JP2756713B2 - Color separation device in color image reading device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a color image reading apparatus or the like that reads color information of a document by color separation and the like, and spectral reflection that selectively reflects a wavelength range of light. The present invention relates to a color separation device in a color image reading device that separates light through a surface for each predetermined wavelength range.

[Related Art] In recent years, reflected light from a document illuminated by a light source is reflected in a predetermined wavelength range (normally, three colors of red: R, green: G, and blue: B).
A color image reading apparatus has been developed and practically used, which reads out the color-separated light of each wavelength region by photoelectric conversion using a light receiving element.

In such a color image reading apparatus, as a method of performing color separation and reading for each predetermined wavelength range, a plurality of light sources for illuminating a document with light in a desired wavelength range are provided, and the document is sequentially illuminated with the plurality of light sources. And white light containing the entire desired wavelength range as the light source, and reading through a filter that transmits only the desired wavelength range in the reflected light path from the document to the light receiving element. Various systems have been considered, such as a system in which color separation is performed by a color separation prism for each predetermined wavelength range and reading is performed.

However, in the former two, the light receiving element may be a line sensor, but the scanning must be performed at least for the number of desired wavelength ranges (three times in the case of R, G, B resolution). There is a problem that it takes a long time to read the image, and in the latter case, the reading scan is performed only once, but the number of light receiving elements (line sensors) in a desired wavelength range is required.
Have to be separately arranged at optically equivalent positions, and there is a problem that their installation requires extremely high accuracy.

In view of this, the present applicant has firstly provided a first spectral reflection surface group in which a plurality of spectral reflection surfaces having different reflection wavelength ranges are stacked and arranged at predetermined intervals in an optical path from a document to a light receiving element. It is proposed to interpose two reflecting surface groups, a second reflecting surface group in which the stacking order of the group and the spectral reflecting surface is reversed, and to set the optical path length for each spectral wavelength region equal. That is, for example, as shown in FIG. 5, one of the reflecting surface groups (the first spectral mirror 10) selectively reflects the respective wavelength ranges of the R component, the G component, and the B component in order from the side where the light beam enters. Dichroic mirrors 10R, 10G,
10B are laminated at a predetermined interval, and the other reflecting surface group (second spectral mirror 20) is arranged in the reverse order (B component, G component).
Component and R component in that order).
B, 20G, and 20R are laminated at predetermined intervals, and the imaging lens 4
The light flux from the light is reflected and bent in the order of the first spectral mirror 10 and the second spectral mirror 20, so that the light is separated into three colors of R, G, and B, and the respective color components are imaged on the same plane. Three rows of line sensors 5R and 5 for reading R, G and B respectively at the imaging position
The sensor 5 in which G and 5B are arranged in parallel on one chip is arranged and configured. Here, the distance between each dichroic mirror of the first spectral mirror 10 and the second spectral mirror 20 is
This is derived based on the relationship between the bending angle of the light beam by each of the spectral mirrors 10 and 20 and the line sensor interval of each color component. In the figure, reference numeral 7 denotes a document placed on the cover glass 2;
Reference numeral 3 denotes a halogen lamp as a light source, and reference numeral 6 denotes a dustproof glass of the sensor 5.

According to this, the reading scan only needs to be performed once, and R,
By configuring the G and B line sensors 5R, 5G, and 5B in parallel on a single chip, it is possible to reduce the mutual pixel pitch error,
Further, since the number of the sensors 5 is one, the installation is easy.

As an example, the spectroscopic mirrors 10 and 20 are, as shown in an enlarged view of the first spectroscopic mirror 10 in FIG. 6, on a base glass 12 having a dichroic coat 10B reflecting the B component on its surface, and R components on the upper and lower surfaces. And a top glass 15 of a predetermined thickness on which a dichroic coat 10R, 10G that reflects the G component is applied.
Optical adhesives 14, 14 via spacer glass 13 of predetermined thickness
It is configured by bonding. In this configuration, the top glass 15
Forms the distance between the dichroic coat 10R and the dichroic coat 10G, and the distance between the dichroic coat 10G and the dichroic coat 10B is the sum of the spacer glass 13 and the adhesive layers 14, 14 on both surfaces thereof.

