JPH11174909A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of easily and accurately estimating toner consumption. SOLUTION: Correction values (b), (c), and (d) are respectively decided based on the kinds of images, toner residual amount, and humidity detected by an image kind detecting part 26, a toner residual amount detecting part 29, and a humidity detecting part 32. A pulse accumulating device 3 outputs pixel density data (x) as toner consumption instructing data. An on-time calculating part 34 calculates the on-time (t) of a toner supplying motor based on the correction value and the pixel density data (x), and outputs them to a driving part 7. For example, the on-time (t) of the motor is calculated by an enumeration expression(t:a.b.c.d.x).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, etc., which visualizes an electrostatic latent image formed on an image carrier with toner.
The present invention relates to an image forming apparatus that predicts a toner consumption amount of a two-component developer and appropriately controls a toner supply amount based on the prediction result.

[0002]

2. Description of the Related Art In an electrophotographic or electrostatic recording type image forming apparatus, a two-component developer mainly composed of a toner and a carrier is used. As is well known, the toner concentration of a two-component developer (ie, the ratio of toner weight to the total weight of carrier and toner) is extremely important in stabilizing image quality. However, the toner of the developer is consumed at the time of development, but the carrier is not consumed, so that the toner concentration changes. For this reason, an image forming apparatus using a two-component developer accurately detects the amount of toner consumed by the developer and replenishes the toner according to the result of the detection to constantly control the toner concentration to be constant. A control unit (ATR) is provided.

FIG. 3 is a diagram showing the overall configuration of a conventional digital printer having a developer concentration control function. The image data generating device 1 supplies a pixel signal having an output level corresponding to the pixel density to each pulse width modulation circuit 2 for each pixel. The pulse width modulation circuit 2, for each pixel signal inputted, and outputs the form of laser driving pulse P _R in the width corresponding to the output level (time length). That is, a wider drive pulse is applied to a high-density pixel signal, a narrower drive pulse is applied to a low-density pixel signal, and an intermediate-width drive pulse is applied to a medium-density pixel signal. Are formed respectively.

[0004] The pulse width laser output from the modulation circuit 2 drive pulse P _R is supplied to the semiconductor laser 4, emit light for a time corresponding to the semiconductor laser 4 in the pulse width. Therefore, the semiconductor laser 4 is driven for a longer period of time for high-density pixels, and is driven for a shorter period of time for low-density pixels. The laser light emitted from the laser device 4 is scanned in the main scanning direction by the polygon mirror 14, passes through the reflection mirror 15, and the photosensitive drum 20 as an image carrier
Irradiated above to form an electrostatic latent image.

[0005] The surface of the photosensitive drum 20 is uniformly charged by the primary charger 17 after being uniformly discharged by the exposure device 18, and is further irradiated with the laser light to receive an electrostatic latent image corresponding to an image signal. Is formed. This electrostatic latent image is developed into a visible image (toner image) by the developing device 11. This toner image includes two rollers 13 driven in the direction of the arrow,
The image is transferred by a transfer unit 21 onto a recording medium 23 such as a recording paper supplied by 24. The transfer device is made of a rubber roll to which a transfer voltage is applied. The residual toner remaining on the photoconductor drum 20 is scraped off by the cleaner 19 and collected in a predetermined container.

[0006] The output signal of the laser driving pulse P _R output from the pulse width modulation circuit 2 is supplied to one input terminal of the AND gate 16, to the other input terminal of the AND gate 16, a reference clock source 25 Supplies a reference clock CLK. Therefore, the AND gate 16, as shown in FIG. 8, the laser driving pulse P _R of the pulse width Wn of the number of accumulated clock pulse P _a corresponding, i.e., the number of clock pulses corresponding to the density of each pixel Will be output. Pulse value unit 3 sends the pulse number of accumulated clock pulse P _a to CPU6 by integrating each pixel. The CPU 6 converts the integrated amount into a supply amount based on the data table registered in the RAM 5 and sends the converted amount to the motor drive circuit 7 as a toner supply signal. The motor drive circuit 7 drives the motor 8 for a time corresponding to the toner supply signal, that is, the data corresponding to the motor-on time, and rotates and drives the toner transport screw 10 in the toner supply tank 9 containing the toner for the above-mentioned predetermined time. Developing device 11 from toner supply tank 9
An appropriate amount of toner is replenished into the
Is kept constant.

[0007]

In THE INVENTION It is an object of the prior art described above, the density of each pixel is converted into a pulse width of the laser driving pulse P _R, counts the reference clock CLK regards the pulse width W _n and toner consumption Therefore, it is predicted that the density of each pixel and the amount of toner consumed for developing the pixel with the toner have a proportional relationship as indicated by a dotted line A in FIG.

