JPH0622838Y2 - Light control device for copiers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a copying machine having a zoom function, and more particularly to a light quantity control device thereof.

[Conventional technology]

As a variable-magnification copying machine, there is a copying machine having a so-called zoom function capable of continuously changing the magnification between 50% and 200%. In such a copying machine,
The position of the optical system such as the lens and mirror is changed according to the set magnification. At this time, the exposure amount on the photoconductor changes due to the reason that the optical path length changes according to the set magnification,
There is an inconvenience that the copy density varies depending on the magnification.
Therefore, it is necessary to adjust the light quantity of the exposure lamp according to the magnification as shown in FIG. Also, this light quantity must be corrected at the time of factory shipment due to the problem of variations in the copying machine.

In order to completely correct this light amount correction according to the magnification,
For example, if the magnification can be adjusted in 1% increments, then 15
It needs to be adjusted at one point, which is very troublesome. For this reason, in a conventional copying machine, as shown in FIG.
%, 65 to 82%, 83 to 122%, 123 to 164%, and 165 to 200% were divided into 5 groups and the light intensity targets were set.

[Problems to be solved by the invention]

However, when divided into groups like this, for example, 64%
When the magnification is changed from 65% to 65%, the light amount may be discontinuously changed as shown in FIG. 8 and the image quality may be different.
Further, since the light amount target of each group is individually adjusted, for example, in the case where the division is performed as shown in FIG. 8, the adjustment process is required five times and it takes a long time to perform the adjustment.

The present invention has been devised to solve the above problems, and simplifies the adjustment by obtaining a continuous light amount target from the light amount target at a specific magnification.
The purpose is to prevent a difference in image quality due to a stepwise change in the amount of light.

[Means for solving problems]

In order to achieve the above-mentioned object, a light quantity control device of a copying machine according to the present invention, in a copying machine having a zoom function, has a first memory for storing a standard light quantity target and a first memory for storing the standard light quantity target. A second memory for storing each light amount target obtained when performing exposure on at least three points at the same magnification, enlargement and reduction based on the standard light amount target, and the first and second memories. Of the standard light amount target and the respective light amount targets according to the set magnification, and interpolating means for obtaining the light amount target corresponding to the set magnification by interpolation, and the light amount target obtained by the interpolating means. And a means for adjusting the amount of light are provided.

[Action]

In the present invention, the correction of the light amount target is performed by multiplying the light amount target (shown by the solid line) shown in FIG. 1 (a) by a constant coefficient.
As shown in (b), the light level target (shown by the one-dot chain line) in which the overall level is corrected is used, and as shown in FIG. 1 (c), the light amount target at equal magnification (100%) is expanded without changing. The side light amount target and the reduction side light amount target are divided into those which are corrected light amount targets (shown by the one-dot chain line). Then, by combining these corrections, the total light amount target is corrected as shown in FIG. 1 (d).

The corrected light amount target thus obtained is stored in the memory. Then, at the time of copying, a light amount target corresponding to the set magnification is obtained by interpolation from these light amount targets,
The light quantity of the exposure lamp is controlled to an appropriate value according to the set magnification.

〔Example〕

Hereinafter, features of the present invention will be specifically described based on embodiments with reference to the drawings.

FIG. 2 is a block diagram of a control circuit of a copying machine to which the light quantity control device according to the present invention is applied.

In the figure, reference numeral 1 is a microprocessor for controlling the entire copying machine.
By changing the position of the optical system such as the input key 2 for inputting the reduction ratio, the instruction to start copying, the scanning of the document, the rotation of the photoconductor, the transportation of the paper 3, the lens, the mirror, etc. A variable magnification device 4 for changing the copying magnification, a light amount adjusting device 5 for adjusting the light amount of the exposure lamp 6, a ROM (read only memory) 7 in which a standard light amount target is recorded, and a correction amount due to variations of the copying machine. The non-volatile memory 8 and the like are connected.

A procedure for adjusting the light amount target in such a copying machine will be described with reference to FIGS. Note that FIG. 3 is a standard light amount target diagram, FIG. 4 is a diagram with overall lens correction, FIG. 5 is a diagram with enlargement side correction, and FIG. 6 is a diagram with reduction side correction.

Now, it is assumed that the light amount target as shown in FIG. 3 is recorded in the ROM 7. Since this light amount target is a standard one, it is necessary to correct this light amount target according to the variation of each copying machine.