[Problems to be Solved by the Invention] However, in the configuration of the spectral mirror as described above, the spectral mirror and the sensor are configured as designed, and they must be accurately arranged. However, some errors inevitably occur during actual manufacturing, and the accumulation of such errors of individual products causes the original, R, G, and B line sensors to shift the position of the original to be read. As a result, there is a problem that manufacturing is difficult because extremely high accuracy is required for the spectral mirror. In other words, it is impossible to make adjustments to read the same position of the original in the R, G, and B wavelength ranges while actually reading the test chart, which is a major obstacle to actual commercialization. Had become.

[Object of the Invention] The present invention has been made in view of the above-described background, and provides a color separation apparatus in a color image reading apparatus capable of variably adjusting an optical path of a color separated wavelength range. With that purpose.

[Means for Solving the Problems] For this reason, a color separation device in a color image reading apparatus according to the present invention uses at least one spectral reflection surface of one of two sets of spectral reflection surfaces. It can be moved with respect to other spectral reflection surfaces and its interval can be adjusted,
The spectral reflection surface in a wavelength range different from the wavelength range in which the other spectral reflection surface group can be adjusted is configured to be movable with respect to another spectral reflection surface so that the distance between them can be adjusted.

In the optical path, a prism that reflects and bends the optical path on two surfaces is interposed, and a spectral reflection surface that selectively reflects a specific wavelength region is formed on each of the reflection surfaces of the prism to form the spectral reflection surface. A group is formed, and a spectral reflection member having a spectral reflection surface that reflects a wavelength range different from the spectral reflection surface of the prism is disposed so as to be movable and opposed to the spectral reflection surface of the prism. A spectral reflection member having a spectral reflection surface that reflects a different wavelength range is stacked and arranged, and a spectral reflection member having a spectral reflection surface that reflects a different wavelength region from the spectral reflection member is disposed so as to be movable and opposed to the spectral reflection member. It is configured.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of an image reading apparatus to which an embodiment of a color separation apparatus in a color image reading apparatus according to the present invention is applied.

The illustrated image reading apparatus includes an original 7 placed on a cover glass 2 with its surface to be read facing downward (the upper left side in the figure).
Of the original 7 is illuminated by a halogen lamp 3 which is a light source having a light emission characteristic over substantially the entire visible wavelength range.
The reflected light from the surface to be read is imaged on the light receiving surface of the sensor 5 by the imaging lens 4, and the image information is photoelectrically converted and read by the sensor 5. Red (R) the image light in the image light path,
A color separation device 1 that separates colors into three colors of green (G) and blue (B) is interposed. The image light from the imaging lens 4 is bent by the color separation device 1 in the optical path at a right angle to the lower side in FIG.
An image is formed on the light receiving surface, and therefore, the dustproof glass 6 and the sensor 5 are arranged on the side (lower side in the figure) of the color separation device 1.

The halogen lamp 3, the imaging lens 4, the sensor 5, the dust-proof glass 6, and the color separation device 1 are integrally formed and extend in a direction perpendicular to the plane of the drawing so as to correspond to the width of the document 7. The scanning target surface of the original 7 is scanned in the longitudinal direction by a vertical drive in the drawing by a driving mechanism (not shown), and the entire reading target surface is read by a sensor 5 described later as a line sensor. It is. The sensor 5 has three one-dimensional pixel rows (line sensors 5R, 5G, 5B)
Are arranged in parallel on a single chip as a predetermined spacing, and red (R) and green (G) color-separated by a color separation device 1 described later on each line sensor 5R, 5G, 5B.
And blue (B) light images are formed, and image information in each wavelength range is individually read.

The color separation device 1 includes a pentaprism 30, a first spectral mirror group 10 as a first spectral reflection surface group, and a second spectral mirror group 20 as a second spectral reflection surface group.

The pentaprism 30 reflects a light beam incident from one of two orthogonal surfaces (incident surface 33) at right angles to the incident surface 33 on two reflecting surfaces (first reflecting surface 31 and second reflecting surface 32). ,
It is formed so as to exit from another orthogonal surface (the exit surface 34) at right angles to the exit surface 34. Image light from the imaging lens 4 enters from the entrance surface 33, and exits from the exit surface 34. It is arranged to emit light toward the sensor 5.

The first reflecting surface 31 of the pentaprism 30 is provided with a dichroic coat 10R for reflecting the R component, and the first spectral mirror 11 is disposed adjacent to the first spectral mirror group 10, thereby forming the first spectral mirror group 10. A dichroic coat 20B for reflecting the B component is applied to the surface 32, and the second spectral mirror 21 is disposed adjacent to the surface 32 to form the second spectral mirror group 20.

