the light source unit is provided on one side surface of the transparent rod has been described. In the present embodiment 10, the case where the light source unit is provided on both end surfaces of the transparent rod will be described.
[0076]
FIG. 22 is a perspective view showing the configuration of the transparent rod of the optical print head according to the tenth embodiment.
[0077]
As shown in FIG. 22, the shape of the transparent rod 9i in the tenth embodiment is such that the width in the sub-scanning direction of the portion B including the light exit surface 13i is the minimum at both end surfaces and the maximum at the center portion. To form. In addition, the shape of the light diffusion layer 12i on the light exit surface 11i is formed such that the area increases as the distance from the both end faces of the transparent rod 9i increases, and the area of the light diffusion layer 12i is the center of the transparent rod 9i. The shape is maximized at the part. And the light source unit 7 which is not shown in figure is provided in the both end surfaces 16-1i and 16-2i of the transparent rod 9i as shown in FIG. Thereby, the light intensity can be increased, and the light emitted from the light exit surface 13i can be made substantially uniform at each position on the transparent rod 9i.
Other configurations and operations are the same as those in the seventh embodiment, and a description thereof will be omitted.
[0078]
Therefore, the light source unit 7 is provided on both end faces 16-1i, 16-2i of the transparent rod 9i, and the shape of the transparent rod 9i in the tenth embodiment is changed to the width in the sub-scanning direction of the B portion including the light exit surface 13i. However, the area of the light diffusion layer 12i on the light exit surface 11i increases as the distance from the both end surfaces of the transparent rod 9i increases. By making the shape such that the area of the light diffusing layer 12i is maximized at the central portion of the transparent rod 9i, the same effect as that of the ninth embodiment is obtained, and in addition, the light intensity is further increased. And an optical print head capable of high-speed printing with a short printing time.
[0079]
Embodiment 11 FIG.
In the first embodiment, the width and thickness of the portion A including the light diffusing surface 11 of the transparent rod 9 in the sub-scanning direction are uniform, and the width of the portion B including the light emitting surface 13 of the transparent rod 9 is equal. In the eleventh embodiment, the case where the width of the A portion is reduced, the thickness is reduced, and the width of the B portion is increased as the distance from the light source unit is increased. To do.
[0080]
FIG. 23 is a perspective view showing the configuration of the transparent rod of the optical print head according to the eleventh embodiment.
[0081]
As shown in FIG. 23, the shape of the transparent rod 9j according to the eleventh embodiment is such that the width in the sub-scanning direction of the portion A of the transparent rod 9j decreases as the distance from the light source unit 7 increases. The transparent rod 9j is configured so that the thickness of the portion A is thin. Thereby, like the transparent rod shown in Embodiment 7, the transparent rod 9j has a smaller cross-sectional area in both the width direction and the thickness direction of the portion A having the light diffusing surface 11j as the distance from the light source unit 7 increases. Therefore, the light flux (density) of the light in the transparent rod 9j also increases at a position far from the light source unit 7. Further, the shape of the transparent rod 9j in the eleventh embodiment is configured so that the area width of the light exit surface 13j becomes wider as the distance from the light source unit 7 increases. Thereby, even at a position far from the light source unit 7, the light flux emitted from the light exit surface 13j becomes relatively large.
Since other configurations and operations are the same as those in the first embodiment, description thereof is omitted.
[0082]
Accordingly, as the shape of the transparent rod 9j becomes farther from the light source unit 7, the width of the A portion of the transparent rod 9j becomes smaller and the thickness of the A portion of the transparent rod 9j becomes thinner. Further, by configuring so that the area width of the light exit surface 13j is widened, the light flux (density) of the light in the transparent rod 9j increases even at a position far from the light source unit 7, Further, since the light flux emitted from the light exit surface 13j is relatively large, the light intensity emitted from the light exit surface 13j can be increased, and the main scanning direction emitted from the transparent rod 9j can be increased. It is possible to reduce the difference in the amount of light, and to obtain an optical print head having high light intensity and more excellent light intensity uniformity in the main scanning direction. As a result, it is possible to obtain a higher-quality printed image without density unevenness.
[0083]
In the eleventh embodiment, as the shape of the transparent rod 9j becomes farther from the light source unit 7, the width of the A portion of the transparent rod 9j in the sub-scanning direction becomes smaller and the A portion of the transparent rod 9j. Although the case where the thickness is configured to be thin has been described, either one of the cross-sectional area in the width direction or the cross-sectional area in the thickness direction of the portion A becomes smaller as the distance from the light source unit 7 increases. Even if configured, the same effect can be obtained.
[0084]
Embodiment 12 FIG.
In the eleventh embodiment, the case where the light source unit is provided on one side surface of the transparent rod has been described, but in the present embodiment 12, the case where the light source unit is provided on both end surfaces of the transparent rod will be described.
[0085]
FIG. 24 is a perspective view showing the configuration of the transparent rod of the optical print head according to the twelfth embodiment.
