JPH01135260A - Image reader - Google Patents

Abstract

PURPOSE:To facilitate the adjusting work of a focus position by deviating a convergent light transmitting body in the optical axis direction in a condition in which an interval between a light-receiving element and an original surface is maintained constant, and adjusting the focus position of the convergent transmitting body. CONSTITUTION:To an image reading means 7, a focus adjusting means 14 to adjust the focus of a convergent light transmitting body 13 in a light reading part 12, and an interval maintaining means 16 to maintain the interval between a photoelectric conversion processing part to contain a light-receiving element 15, the original surface of an original P and the light-receiving surface of the element 15, are provided. The means 16 slide-abuts sliding members 26c and 26d to the lower surface of a transparent carrier 3 by means of a reaction (f) obtained by pressing each roller 28 to a rail 45 with an elastic member 27, and the means 16 maintains the interval between the original surface and the light-receiving surface of the element 15 constant. By displacing the transmitting body 12 in the upper direction or lower direction of an optical axis L in such a condition, the focus position of the transmitting body 13 can be easily adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention reads image information attached to a document and transfers the read image information to an image reading device for forming an image.

(Prior Art) In general, an image reading device uses a light-condensing transmitter (hereinafter also referred to as an "optical transmitter") as an imaging system that optically collects image information attached to a document and forms an image. In order to obtain optimal imaging conditions, one of the extremely important conditions is to arrange the optical transmission body between the document surface and the light-receiving element at the correct position based on the imaging conditions.

The imaging conditions of such an optical transmission body will be explained with reference to FIGS. 6(a) to 6(f). In addition, Fig. 6(a) to (
In C), the conjugate length of the optical transmission body 50 is TC, the object-image distance is l, the deviation from the image point position or the deviation from the center position of conjugate length TC is Δ, and the length is 1/2 of the conjugate length TC. Zawo TC
The following explanation will be given assuming 1.

In the case of FIGS. 6(a) and 6(b), where the conjugate length TC of the optical transmission body 50 is equal to the object-image distance 1, and in FIG. 6(C), the conjugate length TC is shorter than the object-image distance l. The modulation transfer function (M
TF: Modulation Transfer
Function) is as shown in FIGS. 6(d) to (f).

That is, as shown in FIGS. 6(a) and 6(b), the optical transmission body 5
The modulation is better when the optical distances on the object side and the image side of the light transmitting body 50 match as shown in FIG. 6(C) than when the optical distances between 0 and the object side or image side do not match. The drop in transfer function is small.

Here, with reference to FIG. 7, the image reading means 60 in the conventional image reading device will be described.

The image reading means 60 shown in the figure includes a shaft body 51 fixedly arranged on the main body of the apparatus (not shown), and a slider 52 fitted to the shaft body 51 so as to be slidable in the Xl and X2 directions shown in the figure. , and an image reading section 53 supported by the slider 52.

The image reading section 53 includes a carriage 54 supported by the slider 52, an optical transmission body 50 mounted so that the optical axis is perpendicular to the carriage 54,
A light-receiving element (photoelectric conversion element) 55 is arranged horizontally at the position where the light is imaged by the light transmitting body 50, and a light-receiving element 5 is connected to the light-receiving element 55 through a lead terminal 56.
The drive circuit board 56 is equipped with an IC circuit or the like that takes in the output signal of No. 5 and performs predetermined signal processing.

In addition, in FIG. 6, 57 is a cover glass for the light receiving element 55.

Then, the image reading means 60 is indicated by an arrow X1 shown in FIG.
．． By sliding in the X2 direction, the transparent carrier 61
The document P placed thereon is read and scanned.

In such an image reading means 60, the optical distance B between the light transmitting body 50 and the light receiving element 55 depends on the dimensional accuracy of the carriage 54 and the assembly precision of the light transmitting body 50 and the light receiving cable 55.

For this reason, conventionally, as a means to make the optical distance A between the original P and the optical transmission body 50 match the optical distance B, the distance between the shaft 51 and the transparent carrier 61 has been adjusted. was.

However, with such means, compared to the case where the focal point position is adjusted by moving the optical transmitter 50 itself as described above, when the deviation from the focal point position is large, the modulation transfer function decreases rapidly. This poses a problem in that adjustment work becomes difficult.

Further, when moving the shaft 51, the carriage 54 of the image reading means 60 must be mounted in the main body of the apparatus, making adjustment work extremely complicated.

(Problems to be Solved by the Invention) As described above, in the conventional apparatus, due to the configuration of the image reading means, it is difficult to adjust the positions of the optical transmitter, the document surface, and the light receiving element. Another problem is that it is complicated.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an image reading device equipped with an image reading means that can easily adjust the relative position between an optical transmitter, a document surface, and a light receiving element, and can obtain good modulation transfer function characteristics. The purpose is to

[Structure of the Invention] (Means for Solving the Problems) The present invention reads and scans image information attached to a document using an image reading means using a condensing light transmitter and a light receiving element, and reads the read image. An image reading device that uses information to form an image, wherein the image reading means is arranged between a distance maintaining means that maintains a constant distance between the light receiving element and the document surface, and the document surface and the light receiving element. and a focal position adjusting means for displacing the condensing light transmitting body in the direction of its optical axis.

