JPS63219264A - Parallel-plate color separation image reader - Google Patents

Abstract

PURPOSE:To prevent the reading quality of an image from being lowered due to the deviation of alignment, by integrating a spectroscope and a linear image sensor, and attaching a common conjugate position on the image-forming position of each color component light. CONSTITUTION:No deviation of alignment between the spectroscope 20 and each of the linear image sensors 42R, 42G and 42B is generated since the spectroscope 20 and a multiple string image sensor 40 are integrated. Since the virtual image-forming position P of a beam of light (pphi) is set as the common conjugate position for the image-forming position of each of the color component light LR, LG, and LB by the symmetric property of reflection at each of reflecting areas R1-R6, no deviation of reading between each of the linear image sensors 42R, 42G, and 42B is generated even when an image image-formed on the conjugate position P is deviated.

Description

Detailed Description of the Invention (Industrial Application Field) This invention separates light from an original image into a plurality of color component lights, and reads each of the plurality of color component lights with a plurality of linear image sensors. The present invention relates to a reading device, and particularly to a technique for preventing the effects of misalignment of each member.

(Prior Art and its Problems) In a color scanner for plate making, etc., it is necessary to read an image of an original in scanning line sequence for each color component. For this reason,
In such a system, light from the original image is separated into three color components: red (R color), blue (B color), and green (G color), and each is converted into an image using a separate linear image sensor for photoelectric conversion. A reading device is used.

FIG. 10 is a layout diagram showing a conventional example of such an image reading device. This image reading device 2 is equipped with an imaging lens system 3, and at each time point, light 1- from the reading line RD along the main scanning direction X of the original image 1 passes through the imaging lens system 3 to read the image. It is taken into bag j6"2.

This light 1- is separated into three directions by the first and second half mirrors 4a and 4b, and becomes three imaging light beams lRB''G.

, I ItB, 16, R color, B color,
Filters 5R and 58°5G for extracting each color component of G color are provided. Furthermore, each filter 5R.

Behind 5B and 5G is a linear image sensor 6R.

6B and 6G are provided respectively. These linear image sensors 6R, 6B, and 6G include a dimensional array of light-receiving cells, and a filter 5R.

The intensity of the R color component light, B color component light, and G color component light provided through 5B and 5G is read respectively.

Further, the image reading device 2 and the original image 1 move relative to each other at a speed V along the sub-scanning direction Y. For this reason, each linear image sensor 6R, 6B, 6G during a predetermined time t.
The band-shaped area 5 (=V·Δt) where light is received becomes one scanning line. Then, by repeating image reading for each scanning line as described above and continuing the relative movement of the original 1 and the image reading device 2, the entire image of the original 1 is sequentially scanned and read.

By the way, in such an image reading device 2, linear image sensors 6R, 6B, 6G and half mirrors 4a, 45
When a deviation occurs in the alignment of each linear image sensor 6R, 6B.

A shift occurs in the position of each reading line read at 6G. This situation is schematically shown in FIG. 11, in which each linear image sensor 6R, 6B should originally read image information that is applied to the same reading line.

6G takes in image information from mutually different reading lines RR, RB, and RG. As a result, if the image information of the original image 1 read by each of the linear image sensors 6R, 6B, and 6G is combined to reproduce an image, there is a problem in that image quality deteriorates, such as color shift.

Such misalignment can occur during device assembly, but it can also occur after assembly due to expansion due to temperature changes or mechanical deformation during transportation. Therefore, careful assembly adjustment is required. Therefore, it is difficult to solve this problem.Furthermore, since the reading position of the original image 1 itself is shifted, a faithfully reproduced image cannot be obtained even if signal processing such as color masking calculation is performed.

Such problems typically appear in devices that require particularly high-precision image reading, such as color scanners for plate making, but they also occur in devices that read color images, such as color facsimiles and color copiers. This is a general problem.

(Object of the Invention) The present invention is intended to overcome the above-mentioned problems in the prior art, and provides an image reading system in which the quality of image reading does not deteriorate due to misalignment of each component. The purpose is to

(Means for Achieving the Object) In order to achieve the above-mentioned object, the present invention separates light from an original image into a plurality of color component lights, and separates the light from an original image into a plurality of color component lights using a plurality of linear image sensors. Targeted at image reading devices that read scanning lines sequentially, the light from the original image received through a predetermined imaging optical system is separated into a plurality of color component lights, and a plurality of color component lights having a common conjugate position are separated. a spectrometer equipped with a plurality of parallel plane transparent roots each guiding to an image forming position; and (2) a plurality of linear images integrated with the spectrometer to respectively receive the plurality of color component lights at the plurality of light receiving positions. A sensor is provided.

(Embodiment) A. Configuration of the first embodiment FIG. 1 is a perspective layout diagram of the first embodiment of the present invention. The configuration of the image reading device 10 shown in FIG. 1 differs from the conventional device 2 shown in FIG. 10 in the following points.

First, in the apparatus 10 of the first embodiment, light from the image of the original image 1 is applied to the spectroscopic detection device 11 via the imaging lens system 3 as an imaging optical system. This spectroscopic detection device fi11 is formed by integrating a spectroscope 20 and a multi-row image sensor 40, which will be described later, and its detailed arrangement is shown in FIG.

In FIG. 2, the spectrometer 20 has a uniform thickness d.
It has a structure in which transparent glass plates 21a to 2IC are sequentially stacked and bonded together, and a multi-row image sensor 40 is fixed at right angles to the side surface thereof. In addition, an air layer or the like is not formed at the overlapping boundary surfaces between these glass plates 21a to 21C, and these boundary surfaces are, for example, θ- with respect to the optical axis A of the imaging lens system 3. The arrangement is made so as to form an angle of 45°. In this example (and other examples described later), transparent glass plates such as those described above are used, but instead of these, transparent (translucent) parallel plane plates such as plastic or crystal may be used. You can also use This is common to each embodiment.

Furthermore, the first. First surfaces 22a, 22b, 22c and second surfaces 23a of the second and third glass plates, respectively.
, 23b, 23c are provided with the following reflection and transmission characteristics. however,
A light flux φ in the figure is a light flux that enters from above the reading line RD of the original image 1 and travels toward the position P.

(a) First, as shown in FIG. 3(a), an anti-reflection coating is applied to the first surface 22a of the first glass plate 21a, and then an anti-reflection coating is applied to the end of the range where the light beam φ is incident. The area R1 from the vicinity to the multi-row image sensor 40 is designed to be a total reflection surface (indicated by the symbol "co" in FIG. 3) for the inside. Further, a region R2 of the second surface 23a of the first glass plate 21a including the range where the light beam φ enters and its vicinity is a dichroic mirror surface CR that reflects only the R color light.

Also, from the end of this region R2, the multi-row image sensor 40
The region R3 up to is a total reflection surface C6.

(b) First surface 22b of second glass plate 21b
A region R4 corresponding to the region R3 is a total reflection surface C8, and a region R5 of the second surface 23b that includes the incident range of the luminous flux φ is a dichroic mirror surface CG that reflects only 0-color light. (See Figure 3(b)).

(c) The first surface 22c of the third glass plate 21c is not particularly coated, but the second surface 23C
Almost the entire surface (region 1ii1iR6) is a total reflection surface co (see FIG. 3(C)).

By applying the above-mentioned coating, the R envelope component light LR of the luminous flux φ incident on the spectroscope 20 in FIG. By repeating the reflection, an image is formed at the position PR (see FIG. 4). Similarly, the G envelope component light LG is separated in the region R5, reflected within the second glass plate 21b, and is imaged at the position PG. Furthermore, the remaining B envelope component light LB is totally reflected in the region R6 and then forms an image at the position PB.

Next, the multi-row image sensor 40 will be explained. As shown in FIG. 5, this multi-row image sensor 40 has three linear image sensors 42R, 42G, and 42B each including a one-dimensional array of light receiving cells 41 arranged in parallel on the same plane. It is formed integrally. These linear image sensors 42R, 42G, and 42B are for each pixel to receive R-hull component light, G color component light, and B color component light for one line in the main scanning direction. In this embodiment, these linear image sensors 42R, 42G, and 42B are formed on the same substrate SB, and an R color filter 43R is provided on the surface of each cell row.
, G color filter 43G and eight color filter 43B are fixed. In addition, each linear image sensor 42R,'
The distance between the centers of 1.2G and 42B is the same as the thickness d of the glass plates 21a to 21G forming the spectrometer 20.

As shown in FIG. 2, this multi-row image sensor 40 is
The spectrometer 2
It is fixed and integrated.

8. Operation of one embodiment of 71- Next, the operation of the first embodiment will be explained. With the above-described configuration, the luminous flux φ is composed of the respective color component lights LR and LG.

Separated into 1B, linear image sensor 42R942G
, 42B, and is received by these.

However, the spectrometer 20 and the multi-row image sensor 40 (therefore, each linear image sensor 42R, 42G, 42
B> are integrated with each other. For this reason, the spectrometer 20
There is no misalignment between the linear image sensors 42R, 42G, and 42B, and it is possible to prevent image reading quality from deteriorating due to such misalignment.

In addition, the imaging positions PR and P of each color component light LR, LG, and LB are
G and PB make the virtual imaging position P of the light beam φ a common conjugate position due to the symmetry of reflection in each of the reflection regions R1 to R6. This conjugate position P is conjugate point -1 when considered as one point on the image, and becomes a "conjugate line" when considered as one line. In other words, the optical path LO toward the conjugate position
is a common conjugate optical path for each of the component lights LR, 1G, and LB.

Therefore, it is equivalent to all of the linear image sensors +J42R, 42G, and 42B arranged at the imaging positions PR, PG, and PB receiving light at the military service position @1]. Therefore, even if a deviation occurs and the image formed at the conjugate position ff1P (that is, the position of the reading line RD) shifts, the influence of this deviation is common to each linear image sensor 42R, 42G, 42B,
No reading deviation occurs between these pairs of beans. As a result, the property that the images detected by each of the linear image sensors 42R, 42G, and 42B are common is maintained even if misalignment occurs.

For the above reasons, this apparatus is an apparatus in which the quality of the read image does not deteriorate due to misalignment. Further, since the spectrometer 20 and each of the linear image sensors 42R, 4, 2G, and 4.2B are integrated with each other, the size of the device is also compact, and the optical system has a relatively simple structure.

C9 2nd. Third. Fourth and Fifth Embodiments Partial views of the second to fifth embodiments of the present invention are shown in FIGS. 6, 7, 8 and 9, respectively.

These figures correspond to FIG. 2 which follows the first embodiment, and the remaining configuration is the same as that of the first embodiment. Only parts will be explained.

First, in the second embodiment shown in FIG.
1a is provided with a cut surface 130a of, for example, 0-45°. Then, the optical axis A with respect to this cut surface 130a
The direction of incidence of the light beam φ is determined so that the angle is vertical. This makes it possible to prevent refraction of the light incident on the spectroscope 11 along the optical axis A, and the respective color component lights LR to the light receiving surfaces of the linear image sensors 42R142G and 4'2B.

The incident angles of LG and LB are closer to perpendicular than those in FIG. 2. Also, this cut angle θ is 45°
You can also make it louder. In this case, 45°
The angle θ' in the figure becomes smaller than 45° by the amount that is made larger than 45°, and the incident angle of each color component light to the light receiving surface 12 becomes closer to perpendicular.

On the other hand, in the first embodiment (FIG. 2), even if the angle θ is small, the angle α between the light entering the glass plate 21a and the linear image sensors 42R, 42G, and 42B is approximately 42 It cannot be more than °. This is because the refractive index of air and glass are quite different, so if θkon0
This is because even if the beam is incident horizontally (horizontal incidence), the angle α is approximately 42° due to refraction at the first surface 22a of the glass plate 21a. In the example of FIG. 2, the angle α is approximately 30° for θ-45°.

Thus, the second embodiment shown in FIG. 6 has better properties than the first embodiment shown in FIG.

Further, in the third embodiment shown in FIG. 7, an entrance cut surface 130b is provided on the second glass plate 121b. Of the respective regions R10 and R11 of the first and second surfaces 22b and 23b of this glass plate 121b, the second surface 23
The entire area R11 of b is coated to reflect R and G colors. In addition, the first surface 22
A coating that reflects the G color is applied to the region R10 of a. However, it is not necessary to particularly coat the second surface 23c of the third glass plate 121C. This is because the light that enters the second surface 23c from inside the glass is totally reflected and goes toward the linear image sensor 42B (in this sense, the coating in the region R6 in FIG. 6 can be omitted).

Therefore, each color component light LR, LG, LB passes through the optical path shown in FIG.
Images are formed on the light receiving cell surfaces of G and 42B, respectively. Also,
These imaging positions ff1PR, PG.

P B is the common conjugate position t? It has ffP.

In the fourth embodiment shown in FIG.
C is provided on the third glass plate 121C. Also, the second
The first and second surfaces 22b, 23b of the glass plate 121b
Of these, the entire surface area R21 of the second surface 23b is provided with a pattern that violates the color B. Further, the entire area R20 of the first surface 22a reflects the G color]-
Apply tinging.

The fifth embodiment shown in FIG. 9 is a modification of the first embodiment (FIG. 2). That is, a prism 140 is attached to the first glass plate 21a, and the prism 141 is used as the incident surface of the light beam φ.

In this case, the optical axis A of the light beam φ is perpendicular to the incident surface 141. The optical path after entering the prism 140 is the same as that described in the first embodiment (FIG. 2). Note that the angle β between the surface 141 of the prism 140 and the first surface 22a of the first glass plate 21a is 45
However, the angle β can be made larger than 45° and the angle of incidence θ' can be made smaller than 45°. Then, as in the case where θ is made larger than 45° in FIGS.
Light can be incident on the light receiving surfaces of 2R, 4, 2G, and 42B at an angle closer to perpendicular.

D. Modification ■In the above two embodiments, the linear image sensors 42R, 42G, and 42B are integrated to form a multi-row linear image sensor υ40. In this way, there is virtually no misalignment between the linear image sensors 42R, 42G, and 42B, and the effect is further improved.

However, when each linear image sensor 42R, 42G, 42B is fixed to a spectrometer 20 as shown in FIG.
Since the mutual positional relationship of R, 42G, and 42B is fixed,
It is not necessarily necessary to form a multi-row image sensor.

(2) This invention is applicable not only to color scanners for plate making, but also to image reading devices used in color facsimile machines, color copying machines, and the like.

(Effects of the Invention) As explained above, according to the present invention, the spectroscope and the linear image sensor are integrated, and the image formation positions of each color component light are roughly arranged to have a common conjugate position. Accordingly, it is possible to obtain an image reading device in which image reading quality does not deteriorate due to misalignment.

[Brief explanation of drawings]

FIG. 1 is a perspective layout diagram of a first embodiment of the present invention, FIG. 2 is a partial diagram of the first embodiment, and FIG. 3 is a coating distribution diagram of a glass plate constituting a spectrometer. FIG. 4 is a diagram showing the imaging position and conjugate position of each color component light, FIG. 5 is an explanatory diagram of a multi-row image sensor, and FIGS. Second invention. Third. Partial views of the fourth and fifth embodiments, FIG. 10, and FIG. 11 are explanatory diagrams of a conventional image reading device. 1... Original image, 3... Imaging lens system (imaging optical system)
, 11... Spectral detection device, 20... Spectrometer, 21a to 21c, 121a to 121c... Glass plate, 130a to 130C... Incident cut surface, 40... Multi-row image sensor, 42R, 42G, 42B... Linear image sensor, LR, LG, LB... Color component light,

Claims (2)

[Claims] (1) Separate the light from the original image into multiple color component lights,
An image reading device that sequentially reads the plurality of color component lights by a plurality of linear image sensors, each of which sequentially reads the plurality of color component lights, the light from the original image given through a predetermined imaging optical system into the plurality of color component lights. a spectroscope including a plurality of parallel plane transparent plates which are separated and guided to a plurality of imaging positions having a common conjugate position; A parallel plate color separation image reading device comprising a plurality of linear image sensors each receiving light at a light receiving position. (2) The parallel plate color separation image reading device according to claim 1, wherein the plurality of linear image sensors are arranged parallel to each other on the same plane and integrated to form a multi-row image sensor. .