[0086]
As shown in FIG. 24, the shape of the transparent rod 9k in the twelfth embodiment is such that the width shape in the sub-scanning direction of the A portion including the light diffusion surface 11k is the maximum at both end faces 16-1k, 16-2k, and The thickness of the portion A including the light diffusing surface 11k is minimized at the central portion, and the thickness is maximized at both end surfaces 16-1k and 16-2k and is minimized at the central portion. Further, the shape of the transparent rod 9k is formed so that the width in the sub-scanning direction of the B portion including the light emitting surface 13k is minimum at both end surfaces and maximum at the central portion. The shape of the light diffusing layer 12k on the light diffusing surface 11k is formed such that the area thereof increases as the distance from the both end surfaces of the transparent rod 9k increases, and the area of the light diffusing layer 12k is the central portion of the transparent rod 9k. The maximum shape is obtained. And the light source unit 7 which is not shown in figure is provided in the both end surfaces 16-1k and 16-2k of the transparent rod 9k as shown in FIG. Thereby, the light intensity can be increased, and the light emitted from the light exit surface 13k can be made substantially uniform at each position on the transparent rod 9k.
Other configurations and operations are the same as those in the eleventh embodiment, and a description thereof will be omitted.
[0087]
Accordingly, the light source unit 7 is provided on both end faces 16-1k, 16-2k of the transparent rod 9k, and the shape of the transparent rod 9k is the width shape in the sub-scanning direction of the portion A including the light diffusion surface 11k. 1k and 16-2k are maximum and minimum at the center, and the thickness of the A part including the light diffusion surface 11k is maximum at both end faces 16-1k and 16-2k and is minimum at the center. Further, the transparent rod 9k is formed so that the width in the sub-scanning direction of the B portion including the light exit surface 13k is the minimum at both end surfaces and the maximum at the center portion, and The shape of the light diffusing layer 12k on the light diffusing surface 11k is made such that the area increases as the distance from the both end faces of the transparent rod 9k increases, and the area of the light diffusing layer 12k is maximum at the center of the transparent rod 9k. Make it a shape to become More, which has the same effect as Embodiment 11 of the above embodiment, additionally, it is possible to increase the more the light intensity, short printing time, it is possible to obtain the optical print head capable of high-speed printing.
[0088]
In the twelfth embodiment, the light source unit 7 is provided on both end faces 16-1k, 16-2k of the transparent rod 9k, and the shape of the transparent rod 9k is the width shape in the sub-scanning direction of the A part including the light diffusion surface 11k. Is the maximum at both end faces 16-1k and 16-2k and the minimum at the center, and the thickness of the A part including the light diffusing surface 11k is the maximum at both end faces 16-1k and 16-2k and the center. Although the case where the portion is formed to be the smallest at the portion has been described, either the cross-sectional area in the width direction or the cross-sectional area in the thickness direction of the portion A is configured to become smaller as the distance from the light source unit 7 increases. Even if it is done, the same effect can be obtained.
[0089]
【The invention's effect】
As described above, according to the optical print head of the present invention, the shutter that opens and closes according to the image information, the transparent light guide whose longitudinal direction is the main scanning direction, and the longitudinal end of the light guide A light source provided and a cover covering the light guide, and the light guide is formed in a convex cross-sectional shape, and a light diffusion region is provided on the light guide surface on the long side of the convex cross-section. By forming a light diffusing surface and using the light guide surface on the short side of the convex cross section as a light emitting surface, it is compact, inexpensive, and has a uniform difference in exposure amount at each position in the main scanning direction. An optical print head capable of forming a density image can be obtained.
[Brief description of the drawings]
FIG. 1 is an exploded view showing a configuration of an optical print head according to a first embodiment.
FIG. 2 is a perspective view showing a configuration of a transparent rod portion of an optical print head.
FIG. 3 is a side sectional view of an optical print head.
FIG. 4 is an explanatory diagram showing light behavior in a cross section in the main scanning direction of the light source unit 7 and the transparent rod 9 of the optical print head.
FIG. 5 is an explanatory view showing the behavior of light in the sub-scanning direction cross section of the transparent rod 9 of the optical print head.
FIG. 6 is an explanatory diagram that graphs the results of a light intensity measurement experiment in the main scanning direction of the optical print head in the first embodiment and a conventional optical print head.
7 is an explanatory diagram showing the behavior of light incident on the aperture element 1a of the black and white liquid crystal shutter 1. FIG.
FIG. 8 is an explanatory diagram showing another example of the light diffusion layer 12
9 is a cross-sectional view in the main scanning direction of a light source unit and a transparent rod of an optical print head according to Embodiment 2. FIG.
FIG. 10 is a perspective view showing a configuration of a transparent rod of an optical print head.
FIG. 11 is a perspective view showing a configuration of a transparent rod of an optical print head in a third embodiment.
FIG. 12 is a top sectional view of a portion A including a light diffusing surface of a transparent rod.
FIG. 13 is a perspective view showing a configuration of a transparent rod of an optical print head according to a fourth embodiment.
