JP3086730B2 - Optical Machine Magnifier - Google Patents

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 for an optical machine such as a copying machine, and more particularly to a variable power device for correcting a change in a conjugate length due to an error in a focal length of a lens, an error in flatness of a mirror, and the like. It relates to a doubling device.

[0002]

2. Description of the Related Art Generally, a copying machine is provided 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.

In the center registration type magnification changing apparatus, the image forming center does not move when the magnification is changed, and the movement of the lens accompanying the magnification changes along a fixed optical axis.

A conventional center registration type variable magnification apparatus will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a glass on which a document is placed;
The surface in contact with the upper surface of the glass 1 is the document surface 17. 2,
Reference numerals 3 and 4 denote a first mirror for guiding an image on the original surface to the lens 5, and a second mirror.
Reference numerals 6, 7 and 8 denote fourth, fifth and sixth mirrors for guiding the image pickup to the photosensitive drum 9, and the fourth and fifth mirrors 6 and 7 correspond to the optical axis 10 respectively. It is possible to move along.

In such a center registration type copying machine, when a change in the conjugate length due to an error in the focal length of the lens, an error in the flatness of the mirror, or the like is corrected, 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. Also, at the time of zooming, the amount of movement of the lens and the amount of movement of the fourth mirror 6 and the fifth mirror 7 are adjusted according to the degree of completion of the lens 5 and each mirror from among several numerical values prepared in advance. It is general to select and adopt the one that gives the best value for the magnification.

In such a center registration type variable magnification apparatus, for example, when one side on the original side is used as a reference, a phenomenon occurs that an image forming position is shifted due to magnification, and operability is reduced.
There is a problem in handling. Therefore, at present,
2. Description of the Related Art A corner registration type variable magnification device in which one side serving as a reference is formed on the image forming side when a side is used as a reference has been widely used.

In the variable magnification apparatus of the corner registration type, as shown in FIG. 7, the lens 5 is moved in the direction of the optical axis and also in the direction perpendicular to the optical axis. 10 moves.

In FIG. 7, reference numeral 17 denotes a document surface at the same magnification, 17a denotes a document surface at the time of enlargement, 17b denotes a document surface at the time of reduction, 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 at the same magnification, 18a is the image at the time of enlargement, Reference numeral 18b denotes an image formed at the time of reduction.

In general, a lens moving mechanism of the corner registration type includes a lens moving plate provided with a lens moving groove, and moves the lens along the moving groove.
Corresponding to the movement of the lens in the direction of the optical axis, the movement of the optical axis in the direction perpendicular to the optical axis is similarly performed.

[0011]

In such corner registration as well, errors in the focal length of the lens, errors in the flatness of the mirror, and errors in the installation of the mirror must be corrected. In the method of simply moving the lens as in the center registration method, displacement in the direction perpendicular to the optical axis also occurs due to movement in the optical axis direction, which leads to misregistration of the image. It is not possible to adopt a correction method that merely moves the.

Therefore, conventionally, a very complicated operation of preparing several types of lens moving plates having different curves of the moving grooves and performing correction while appropriately replacing the lens moving plates according to the completed condition of the lens and the mirror. Had gone. For this reason, the workability is poor and the cost is increased due to the need to prepare a plurality of types of lens moving plates.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims to provide a zooming device which can easily perform correction with one kind of lens moving plate.

[0014]

SUMMARY OF THE INVENTION The present invention relates to a variable magnification apparatus for a corner registration type optical machine in which a lens moves along a lens moving groove provided in a lens moving plate to change the magnification. The moving plate is rotatable around a reference magnification position of the lens.

[0015]

In the variable magnification apparatus of the corner registration type, the error of the lens and the error of 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]

An embodiment of the present invention will be described below with reference to the drawings.

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

In the drawing, reference numeral 11 denotes a lens moving plate, in which a lens moving groove 16 is provided, and a slide pin 14 provided in the lens moving groove 16 so as to match the center of the lens is slidable. It is movably fitted.

By sliding the lens 5 along the lens moving groove 16 by a required means, the image can be enlarged or reduced based on a required point.