However, in practice, narrow latent image width (i.e., the pulse width is short of the laser driving pulse P _R) the toner in area is not adsorbed, the toner consumption for pixel density is reduced. Further, when the latent image width is increased to some extent, the toner is surely adsorbed to the latent image, so that the pixel density and the toner consumption show a proportional relationship. further,
If the width of the latent image is too large, the interval between adjacent latent images will not be narrow, and each latent image will be continuous, so that the toner consumption will be constant regardless of the latent image width. Therefore, the relationship between the actual pixel density and the toner consumption shows an S-shaped non-linear relationship as shown by a solid line B in FIG. Therefore, the above-described related art has a problem that a large error occurs between the toner consumption amount predicted from the pixel density and the actual consumption amount.

Therefore, there has been proposed an image forming apparatus provided with a table for converting the image density signal output from the AND circuit 16 so as to reflect the actual toner consumption (Japanese Patent Laid-Open No. 5-323793). Gazette). But,
In this conventional image forming apparatus, since the conversion table for converting the image density signal has conversion values over the entire density range, there is a problem that a large memory capacity is required.

Further, even if the toner consumption is predicted as described above, the toner must be accurately fed from the toner supply system to the developing device 11 based on the predicted value. However, in practice, the toner supply amount may vary depending on, for example, the bulk density of the toner. Therefore, the device described in the above publication has two toner supply devices,
By stabilizing the amount of toner in the toner supply device on the developing device side, the toner supply amount is stabilized. But,
In this case, there is a problem that the image forming apparatus becomes large due to having two toner supply devices.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to make it possible to easily estimate the toner consumption amount without increasing the memory capacity and to accurately supply toner. An object of the present invention is to provide a forming apparatus.

[0012]

In order to achieve the above object, according to the present invention, an image to be transferred onto a transfer medium by developing an electrostatic latent image formed based on an image signal with a two-component developer is used. In the forming apparatus, a toner consumption estimation unit that outputs a toner consumption estimation value, an image type detection unit that detects a type of an image to be formed, and a correction value determination that outputs a scheduled correction value based on the type of the image Means, and toner supply amount instruction data output means for correcting toner supply amount instruction data determined based on the toner consumption amount prediction value with the correction value and outputting corrected toner supply amount instruction data. There is a first feature.

According to the first feature, the toner consumption predicted by the toner consumption predicting means is corrected based on the type of image, for example, characters / lines, photographs, maps, and the like. For example, a map that is often printed at a halftone density uses a screen with a high number of lines to increase the gradation, the toner consumption tends to be lower than the predicted value, and characters printed at a high density are generally used. The / line tends to increase the toner consumption. Therefore, by determining the correction value in consideration of such a tendency, an accurate toner consumption estimation value can be obtained.

According to the present invention, there is provided an image forming apparatus for developing an electrostatic latent image formed on the basis of an image signal with a two-component developer and transferring the image onto a transfer medium. Consumption amount estimating means, a toner cartridge for replenishing toner, a toner remaining amount detecting means for detecting the remaining amount of toner in the toner cartridge, and a correction value determining means for outputting a scheduled correction value based on the toner remaining amount And a toner replenishment amount instruction data output unit that corrects the toner replenishment amount instruction data determined based on the toner consumption prediction value with the correction value and outputs corrected toner replenishment amount instruction data. There are two features.

According to the second feature, the correction value is determined by the remaining amount of toner. In other words, when the remaining amount of toner is large, the bulk density of the toner tends to increase because the self-weight of the toner is large, and when the remaining amount of toner decreases, the self-weight of the toner tends to decrease and the bulk density tends to decrease. In the present invention, the predicted toner consumption value can be corrected in consideration of this tendency.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. In the present embodiment, since the present invention is applied to the digital printer described with reference to FIG. 3, the description of FIG. 3 will be referred to below, and the description will be given with reference to the reference numerals in FIG. In the present embodiment, a toner cartridge filled with a predetermined amount of a developer in which toner and a carrier are mixed at a predetermined ratio is used as the toner supply tank 9.

The CPU 6 reads the integrated pulse number x output from the pulse accumulating device 3. Then, the on-time t of the motor 8 is calculated by applying the integrated pulse number x and the correction value according to the image mode or the like to a scheduled function formula, and the calculation result is output to the motor drive circuit 7.

FIG. 1 shows a CPU for calculating the on-time t.
FIG. 6 is a block diagram showing main functions of the sixth embodiment. The image type detection unit 26 determines an image type from an image mode such as a character / line mode, a photograph mode, and a map mode input from the operation panel 27 or the like. The determination result is input to the correction value b determination unit 28, and the correction value b determination unit 28 determines the correction value b according to the image type.

The toner remaining amount detecting section 29 detects the remaining amount of toner in the toner supply tank 9 from the integrated value of the driving time of the motor 8 detected by the motor driving time integrating section 30. The motor drive time integrating unit 30 detects the integrated time of the drive time of the motor 8 from the time when the toner cartridge 9 is newly mounted and supplies the integrated time to the toner remaining amount detecting unit 29. That is, the amount T (g) of the developer in the new toner cartridge 9 and the toner supply amount TS (g / g) by driving the motor 8 per unit time.
h) can be known in advance, so that the remaining amount of toner TL (%) can be calculated as TL = (T−td · TS) / T × 100 based on both of them and the motor driving time td (h). it can. The calculation result is input to the correction value c determining unit 31,
The correction value c determining unit 31 determines a correction value c according to the remaining amount of toner.

The humidity detector 32 detects the humidity inside the printer and supplies it to a correction value d determiner 33. Humidity, for example,
It can be represented by a voltage supplied to the transfer device 21.
That is, the transfer device 21 is controlled so as to be supplied with a constant current, and the resistance value of the rubber roll constituting the transfer device 21 has a property of changing with humidity. Therefore, the humidity detector 32 can be configured to detect a voltage supplied to the transfer device 21 to obtain a known humidity corresponding to the voltage. The correction value d determining unit 33 determines a correction value d according to the humidity.

The correction value b determining section 28, the remaining toner amount detecting section 31, and the humidity detecting section 33 are provided with correction values b,
This can be realized by creating a program for the CPU 6 so as to output c and d.

The on-time calculator 34 calculates correction values b, c, d,
And the integrated pulse number x output from the pulse accumulating device 3
To output the on-time t of the motor 8 to the motor drive circuit 7 as toner supply amount instruction data in accordance with a calculation formula described later.

FIG. 2 is a flowchart showing the operation of the main part of the CPU 6. In step S1, the pulse accumulating device 3
Reads the integrated pulse number x output from. Step S
In step 2, the image type is read from the image type detection unit 26.
The image type is determined based on the mode input from the operation panel 27 or the like of the digital printer. In addition, character /
The line mode, the photograph mode, and the map mode may be supplied as the number of lines from an image processing device such as a host computer. In general, a higher gradation is required in the map mode to print smaller characters in the map mode than in the photograph mode, and therefore a screen with a higher number of lines is selected. As an example, 150 lines are selected in the photo mode and 300 lines are selected in the map mode.

In step S3, a correction value b is determined based on the image type. For example, the character / line mode (b =
1.0), a photograph mode (b = 0.95), and a map mode (b = 0.9).

In step S4, the remaining amount of toner in the toner supply tank, that is, in the toner cartridge 9, is read. In step S5, a correction value c is determined based on the remaining amount of toner. For example, the remaining toner amount is 100 to 51% (c = 1.
0), toner remaining amount 50 to 21% (c = 0.95), 20
% Or less (c = 0.9).

In step S6, the humidity is read, and in step S7, a correction value d is determined based on the humidity. For example, humidity 20 to 49% (d = 1.05), humidity 50 to 49%
79% (d = 1.0), humidity 80% or more (d = 0.9
5).

In step S8, the ON time t of the toner supply motor 8 is calculated based on the correction value. The calculation formula is shown in the figure. The symbol a in the equation is a constant. Note that the calculation formula is not limited to this, and various formulas determined in advance by experiments or the like can be used. Further, the correction value b,
It is not necessary to take all of c and d into consideration, and the modification can be made such that at least b or c is taken into account, or the correction value b and the correction value c or d are taken into account to determine the ON time of the motor 8. .

The reason why the on-time of the motor 8 can be corrected by the correction values corresponding to the image type, the remaining amount of toner, the humidity, and the like will be described. FIG. 4 is a diagram showing the relationship between the density and the actual toner consumption with respect to two types of lines. Here, the density is represented by the ratio of the pixel having the value “1” in the planned target pixel. As shown in this figure,
The relationship between the density and the actual toner consumption deviates from the linear relationship indicated by the dotted line. 150 lines and 300 in low concentration range
The line images are all shifted downward from the linear relationship, and in the high density range, the 150-line and 300-line images are all shifted upward from the linear relationship. This shift is larger in the 300-line image. In other words, the toner consumption is lower in the low density range, and the toner consumption is higher in the high density range.

Therefore, it is preferable to have the density information supplied from the pulse accumulating device 3, that is, the data of all the toner consumption according to the integrated pulse number x, but the memory capacity is increased. Therefore, in the present embodiment, the correction value b is determined according to the image type. Even in this case, generally, for example, a photograph or a map has a halftone density, and the density range most frequently selected for the image type according to the image type is limited. No problem occurs unless an image out of the specified density is output in an extremely large amount.

