JPS6358431A - Automatic exposing device - Google Patents

Abstract

PURPOSE:To simplify initial setting work for automatic exposure by generating the light intake quantity-proper exposure characteristic by an arithmetic means on the basis of two light intake quantities and proper exposures obtained from a proper quantity setting means. CONSTITUTION:The quantity of light intake and quantity of proper exposure corresponding to originals of two kinds of density are obtained from a proper quantity setting means, and quantity of light intake-quantity of proper exposure characteristic is generated by an arithmetic means on the basis of two quantities of light intake and quantities of proper exposure obtained. Initial setting for automatic exposure is made thereby, and thereafter, copies of proper density are obtained by selecting automatically proper exposure corresponding to the density of original basing on the quantity of light intake-proper exposure charac teristic. In case of the two kinds of originals are newspapers and standard originals for setting, the quantity of light intake-quantity of proper exposure characteristic approximate to desirable quantity of light intake-quantity of proper exposure can be generated basing on the two originals different consider ably in density.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an automatic exposure apparatus, and more particularly, to an automatic exposure apparatus that controls the output light intensity of a light source in accordance with the density of a document.

<Prior Art> Conventionally, automatic exposure apparatuses have been provided in a pre-scan type and a real-time type.

The pre-scan method described above has a configuration in which the document is exposed to light before performing the image forming operation, and the optimum power applied to the light source is set for the portion with the lightest density.

Further, the real-time method is configured to read the density of the original while performing the image forming operation and set the optimum power applied to the light source for the density of the original at each point in time.

In either method, it is necessary to initially set the received light amount-appropriate exposure amount characteristic for automatic exposure, and manual operations are required to perform the initial setting.

To explain in more detail, the above-mentioned manual operation involves visually checking the density of the copy by copying the newspaper and the standard original for setting one sheet at a time, and performing manual operations to ensure that the density of the copy is at an appropriate value. Adjustments are being made.

<Problems to be Solved by the Invention> Even in the automatic exposure apparatus of the above-mentioned former type, in order to perform initial settings, it is necessary to copy newspapers and standard manuscripts for settings one by one, and the resulting copies. It is necessary to adjust the exposure amount based on the density (in case 2), it is necessary to repeat the above operation many times, so it is necessary to initialize the received light amount-appropriate exposure amount characteristics for automatic exposure as a whole. Not only does the work for setting up become complicated,
There is a misunderstanding that the time required will be longer.

<Object of the invention> This invention was made in view of the above problems,
The purpose of the present invention is to provide an automatic exposure device that can simplify the work for initially setting the received light amount-appropriate exposure amount characteristic for automatic exposure.1. ing.

Means for Solving the Problems> In order to achieve the above object, the automatic exposure apparatus of the present invention has an appropriate amount setting means for obtaining a received light amount and an appropriate exposure amount corresponding to originals of two types of density. , a calculation means for generating a received light amount-appropriate exposure amount characteristic based on the two amounts of received light obtained by the appropriate amount setting means and the appropriate amount of exposure.

However, the above two types of originals are preferably newspapers and standard originals for settings, and the calculation means may be one that generates a linear received light amount-appropriate exposure amount characteristic. .

Function> In the automatic exposure device having the above configuration, the exposure amount is changed based on the original density to obtain a copy with the appropriate density. The received light amount and the appropriate exposure amount corresponding to the original are obtained, and the received light amount--appropriate exposure amount characteristic is generated by the calculation means based on the two received light amounts obtained by the appropriate amount setting means and the appropriate exposure amount. , perform initial settings for automatic exposure, and then automatically select the appropriate exposure amount corresponding to the original density based on the above-mentioned received light amount-appropriate exposure amount characteristic to obtain copies with appropriate density. can.

In addition, when the above two types of originals are a newspaper and a standard original for settings, based on the two originals with considerably different densities, a received light amount-appropriate exposure amount characteristic that approximates the desired received light amount-appropriate exposure amount characteristic is determined. can be generated.

Furthermore, when the calculation means generates a linear received light amount--appropriate exposure amount characteristic, the received light amount-- is calculated based only on the received light amount and the appropriate exposure amount for the two types of originals.
Appropriate exposure amount characteristics can be generated.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 5 is a schematic diagram showing an embodiment of the automatic exposure apparatus of the present invention, which includes an exposure lamp (S) for exposing an original (D) set on the upper surface of a reciprocally movable original platen (1); It has a slit (a) and a lens (3) that guide the reflected light from the document (D) to the photosensitive drum (4).The light receiving sensor (S have.

