JPH07170376A - Optical unit - Google Patents

Abstract

PURPOSE:To eliminate the need for a highly accurate short focal length lens and to miniaturize the optical unit by arranging a reflection mirror at the focus position of a lens that makes reflected light from an original pass through and focus it and providing a read sensor for receiving the reflected light. CONSTITUTION:A pair of mirrors 26 and 28 and first, second and third mirrors 30, 32 and 34 are arranged and optical paths not only in a horizontal direction but also in a vertical direction crossing it are provided with the mirrors. Thus, the entire dimensions are miniaturized while maintaining a required optical path length. The mirror 34 is arranged between the lens 14 and a CCD 16 and the optical path length between them is prolonged. Namely, a lens of a long focal length can be used as the lens 14. Required accuracy is not high for the lens of the long focal length. Therefore, it can be manufactured of inexpensive plastic instead of glass, for instance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical unit,
In particular, the present invention relates to a document reading optical unit in an electronic device such as a facsimile machine.

[0002]

2. Description of the Related Art FIG. 4 is a schematic perspective view showing a basic structure of a conventional document reading optical system in a facsimile apparatus. As shown in FIG. 4, in this optical system, a light source 12 that irradiates the original 10 with light, a lens 14 that forms a reduced real image at the focal position through the light reflected from the original 10,
A reduction optical system including a CCD (charge coupled device) 16 as a reading sensor arranged at a focal position to read a real image is used.

FIG. 5 is a schematic side view showing another conventional optical system obtained by improving the optical system shown in FIG. As shown in FIG. 5, in this conventional example, the actual length between the document 10 and the CCD 16 is shortened to downsize the optical system. That is,
Insert mirrors 18 and 20 between the original 10 and the lens 14,
Miniaturization is achieved by reflecting light and folding the optical path.

FIG. 6 is a schematic side view showing a part of still another optical system of the conventional example in which the disturbance light is prevented from entering and the size is reduced. As shown in FIG. 6, in this optical system,
The lens 14 and the CCD 16 are held by, for example, a case 22, so that the lens and the CCD are integrated. Since the case 22 is used, light other than the light passing through the lens 14, that is, ambient light, is blocked by the case 22 and prevented from reaching the CCD 16. Further, the distance between the lens 14 and the CCD 16 is shortened to reduce the size of the unit including the lens and the CCD.

FIG. 7 is a schematic side view showing still another conventional optical system. In this conventional optical system, a mirror is used as shown in the conventional example of FIG. 5 in order to reduce the size of the entire optical system. However, in order to further shorten the entire length of the optical system, the mirror 26, It is configured to reflect light a large number of times between 28. In addition, what is shown by a dotted line in FIG.
This is a case 22 having a glass window 24.
2, light source 12, mirrors 26, 28, lens 14, C
It contains a CD 16.

[0006]

In the conventional optical system shown in FIG. 6, the lens and the CCD are shortened and integrated by a case in order to prevent the entry of ambient light and to reduce the size. However, in order to shorten the distance between the lens and the CCD, a lens with a short focal length must be used. To shorten the focal length of the lens,
It is necessary to increase the accuracy of the lens, and since the depth of focus is shallow, it is necessary to adjust the distance between the lens and the CCD with high accuracy. Therefore, the case itself for housing the lens and the CCD is required to be stable and accurate with no change over time.

Further, in the conventional optical system shown in FIG. 7, the distance between the original and the CCD can be made shorter than that in the optical system shown in FIG. 5, but the distance between the mirror passing through the lens which is the final optical path and the CCD is reduced. The size is large, and even if the focal length of the lens is shortened, there is a limit, and the size cannot be sufficiently reduced. For example, the dimensions of the optical system of this conventional example are about 85 mm in the horizontal direction and about 35 mm in the vertical direction in FIG.

Therefore, a first object of the present invention is to use a lens having a short focal length, which requires high accuracy,
An object is to provide an optical unit that can downsize an optical system.

A second object of the present invention is to provide an optical unit whose overall size can be reduced.

[0010]

In order to achieve the above-mentioned first object, the present invention relates to a document reading optical unit in an electronic apparatus, and in a document reading optical unit, a light source for irradiating a document and a focus through reflected light from the document. The optical unit is characterized in that it has a lens that connects the lens, a mirror that reflects light that has passed through the lens, and a reading sensor that is arranged at the focal position of the lens and that receives light from the mirror. .

In order to achieve the second object, the present invention provides, in an original reading optical unit in an electronic device, a light source for irradiating an original with a light source and a pair of light sources for reflecting the reflected light from the original a plurality of times. A mirror; a first mirror that receives light from the pair of mirrors and reflects it across the optical paths of the pair of mirrors; and a light that receives light from the first mirror and is substantially parallel to the optical paths of the pair of mirrors. A second mirror for reflecting the light in a direction, a lens for focusing the light from the second mirror, and a light for receiving the light passing through the lens and reflecting the light again across the optical paths of the pair of mirrors.
The mirror and the third focus lens disposed at the focal position of the lens;
An optical unit having a reading sensor for receiving light from a mirror is adopted.

[0012]

EXAMPLES Next, examples of the optical unit of the present invention will be described. FIG. 1 is a side view showing an optical system according to the present invention, and FIG. 2 is a perspective view showing the optical system according to the present invention.
FIG. 3 is a sectional view showing an optical unit using the optical system according to the present invention.

As shown in FIGS. 1 and 2, the optical system of the present invention includes a light source 12 for irradiating the original 10 with light and a light from the original 10 for reflecting the light a plurality of times while slightly shifting the reflection position. From the mirror 30 (first mirror), and a pair of mirrors 26, 28 for reflecting the light, and a mirror 30 for receiving the light after being reflected a plurality of times and reflecting the light in a direction crossing the optical path in the reflection by the pair of mirrors. A pair of mirrors 2 that receive light
Mirror 3 for reflecting light in a direction substantially parallel to the optical paths 6 and 28
2 (second mirror) and a lens barrel 1 that allows light from the mirror 32 to pass therethrough
From the lens 14 held by 4a, the mirror 34 (third mirror) that receives the light that has passed through the lens 14 and reflects it again in the direction crossing the optical paths of the pair of mirrors, and the CCD that receives the light from the mirror 34. Consisting of a sensor 16.

In particular, as is apparent from FIG. 1, in the optical system of the present invention, a pair of mirrors 26, 2 is provided as compared with the conventional example.
In addition to 8, the mirrors 30, 32, 34 (first to third mirrors) are arranged in three, and these mirrors allow the optical path not only in the horizontal direction in the figure but also in the direction transverse to it (vertical direction). By providing, the overall size is reduced while maintaining the required optical path length. In this embodiment, the vertical dimension is about 45 mm, which is slightly larger than that of the conventional example.
The lateral dimension can be significantly reduced, for example about 45 mm.

Further, in the present invention, the lens 14 and the CCD 1
A mirror 34 is arranged between the optical path 6 and the optical path 6 to increase the optical path length therebetween. That is, the lens 14 having a long focal length can be used. A lens with a long focal length does not require high precision, and thus can be manufactured, for example, from inexpensive plastic instead of glass.

Next, referring to FIG. 3, FIG.
3 shows an optical unit using the optical system of the present invention shown in FIG. As shown in FIG. 3, the above-mentioned members are integrally held by a case. The case has, as main parts, parts 22a, 22b and 22c, the part 22a extending over the entire optical unit (in the direction through the drawing in FIG. 3), and the parts 22b are arranged only on both sides of the optical unit. The portion 22c is arranged only at the central position of the optical unit. Because it is configured like this,
The light source 12, the lens barrel 14a, and the mirrors 32 and 34 are portions 22a.
Is held by the pair of mirrors 26, 28,
The CCD 1 is held by the portions 22a and 22b.
6 and the mirror 30 are held by the portion 22c.
In the figure, A to E indicate optical paths from the light source 12 to the CCD 16. The cover glass 24 is held by the case so as to cover the light source 12.

[0017]

As described above, according to the present invention,
An optical unit having the following effects can be obtained. (1) The size can be reduced. In particular, it is possible to obtain an optical unit in which the distance from the document is within a short range. (2) Since the lens has a long focal length, the required accuracy is not high and the lens can be manufactured at low cost. (3) Since the focal length of the lens is long, the depth of focus can be deep, and the accuracy between the lens and the CCD is not so severe. Therefore, a mirror can be inserted between them. Further, the precision of the case (frame) that holds the lens, the mirror, and the CCD is not so severe, so that the case can be easily configured. (4) Since the entire optical system is completely covered with a frame, a mirror, a CCD, etc., ambient light does not enter and stable document reading can be performed. (5) The first to third mirrors may be small mirrors of about 10 to 15 mm square, and are therefore inexpensive, easy to fix to the frame, and strong against vibration and the like.

[Brief description of drawings]

FIG. 1 is a side view showing an optical system according to the present invention.

FIG. 2 is a perspective view showing an optical system according to the present invention.

FIG. 3 is a cross-sectional view showing an optical unit using an optical system according to the present invention.

FIG. 4 is a schematic perspective view showing an original reading optical system having a basic configuration of a conventional example in a facsimile apparatus.

FIG. 5 is a schematic side view showing another optical system of a conventional example in which the optical system of FIG. 4 is improved.

FIG. 6 is a schematic side view showing a part of still another optical system of the conventional example in which disturbance light is prevented from entering and size is reduced.

FIG. 7 is a schematic side view showing still another conventional optical system.

[Explanation of symbols]

 10 Original Document 12 Light Source 14 Lens 16 CCD 26, 28, 30, 32, 34 Mirror 24 Cover Glass

Claims (2)

[Claims] 1. In a document reading optical unit in an electronic apparatus, a light source for irradiating a document with light, a lens for focusing through reflected light from the document, a mirror for reflecting light passing through the lens, and a lens for the lens. An optical unit having a reading sensor arranged at a focal position for receiving light from the mirror. 2. An original reading optical unit in an electronic apparatus, comprising: a light source for irradiating an original with light; a pair of mirrors for reflecting light reflected from the original a plurality of times; and a pair of mirrors for receiving light from the mirror. A first mirror for reflecting light across the optical paths of the pair of mirrors; a second mirror for receiving light from the first mirror and reflecting it in a direction substantially parallel to the optical paths of the pair of mirrors; From the third mirror disposed at the focal position of the lens, and a third mirror for focusing the light through the light, a third mirror for receiving the light passing through the lens and reflecting the light again across the optical paths of the pair of mirrors. An optical unit having a reading sensor for receiving light.