JPH09197912A - Image forming device and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decide residual toner by a simple constitution. SOLUTION: A D/A setting part sets the luminance level of a light source 102 which emits light corresponding to the density of an image to be formed and the light source 102 emits light at the set luminance. The light is reflected by the formed image, detected by a detecting part 103 and inputted in a comparison part 112. The comparison part 112 compares the value inputted from the A/D intake part with the value set by the D/A setting part, and when the difference between both becomes equal to or above a specified value, a fluorescent light of an operation panel 113 is turned on, on judgement that the residual toner becomes little. Moreover, a signal detected by the detecting part 103 is inputted to a developing bias decision part 109, the developing time bias is controlled thereby, and thus the density of the formed image is controlled. Since the residual toner is judged in this way, an additional circuit therefor becomes unnecessary.

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 an electrophotographic system or an electrostatic recording system and a control method therefor, and particularly, to prevent deterioration of print quality when the remaining toner amount is low. Image forming apparatus and its control method.

[0002]

2. Description of the Related Art A conventional example will be described below with reference to FIG.

FIG. 2 is a diagram showing a schematic configuration of signal processing of a laser beam printer.

The laser beam printer shown in FIG. 2 is a terminal device which is connected to a computer via a predetermined interface cable and outputs the result of information processed by the computer onto a recording sheet.

In FIG. 2, 201 is a signal processing unit, 20
2 is a laser driver, 203 is an amplifier, 204 is a semiconductor laser, 205 is a polygon mirror, 206 is an f-θ lens, 207 is a reflection mirror, and 208 is a photosensitive drum.

First, image information is input to the signal processing unit 201 as R (red), G (green) and B (blue) components, and the input signal is subjected to predetermined signal processing in the signal processing unit 201. , Y (yellow), M (magenta), C (cyan), and K (black).

Y, M, C converted by the signal processing unit 201
The image information of K and K is sent to the laser driver 202.
The laser driver 202 modulates the input Y, M, C, and K image information and outputs a modulated signal to the amplifier 203. The amplifier 203 drives the semiconductor laser 204 according to the modulation signal output from the laser driver 202.
The laser light output from the semiconductor laser 204 is a polygon mirror 205, an f-θ lens 206, and a reflection mirror 20.
After 7, the photosensitive drum 208 is exposed and scanned.

Photosensitive drum 2 by electrostatic force according to laser light
When the electrostatic latent image is formed on the photosensitive drum 08 in the exposure process, the toner is ejected onto the photosensitive drum, and the toner is adhered onto the photosensitive drum according to the electrostatic latent image to develop and visualize the electrostatic latent image. Image.

After that, the developed toner image is fixed on the output paper through a transfer and fixing process, and the output paper is discharged.

Next, the detection of the remaining toner amount will be described with reference to FIG.

Sensor windows 502 are provided above and below the toner cartridge 501, and a light emitting side 503 and a receiving side 504 of the photocoupler are provided in the respective windows. Toner cartridge 5
In No. 01, there is a stirring blade for stirring the toner to make it uniform.

The signal output from the light emitting side 503 of the photocoupler is received by the receiving side 504. Here, paying attention to the fact that the remaining toner amount and the toner transmittance are in inverse proportion to each other, since the transmittance increases when the remaining toner amount decreases, the signal level received by the receiving side is integrated. When the integrated signal level exceeds a predetermined level, the Flag signal indicating a toner warning becomes active.

[0013]

However, in the above-mentioned prior art example, when the toner remaining amount becomes low, the toner remaining amount detector only detects the absence of toner and only the warning lamp indicating the toner replacement is displayed on the operation panel. If the printing is continued as it is, the quality of the output image will be deteriorated for each printing.

Further, since it is necessary to provide the toner remaining amount detecting circuit, the cost is increased accordingly, and the space in the apparatus is required, which hinders downsizing of the apparatus. The present invention has been made in view of the above-described conventional example, and an image forming apparatus and a control method therefor capable of detecting the toner remaining amount (no toner) without providing a dedicated circuit for detecting the toner remaining amount. The purpose is to provide.

[0015]

The present invention has been made to solve the above problems and has the following structure. That is, image forming means for forming an image by adhering a recording material on a print medium, and detecting means for detecting the density of the image on the print medium formed by the image forming means,
A comparison unit that compares the density detected by the detection unit with the density of the image to be formed by the image forming unit, and a determination that determines the amount of remaining recording material based on the comparison result by the comparison unit And means.

Alternatively, it is a control method for controlling the density of an image by an image forming apparatus which forms an image by adhering a recording material on a print medium, and sets a signal level according to the density of the image to be printed. A setting step, a detecting step of detecting the density of an image formed on the print medium, a comparing step of comparing the signal level set by the setting step with the density detected by the detecting step, and the comparing step. And a determination step of determining the remaining amount of the recording material based on the comparison result of 1.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] An embodiment of the present invention will be described below in detail with reference to the drawings.

An outline of the printing process in the color laser beam printer of this embodiment will be described with reference to FIG.

Since the steps up to the laser exposure shown in FIG. 2 have been described in the conventional example, they are omitted here and the other steps will be described.

First, in the charging step 301, the surface layer of the photosensitive drum 208 is formed by laminating a photoconductor on a conductive substrate. The surface of the photosensitive drum 208 is uniformly charged by performing constant current control so as to be constant regardless of the above.

Next, in the exposure step 302, as shown in FIG. 2, the photosensitive drum 208 is scanned with the laser light according to the image information, so that the photosensitive drum 208 is electrostatically moved with the electrostatic force according to the laser light. A latent image is formed.