FIG. 5 is a diagram showing the relationship between the remaining amount of toner in the toner cartridge 9 and the actual amount of supplied toner. As shown in this figure, when the remaining amount of toner decreases, the toner supply amount decreases even when the on-time of the motor 8 is fixed. Therefore, in the present embodiment, the correction value c is determined based on the remaining amount of toner.

FIG. 6 is a graph showing the relationship between the density and the actual toner consumption with respect to humidity. As shown in this figure, even when the humidity changes, the relationship between the density and the toner consumption is shifted from a linearly proportional relationship (represented by a dotted line) and exhibits an S-shape. Therefore, in the present embodiment, the correction value d is determined based on the humidity. Also in this case, similarly to the case of determining the correction value a corresponding to the image type, the density range that is most frequently selected for the image type is generally limited according to the image type. No problem occurs unless an extremely large number of images out of the range are output.

In this embodiment, an example has been described in which a program for determining a correction value according to the image type, the remaining amount of toner and the humidity is set. However, the correction value is determined according to the image type, the remaining amount of toner and the humidity. A table to be output may be used. Even in this case, unlike the case where the correction value and the ON time of the toner supply motor are directly searched from the table based on the density information, the memory capacity of the table can be extremely reduced.

In this embodiment, the density information for each pixel, that is, the number of clock pulses corresponding to the density of the pixel is set as a value representative of the toner consumption, and this value is used as a correction value b,
Correction is made based on c, d, and the like. However, the value representing the toner consumption is not limited to this. For example, a toner consumption prediction unit configured to count the number of pixels of an image to be formed and represent the toner consumption by the number of pixels is used. The present invention can be applied to the used image forming apparatus.

[0034]

As is apparent from the above description, according to the present invention, the estimated toner consumption can be made closer to the actual toner consumption based on the image type and the like. Therefore, by controlling the toner replenishment amount in accordance with the estimated toner consumption amount, the toner concentration in the developing device can be stabilized. In particular, the memory capacity for storing the correction value of the predicted toner consumption value can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating main functions of a digital printer according to an embodiment of the present invention.

FIG. 2 is a flowchart for calculating a toner supply motor ON time.

FIG. 3 is a diagram illustrating an overall configuration of a digital printer.

FIG. 4 is a diagram illustrating a relationship between density and toner consumption for each number of lines.

FIG. 5 is a diagram illustrating a relationship between a remaining toner amount and a toner supply amount.

FIG. 6 is a diagram illustrating a relationship between density and toner consumption for each humidity.

FIG. 7 is a diagram illustrating a relationship between density and toner consumption.

FIG. 8 is a timing chart showing the relationship between input and output signals of an AND circuit.

[Explanation of symbols]

3: pulse accumulator, 7: motor drive circuit, 8: toner supply motor, 26: image type detection unit, 29: toner remaining amount detection unit, 32: humidity detection unit, 34: on-time calculation unit

Claims (5)

[Claims] 1. An image forming apparatus for developing an electrostatic latent image formed based on an image signal with a two-component developer and transferring the electrostatic latent image onto a transfer medium, wherein a toner consumption estimation unit outputs a toner consumption estimation value. Image type detecting means for detecting the type of an image to be formed; correction value determining means for outputting a predetermined correction value based on the type of the image; and toner replenishment determined based on the predicted toner consumption amount. An image forming apparatus comprising: a toner supply amount instruction data output unit that corrects the amount instruction data with the correction value and outputs corrected toner supply amount instruction data. 2. An image forming apparatus for developing an electrostatic latent image formed on the basis of an image signal with a two-component developer and transferring the electrostatic latent image onto a transfer medium, wherein a toner consumption estimation unit outputs a toner consumption estimation value. A toner cartridge for replenishing toner; a toner remaining amount detecting unit for detecting a remaining amount of toner in the toner cartridge; a correction value determining unit for outputting a predetermined correction value based on the remaining toner amount; Image forming apparatus comprising: toner supply amount instruction data output means for correcting toner supply amount instruction data determined based on a consumption amount predicted value with the correction value and outputting corrected toner supply amount instruction data. apparatus. A humidity detecting unit that detects humidity in the image forming apparatus; a correction value determining unit that outputs a second correction value based on the humidity; and a toner supply amount instruction data output unit. The image forming apparatus according to claim 1, wherein the correction toner supply amount instruction data is further corrected by the second correction value. 4. The apparatus according to claim 1, wherein said toner consumption predicting means outputs a laser drive pulse width representing a pixel density as a toner consumption predicted value. The image forming apparatus as described in the above. 5. The image forming apparatus according to claim 1, wherein said toner consumption predicting means is configured to output the number of pixels of a formed image as a predicted toner consumption value. apparatus.