(for production) The operation of the apparatus having the above configuration will be explained below.

When the image reading means of this apparatus performs reading scanning on a document, the distance maintaining means maintains a constant distance between the light receiving element and the surface of the document.

In this state, the focal position adjustment means can shift the condensing optical transmission body in the direction of its optical axis to adjust the focal position of the condensing optical transmission body, thereby making it possible to adjust the focal position. This becomes easy and also prevents a decrease in the amount of light at the light receiving element.

(Example) Examples of the present invention will be described in detail below.

The image reading device 1 shown in FIG. A platen cover 5 that covers the original with image information attached thereto and placed in a fixed state on the exposure glass forms a part of the exposure glass 3 and the original transport means 4. An image reading means 7 moves horizontally below the conveyor (platen roller) 6 to read and scan the document on the exposure glass 3 and the document conveyed by the conveyor 6; It has a traveling drive means 8 for driving.

It should be noted that the platen cover 5 is connected to the apparatus main body 2 so as to be openable and closable by a connecting means, but details regarding this will be omitted.

The image reading means 7 is provided between the transparent carrier 3 on which the original P is placed and a flat rail 45 provided inside the image reading device 1, as shown in FIG.

That is, this image reading means 7 has a carriage plate 11a.
, 11b, an optical reading unit 12 held by a frame 17 attached to the carriage plate 115° 11b, a focus adjusting means 14 for adjusting the focus of the condensing light transmitting body 13 in this optical reading unit 12, and a light receiving unit It comprises a photoelectric conversion processing section 10 including an element 15, and a distance maintaining means 16 for maintaining a constant distance between the document surface of the document P placed on the transparent carrier 3 and the light receiving surface of the light receiving element 15. There is.

Here, the optical reading section 12 and the focal position adjusting means 14
This will be explained with reference to FIG.

The optical reading unit 12 includes a condensing light transmitting body 13 having a conjugate length TC, and an illumination lamp 38 fixedly arranged in the same direction as the mounting direction of the condensing light transmitting body 13 with respect to the carriage plate 118.11b. It is made up of.

Further, the focus position adjusting means 14, as shown in FIG.
Notches 13a and 13b having a predetermined depth are provided on both sides of the condensing light transmitting body 13, and the notches are formed on both sides of the light shielding plate 18 disposed along the side surface of the condensing light transmitting body 13. Through-long holes 18a and 18b provided at positions corresponding to the holes 13a and 13b, respectively, and the cutout hole 1 provided in the joint surface 17a of the frame 17 to the condensing light transmitting body 13.
two screw holes 19a corresponding to 3a and 13b, respectively;
19b and the notch hole 13a2 through the elongated hole 18b, respectively, and has a knurling 20 on the outer periphery.
It passes through two adjustment collars 20a, 29b having diameters c and 20d and eccentric holes 21a, 31b provided at positions eccentric from the center of these adjustment collars 20a, 20b, and into the two screw holes 19a, 19b. Both adjustment collars 20a,
20b is fitted into the notch hole 13a2 penetrating elongated hole 18a and the notch hole 13b1 penetrating elongated hole 18b, respectively, while rotating both adjusting collars 20a, 20b, tightening screw 22a,
22b and the side screw holes 19a, 19b, the condensing optical transmitter 13 is displaced in the direction of the optical axis.

The photoelectric conversion processing unit 10 includes a substrate 23 on which the light receiving element 15 is formed on the top surface is attached to a holder portion 17a provided at the bottom of the frame 17, and one end of the substrate 23 is fixed to the holder portion 17a with a fixing screw 24. By pressing with a fixed plate spring 24a, the light receiving surface of the light receiving element 15 is made to face the optical axis of the condensing light transmitting body 13.

Further, the board 23 has a lead terminal 23a projecting downward from one side thereof, and this lead terminal 23a is connected to a drive circuit board 25 connecting the carriage plates 11a and 11b.

This drive circuit board 25 includes an I that drives the light receiving element 15.
Equipped with C circuit etc.

The distance maintaining means 16 includes both the carriage plates 11a,
A total of four sliding members 26a, 2 provided at the upper end of 11b.
6b, 26c, 26d (26a is not shown), an elastic member 27 provided on the lower surface side of the drive circuit board 25, and a total of four rollers 28 (a third (only two are shown in the figure), and the reaction force f obtained by pressing each roller 28 against the rail 45 by the elastic portion 27 causes the sliding member 2 to
6a to 26d are always brought into sliding contact with the lower surface of the transparent carrier 3, so that the distance between the document surface and the light-receiving surface of the light-receiving element 15 is kept constant on the transparent carrier 3.

That is, the distance between the document surface and the light receiving element 15 is determined by the frame 17.
The conjugate length TC of the condensing optical transmitter 13 is determined depending on the precision of the sliding members 27a to 26d and also in consideration of the refractive index of the cover glass 29 disposed on the light receiving element 15.
It is designed to be maintained close to .

