JPH08304931A - Image reader - Google Patents

Abstract

PURPOSE: To easily embody a double variable power mechanism by inverting an imaging lens in an optical axis direction. CONSTITUTION: This image reader has a first original 11 which has a first width h1 , a second original 12 which has a second width h2 different from the first width, an imaging optical system 30 which forms the images of the first original 11 and the second original 12, a photoelectric conversion means 20 which photoelectrically converts the image formed by this imaging optical system 30 and has a third width h3 and an inverting mechanism 40 which inverts the imaging optical system 30 in the optical axis direction on the optical axis connecting the originals 11, 12 to the photoelectric conversion means 20. The ratio of the first width h1 and the third width h3 is n-times and the ratio of the third width h3 and the second width h2 is n-times. The ratio of the distance from the originals 11, 12 to the imaging optical system 30 and the distance from the imaging optical system 30 to the photoelectric conversion means 20 is n-times before the inversion and 1/n-times after the inversion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for reading an image of a small original or a large original, and in particular, reading a small original and a large original by reversing the imaging optical system in the optical axis direction. The present invention relates to an image reading device.

[0002]

2. Description of the Related Art An image reading apparatus having no variable-magnification optical system, for example, an image reading apparatus capable of reading an original document having a width of 250 mm, is used when reading an original document having a width of, for example, 35 mm. An image corresponding to the width is read, a part of the image signal is taken out, and the image signal is displayed on the entire monitor, so that the image signal is artificially output between pixels of the monitor. Therefore, the resolution of the image of the original having a width of 35 mm becomes poor.

Therefore, when reading a document with a width of 250 mm and a document with a width of 35 mm at a predetermined resolution, a variable-magnification optical system is further added on the optical axis connecting the document and the CCD sensor. I moved the system to read both documents. Even if the variable-magnification optical system is not provided, two image-forming optical systems having different magnifications are prepared and a mirror or the like is used to switch the document with a predetermined resolution of 250 mm in width and 35 mm in width.
I was reading a manuscript with a width of.

[0004]

The former image reading apparatus equipped with a variable power optical system requires a variable power optical system and a mechanism for moving the variable power optical system, which causes an increase in cost, and also causes a problem when moving the same. There is a problem such as backlash in positioning, and there is also a technical problem. The image reading apparatus of the latter type, in which the two types of image forming optical systems are switched by mirrors, must include two image forming optical systems and two CCD sensors, which require high processing accuracy, and delicate adjustment. Had to be separate.

Therefore, the present invention has been made in view of such a point, and simply realizes the two-magnification mechanism by reversing the imaging lens in the optical axis direction.

[0006]

The image reading apparatus of the present invention comprises a first original (11) having a first width and the first original (11).
An image reading apparatus for reading a second original (12) having a second width different from the width of the first original, and an imaging optical system (30) for forming images of the first original and the second original; The image forming optical system is inverted in the optical axis direction on the optical axis connecting the photoelectric conversion means (20) for photoelectrically converting the image formed by the image forming optical system and the original and the photoelectric converting means. And a ratio of the first width to the third width is n times, and a ratio of the third width to the second width is n times. The ratio of the distance from the document to the image forming optical system and the distance from the image forming optical system to the photoelectric conversion means is n times before inversion and 1 / n times after inversion. To do.

[0007]

Operation: The first width (h1) of the document and the second width (h
The relationship between 2) and the width (h3) of the sensor is as follows. h1: h3 = h3: h2 = 1: n Here, the imaging lens is inverted on the optical axis by an inversion mechanism.

The distance from the original before reversal to the imaging lens (b1) and the distance from the imaging lens to the sensor (b
2), the distance from the original to the image forming lens after reversal (b4) and the distance from the image forming lens to the sensor (b)
The relationship with 3) is as follows. b1: b2 = b3: b4 = 1: n Therefore, by inverting the imaging lens on the optical axis, it is possible to provide a two-system variable magnification mechanism.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. In FIG. 1, a document 11 having a width h1 and a width h2
The original 12 having (h1 <h2) is placed on the original table (not shown) of the image reading apparatus. Here, the document 11 and the document 12 do not have to be separate documents, and the document 11 may be considered as a predetermined area of the document 12.

The one-dimensional CCD sensor 20 is arranged at a fixed position and converts an image into an image signal. The width in which the pixels forming the one-dimensional CCD sensor 20 are lined up is the width h.
Set to 3. The imaging lens 30 has a magnification of n and is arranged on the optical axis connecting the one-dimensional CCD sensor 20 and the manuscript 11 and the manuscript 12. The imaging lens 30 forms an image having a width h1 at a position of a distance b1 from the document 11 by the one-dimensional CCD sensor 2
It is designed to be tied on 0. However, the imaging lens 30 needs to be designed with a field stop, vignetting, etc. on the assumption that the original 12 is imaged on the CCD sensor 20.

