JPH0580432A - Variable power device for optical instrument - Google Patents

Abstract

PURPOSE:To easily correct a deviation in an optical axis, in a corner registration system variable power device for an optical instrument. CONSTITUTION:In the corner registration system variable power device for the optical instrument, varying power in such a manner that a lens 5 is moved along a lens moving groove 16 provided on a lens moving plate 11, the lens moving plate can be rotated centering the reference magnification position 12 of the lens, and the position of the lens, except a reference position is moved in a direction perpendicular to the optical axis, by rotating the lens moving plate, to correct the deviation in the optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable power device in an optical machine such as a copying machine, and more particularly to a variable power device for correcting a change in conjugate length due to an error in a focal length of a lens, an error in a flatness of a mirror and the like. It relates to a double device.

[0002]

2. Description of the Related Art Generally, a copying machine is equipped with a variable power device capable of changing an image forming magnification. One of the variable power devices is a so-called center registration system.

The center registration type zooming device is one in which the center of image formation does not move during zooming, and the movement of the lens accompanying zooming is along a fixed optical axis.

A conventional center registration type scaling device will be described with reference to FIGS.

In the figure, 1 is a glass on which a document is placed,
The surface in contact with the upper surface of the glass 1 is the original surface 17. Two
Reference numerals 3 and 4 are a first mirror and a second mirror for guiding the image on the document surface to the lens 5.
Mirrors and third mirrors 6, 6 and 7 and 8 are a fourth mirror, a fifth mirror and a sixth mirror for guiding an image to the photosensitive drum 9, and the fourth mirror 6 and the fifth mirror 7 are an optical axis 10. It is possible to move along.

In the variable magnification device of the copying machine of the center registration type, when correcting the change of the conjugate length due to the error of the focal length of the lens, the error of the flatness of the mirror, etc., the fourth mirror is used at the same magnification. The conjugate length is corrected by moving the sixth and fifth mirrors 7, and the magnification is corrected by moving the lens. In addition, at the time of zooming, the focusing amount is selected from several types of numerical values prepared in advance for the moving amount of the lens 5 and the moving amounts of the fourth mirror 5 and the fifth mirror 7 in accordance with the finished state of the lens 5 and each mirror. It was general to select and adopt the one with the optimum value of and the magnification value.

In such a center registration type zooming device, for example, when one side on the original side is used as a reference, a phenomenon occurs in which the image forming position is displaced due to zooming, resulting in operability,
There is a problem in handleability. Therefore, it is currently 1
A corner registration type zooming device in which one side serving as a reference also appears on the image forming side when the side is used as a reference is widely used.

In the zooming apparatus of the corner registration type, as shown in FIG. 7, the lens 5 is moved in the optical axis direction and at the same time in the direction perpendicular to the optical axis. 10 moves.

In FIG. 7, 17 is the original surface at the same size, 17a is the enlarged original surface, 17b is the reduced original surface, and 1
0 is the position of the optical axis at the same magnification, 10a is the position of the optical axis at the time of enlargement, 10b is the position of the optical axis at the time of reduction, 18 is the image formation at the same magnification, 18a is the image formation at the time of enlargement, 18b shows the image formation at the time of reduction.

Generally, a corner registration type lens moving mechanism is provided with a lens moving plate in which a lens moving groove is formed, and the lens is moved along the moving groove.
Corresponding to the movement of the lens in the direction of the optical axis, the movement in the direction perpendicular to the optical axis is similarly performed.

[0011]

In such corner registration as well, it is necessary to correct an error in the focal length of the lens, an error in the flatness of the mirror, an installation error when the mirror is installed, etc. In the method of simply moving the lens such as the center registration method, the movement in the optical axis direction also causes a displacement in the direction perpendicular to the optical axis direction, which causes an error in image registration. It is not possible to adopt a correction method that simply moves the.

Therefore, conventionally, several kinds of lens moving plates having different curves of the moving groove are prepared, and the lens moving plate is appropriately replaced and corrected according to the finished state of the lens and the mirror. Was going on. For this reason, workability is poor, and a plurality of lens moving plates are prepared, which causes a high cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a variable power device which can be easily corrected by using one type of lens moving plate.

[0014]

SUMMARY OF THE INVENTION The present invention is directed to a zooming apparatus for a corner registration type optical machine in which a lens moves along a lens moving groove provided on a lens moving plate to perform zooming. The movable plate is rotatable about the reference magnification position of the lens.

[0015]

In the corner registration type variable power device, the error of the lens and the flatness of the mirror appear as the error of the optical axis position, but the error of the optical axis position is eliminated by rotating the lens moving plate.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 to 3, the same parts as those in FIGS. 6 and 7 are designated by the same reference numerals.

In the figure, reference numeral 11 denotes a lens moving plate, and a lens moving groove 16 is provided in the lens moving plate 11, and a slide pin 14 provided in the lens moving groove 16 so as to match the lens center is slid. It is fitted so that it can move freely.

By sliding the lens 5 along the lens moving groove 16 by a required means, the image formation can be enlarged or reduced with reference to a required point.

Next, the correction in this embodiment will be described.