Next, the operation of the device having the above configuration will be explained.

When the image reading means 7 reads and scans the original P, the image reading means 7 is driven by the traveling drive means 8 in the Xl and X2 directions shown in FIG.

At this time, the distance between the light receiving element 15 of the image reading means 7 and the document P on the transparent carrier 3 is maintained at a value close to the conjugate length TC by the distance maintaining means 17 as described above.

In this state, first loosen both the tightening screws 22a, 22b of the focal position adjusting means 14 and rotate both the adjusting collars 20a, 20b with your fingers.
b performs an eccentric movement around the screw holes 19a and 19b, and as a result, the condensing light transmitting body 13 is displaced upward or downward along the optical axis.

Thereby, the focal position of the condensing light transmitting body 13 can be easily adjusted.

In this case, for example, the image reading means 7 is removed from the main body 2 of the apparatus, placed on a plate-like member having the same refractive index and thickness as the transparent carrier 3, with each movable member 26a to 26d facing downward, and A test chart with a specific pattern formed thereon is placed under this plate-like member.

Then, the light-receiving element 15 is driven in the same manner as in the image reading device 1, and the focal position adjusting means 14 transmits the light so that the modulation transfer function is highest based on the output signal of the light-receiving element 15. Adjust the position of the body 13 and tighten the tightening screw 22a.

By tightening 22b, optimum imaging conditions can always be obtained.

As described above, according to the device of this embodiment, it is possible to avoid the trouble of adjusting the position of the shaft 51 at both ends as in the conventional device, and it is possible to simplify the adjustment work.
3 itself is moved in the direction of the optical axis, it is possible to improve the characteristics of the modulation transfer function compared to the conventional device that adjusts the distance between the document surface and the condensing light transmitter 54. can be taken as a thing.

Next, another embodiment of the present invention will be described with reference to FIG.

The image reading means 7A shown in the figure has a support plate 30 between both carriage plates 11a and 11b instead of using the frame 17.
is constructed, and a first light shielding plate 31. is attached to this support plate 30. Light condensing light transmitter 13. A second light-shielding plate 32 is attached, and the same adjusting collars 20a, 20b and tightening screws 22a, 22b as in the case of the focal position adjusting means 14 are attached thereto.
The focal position adjusting means 14A is configured using the following. Further, the substrate 23 is also supported by a substrate holder 33 provided between both carriage plates 11a and 11b.

According to this image reading means 7A, the condensing light transmitting body 13 and the first . While maintaining a constant positional relationship with the second light shielding plates 31 and 32, these are moved in the direction of the optical axis by the action of the focal position adjusting means 14A, and as a result, the light amount distribution to the light receiving element 15 is kept constant. can do.

FIG. 5 shows yet another embodiment of the invention.

The image reading means 7B shown in the figure is the image reading means 7A.
It has almost the same configuration as , but the first light-shielding plate 31 is extended laterally, the illumination lamp 18 is fixed to the end thereof, and the part that blocks the optical path from this illumination lamp 18 to the original P is omitted. The difference is that .

According to this image reading means 7B, the condensing light transmitting body 13 and the illumination lamp 18 move in conjunction with each other, so that the exposure state when the reflected light from the document P forms an image on the light receiving element 15 is always constant. This allows the imaging conditions to be adjusted more accurately.

-14= The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the gist.

[Effects of the Invention] According to the present invention described above, it is possible to easily adjust the focal position of the condensing optical transmitter while maintaining a constant distance between the document surface and the light receiving element, and to adjust the focal position of the light-condensing light transmitting body with ease. Accordingly, it is possible to provide an image reading device equipped with an image reading means that can obtain a suitable imaging condition.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of an embodiment of the device of the present invention, Fig. 2 is a sectional view showing the image reading means of the same device, Fig. 3 is an exploded perspective view of the same, and Fig. 4 is the other side of the image reading means. FIG. 5 is a cross-sectional view showing yet another example of the image reading means; FIG.
Figures (a), (b). (C) is an explanatory diagram showing the relationship between the conjugate length and positional deviation of the condensing optical transmission body, and FIGS. 6(d) and (e). (f) is a characteristic diagram of the modulation transfer function corresponding to FIGS. 6(a), (b>, and (C), respectively, and FIG. 7 is a cross-sectional view showing the image reading means of the conventional device. 1... Image reading device, 7... Image reading means, 13.
...Condensing optical transmission body, 14...Focus position adjusting means, 16... Distance maintaining means. n

Claims (1)

[Claims] An image reading device that reads and scans image information attached to a document by an image reading means using a condensing light transmitter and a light receiving element, and uses the read image information for image formation, the image reading means comprising: a distance maintaining means for maintaining a constant distance between the light-receiving element and the document surface; and a focal position adjusting means for displacing a condensing light transmitting body disposed between the document surface and the light-receiving element in the direction of its optical axis. An image reading device comprising: