JPH0333774A - Exposure quantity adjusting device for image forming device - Google Patents

Abstract

PURPOSE:To permit a designated image density and the density of an actual image to properly correspond in any area by setting the change rate of the exposure quantity to the image density in an area, in which the designated image density is thin, and in an area in which it is dense, so as to be large. CONSTITUTION:A storage means 31 stores a lamp voltage corresponding to a reference copy density (EXP 4) as to each of photosensitive body sensitivities, namely, high, middle and low, and it stores the change rate of the lamp voltage to the change of the copy density, namely, the inclination of the lamp voltage to the copy density. In such a case, in each characteristic straight line, the change rate of the lamp voltage to the designated copy density in areas (EXP 1-2 and EXP 6-7) in which the image density is dense and thin, are set larger than the change rate in middle areas (EXP 3-5). Thus, even in the case of an application to the image forming device in which the area of the designated image density is wide, the proper image according to the designated image density can be obtained in all areas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for automatically adjusting the exposure amount in an image forming device such as a copying machine.

[Conventional technology]

2. Description of the Related Art Among image forming VR apparatuses such as electrophotographic copying machines, there are known ones that automatically adjust the exposure amount according to the image resolution selected from the outside. In such am, control is performed such that the darker the image 1a is specified, the lower the exposure amount is, and generally, the specified image llr! The relationship between i and the actual exposure amount is given by a simple #i line. In other words, the rate of change in exposure amount with respect to the specified maw degree is specified ii! iaw
It is assumed to be constant regardless of the degree.

[Problem to be solved by the invention]

As mentioned above, in the past, the relationship between the specified 1iIiSS degree and the actual exposure amount was given by a simple right wheel.
The surface potential of the photoreceptor (corresponding to the exposure amount) at the same temperature and l! i
i image i! The relationship with the degree of development is shown in the development sensitivity curve in Figure 10, where in the intermediate image region of 11 degrees, the rate of change in image density with respect to change in surface potential is approximately constant; In the region C where the image [[ is extremely thick and the region A where it is thin, the rate of change of the characteristic iii with respect to the surface potential gradually decreases.

Therefore, as mentioned above, such an iil! that gives a constant rate of change for the entire area! ! When doing this, the image iii is within the dry range of the above v4 area! Although there is no problem when applied to an apparatus with an image density of 1 degree, image formation f! If the range of image density that can be specified is expanded in order to improve the performance of the device, it may become impossible to obtain an appropriate image depending on the density, especially when an extreme image density is set. This will cause inconvenience. That is, conventionally, the area of 11 degrees of the image that can be specified has been limited.

In view of these circumstances, the present invention provides an exposure ti:lll adjustment method for an image forming apparatus that can appropriately adjust the actual exposure amount for iii*11 degrees even when the area of the specified image 111a degrees is wide. The purpose is to provide equipment.

[Means to solve the problem]

The present invention includes a setting means for setting an actual exposure amount for each specified image density, and an adjustment means for adjusting the actual exposure amount based on the set exposure amount, and the setting means is provided for setting an actual exposure amount for each specified image density. (A region with a low IGli degree and a high ft
The structure is such that the rate of change in the actual exposure amount with respect to the change in the specified image 1 [f in the four regions is larger than the rate of change in the intermediate region.

[For production]

According to the above configuration, since the change rate of the exposure amount with respect to the image density is set to be large in areas where the specified image density is light and dark, the specified image density and the 11 degrees of the actual image are properly adjusted in any area. handle.

〔Example〕

A first embodiment of the present invention will be described based on FIGS. 1 to 6.

The copying machine (image forming 1jl) 1 shown in FIG. 5 has a contact glass 2 and a document holder 3 on its upper surface, and an optical system below. The optical system includes a halogen lamp 4 as a light source, mirrors 51 to 54, and a lens 6, and serves to irradiate the image of the document on the contact glass 2 onto the photosensitive drum 7 below. Therefore, II! of the image to be copied! (The degree of copy 'a' varies depending on the exposure amount of the halogen lamp 4.

