JP2726296B2 - Imaging element and image reading device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging element used for a copying machine, a facsimile, and the like, and an image reading apparatus using the imaging element.

2. Description of the Related Art Conventionally, in a copying machine, a facsimile, and the like, an imaging element including an optical path separating mirror, a lens, and a roof mirror has been used. To read a large original, etc., as shown in FIG. 9, a lens array 3 in which an optical path separating mirror 1 and a plurality of lenses 2 are integrally formed in a line with equal pitch, and a plurality of lenses corresponding to each lens 2 are formed. An imaging element including a roof mirror array 5 in which roof mirrors 4 are arranged in a row is used.

Problems to be Solved by the Invention Here, the displacement of the image point from the conjugate point when the curved surface of the lens is decentered will be described with reference to FIGS. 10 and 11. First, the imaging element is a roof mirror 6
Since the optical system is a retroreflective optical system in the direction (Y direction) orthogonal to the ridge line direction (Z direction), if the eccentricity of the curved surface of the lens 7 exists along the Y direction, it is shown in FIG. As described above, the image point does not shift from the conjugate point.

Next, when the eccentricity of the curved surface of the lens 7 appears in the Z direction by rotating the lens 7 in the “ZY plane”, the amount of eccentricity is shown in FIGS. 10 (b) and 10 (c). , The image point is displaced from the conjugate point. FIG. 11 is a graph showing the amount of eccentricity of the curved surface of the lens 7 in the Z direction and the amount of positional deviation from the conjugate point of the image point corresponding to the amount of eccentricity. As can be seen from these figures, when the curved surface of the lens 7 is decentered along the ridge line direction of the roof mirror 6, the image point moves away from the conjugate point according to the amount of the decenter, and the resolution is reduced.

Means for Solving the Problems An optical path separating mirror is provided which reflects a light beam from an object surface toward a roof mirror and reflects a light beam which is reflected twice and reflected back by the roof mirror toward an image surface. A pair of lenses created under the same conditions are arranged between a mirror and the roof mirror, and the pair of lenses are arranged symmetrically with an axis orthogonal to both the ridge line and the optical axis of the roof mirror being a rotationally symmetric axis. .

Further, an optical path separating mirror for reflecting the light beam from the object surface toward the roof mirror array and for reflecting the light beam reflected twice and returned from the roof mirror array toward the image plane is provided. A pair of lens arrays prepared under the same conditions were arranged between the roof mirror array and the pair of lens arrays, and the pair of lens arrays were symmetrically arranged with an axis parallel to the array direction of the roof mirror array being a rotationally symmetric axis.

Further, there is provided an optical path separating mirror for reflecting the light beam from the object surface toward the roof mirror and for reflecting the light beam reflected twice and returned from the roof mirror toward the image plane, wherein the optical path separating mirror and the roof mirror are provided. And a pair of lenses created under the same conditions are arranged between the lens and the pair of lenses are symmetrically arranged with an axis orthogonal to both the ridge line and the optical axis of the roof mirror as a rotationally symmetric axis, and the light-collecting element is disposed. And an illumination device for irradiating the object surface with an illumination light beam, and a sensor having a light receiving unit positioned at a conjugate position of an object height at which the light amount distribution on the object surface is maximum.

The light beam separating mirror is directed to the roof mirror, and
The light flux that is reflected by the roof mirror and travels toward the optical path separation mirror is created under the same conditions, and a pair of lenses arranged symmetrically with the axis orthogonal to both the ridge line of the roof mirror and the optical axis being the rotational symmetry axis. Since the light passes through the lens, even if the curved surface of the lens is decentered, the decentering is canceled, and the image point and the conjugate point coincide.

In addition, the light beam traveling from the optical path separating mirror to the roof mirror array and the light beam traveling toward the optical path separating mirror after being reflected by each roof mirror of the roof mirror array are created under the same conditions and are parallel to the array direction of the roof mirror array. When the curved surface of the lens of the lens array is eccentric, the eccentricity is canceled out, and the image point and the conjugate point are shifted. The image points coincide with each other and are combined by the adjacent lenses.

Further, since the displacement of the image point is eliminated, information on the object height where the amount of illumination light on the object plane is maximum is read.

Embodiment An embodiment of the present invention will be described with reference to FIGS. First, an optical path separating mirror 10 is disposed between the object plane 8 and the image plane 9, and a roof mirror 11 is provided to face the optical path separating mirror 10 and on a common optical axis. A pair of lenses 12, 13 are disposed between the optical path separating mirror 10 and the roof mirror 11, and these lenses 12, 13 are injection-molded or injection-compressed using the same mold or mother die. And 2P molding under the same conditions. Accordingly, the eccentricity of a curved surface of a mold or the like is similarly transferred to the lenses 12 and 13. Here, the lenses 12 and 13 are in a direction (Y direction) orthogonal to both the ridge direction (Z direction) of the roof mirror 11 and the optical axis direction (X direction).
Are arranged symmetrically close to each other with the axis of rotation as the axis of rotational symmetry.

In such a configuration, the luminous flux from the object plane 8 is transmitted through the optical path separating mirror 10 and the lenses 12 and 13 to the roof mirror 11.
After being reflected twice by the roof mirror 11, an image is formed on the image plane 9 via the lenses 13 and 12 and the optical path separating mirror 10. Here, even when the curved surfaces of the lenses 12 and 13 are eccentric, the amount of eccentricity is the same in the lenses 12 and 13, and such lenses 12 and 13 are aligned with the ridge line of the roof mirror 11 and the optical axis. Since the axes orthogonal to each other are symmetrically arranged as the rotational symmetry axis, the light flux
When passing through, the eccentricity of the lenses 12 and 13 is cancelled. For this reason, as shown in FIG. 3, the image point always coincides with the conjugate point, the displacement of the imaging position is prevented, and the resolving power is increased.

Next, an embodiment of the invention described in claim 2 will be described with reference to FIGS. An optical path separating mirror 14 is disposed between the object plane 8 and the image plane 9, and includes a plurality of roof mirrors.
A roof mirror array 16 in which 15 are arranged in a row is provided to face the optical path separating mirror 14. Between the optical path separating mirror 14 and the roof mirror array 16 are arranged a pair of lens arrays 18 and 19 in which a plurality of lenses 17 are integrally formed in a line with equal pitch.
Are produced under the same conditions by injection molding, injection compression molding, 2P molding, or the like using the same mold, mother die, or the like. Accordingly, the eccentricity of a curved surface of a mold or the like is similarly transferred to each lens 17 of the lens arrays 18 and 19. Here, the lens arrays 18 and 19 are arranged symmetrically and closely as a rotationally symmetric axis parallel to the array direction (Y direction) of the roof mirror array 16.

In such a configuration, the light beam traveling from the optical path separating mirror 14 to the roof mirror array 16 and the light beam reflected by the roof mirror array 16 and traveling toward the optical path separating mirror 14 are created under the same conditions, and Since the light passes through a pair of lens arrays 18 and 19 arranged symmetrically with the axis parallel to the array direction as the axis of rotational symmetry, even if the curved surface of each lens 17 in the lens arrays 18 and 19 is eccentric, The eccentricity is canceled, and the image point and the conjugate point coincide. Further, the information of the object point is synthesized by the lenses 17 adjacent to each other, but even if each lens 17 is decentered, the image synthesized by those lenses 17 does not cause a positional shift and the resolution is increased. .

Next, an embodiment of the invention will be described with reference to FIG. 1 to 4 are denoted by the same reference numerals, and description thereof will be omitted. FIG. 8 shows an image reading apparatus using the imaging element described in FIGS. 1 to 4. First, a plurality of light emitting elements 21 arranged on a substrate 20 and a light emitting element 21 are shown. An illumination element 23 is provided, which is composed of a light-collecting element 22 for irradiating the object surface 8 with an illumination light beam obtained by condensing light from the light source. Further, a sensor 25 is provided in which a sensor photoemitter 24 as a light receiving unit is located at a conjugate position of the object height where the distribution of the illumination light amount on the object plane 8 is maximized.

