JPS6362941B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a contact image sensor that focuses an image on a document surface at a 1:1 size on a photoelectric conversion section and reads it, and in particular, The present invention relates to a contact image sensor configured by arranging a plurality of photoelectric conversion element arrays in two rows.

[Technical background of the invention and its problems] In general, when reading an image on a document surface in a facsimile machine, etc., the image on the document surface is reduced by a lens system, and the image is, for example, about 2048 bits long and 32 to 30 bits long.
The structure is such that the image is focused on a photoelectric conversion unit made of a CCD chip approximately 40 mm long. With such an image sensor, it is necessary to reduce the width of an A4-sized document, for example, from 200 mm to 32 mm, so the optical path length from the document surface to the photoelectric conversion unit becomes long, making it difficult to miniaturize the device.

Therefore, we use a photoelectric conversion unit whose array length is equal to the width of the original, and convert the image on the original surface to the same magnification, that is, 1:1.
The development of a so-called contact image sensor that forms an image on a photoelectric conversion unit with a size of . In such a close-contact image sensor, the optical path length from the document surface to the photoelectric conversion unit can be significantly reduced to more than 10 mm because a 1-magnification imaging system such as a rod lens array can be used as the imaging system. be shortened. In this case, since it is currently difficult to realize the long photoelectric conversion section required in a contact image sensor using a single CCD chip, etc., there is a method of arranging multiple photoelectric conversion element arrays made of CCD chips, etc. Be taken.

By the way, since photoelectric conversion element arrays such as CCD chips have non-photosensitive areas on both ends of the array, if they are arranged in a straight line, the image in the area between the chips becomes unreadable. In order to solve this problem, it has been considered to arrange a plurality of photoelectric conversion element arrays 1a, 1b, . . . in two rows in a so-called staggered arrangement as shown in FIG. That is, odd numbered arrays 1a, 1c,...
... are arranged on the first line L1, and the even numbered arrays 1b, 1d, ...... are arranged on the second line parallel to the first line L1.
They are arranged on the line L2.

FIG. 2 shows the configuration and arrangement of this contact-type image sensor including the imaging system, in which two rows of photoelectric conversion element arrays 1 of photoelectric conversion units arranged on a substrate 2 are shown.
Rod lens arrays 3a, 3b are provided opposite to a, 1c, . . . and 1b, 1d, .
The image is formed on the photoelectric conversion section by a and 3b. Here, the rod lens arrays 3a and 3b are arranged obliquely to the document surface 4 at an angle of θ so that their respective optical axes intersect at one point on the document surface 4, but due to their thickness, Since θ needs to be larger than a certain degree, the distance 2·d between the rows of the photoelectric conversion sections cannot be made very small, which has been an obstacle to miniaturizing the device.

Furthermore, since the optical axes of the rod lens arrays 3a and 3b are also oblique to the light receiving surface of the photoelectric conversion section,
The depth of focus will be reduced to cosθ, and the alignment margin will also be reduced accordingly. Therefore, it is very difficult to align the photoelectric conversion section and the rod lens arrays 3a, 3b, and there are also problems in terms of manufacturability.

[Object of the Invention] The object of the invention is to provide an imaging system that forms an image on a document surface at the same magnification on a photoelectric conversion section that is configured by arranging a plurality of photoelectric conversion element arrays in two rows. It is an object of the present invention to provide a contact type image sensor in which the optical axes of two sets of lens systems used can be made parallel, and the size can be reduced and the productivity can be improved.

[Summary of the Invention] A contact image sensor according to the present invention includes, in an imaging system from an original surface to a photoelectric conversion unit, a first mirror that divides light from the original surface into four parts: light from the original surface, reflected light, and transmitted light; A second mirror that reflects the light reflected by the first mirror, a third mirror that reflects the light that has passed through the first mirror, and a second mirror that reflects the light that has been reflected by the third mirror. A fourth mirror is provided that reflects the light reflected by the mirror in the same direction as the light reflected by the mirror, and the light reflected by the second mirror is reflected by a fourth mirror provided facing the first row of photoelectric conversion element arrays of the photoelectric conversion unit. 1 lens system, and the light reflected by the fourth mirror is made to enter the second lens system provided facing the second row of photoelectric conversion element arrays of the photoelectric conversion section. It is a feature.

[Effects of the Invention] According to the present invention, since the optical axes of the first and second lens systems can be made parallel, the space factor can be improved and the distance between the rows of photoelectric conversion units can be shortened. , the whole can be made more compact.

Further, since the optical axis of the lens system can be made perpendicular to the light receiving surface of the photoelectric conversion section and its depth of focus can be maximized, the alignment margin of the lens system becomes larger and adjustment becomes easier. Therefore, manufacturability is improved and it is possible to reduce the price.

[Embodiment of the Invention] FIG. 3 shows an embodiment of the present invention, in which the photoelectric conversion section is composed of a plurality of photoelectric conversion element arrays made of CCD chips, etc., as explained in FIGS. 1 and 2. 1a, 1b, . Then, the images on the document surface 4 are
The fourth mirrors 11 to 14 and the first and second lens systems (for example, rod lens arrays) 3a and 3b form the first and second rows of photoelectric conversion element arrays 1a, 1c, . . . of the photoelectric conversion unit. ...and 1b, 1d,
...The image is now focused upwards.

