JP2512501B2 - Image density control device - Google Patents

Description

The present invention relates to an image density control device of an image forming apparatus in which a copy image density is set to a predetermined level in advance and which can be manually corrected, and an electrophotographic copying machine or a facsimile. Used for etc.

(B) Conventional Technology Conventionally, in such an image density control device, the copy image density is set to a predetermined density level in advance at the start of copying work. However, this density level does not necessarily match the user's preference. However, there is a problem in that even if the level is appropriate for the user, the set level changes due to fatigue of the drum of the copying machine, dirt of the optical system, fatigue of the developer, and the like. .

Therefore, a control device that detects the density level with the highest setting frequency and sets it to that level (for example, Japanese Patent Laid-Open No. 61-77066).
Japanese Patent Laid-Open No. 60-207156), a setting device for detecting an average value of density levels used, and setting the level corresponding to the average value (for example, see Japanese Patent Laid-Open No. 60-207156).

(C) Problems to be Solved by the Invention However, in the former case, for example, when a white original and a colored original are mixed and copied, the copy density level manually set correspondingly becomes large. Since the change occurs, the concentration level set at the start of injection changes drastically and rapidly, which causes confusion when setting the concentration level. In the latter case, the average of the density levels actually set, that is, an intermediate density level that is not actually used is set, which is not practical.

The present invention has been made in consideration of such circumstances, and provides an image density control device that is automatically set to a density level that is always convenient for the user.

(D) Means for Solving the Problems FIG. 1 is a block diagram showing the configuration of the present invention.
1 is a setting means capable of setting a density level selected from a plurality of density levels as a reference density level, 103 is a manual correction means for manually correcting the set reference density level, 104
Is a counting means for counting the number of image formations for each density level when a predetermined number of image formations are completed, and 105 is a weighting coefficient set in advance corresponding to each density level to the number of image formations for each density level. Numeral 106 is a weight adding means for multiplying and adding weight, and is a judging means for judging the density level at which the weighted value shows the maximum value and causing the setting means 102 to reset it as the reference density level.

(E) Operation The image forming apparatus 101 performs image formation with various image density levels corrected and set by the manual correction means 103, and the number of images for each set level is counted by the coefficient means 104. When the weight adding means 105 adds a desired weight corresponding to each density setting level to the number of copies for each setting level, the determining means 107 then determines the density level indicating the optimum value, and the setting means 102. Sets its density level and prepares for the next image forming operation. By setting the image density level in this manner, even if manual correction is frequently performed during image formation, the image density level that is convenient for use is set without being affected by it.

(F) Embodiments The present invention will be described below based on embodiments shown in the drawings. This does not limit the present invention.

FIG. 2 is a block diagram showing a main circuit of an embodiment of the present invention. 11 is a microcomputer (hereinafter referred to as a microcomputer) having RAM, CPU, ROM and I / O ports built therein, 12 is a copy key 12a, and copy. A keyboard having various operation keys such as a number-of-sheets setting key 12b and a copy density setting key 12c, which is input to the I / O port of the microcomputer 11, and 13 indicates nine levels of density levels to be set A display device for displaying "8", an exposure amount control device 14 for controlling the exposure amount of the document in accordance with the image density level displayed on the indicator light 13a in response to the output of the microcomputer 11, and 15 various settings of the keyboard 12 The control device controls various copying operations according to copying conditions set by keys.

The operation of such a copying machine will be described with reference to the flowcharts shown in FIGS. First, in FIG. 3, a power switch (not shown) is turned on (step 20).
1) When the copying conditions such as the number of sheets and the document density are set by the keyboard 12 (step 202) and the copy key 12a is turned on (step 203), a plurality of operations corresponding to the set copying conditions are performed by the controller 15. Then, the exposure amount control device 14 executes it (step 204), and the copying operation ends (step 205). By the way, step 203 and step 20
Between 4 and 4, the subroutine (SUB1) shown in FIG. 4 is inserted. In FIG. 4, the set density setting level and the number of copies to be copied at that setting level are read (steps 206 and 207), and the setting level is changed every time the user changes the setting level with the copy density setting key 12. Separately, the number of copies is counted and stored in the RAM of the microcomputer 11 (step 208).