Around the photosensitive drum 7, as image forming means, a charging device 8, a blank lamp 9, a developing device 10, a transfer bag @
11, a minute 11 device 12, a cleaning device 13, etc. are provided. In addition, in this copy l1lI, as paper conveyance means, a plurality of paper feed cassettes 14, a paper feed roller 15, and a pair of conveyance rollers 16.1 are arranged in order from the upstream side in the conveyance direction.
7, a pair of registration rollers 18, a conveyor belt 19, a fixing device 2o, a pair of discharge rollers 21, a discharge tray 22, and the like are provided.

On the other hand, an operating section 23 as shown in FIG. 6 is disposed at a suitable location on the outer surface of the copying machine 1. As shown in FIG. This operation section 23 includes various operation keys such as a numeric keypad 24 and a print key 27, a display section such as a segment 25, and a copy mode where the user can freely select a desired copy density (image density). It is equipped with a knob 26. In this embodiment, EX
The copy density is selected in seven steps from P1 to EXP7, and the smaller the index, the darker the image is formed.

Further, inside the copying machine 1, an exposure amount adjustment device as shown in FIG. 1 is provided. This @ position adjusts the appropriate exposure amount by appropriately setting the voltage of the halogen lamp 4, and in this embodiment, the adjustment is made in consideration of the sensitivity of the photoreceptor drum 7. has been done.

This device is equipped with a microcomputer 30 having the functions of a storage means 31, a setting means 32, and an adjustment means 33.
Information regarding the sensitivity of the photosensitive drum 7 to be set is input by operating the numeric keypad 24 or the like. In this embodiment, the sensitivity of the photoreceptor drum 7 is input as information about one of "early", "intermediate", and "slow".

The storage means 31 stores the photoreceptor sensitivity, that is, "early"
The lamp voltage corresponding to the reference copy density (EXP4 in this case) for each of "middle" and "slow" and the rate of change of lamp voltage with respect to change in copy am, that is, the slope of lamp voltage with respect to copy density, are stored. . Specifically, as shown in Figure 2, as a general rule, the slower the photoreceptor sensitivity, the larger the lamp voltage value and slope at EXP4 are given, and a characteristic line is given, and based on this characteristic line, each specified The lamp voltage at copy density is calculated. Specifically, the formula of each characteristic line and the lamp voltage at EXP4 are as shown in the table below.

Further, as a feature of the present invention, the rate of change of the lamp voltage with respect to the specified copy S degree in areas with high image density and areas with low image density (in this case, areas of EXP 1 to 2 and EXP 6 to 7) in each characteristic line is in the intermediate area ( It is set to be larger than the rate of change of EXP 3 to 5.Specifically, in each characteristic line, a line with a larger slope than the intermediate area is set for the dark and light areas. The region to be made thicker may be determined based on the development sensitivity curve shown in FIG. 10.

The setting means 32 calculates and sets the lamp voltage for each designated copy density based on the information stored in the storage means 31 and the information regarding the photoreceptor sensitivity inputted from the operation section 23. The adjusting means 33 adjusts the actual voltage of the halogen lamp 4 based on the set lamp voltage, and performs on/off control through the AVR (output circuit) 40.

Next, the adjustment operation performed by this device will be explained with reference to the flowcharts of FIGS. 3 and 4. Third
The figure shows the flow of operations before using the copying machine, and FIG. 4 shows the flow of operations during use.

First, when an arbitrary photoreceptor drum 7 is set in the copying machine 1, the sensitivity information obtained in advance for that photoreceptor drum 7, that is, one of "early", "intermediate", and "slow" is operated. The information is input to the microcomputer 30 using the numeric keypad 24 of the section 23 (step 37 in FIG. 3).