The lens moving groove 16 of the lens moving plate 11
Position of the lens, that is, the position 1 of the lens that is expected at the same magnification.
2 is defined, and arc-shaped elongated holes 13a, 13b, 13c, 13d centered on the same-magnification lens position 12 are bored, and the lens moving plate 11 is rotatable about the same-magnification lens position 12 by a required angle. To do.

The elongated holes 13a, 13b, 13c, 1
The pin 15 fitted into 3d may be a guide pin provided for adjustment or a bolt for fixing the lens moving plate 11.

First, the error correction in the normal size state will be described.

The lens moving plate 11 is attached to the apparatus main body (not shown), the lens 5 is set at the same-magnification lens position 12, and in this state, the second mirror 3, the third mirror 4, and the fourth mirror 6, The fifth mirror 7 is moved in the optical axis direction to adjust the magnification and the conjugate length.

Next, at the time of zooming, the same-magnification lens position 12 is used.
The amount of movement of the lens 5 with respect to the fourth mirror 6, the fifth
A value that optimizes the combination of focus and magnification for the movement amount of the mirror 7 is appropriately selected from the numerical values prepared in advance.

When the optical axis deviates from the intended position, that is, the registration is deviated during this magnification change, the lens moving plate 11 is rotated around the same-magnification lens position 12 to perform the registration. Correct the madness.

In the above embodiment, the variable power device having the six-mirror structure has been described. However, the variable power device having the four-mirror structure in which the fourth mirror 6 directly projects the image on the photosensitive drum 9 is also implemented. It is possible, and in this case, the conjugate length is adjusted by moving and rotating the fourth mirror 6 instead of moving the fourth mirror 6 and the fifth mirror 7.

The operation of correcting the registration in this embodiment will be described below.

When f is the focal length of the lens 5 and β is the image forming magnification, the object distance A is given by the formula 1 from the lens formula.

[0030]

## EQU00001 ## A = (1 + 1 / B) f Further, the change amount .DELTA.A of the object distance from the time of unity magnification is given by Formula 2.

[0031]

## EQU00002 ## .DELTA.A = (1 / .beta.-1) f From FIG. 7 showing the relationship of the variable magnification system of the corner registration system, the optical axis movement amount .DELTA..epsilon. Due to the variable magnification becomes Formula 3 when y is the document length. The deviation Δn ′ of the registration when the optical axis is moved by Δn as shown in FIG.

[0032]

## EQU3 ## Δε = y (β = 1) / 2 (β + 1)

[0033]

## EQU00004 ## .DELTA.n '= (. Beta. + 1) .multidot..DELTA.n Therefore, the magnification .beta. Corresponding to the change .DELTA.A in the object distance is given by the mathematical expression 2.

[0034]

## EQU00005 ## .beta. = F / (f + .DELTA.A) From Equation 1, Equation 2, and Equation 3, the focal length of the lens is 300
Table 1 is obtained when the respective reference values of the zooming system of mm, magnification 2.0x to 0.5x, and document size 432 are obtained.

[0035]

[Table 1]

Lens moving plate 1 obtained from the values in Table 1
The relation when the focal length is + 1% is obtained by using 1, and when the conventional adjustment method of the center registration method is simply applied, it can be obtained by using Equations 1 to 5 as shown in Table 2. Becomes

[0037]

[Table 2]

Next, when the correction according to this embodiment is performed, the values shown in Table 3 are obtained.

[0039]

[Table 3]

As is clear from the value of Δn 'after adjustment in Table 3, the amount of movement of the lens at the time of zooming due to an error in the focal length of the zooming system of the corner registration system, an error in the flatness of the mirror and the like, and the fourth The deviation of the registration due to the change in the movement amount of the mirror 6 and the fifth mirror 7 can be reduced.

In the above embodiment, the lens moving plate is rotated about the unit magnification lens position, but it may be rotated about the lens position at a required reference magnification, for example, the two times lens position. Good. Further, the number of elongated holes formed in the lens moving plate may be 3 or 5 or more.

[0042]

As described above, according to the present invention, in the zooming apparatus of the corner registration type, the focal length of the lens can be easily corrected with a simple structure and a simple operation.
It has an excellent effect that the conjugate length can be corrected by the error of the flatness of the mirror and the deviation of the optical axis can be corrected.

[Brief description of drawings]

FIG. 1 is a schematic front view of a variable power device according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of a variable power device according to the embodiment.

FIG. 3 is a plan view of a lens moving plate used in the embodiment.

FIG. 4 is an explanatory diagram showing a shift of an image forming reference point with respect to a movement of an optical axis of a corner registration variable magnification system.

FIG. 5 is a schematic front view of a conventional center registration type scaling device.

FIG. 6 is a schematic plan view of the same zoom device.

FIG. 7 is an explanatory diagram of optical axis movement of a corner registration variable magnification system.

[Explanation of symbols]

 5 lens 10 optical axis 11 lens moving plate 12 same-magnification lens position 16 lens moving groove

Claims (1)

[Claims] 1. In a zooming apparatus for a corner registration type optical machine, wherein a lens moves along a lens moving groove provided in the lens moving plate to change the magnification, the lens moving plate is used as a reference magnification position of the lens. A variable power device for an optical machine characterized by being rotatable around the.