That is, light corresponding to image information from the document surface 4 is first guided to the first mirror 11, which is a semi-transparent mirror, and
The light is divided into two parts: reflected light and transmitted light. Of these lights, the reflected light is guided to the second mirror 12, where it is totally reflected and enters one end of the first lens system 3a. On the other hand, the light transmitted through the first mirror 11 is totally reflected by the third mirror 13 and then guided to the fourth mirror 14, where it is totally reflected and enters one end of the second lens system 3b. Ru. And the first and second
The light incident on the lens systems 3a and 3b is transmitted to the first and second rows of photoelectric conversion element arrays 1a, 1c, respectively.
. . . and 1b, 1d, . . . are imaged on.

Here, the light incident on the first and second lens systems 3a and 3b is reflected twice by mirrors 11 and 12 and mirrors 13 and 14, respectively, so that both form erect images. In addition, A, B,
If the dimensions of C and D are set in the relationship A=B and C=D, the first and second lens systems 3a and 3
The optical path lengths up to b can be made equal.

By doing so, it becomes possible to set both the optical axes of the first and second lens systems 3a and 3b parallel to each other and perpendicular to the light receiving surface of the photoelectric conversion section. Therefore, the distance between the lens systems 3a and 3b, that is, the photoelectric conversion element array 1 of the first row of the photoelectric conversion section
a, 1c, ...... and the second photoelectric conversion element array 1
b, 1d, . . . , and the lens systems 3a and 3b can be easily aligned with respect to the photoelectric conversion section.

Note that the photoelectric conversion element arrays 1 in the first and second rows
In order to equalize the amount of incident light on the photoelectric conversion element arrays 1b, 1d, . It is desirable to select the light reflectance of each of the fourth mirrors 12 to 14 so that the respective optical losses from the document surface 4 to the first and second lens systems 3a and 3b are equal.

FIG. 4 shows a more specific configuration of the embodiment shown in FIG. 3, in which the imaging system is integrated. That is, the mirrors 11 to 1 in FIG.
4. The lens systems 3a, 3b, etc. may be supported by separate supports, but if they are integrated, assembly becomes very easy and manufacturing efficiency is significantly improved.

In FIG. 4, the first mirror 11 consists of a semi-permeable membrane attached to one surface of a long triangular prism 21, and the second to fourth mirrors 12 to 1
4 consists of a reflective film deposited on opaque supports 22-24. A prism 25 is provided between the first mirror 11 and the second mirror 12 in close contact with both mirrors 11 and 12. This prism 25 is used to equalize the refractive index of the transmission film of the first mirror 11 and the reflection side. On the other hand, the first and second lens systems 3a and 3b are made of graded index optical fibers, for example.
It is inserted into a hole provided in the opaque support 26. The members 21 to 26 are joined and integrated using a transparent adhesive. In this case, if transparent bodies are also provided in the spaces indicated by 27 and 28 in the figure,
It is possible to make the whole even more solid. In addition,
Instead of integrating the entire imaging system in this way, it is possible to integrate only the first to fourth mirrors 11 to 14, only the first and second lens systems 3a and 3b, or to integrate these individually. Even in this case, an effect similar to the configuration shown in FIG. 4 can be obtained.

This invention is not limited to the above-mentioned embodiments, and can be modified in various ways without departing from the gist thereof. For example, the two rows of photoelectric conversion element arrays in the photoelectric conversion section may not necessarily be arranged in a staggered manner. Tomoyoshi.

[Brief explanation of drawings]

Figure 1 is a diagram showing the arrangement of the photoelectric conversion element array that constitutes the photoelectric conversion section in a contact type image sensor, Figure 2 is a diagram showing the configuration of an imaging system in a conventional contact type image sensor, and Figure 3 is a diagram showing the configuration of an imaging system in a conventional contact type image sensor. FIG. 4 is a cross-sectional view showing the structure of an imaging system in a contact image sensor according to another embodiment of the invention. 1a, 1b...Photoelectric conversion element array, 2...Substrate, 3a, 3b...Lens system, 4...Document surface, 1
1 to 14...first to fourth mirrors, 21, 25...
... Prism, 22-24, 26... Opaque support.

Claims (1)

[Scope of Claims] 1. A close-contact device comprising a photoelectric conversion section in which a plurality of photoelectric conversion element arrays are arranged in two rows, and an imaging system that forms an image on the document surface at the same magnification on the photoelectric conversion section. type image sensor, the imaging system includes a first mirror that divides the light from the document surface into reflected light and transmitted light, and a second mirror that reflects the light reflected by the first mirror. , a third mirror that reflects the light that has passed through the first mirror, and a fourth mirror that reflects the light reflected by the third mirror in the same direction as the light reflected by the second mirror. and a first lens system that guides the light reflected by the second mirror to a first row of photoelectric conversion element arrays of the photoelectric conversion unit;
A second lens system is provided in parallel with the first lens system and guides the light reflected by the fourth mirror to a second row of photoelectric conversion element arrays of the photoelectric conversion section. Close-contact image sensor. 2. A close-contact image according to claim 1, characterized in that the first to fourth mirrors are arranged so that the respective optical path lengths from the document surface to the first and second lens systems are equal. sensor. 3 Adjust the division ratio between reflected light and transmitted light of the first mirror and the light reflectance of each of the second to fourth mirrors so that the respective optical losses from the document surface to the first and second lens systems are equal. The contact type image sensor according to claim 1 or 2, characterized in that: 4. The contact type image sensor according to any one of claims 1 to 3, wherein the first to fourth mirrors are integrated. 5. The contact image sensor according to claim 1, wherein the first and second lens systems are integrated. 6. The contact image sensor according to any one of claims 1 to 3, wherein the first to fourth mirrors and the first and second lens systems are integrated. 7. The contact image sensor according to any one of claims 1, 5, and 6, wherein the first and second lens systems are each rod lens arrays.