The microcomputer 30 stores this input information and
Based on the information stored in the storage means 31, the lamp voltage for the reference copy density (EXP4) is determined (step S2), and the rate of change (slope) of the lamp voltage with respect to the change in copy density is determined (step 83).
). As described above, this rate of change is individually set for 1ilbR, where the designated copy density is intermediate, and the regions at both ends. That is, at this point, a characteristic straight line corresponding to the sensitivity of the photoreceptor is specified.

After such a preliminary operation, by specifying the desired copy density using the copy density knob 26 (step S4 in FIG. 4) and turning on the print key 27 (step S5),
The lamp voltage for the specified copy 1tf is calculated and set based on the characteristic line (step S8),
A predetermined copying operation is actually performed using the exposure amount corresponding to the designated lamp voltage (step 37).

As mentioned above, this apparatus can perform the development as shown in FIG. 10! i! ! The intermediate tr4F! Since the rate of change is greater than the rate of change of a, even if a particularly extreme copy density is specified, a good image can be formed according to the specified copy density.

Further, in this embodiment, by simply inputting the sensitivity information of the photosensitive drum 7, the lamp voltage can be automatically and quickly adjusted in accordance with the sensitivity. Moreover, since the slope of the lamp voltage with respect to the designated copy of 11 degrees is changed as appropriate according to the sensitivity of the photoreceptor, adjustment can be made in accordance with the sensitivity of the photoreceptor.

Next, a second embodiment will be described based on FIGS. 7 and 8. In this embodiment, the lamp voltage corresponding to the reference copy density is obtained by actual measurement for the set photoconductor drum 7, and the slope is determined based on the input sensitivity information as in the previous embodiment. There is.

As a means for this purpose, as shown in FIG.
is provided, and the detection signal is sent to the microcomputer 30.
is now entered.

Next, the exposure adjustment operation performed by this apparatus will be explained with reference to the flowchart of FIG.

First, after setting the photosensitive drum 7, by copying the test chart (reference original w1) with the reference copy density (EXP4) specified, 81 degrees of the actually copied image is set to the above specified copy density. A lamp voltage that matches this is actually measured, and this measured lamp voltage is set as the lamp voltage corresponding to the reference copy +1 degree (Stellaf 3g).

Next, information regarding the sensitivity of the set photoreceptor drum 7 is inputted from the operation section 23 (step S9). Based on this information, the microcomputer 30 determines the slope (rate of change in lamp voltage with respect to change in designated copy density) for the entire area according to the photoreceptor sensitivity (step 5).
io). The final characteristic line is determined based on this slope and the lamp voltage actually measured in step S8.

That is, in this device, the height of the characteristic straight line in the γ-axis direction as shown in FIG. 2 is actually measured, and the slope is determined based on input information. Thereafter, by performing the same operations as in the flowchart of FIG. 4, a copying operation is performed with an appropriate exposure amount.

In this device, the height in the direction of one wheel of the characteristic straight line shown in FIG. memory etc. is reduced. Also,
When setting the slope on the characteristic line by actual measurement, it is necessary to measure the lamp voltage at two or more specified copy densities, but with this device, it is only necessary to actually measure the lamp voltage at the reference copy myI. The actual measurement time is also reduced to about 1/2.

Next, a third embodiment will be described. Here, each characteristic straight line is stored in the storage means 31, but information is not inputted from the operating section 23 as in the apparatus shown in FIG. I'm trying to get the most out of it.

The adjustment operation will be explained based on the flowchart of FIG. First, after setting the photosensitive drum 7, the lamp voltage for the reference copy density is actually measured and set in the same manner as in step S8 above (step 511).