The imaging lens 30 is held by a supporting member 40 that supports the lens, and the supporting member 40 can be manually rotated about an axis O by a dial (not shown). Further, stoppers 21 and 22 are provided so that they can be positioned on the optical axis when the imaging lens 30 rotates. When the imaging lens 30 is at the position drawn by the solid line, the distance from the originals 11 and 12 to the imaging lens 30 is b1, and the distance from the imaging lens 30 to the CCD sensor 20 is b2. ing. Further, the imaging lens 30 moves to the position drawn by the dotted line when it is inverted by the rotation of the dial, the distance from the originals 11 and 12 to the imaging lens 30 is b4, and the distance from the imaging lens 30 to the CCD sensor 20 is increased. The distance becomes b3.

The relationship between the width h1 of the original 11, the width h2 of the original 12, and the width h3 of the CCD sensor is as follows. h1: h3 = h3: h2 = 1: n Further, the distance b from the originals 11 and 12 to the imaging lens 30
The relationship between 1 and b4 and the distances b2 and b3 from the imaging lens 30 to the CCD sensor 20 is as follows.

B1: b2 = b3: b4 = 1: n Next, the reading operation of the first embodiment will be described. A light source (not shown) irradiates the original 11 or the original 12 with light, and the transmitted light or reflected light is read by the one-dimensional CCD sensor 20 through the imaging lens 30. First, the manuscript 11
When reading the image, the imaging lens 30 is installed at a position at a distance b1 from the original. At this time, the magnification of the imaging lens 30 becomes n, and the imaging lens 30 forms an image of the width h1 of the original 11 on the width h3 of the one-dimensional CCD sensor 20. That is, the original 11 can be read using all the pixels of the CCD sensor.

Next, as for reading the original 12,
At this time, the dial is rotated to rotate the imaging lens 30 about the axis O as a fulcrum so as to hit the stopper 22.
The surface of the imaging lens 30 facing the CCD sensor 20 until then faces the document side. Then, the magnification of the imaging lens 30 becomes 1 / n, and the imaging lens 30 works so as to connect the image of the width h2 of the original 12 to the entire pixels of the width h3 of the CCD sensor 20.

Therefore, the original 11 or the original 12 having different widths is used.
Even with this, it is possible to read using all pixels of the CCD sensor without lowering the resolution with a simple configuration. A second embodiment of the present invention will be described. Figure 2
Shows an image reading device for reading a transmissive color original such as a film by a color filter switching mechanism.

In FIG. 2, only members different from the first embodiment will be described. A lamp 50 as a light source is arranged at a predetermined position, and in front of it, a filter group such as a light diffusion plate, a heat absorption filter, a color correction filter, and R (red) G (green) B (blue) color separation filters. 60 is arranged. In front of it, condenser lenses f1, f2 and f2 ′ for illuminating the original 11 or the original 12 are arranged. The condenser lenses f1 and f2 are combined to form an original 12
Illuminate. The original 11 is illuminated by combining the condenser lenses f1 and f2 ′. The reason for changing the combination in this way is that the imaging magnification differs depending on the width of the original,
This is because it is necessary to adjust the amount of light. That is, manuscript 1
This is because, when the document 1 is illuminated, the storage time of the one-dimensional CCD sensor becomes long unless the document 11 is illuminated with a high light amount.

Also in this embodiment, the width h1 of the document 11 is
The relationship between the width h2 of the original 11 and the width h3 of the CCD sensor 20 is the same as that in the first embodiment. Further, the distance from the originals 11 and 12 to the imaging lens 30 and the distance from the imaging lens 30 to C
The relationship of the distance to the CD sensor 20 is the same as in the first embodiment. The imaging lens 30 is mounted on the gear plate 35. When a stepping motor or a DC motor (not shown) rotates the gear 36, the gear plate 35 rotates about the axis O. At the same time, the condenser lens f
2, f2 'are alternately inserted into and ejected from the optical path. On the gear plate 35, a pin 43 for turning on / off the contact switch 41 is fixed (see FIG. 4), and a counterbore 35a into which a ball forming the click mechanism 42 is inserted is formed (see FIG. 5). reference). Above the moving plate 37, the gear plate 35, the gear 36, the CCD sensor 20,
A contact switch 41 and a click mechanism 42 are mounted. The moving plate 37 moves in the optical axis direction by the rotation of the gear 38. Since the CCD sensor 20 is mounted on the moving plate 37, the distance between the CCD sensor 20 and the axis O of the gear plate 35 must be adjusted in advance. Further, since gear backlash occurs, the positions of the contact switch 41 and the pin 43 must be adjusted so that the imaging lens 30 stops accurately on the optical axis. Since the stepping motor can ensure high positional accuracy, the click mechanism 42 shown in FIG. 5 is unnecessary when the gear 36 is rotated by the stepping motor.