14 is a perspective view showing a configuration of a transparent rod of an optical print head in a fifth embodiment. FIG.
FIG. 15 is a cross-sectional view in the main scanning direction of the transparent rod covered with a cover.
FIG. 16 is a perspective view showing a configuration of a transparent rod of an optical print head according to a sixth embodiment.
17 is a perspective view showing a configuration of a transparent rod of an optical print head according to a seventh embodiment. FIG.
FIG. 18 is a side view of the transparent rod 9f as viewed from the end face 16-2f side.
FIG. 19 is a perspective view showing a configuration of a transparent rod of an optical print head in an eighth embodiment.
FIG. 20 is a perspective view showing a configuration of a transparent rod of an optical print head according to a ninth embodiment.
FIG. 21 is a structural view of a transparent rod covered with a cover, as viewed from the light exit surface 13h side.
22 is a perspective view showing a configuration of a transparent rod of an optical print head according to a tenth embodiment. FIG.
FIG. 23 is a perspective view showing a configuration of a transparent rod of an optical print head in an eleventh embodiment.
24 is a perspective view showing a configuration of a transparent rod of an optical print head in Embodiment 12. FIG.
FIG. 25 is an explanatory diagram showing a configuration of a conventional optical print head.
FIG. 26 is an explanatory diagram showing a configuration of a conventional optical print head.
FIG. 27 is a perspective view showing a configuration of a conventional optical print head.
[Explanation of symbols]
1 Black and white LCD shutter
1a Aperture element
1b Driver IC
2 Photosensitive recording media
7 Light source unit
8a Red LED
8b Green LED
8c Blue LED
9, 9a-9k Transparent rod
10, 10a, 10b, 10d, 10h cover
11, 11a-11k Light diffusing surface
12, 12a-12k Light diffusion layer
13, 13a-13k Light emission surface
14 Focusing lens array
15 housing
16-1, 16-1a to 16-1k, 16-2, 16-2a to 16-2k End surface of transparent rod

Claims (9)

A light source that emits light;
A shutter provided with an aperture element that transmits or blocks light according to image information;
A cover formed of a reflective member whose inner surface reflects light;
The cross-sectional shape is formed of a convex transparent member, the surface on the long side of the convex is a light diffusion surface, the surface on the short side is a light emission surface, and the light emission surface is the opening element of the shutter. The length of the short side is W, the length of the opening element of the shutter in contact with the short side is L, the critical angle of the transparent member is θ c , and the height of the convex convex portion is t The transparent member among the light of the light source that satisfies the relationship of t> (W−L) / 2 tan θ c and is incident on the inside of the transparent member and diffused by the light diffusion surface. The light that is totally reflected inside and incident on the convex portion and the light that is not totally reflected reflected by the reflecting member of the cover are converged by the convex portion, and the light exit surface A light guide that exits to the aperture element of the shutter;
Optical print head with a. The light exit plane of the light guide body, to no position in the bottom flush with the cover covering the light guide, by being positioned so as to protrude from the bottom surface position of the cover, the light guide The optical print head according to claim 1, wherein the light emission surface of the shutter is in close contact with the aperture element of the shutter. The convex section of the light guide, and a region including the light diffusing surface, divided into a region including the light exit surface,
3. The optical print head according to claim 1, wherein the region including the light diffusion surface is formed so as to become narrower as the distance from the light source increases. The convex section of the light guide, and a region including the light diffusing surface, divided into a region including the light exit surface,
Claim 1 or claim 2 optical print head according to form a region including the light diffusing surface, so that the thickness becomes thinner with increasing distance from the light source. The convex section of the light guide, and a region including the light diffusing surface, divided into a region including the light exit surface,
Claim 1 or claim 2 optical print head according to region including the light exit surface is formed such that the width with increasing distance from the light source is widened. The convex section of the light guide, and a region including the light diffusing surface, divided into a region including the light exit surface,
Having light sources at both longitudinal ends of the light guide;
The region including the light diffusing surface of the light guide, wherein the width light guide end portions is maximized, according to claim 1 or claim 2, wherein a width in the light guide central portion is formed so as to minimize Optical print head. The convex section of the light guide, and a region including the light diffusing surface, divided into a region including the light exit surface,
Having light sources at both longitudinal ends of the light guide;
Wherein a region containing a light diffusing surface of the light guide body, the thickness of light guide body both end portions is maximized, according to claim 1 or claim 2 thickness in the light guide central portion is formed so as to minimize The optical printhead described. The convex section of the light guide, and a region including the light diffusing surface, divided into a region including the light exit surface,
Having light sources at both longitudinal ends of the light guide;
The region including the light emitting surface of the light guide, the width is minimized at the light guide end portions, according to claim 1 or claim 2, wherein a width in the light guide central portion is formed so as to maximize Optical print head. 3. The optical print head according to claim 1, wherein the light diffusion region on the surface of the light guide is formed by changing a width based on a shape of the light guide and a position having the light source.

Images