Next, correction in this embodiment will be described.

The lens moving groove 16 of the lens moving plate 11
At a predetermined position, that is, a position 1 of the lens which is expected at the time of equal magnification.
2 and arc-shaped long holes 13 a, 13 b, 13 c, and 13 d centered on the same-magnification lens position 12, so that the lens moving plate 11 can rotate by a required angle about the same-magnification lens position 12. I do.

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

First, an explanation will be given of the error correction in the equal magnification state.

The lens moving plate 11 is mounted on an apparatus main body (not shown), and the lens 5 is set at the same-magnification lens position 12. 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 lens position 12
The amount of movement of the lens 5 with respect to
For the amount of movement of the mirror 7, a value at which the combination of focus and magnification is optimal is appropriately selected from numerical values prepared in advance.

If the optical axis shifts from a predetermined position, that is, the registration is misaligned at the time of the magnification change, the lens moving plate 11 is rotated around the equal-magnification lens position 12 so that the registration can be performed. Correct the inconsistency.

Although the above embodiment has been described with respect to a variable magnification apparatus having six mirrors, the same applies to a four-magnification magnification apparatus which directly projects the fourth mirror 6 onto the photosensitive drum 9. In this case, the adjustment of the conjugate length is performed by moving and rotating the fourth mirror 6 instead of moving the fourth mirror 6 and the fifth mirror 7.

The operation of the embodiment for correcting the registration will now be described.

When f is the focal length of the lens 5 and β is the imaging magnification, the object distance A is given by the following equation (1) according to the lens formula.

[0030]

A = (1 + 1 / B) f The change amount ΔA of the object distance from the case of the same magnification is represented by Expression 2.

[0031]

## EQU2 ## From FIG. 7, which shows the relationship of the variable magnification system of the corner registration method, ΔA = (1 / β-1) f. The deviation of the registration Δn ′ when the optical axis moves by Δn as shown in FIG.

[0032]

Δ３ = y (β = 1) / 2 (β + 1)

[0033]

Δn ′ = (β + 1) · Δn Therefore, according to Expression 2, the magnification β corresponding to the change ΔA in the object distance is expressed by Expression 5.

[0034]

Β = f / (f + ΔA) From equations 1, 2, and 3, the focal length of the lens is 300
Table 1 shows the respective reference values of the variable power system of mm, magnification 2.0x to 0.5x, and document size 432.

[0035]

[Table 1]

The moving plate 1 of the lens obtained from the values in Table 1
The relationship when the focal length is + 1% is obtained by using Equation (1). When the adjustment method of the conventional center registration method is simply applied, the relationship is obtained by using Equations (1) to (5). Becomes

[0037]

[Table 2]

Next, when the correction according to the present 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 lens movement amount during zooming due to the focal length error of the corner registration type zooming system, the flatness error of the mirror, etc. 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 same-magnification lens position. However, the lens moving plate may be rotated about the lens position at a required reference magnification, for example, about the double-magnification lens position. Good. Further, the number of the long holes formed in the lens moving plate may be three or five or more.

[0042]

As described above, according to the present invention, in a corner registration type variable magnification device, the focal length of the lens can be easily corrected by a simple operation with a simple operation.
This provides an excellent effect that the conjugate length can be corrected due to an error in the flatness of the mirror and the deviation of the optical axis can be corrected.

[Brief description of the drawings]

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

FIG. 2 is a schematic plan view of a variable power device according to the first 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 imaging reference point with respect to a movement of an optical axis of a corner registration variable power system.

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

FIG. 6 is a schematic plan view of the variable magnification device.

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

[Explanation of symbols]

 5 Lens 10 Optical axis 11 Lens moving plate 12 1: 1 lens position 16 Lens moving groove

Claims (1)

(57) [Claims] In a magnification changing device of a corner registration type optical machine in which a lens moves along a lens moving groove provided in a lens moving plate to change the magnification, the lens moving plate is moved to a reference magnification position of the lens. A magnification changing device for an optical machine, characterized in that it is rotatable around a center.