A control unit (not shown) controls rotation of the gears 36 and 38, switching control of the filter group 60, and switching control of the condenser lenses f2 and f2 'on the optical axis. Next, the operation of the second embodiment will be described. First,
Document 11 that is 1 / n times the size of the one-dimensional CCD sensor 20
When reading, arrange as shown in FIG. At this time, the condenser plates f1 and f2 ′ are used, and the gear plate 35 is rotated so that the imaging lens 30 is located at a position b1 from the original 11. By using the condenser lenses f1 and f2 ', the illumination light suitable for the original 11 can be irradiated, and by placing the image forming lens 30 at a position b1 from the original 11, the entire image of the original 11 is formed on the CCD sensor 20. be able to. Here, the image of the entire document 11 may not be in focus because of some deviation of the document 11 in the optical axis direction. In such a case, the moving plate 37 is finely adjusted in the optical axis direction to bring it into a focused state. Then, set the color filter to R
By changing GB sequentially, CC color images of RGB 3 colors
Read with the D sensor 20.

Next, when reading the original 12 having a size n times larger than that of the one-dimensional CCD sensor 20, as shown in FIG. 3, the condenser lens f2 'is inserted in the illumination unit instead of the condenser lens f2', and the imaging lens 30 is inserted. The original 12 is rotated to a position at a distance b4. By replacing the condenser lens f2 ′ with f2, it is possible to obtain the optimum illumination light for reading the original 12 with the CCD sensor 20. When there is a large difference in size between the two transparent originals 11 and 12 to be read in this way, problems occur due to differences in the angle of view and focal length under the same illumination light, so the condenser lens is switched. Further, by rotating the gear plate 35 so that the image forming lens 30 is located at the position of the distance b4 from the original 12, the image forming lens 30 functions as a magnifying optical system of 1 / n times, and the entire image of the original 12 is CCD. Tie to sensor 20. Similarly, after that, the focus adjustment by the moving plate 37, the selection of filters of three colors of RGB, and the like are repeated to obtain color image data.

In the present embodiment, the one-dimensional CCD sensor has been described, but the effect of the present invention can be obtained even with a two-dimensional CCD sensor.

[0021]

According to the present invention, by reversing the imaging optical system on the optical axis and changing the distance from the original, it is possible to achieve
A system variable magnification mechanism can be realized. The cost is lower than the case where the variable power optical system is provided, the number of parts is reduced as compared with the case where two image forming optical systems are provided, and the labor of the adjustment work can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a first embodiment.

FIG. 2 is a configuration when reading a narrow original 11 in the second embodiment.

FIG. 3 is a configuration for reading a wide original 12 in the second embodiment.

4 is a diagram showing a contact switch 41 and a pin 43 fixed to a gear plate 35. FIG.

FIG. 5 is a view showing a click mechanism 42.

[Explanation of symbols]

11 ・ ・ ・ ・ Original (small) 12 ・ ・ ・ ・ Original (large) 20 ・ ・ ・ ・ One-dimensional CCD 30 ・ ・ ・ ・ Imaging lens 35 ・ ・ ・ ・ Gear plate 37 ・ ・ ・ ・ Movable plate 40 ・... Supporting member 43 ... Position sensor pins f1, f2, f2 '... Condenser lens

Claims (2)

[Claims] 1. An image reading apparatus for reading an image of a first original having a first width and a second original having a second width different from the first width, wherein the first original and the second original are provided. An image forming optical system for forming an image of the image, a photoelectric conversion unit having a third width for photoelectrically converting the image formed by the image forming optical system, and the original and the photoelectric converting unit. A reversing mechanism for reversing the imaging optical system in the optical axis direction on the connecting optical axis, wherein the ratio of the first width to the third width is n times, and the third width And the second width is n times, and the ratio of the distance from the document to the imaging optical system and the distance from the imaging optical system to the photoelectric conversion means is n times before inversion. The image reading device is characterized in that after reversing, it becomes 1 / n times. 2. The image reading apparatus according to claim 1, wherein the first original document is within a predetermined range of the second original document.