In such a configuration, since the displacement of the image point is eliminated, the displacement of the image height with respect to the object height at which the illumination light amount on the object plane 8 is maximum is eliminated, and the object height at which the illumination light amount on the object plane is maximum is eliminated. Information is read reliably, and an image with high light use efficiency is obtained.

According to the present invention, as described above, a pair of lenses created between the optical path separating mirror and the roof mirror under the same conditions are symmetrical with the axis orthogonal to both the ridge line of the roof mirror and the optical axis being the rotationally symmetric axis. , The eccentricity can be canceled even if the curved surface of the lens is eccentric, and therefore, the image point and the conjugate point are always coincident to prevent displacement of the image forming position. Furthermore, a pair of lens arrays created under the same conditions between the optical path separating mirror and the roof mirror lens are symmetrically arranged with the axis parallel to the array direction of the roof mirror array being the rotationally symmetric axis. Even if the curved surface of each lens of the array is decentered, the decentering is canceled, the image point and the conjugate point can always be made coincident, and the image point and the conjugate point are combined by the adjacent lens. An image reading apparatus provided with an illuminating device having a condensing element for irradiating an object surface and a sensor having a light receiving portion located on the image point can improve the resolving power by matching the image points. Has an effect such that information on the object height where the amount of illumination light is maximum can be read.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the invention described in claim 1,
FIG. 2 is a plan view of the lens, FIG. 3 is an explanatory view showing that the image point and the conjugate point coincide even when the curved surface of the lens is decentered, and FIG. FIG. 5 is a graph showing the relationship between the amount of misregistration with the conjugate point, FIG. 5 is a front view showing an embodiment of the second aspect of the present invention, FIG. 6 is a plan view thereof, and FIG. FIG. 8 is a front view showing an embodiment of the invention according to claim 3, FIG. 9 is a perspective view showing a conventional example, and FIG. FIG. 11 is an explanatory diagram showing that an image point and a conjugate point are displaced when the image is centered, and FIG. 11 is a graph showing a relationship between an eccentric amount of the curved surface of the lens and an amount of displacement between the image point and the conjugate point. 8 ... object plane, 9 ... image plane, 10 ... optical path separation mirror, 11
…… Roof mirror, 12,13 …… Lens, 14 …… Optical path separating mirror, 16 …… Roof mirror array, 18,19 …… Lens array, 22… Condenser, 23 …… Illumination device, 24 …… Light-receiving part, 25 ... Sensor

Claims (3)

(57) [Claims] An optical path separating mirror is provided for reflecting a light beam from an object surface toward a roof mirror and for reflecting a light beam reflected twice by the roof mirror and returned toward an image plane. A pair of lenses created under the same conditions are arranged between the roof mirror and the pair of lenses, and the pair of lenses are symmetrically arranged with an axis orthogonal to both the ridge line and the optical axis of the roof mirror being a rotationally symmetric axis. Characteristic imaging element. 2. An optical path separating mirror for reflecting a light beam from an object surface toward a roof mirror array and reflecting a light beam reflected twice and returned from the roof mirror array toward an image surface, wherein the optical path separating mirror is provided. A pair of lens arrays created under the same conditions are arranged between a mirror and the roof mirror array, and the pair of lens arrays are symmetrically arranged with a rotation axis of rotation parallel to an array direction of the roof mirror array. An imaging element, characterized in that: 3. An optical path separating mirror for reflecting a light beam from an object surface toward a roof mirror and for reflecting a light beam reflected twice and returned from the roof mirror toward an image plane. A pair of lenses created under the same conditions are arranged between the roof mirror and the pair of lenses, and the pair of lenses are symmetrically arranged so that an axis orthogonal to both the ridge line of the roof mirror and the optical axis is a rotationally symmetric axis. An illumination device having an optical element and irradiating the object surface with an illumination light beam, and a sensor having a light receiving unit positioned at a conjugate position of an object height at which a light amount distribution on the object surface is maximized, is provided. Image reading device.