The first spectral mirror 11 is provided with a dichroic coat 10B for reflecting the B component on the surface of the base glass 12, and a dichroic coat 10B for reflecting the G component on the surface.
The spacer glass 13 to which G is applied is bonded and fixed via an adhesive layer 14. Dichroic coat 10B
And the dichroic coat 10G are set in parallel at a predetermined interval: H.

The first spectral mirror 11 is a dichroic coat.
10G is arranged in parallel with the dichroic coat 10R (that is, the first reflecting surface 31), and is movable in a direction indicated by an arrow in the drawing while maintaining the parallel state by an adjustment mechanism (not shown). The interval D is variably adjustable.

The second spectral mirror 21 has a dichroic coat 20R for reflecting the R component on the surface of the base glass 22, and a dichroic coat for reflecting the G component on the surface.
The spacer glass 23 to which 20G has been applied is bonded and fixed via an adhesive layer 24. The dichroic coat 20R and the dichroic coat 20G are set in parallel at a predetermined interval: h.

The second spectral mirror 21 is a dichroic coat.
20G is arranged in parallel with the dichroic coat 20B (that is, the second reflecting surface 32), and is movable in the direction indicated by the arrow in the drawing while maintaining the parallel state by an adjustment mechanism (not shown). The interval d is variably adjustable.

Here, in the present embodiment, the optical path bending angles of the first and second spectral mirror groups 10 and 20 are set to be equal, and the intervals H, D, h, and d between the dichroic coats are also basically equal. Are set equal.

Thus, in the color separation device 1 configured as described above, the image light that enters the pentaprism 30 from the entrance surface 33 via the imaging lens 4 is separated by the first spectral mirror group 10 for each of the RGB components. The light is spectrally reflected, and further reflected by the second spectral mirror group 20 for each of the RGB components.

That is, in the first spectral mirror group 10, only the R component is reflected by the dichroic coat 10R of the first reflecting surface 31, and then the dichroic coat 10 of the first spectral mirror 11 separated by D:
G component is reflected by G, and dichroic coat 10B
, The remaining B component is reflected, and color separation is performed for each of the RGB components.

The second spectral mirror group 20 reflects each of the RGB components separated by the first spectral mirror group 10 for each component, but dichroic coats 20B and 20B that selectively reflect each spectral component.
The arrangement of G, 20R is opposite to that of the first spectral mirror group 10, and the incident angles to the two spectral mirror groups 10, 20 and the intervals H, D, h, d between the dichroic coats are set to be equal. From, R
The optical path length for each component of GB is equal. At this time, the interval between the respective optical paths of the RGB components becomes a predetermined interval due to the reflection bending by the second spectral mirror group 20, and the image lights of the RGB components are arranged on one chip at an interval corresponding to this interval. The image is formed and read on the light receiving surfaces of the line sensors 5R, 5G, and 5B, respectively.

Here, the dichroic coat of the first spectral mirror group 10
Distance between 10B and dichroic coat 10G: H, and distance between dichroic coat 20R and dichroic coat 20G of second spectral mirror group 20: h If the position where the image is formed on the original is shifted (when the image at the same position of the document is not formed on the light receiving surfaces of the line sensors 5R, 5G and 5B of the RGB components), the first spectral mirror group 10 By moving and adjusting the first spectral mirror 11 or the second spectral mirror 21 of the second spectral mirror group 20, the image at the same position of the document can be converted to the line sensor 5 of each component of RGB.
It can be adjusted to form an image on the light receiving surfaces of R, 5G, and 5B.

In this configuration, a pentaprism that can be formed with high precision
By applying the dichroic coats 10R and 20B to the first reflecting surface 31 and the second reflecting surface 32 of 30 and configuring the first spectral mirror 11 and the second spectral mirror group 20, especially the surface accuracy of the dichroic coats 10R and 20B is improved. High accuracy,
In addition, since only one glass layer (spacer glass 13, 23) adheres to the surface of the base glass 12, 22 of each spectral mirror 11, 21, the dichroic coats 10 R, 20 G formed on the surface of the spectral mirror 11, 21 can be used. Accuracy can be easily maintained.
That is, it is easy to maintain a high-accuracy configuration and its accuracy.

FIG. 4 shows a second embodiment of the present invention.
In the first embodiment described above, dichroic coats 10G and 20G for reflecting the G component provided on the spectral mirror 11 and the second spectral mirror 21 are provided on the pentaprism 30 side.