FIG. 4 is a block diagram showing the electrical configuration of the automatic exposure apparatus, in which the reflected light amount detection signal from the light receiving sensor (S) is transmitted to the CPU, RAM, ROM, etc. via an A/D converter (not shown) and a manual interface. It also supplies the control signal output from the microcomputer (6) to the exposure lamp lighting circuit port via an output interface (not shown) and a D/A converter. .

FIGS. 1 and 2 are flowcharts illustrating the operation of the automatic exposure apparatus. FIG. 1 shows the initial setting operation, and FIG. 2 shows the automatic exposure operation.

First, to explain the initial setting operation, set the standard document for setting (hereinafter abbreviated as NTC) in step ■, wait until the print key is turned ON, and then start moving the document table (1) in step ■. , In step (2), the exposure lamp (S) is turned on so that the exposure amount reaches the intermediate value EXP5 (see Fig. 3), and
In step (2), wait until the document leading edge timing switch (not shown), which also serves as the timing for transporting the copy paper, is turned on, then in step (2) wait for a predetermined time, and in step (2), sample the light reflected from the leading edge of the document In other words, in a normal document, the leading edge is the background, so the shading of the background is detected, and the average value (I) of the amount of sampled received light is calculated in step (2) (see Figure 3). , stored in memory.

Next, in step (2), the exposure amount of the exposure lamp (S) is set to the lower limit value EXP4 (see Figure 3), and after waiting until the exposure amount of the exposure lamp (S) is stabilized in step (2), the exposure amount of the exposure lamp (S) is set to the lower limit value EXP4 (see Figure 3). The time required is several 1
The reflected light is sampled over a period of about 0isec),
Average value of sampled received light amount (■) at step ■
(see Figure 3) is calculated and stored in memory.

Thereafter, in step (2), the document table (1) is returned to the home position, a newspaper or a standard document for newspapers is set, and the same determination and processing as in steps (2) to (2) are performed.

However, the average value [1[) (see Figure 3) is calculated based on the amount of received light sampled by exposure fiEXP5, and instead of sampling at the lower limit EXP4, sampling is performed at the upper limit EXP6 (see Figure 3). However, the difference is that the average value ■ (see Figure 3) is calculated.

Therefore, by performing the above series of operations, it is possible to obtain the average value of the received light amount corresponding to the lower limit and the intermediate value of the exposure amount for NTC, and also to obtain the average value of the amount of light received corresponding to the lower limit value of the exposure amount for NTC and the intermediate value, and also to obtain the average value of the amount of light received corresponding to the lower limit value of the exposure amount for NTC and the intermediate value, and also The average value of the amount of received light corresponding to the upper limit value and the intermediate value can be obtained.

Next, automatic exposure operation will be explained.

In step ■, the exposure amount is set to the intermediate value EXP 5, and in step ■, the document leading edge timing switch is set to OFF.
After waiting for a predetermined time in step (2), the reflected light from the leading edge of the document is sampled for a short time (about several m5ec) in step (2), and the average value M of the sampled received light amount is calculated in step (2). Then, in step ■, an intermediate value ■ between the above average value (I) and the average value l is calculated, and in step ■, the above average value M
The magnitude relationship between the average value M and the intermediate value ■ is determined, and if the average value M is larger, the exposure amount is set to the lower limit EXP in step ■.
4, and if the average value M is smaller, the exposure amount is set to the upper limit value EXP6 in step (3). After performing any of the above steps, proceed to step O.
Wait for a predetermined time until the exposure stabilizes, and in step 0 sample the reflected light from the document for a predetermined time to calculate the average value ■.
In this step, a ratio A of the difference between the current exposure value and the lower limit value EXP4 to the difference between the upper limit value EXP6 and the lower limit value EXP4 is calculated. After that, in step (2), the appropriate amount of received light B corresponding to the current exposure value is calculated. Specifically, B-A [[
Vl- (obtained by calculating I[]l + (If)), by dividing the difference between the above average value ■ and the appropriate amount of received light B by a predetermined value n determined by the copying machine in step ■. , a determination reference value C is calculated, and it is determined in step (2) whether or not the determination reference value C is positive.

If the judgment reference value C is determined to be positive in the above step If it is determined that the value is 1 or more, the value obtained by dividing the judgment reference value C from the above-mentioned current exposure value is set as the appropriate exposure value in step (2), and in step (2) it is determined whether the above value is smaller than the lower limit value EXP4. Determine whether or not. If it is determined that the exposure value is smaller than the lower limit value EXP4, the lower limit value EXP4 is set as the appropriate exposure value in step (3), and it is determined in step [phase] whether or not the exposure has ended. If it is determined that the exposure has been completed in step (2), the exposure lamp (S) is turned off in step (2), and conversely, if it is determined that the exposure has not been completed, the step [phase] is continued. The automatic exposure operation is continued by performing the following determination and processing.