First, the light amount is adjusted according to the magnification of 100%. For example, an optical sensor is arranged on the photoconductor portion, and the light amount of the exposure lamp 6 is adjusted so that the light amount on the photoconductor becomes a predetermined constant value. Alternatively, the light amount of the exposure lamp 6 is adjusted so that the best image quality is obtained by actually making a copy. At this time, if the required light intensity is 11, the overall level is 10
%, And the light quantity shown in FIG. 4 is used as the light quantity target. This correction corresponds to the correction shown in FIG.

Next, the light amount is adjusted according to the magnification of 200%. Here, when the required light amount is 112, the current light amount target is 85% at a magnification of 200%. At this time, the correction value on the enlargement side other than 200%, for example, the correction value L ₁₂₀ for the magnification of 120% is linearly approximated by the interpolation calculation as follows, and the light amount target is as shown in FIG. However, L ₁₂₀ ′ is the current light amount target.

In other words, the current 15% reduction is at the 200% magnification, so the reduction is 3% at the 120% magnification.

Next, the light amount is adjusted according to the magnification of 50%. The required amount of light
When it reaches 80, the target amount of light will be the current 20% increase with 50% magnification. Correction value on the reduction side other than 50%, for example, magnification 70
The% correction value L ₇₀ is interpolated as follows, and the light amount target is as shown in FIG. However, L ₇₀ ′ is the current light amount target.

In other words, the current 20% increase at the position of 50% magnification,
12% increase at 70% magnification.

The correction on the enlargement side and the reduction side corresponds to the correction in FIG.

The difference between the light amount target at three points with the magnifications of 50, 100, and 200% or the standard light amount target obtained by the above-described procedure is stored in advance in the nonvolatile memory 8 shown in FIG.
At this time, the variation of each copying machine needs to be corrected for only three points, so that the adjustment becomes easy.

Next, the operation of the above copying machine when copying is described.

First, when the number of copies, a reduction ratio, etc. are input from the ten keys of the input keys 2, the magnification changing device 4 controls the optical system of the copying machine to change the copying magnification. Next, enter key 2
When the start key is pressed, the copying unit driving device 3 starts the copying operation and a predetermined number of copies are made. At this time, the light amount adjusting device 5 controls the light amount of the exposure lamp 6 based on the light amount target previously stored in the nonvolatile memory 8 according to the set magnification and the variation of each copying machine. That is, the light amount target corresponding to the magnification set by the input key 2 is obtained by the interpolation calculation by the microprocessor 1 from the light amount targets at the three points read from the nonvolatile control memory 8.

Therefore, the exposure lamp 6 changes according to the set magnification.
In addition, it emits light with a light amount in which the variation of the copying machine is corrected. This makes it possible to obtain an appropriate exposure amount at any magnification and obtain a good quality image.

[Effect of device]

As described above, in the present invention, the light amount targets in which the variation of each copying machine is corrected are obtained at a predetermined number of magnifications, and at the time of copying, the light amount targets are interpolated to the set magnification by interpolation. I am trying to get a corresponding light intensity target. Therefore, the variation of each copying machine can be easily corrected, the adjustment process can be greatly reduced, and an appropriate light amount can be obtained at any magnification. In this way, since the light amount does not change discontinuously depending on the magnification, it is possible to always obtain a copy of uniform image quality.

[Brief description of drawings]

FIG. 1 is a graph illustrating the basic concept of light quantity adjustment, second
FIG. 3 is a schematic block diagram of a copying machine to which the light amount control device is applied, FIG. 3 is a standard light amount target diagram, FIG. 4 is a diagram with overall level correction, and FIG. 5 is a diagram with enlargement side correction, FIG. 6 is a diagram with reduction side correction, FIG. 7 is a continuous light amount target diagram,
FIG. 8 is a stepwise light amount target diagram in a conventional copying machine.

Claims (1)

[Scope of utility model registration request] 1. In a copying machine having a zoom function, a first memory for storing a standard light amount target, and at least an equal magnification based on the standard light amount target stored in the first memory, A second memory for storing each light amount target obtained when exposure is performed for three points at the time of enlarging and reducing, and the standard amount of light from each of the first and second memories according to a set magnification. It is characterized in that an interpolating means for reading out the target and each of the light quantity targets to obtain a light quantity target corresponding to a set magnification by interpolation and a means for adjusting the light quantity according to the light quantity target obtained by the interpolating means are provided. Light control device for copiers.