Next, the photoreceptor sensitivity of the set photoreceptor drum 7 is calculated from the lamp voltage at this reference copying temperature of 11 degrees (
Step 512). Since the storage means 31 stores the relationship between the specified copy S degree and the lamp voltage according to the photoconductor sensitivity, the photoconductor sensitivity can be calculated by knowing the lamp voltage at the standard copy m degree. be. For example, if the lamp voltage actually measured at the standard copy density is 65V, it can be known from the above table or the characteristic line in FIG. 2 that the photoreceptor sensitivity of the photoreceptor drum 7 belongs to the "intermediate" group. I can do it. The slope of the characteristic straight line is determined based on this photoreceptor sensitivity (step S8), and copying operations similar to those in the flowchart of FIG. 4 are performed, thereby making it possible to perform copying with an appropriate exposure amount. Note that if the actually measured voltage values are not on each straight line, the photoreceptor sensitivity corresponding to the straight line closest to that value is selected as the actual photoreceptor sensitivity.

According to the apparatus of this embodiment, the actual measurement value of the lamp voltage at the reference copy S degree is used to calculate the photoreceptor! Since 8 degrees of Ii is extracted, even if the sensitivity of the photoreceptor to be set is not known in advance, the appropriate exposure amount can be adjusted according to the actual rsfi.

There is also the advantage that the operation of inputting information regarding the photoreceptor sensitivity can be omitted.

Note that the present invention is not limited to the above-described embodiments, and may take the following embodiments as examples.

(1) In the above embodiment, the relationship between the copy density and the exposure amount in areas where the specified copy IIa is dark and light is set as a straight line, but this portion is set as a straight line in the developing sensitivity curve shown in FIG. It may also be set using a corresponding curve. In this case, the rate of change in exposure amount with respect to change in copy density is E
It will gradually increase towards XPl or 7.

(2) In the above embodiment, an adjustment device that also takes into account the sensitivity of the photoreceptor is shown, but the present invention is an apparatus that performs adjustment regardless of the S degree of the photoreceptor, that is, the sensitivity range of the photoreceptor used is small. Similar effects can be obtained as an adjustment device for an image forming apparatus.

(3) Regarding one designated copy, in the above embodiment, it is divided into seven ranks, but this can also be applied to those that are adjusted in an analog manner.

(4) In the above embodiment, the characteristic straight line is stored in the microcomputer 30, but in the case where the designated copy 1 degree is digitally set as shown in the same embodiment, it corresponds to each m degree. (5) In the above embodiment, the reference copy a degree (reference image density) is set to the intermediate value (EXP4), but this image 11 degree It may be based on concentration.

[Effects of the Invention] As described above, the present invention calculates the rate of change in exposure amount with respect to a change in image 81 degrees in areas where the image density is high and low, that is, in areas where the image density is difficult to change. Since the rate of change is larger than the rate of change, even if it is applied to a III image forming apparatus with a wide range of designated image * density, it is effective in obtaining an appropriate image for the designated image once in the entire area. be.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the exposure amount adjustment device according to the first embodiment of the present invention, FIG. 2 is a graph showing the relationship between the copy Iff stored in the EJ adjustment device and the lamp voltage, and FIGS. The figure is a flowchart showing the adjustment operation performed by the same Ill! device, FIG. 5 is an overall configuration diagram of a copying machine equipped with a synchronized I! Figure 7 is a block diagram of the exposure adjustment device in the second embodiment, Figure 8 is a flowchart showing the adjustment operation performed by the adjustment equipment, and Figure 9 is the third height/Il.
! A flowchart showing the adjustment operation performed by the exposure amount adjustment device in Example i, and FIG. 10 is a graph showing the development sensitivity curve. DESCRIPTION OF SYMBOLS 1... Copying machine (image forming device), 4... Halogen lamp, 7... Photosensitive drum, 30... Microcomputer, 31... Storage means, 32... Setting means,
33... Adjustment means, a... Area with low image density, b
... intermediate area, C... image @ high density area.

Claims (1)

[Claims] 1. A setting means for setting the actual exposure amount for each specified image density, and an adjusting means for adjusting the actual exposure amount based on the set exposure amount, and the setting means is set when the specified image density is 1. An exposure amount adjustment device for an image forming apparatus, characterized in that the rate of change in the actual exposure amount with respect to the change in the specified image density in the light area and the dark area is greater than the rate of change in the intermediate area.