In addition, if it is determined that the determination reference value C is less than 1 in the above step [phase], step [phase] is performed without changing the exposure value in order to prevent flickering of the copy.
If the lower limit value EXP is determined to be equal to or higher than the lower limit EXP4 in step [stock], the following determination and processing are performed in step [phase] based on the exposure value obtained in step @. Do the following.

Furthermore, if the judgment reference value C is determined to be negative in the above step (■), the judgment reference value C is converted into a positive value C' in the step [phase], and the value C is determined in the step (■).
- is 1 or more, and if it is 1 or more, it is determined in step 0 whether or not the current exposure value is greater than the lower limit EXP4, and the lower limit EXP4 is determined.
If it is determined that the value is larger than that, the value obtained by adding the value C to the current exposure value is set as the appropriate exposure value in step 0, and the above value is set as the upper limit EXP in step [phase].
It is determined whether the value is greater than 6 or not. And upper limit EXP
If it is determined that it is larger than 6, step [phase]
In this step, the upper limit value EXP6 is set as the appropriate exposure value, and the determination and processing in step [phase] and subsequent steps are performed.

In addition, if the value C' is determined to be less than 1 in step 0 above, in order to prevent flickering of the copy, the determination and processing in step [phase] and below are performed without changing the exposure value. , Even if it is determined that the lower limit value EXP is equal to or less than 4 in the above step [phase], the determination and processing below the step [phase] is performed as is, and if it is determined that the upper limit value EXP is equal to or greater than 6 in the above step [phase]. In this case, the determination and processing in step [stock] and subsequent steps are performed based on the exposure value obtained in step 0.

To summarize the above, four simple arithmetic operations and determination of size relationships are performed based on the initial setting values obtained in the flowchart of Fig. 1 and the amount of received light obtained by actually exposing the original. Accordingly, it is possible to obtain an appropriate amount of exposure and obtain a copy with an appropriate density. In addition, if the appropriate exposure amount is set to the lower limit value EXP4 -1, it continues to be held at the lower limit value EXP4, so even if a solid black part is detected midway through, the image quality will deteriorate at the periphery of the solid black part. There's nothing to do.

Note that the present invention is not limited to the above-mentioned embodiment. For example, in the embodiment shown in FIG. 2, it is possible to calculate the value obtained by adding the temperature correction value in step (■) as the determination reference value C. In addition, by installing a dedicated switch for detecting the timing of receiving reflected light from a document, it is possible to omit step 1 in FIG. 1 and step 2 in FIG. Various design changes can be made without changing the gist of the invention.

<Effects of the Invention> As described above, the present invention obtains the exposure value and the light reception value from the original by exposing two types of originals with different densities once, and automatically calculates the After completing the initial settings for exposure and performing automatic exposure operation,
Based on the above factors, an appropriate exposure value can be obtained corresponding to the density of the original, and the time required for initial setting for automatic exposure can be significantly shortened, which is a unique effect.

[Brief explanation of the drawing]

Fig. 1 is a flowchart explaining the initial setting operation of the automatic exposure device, Fig. 2 is a flowchart explaining the automatic exposure operation, and Fig. 3 is a received light amount-appropriate exposure amount characteristic explaining the initial setting operation and automatic exposure operation. FIG. 4 is a block diagram showing the electrical configuration of an embodiment of an automatic exposure apparatus, and FIG. 5 is a schematic diagram showing the main parts of an automatic exposure copying machine. [S... Optical sensor, (6)... Microcomputer, (7)... Exposure lamp lighting circuit, (S)... Exposure lamp Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Claims] 1. In an automatic exposure device that changes the exposure amount based on the density of the original to obtain a copy with an appropriate density, the amount of received light and the appropriate exposure amount corresponding to originals with two types of densities are provided. and 2 obtained by the appropriate amount setting means.
1. An automatic exposure apparatus comprising: two received light amounts, and a calculation means for generating a received light amount-appropriate exposure amount characteristic based on the received light amount and the appropriate exposure amount. 2. The automatic exposure apparatus according to claim 1, wherein the two types of documents are a newspaper and a standard document for setting. 3. The automatic exposure apparatus according to claim 1, wherein the calculation means generates a linear received light amount-appropriate exposure amount characteristic.