That is, on the dichroic coat 10R of the first reflection surface 31 of the pentaprism 30, the spacer glass 13 on the surface of which the dichroic coat 10G reflecting the G component is adhered and fixed via the adhesive layer 14, A spacer glass 23 having a dichroic coat 20G reflecting the G component on the surface thereof on the dichroic coat 20B of the two reflecting surfaces 32.
Are bonded and fixed, and the first spectral mirror 11 and the second spectral mirror 21 are fixed.
Are provided on the surfaces of the base glasses 12 and 22, respectively, with a dichroic coat 10B for reflecting the B component and a dichroic coat 20R for reflecting the R component.

The first spectral mirror 11 and the second spectral mirror 21 have their dichroic coats 10B and 20R parallel to the dichroic coat 10G and the dichroic coat 20G on the pentaprism 30 side, as in the first embodiment. The mechanism is capable of moving away from and approaching while maintaining the parallel state by a mechanism, and the intervals H and h are variably adjustable.

According to this configuration also, by moving and adjusting the first spectral mirror 11 and the second spectral mirror 21, an image at the same position of the document is formed on the light receiving surfaces of the line sensors 5R, 5G, and 5B of the RGB components. Can be adjusted. In this configuration, since the positions of the dichroic coat 10G and the dichroic coat 20G are invariable, the reading position of the B component is determined by the first spectral mirror 11 based on the reading position of the G component, The reading position of the R component can be adjusted independently, and the adjustment operation can be easily performed.

It is needless to say that the arrangement order of the dichroic coats in the above embodiment is merely an example and can be changed as appropriate. In addition, although a pentaprism is used as the prism, any prism that can use two reflecting surfaces, such as a parallel prism, can be applied.

[Effects of the Invention] As described above, according to the color separation device in the color image reading device according to the present invention, it is possible to adjust the optical path in the wavelength region where the color separation is performed. Can be eased, manufacturing can be facilitated and assembling workability can be improved, which can contribute to cost reduction.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image reading apparatus to which one embodiment of a color separation apparatus in a color image reading apparatus according to the present invention is applied;
2 is a partially enlarged view of the first spectral reflection surface group, FIG. 3 is a partially enlarged view of the second spectral reflection surface group, FIG. 4 is a schematic configuration diagram of another embodiment, and FIG. And FIG. 6 is an enlarged view of a spectral mirror of the color image reading apparatus using the color separation apparatus. DESCRIPTION OF SYMBOLS 1 ... Color separation apparatus 10 ... 1st spectral mirror group (1st spectral reflection surface group) 11 ... 1st spectral mirror (spectral reflection member) 20 ... 2nd spectral mirror group (2nd spectral reflection surface group) 21: Second spectral mirror (spectral reflecting member) 30: Penta prism (prism) 10R, 10G, 10B, 20R, 20G, 20B: dichroic coating (spectral reflecting surface)

Claims (4)

(57) [Claims] 1. A color separation device for separating light into predetermined wavelength ranges through a spectral reflection member that selectively reflects a wavelength range of light, wherein a plurality of spectral reflections having different reflection wavelength ranges are provided in an optical path. A first spectral reflection surface group in which surfaces are stacked at a predetermined interval, and a second spectral reflection surface group in which the stacking order of the first spectral reflection surface group and the spectral reflection surface is reversed are interposed. And, when the optical path length for each spectral wavelength region is set to be equal, at least one spectral reflection surface of one of the two sets of spectral reflection surfaces is set with respect to another spectral reflection surface. The interval can be adjusted by making it movable so that the spectral reflection surface of the other spectral reflection surface group in a wavelength region different from the adjustable wavelength region can be moved with respect to another spectral reflection surface. A color separation device in a color image reading device, characterized in that: . And a prism that reflects and bends the optical path on two sides in the optical path, and forms a spectral reflective surface for selectively reflecting a specific wavelength range on each of the reflective surfaces of the prism. 3. A color separation device according to claim 1, wherein said plurality of reflection surfaces are formed. 3. A spectral reflection member having a spectral reflection surface which faces a spectral reflection surface of the prism and reflects a wavelength range different from the spectral reflection surface, and is arranged so as to be movable. 2) A color separation device in the color image reading device according to the above. 4. A spectral reflection member having a spectral reflection surface that reflects a wavelength range different from that of the prism is laminated on the spectral reflection surface of the prism, and faces the spectral reflection member to reflect a wavelength range different from these. 3. A color separation apparatus according to claim 2, wherein a spectral reflection member having a spectral reflection surface is arranged so as to be movable.