Further, in the flowchart of FIG. 3, step 20
Subsequent to 5, the subroutine (SUB2) shown in FIG. 5 is inserted. In FIG. 5, when the total number of copies reaches N = 1000 (step 209), the number of copies for each set level is read as shown in Table 1 (step 210). Then, the weighting factor (Table 1) that is determined in advance for each set level and stored in the RAM or ROM of the microcomputer 11 is When the number of copies for each set level is multiplied, the calculation result is as shown in Table 1 (step 211). From this calculation result, the set level "3" indicating the maximum value (150.0) is selected (step 212), and the injection density level of the copying machine is set to the level "3" in the microcomputer 11 (step 213). "3" of the indicator light 13a of the display device 13 lights up. In this way, an appropriate copy density is automatically set in advance for the next copy operation.

Further, FIG. 6 is a flow chart showing a case where the weighting coefficient in the above-mentioned embodiment is determined in accordance with the preference of the user. That is, in FIG. 6, each time the copying operation is completed (step 301), the number of copies for each set level is read (step 302), and when the preset monitor number of copies M = 1000 is reached (step 303). , Density levels “0” to “8” are A (“0” to “2”), B
(“3” to “5”) and C (“6” to “8”), the number of copies is totaled (step 304), and the group having the maximum total value is selected (step 30).
Five). Then, the maximum weighting coefficient is determined so as to correspond to the setting level having the largest number of copies in the selected groove, and the setting coefficients before and after that are determined in correspondence with the gradually decreasing weighting coefficients (steps). 306). FIG. 7 (a) and FIG. 7 (b) show the determination of this weighting factor in two.
FIGS. 7A and 7B are explanatory diagrams specifically explaining one example, and when the copy work of a predetermined monitor copy number M = 1000 is completed in step 303, the copy number for each set level is shown in the example of FIG. 7A. In the case as shown, the number of copies Ma, Mb, Mc of each of the groups A, B, C is Ma = 55 + 305 + 217 = 5.
77, Mb = 98 + 131 + 90 = 319, Mc = 50 + 39 + 15 = 104. Therefore, the number of copies in group A is the maximum.
Setting level "1" with the highest number of copies from the group
Is selected, and the weighting coefficient that makes this setting level the maximum value of 1.0 is determined as shown in Example 1 of Table 2. Also, the seventh
In the example shown in FIG. 6B, the B group having the maximum total number of copied sheets is selected in the same manner, and the maximum weighting factor 1.0 corresponds to the setting level “5” having the largest number of copied sheets. Then, as shown in Example 2 of Table 2, the weighting factor for each setting level is determined.

If the embodiment shown in FIG. 2 is controlled using the weighting factor thus determined, the image density level more faithful to the user's preference will be automatically set.

As described above in detail, since the copy density level to be automatically set is set by the value obtained by multiplying the number of copies for each set level by a predetermined weighting coefficient, the density level automatically set as in the past is swift. An appropriate density level is always automatically set without changing or being set to a simple average level irrelevant to the setting frequency.

(G) Effect of the invention The set value does not change rapidly and is not set to an unintended level, and the proper copy density is set automatically and efficiently.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining the configuration of the present invention, FIG. 2 is a block diagram showing the essential parts of an embodiment of the present invention, and FIGS. 3 to 6 show the operation of the embodiment shown in FIG. The flowchart shown in FIGS. 7A and 7B is a graph illustrating the relationship between the set level and the number of copies in the embodiment shown in FIG. 11 ... Microcomputer, 12 ... Keyboard, 13 ... Display device, 14 ... Exposure amount control device, 15 ... Various copying operation control devices.

Claims (1)

(57) [Claims] 1. An image forming apparatus capable of adjusting a copy image density to a plurality of density levels, a setting means capable of setting a density level selected from the plurality of density levels as a reference density level, and the set reference density. Manual correction means for manually correcting the level, counting means for counting the number of image formations for each density level when a predetermined number of image formations are completed, and weighting factors preset corresponding to the respective density levels Weighting means for multiplying the number of image formations for each density level to add weight, and determination means for determining the density level at which the weighted value shows the maximum value and causing the setting means to reset the reference density level An image density control device characterized by the above.