In the developing step 303, the exposing step 30
The electrostatic latent image formed in 2 is visualized by a developing machine.
In the case of a color printer, each color of YMCK is developed, and the details of the developing step 303 will be described with reference to the configuration diagram of the developing roller shown in FIG.

The developing roller 400 shown in FIG. 4 is composed of a fixed magnet 403 and a magnetic cylinder (sleep) 404 that rotates around the outer circumference of the fixed magnet 403.
It is electrified by friction with and adheres to the sleeve 404 as a uniform layer by the blade 401. An interval of several hundreds of microns is maintained between the photosensitive drum 208 and the sleeve 404, and the toner 402 is caused to fly in the alternating magnetic field, so that the toner 402 is transferred according to the electrostatic latent image formed in the exposure step 302. The electrostatic latent image is made visible by attaching it on top. At that time, the developing bias controller 110 controls the bias voltage applied to the sleeve 404.
As a result, the potential difference generated between the sleeve 404 and the photosensitive drum 208 is controlled, and the amount of toner attached to the photosensitive drum is further controlled.

As described above, the developing process 3 shown in FIG.
At 03, the electrostatic latent image is visualized with toner.

Next, in the transfer step 304 shown in FIG. 3, the print sheet supplied from the supply step 309 is brought into contact with the photosensitive drum 208 in synchronism with the formation of an image, wound around the transfer drum, and printed by the transfer charger. By applying an electric charge having a polarity opposite to that of the toner on the surface of the toner image, the toner image is transferred onto the toner print paper on the photosensitive drum 208.

In the subsequent drum cleaning step 306, the remaining toner on the photosensitive drum 208 of the photosensitive drum 208 on which the visible image is taken is removed by a cleaning blade (not shown).

The steps of the exposure step 302, the development step 303, the transfer step 304, and the drum cleaning step 306, which have been performed so far, are performed according to the number of colors to be used.
It is repeated 4 times for each of C and K.

When the transfer is completed for all the colors, in the next separation step 305, the print paper on which the toner image has been transferred in the transfer step 304 is separated from the photosensitive drum 208.

Finally, in the fixing step 307, the toner transferred onto the print paper is heated and fixed by a fixing roller (not shown), and the toner image is fixed on the print paper.

Thereafter, in the paper discharge step 308, the print paper on which the toner image is fixed is discharged.

As described above, the color printing by the color laser printer of this embodiment is completed.

Next, the signal processing unit 201 shown in FIG. 2 will be described below.

First, the image signal processing unit 209 is shown in FIG.
Based on.

The image signal is A / D converted and input to the input terminal as 8-bit RGB signals. ROM601
Then, the RGB signal which is the luminance signal is converted to the YMC which is the density signal.
In order to convert the data into a signal, the data corresponding to the input signal 00 (H) to FF (H) is converted to LU by using the coefficient shown in the following formula.
Output by T.

Y = -log (aB), M = -log (a
G), C = -log (aR) (a is a coefficient) The 8-bit YMC data output from the ROM 601 is input to the UCR circuit 603 via the selector 602. Here, masking processing is performed using a known undercolor removal method, and each of Y, M, C, and K is signal / VDO.
7 to / VDO0 are sequentially output. The output signal is modulated and driven by the laser driver unit 202.

Next, the image density detecting section will be described with reference to FIG. FIG. 6 is a schematic diagram showing the photosensitive drum, the developing device, the transfer drum, and the image density detecting unit 101. Generally, in a full-color printer, it is necessary to guarantee color viewing in environments such as humidity and temperature. Therefore, the image density is detected, and the developing bias value is controlled according to the detected density value so that the image can be printed at the optimum density, and the image density is adjusted.

First, while the printer is powered on and initialized to a printable state, the magenta (700a) yellow (700b) cyan (700
b) Each toner of black (700d) is formed on the transfer drum 701 via the photosensitive drum 208 with a predetermined density value.

The toner thus formed is subjected to the density detecting section 10
Detected at 1. The structure of the density detecting unit 101 is shown in FIG.

The density detecting section 101 is composed of a photocoupler having a light emitting element 102 and a light receiving element 103, and controls the developing bias according to the amount of reflected light.

For example, as a default, 8 bits (0 to
255) When the FAhex (250) level image of the gradation image data is printed, the D / A setting unit 106 sets the signal value of the corresponding level, and the emission light source 102
Light is emitted at the set image density level of FAhex (250). On the other hand, in the reflected light detection unit 103, FFhex
Suppose a (255) level is detected. This value is C
Input to the A / D capture unit 107 of the PU 105,
D conversion is performed.

The density conversion unit 108 is composed of a conversion ROM, and converts the image density input from the A / D loading unit 107 into a developing bias setting value and inputs it to the developing bias determining unit 109. The value is determined. In this case, since the detected density value is high, feedback is made in the direction of lowering the developing bias.

On the other hand, on the contrary, the reflected light amount detection unit 103 outputs EAh.
If the density level of ex (234) is detected, feedback is performed in the direction of increasing the transfer bias, contrary to the above. The relationship between the developing bias and the density is shown in FIG. In this way, as the developing bias increases, the toner density increases, so by controlling the developing bias according to the detected image density, it is possible to print at the optimum image density without being influenced by the environment such as the ambient temperature. It has become possible.

Further, in the present embodiment, the image density set value to be printed, which is set by the D / A setting section 106 provided inside the CPU 105, and the image density detecting section 101.
A is detected by the reflected light amount detection unit 103 provided inside.
The density value converted by the / D capture unit 107 is the comparator 1
Compared at 12. If it is detected that the image density value detected by comparing the two becomes lighter than the degree of change due to the environment or the like, the comparator 112 judges that the toner cartridge is out of toner, and the operation panel 113. Turn on the warning light to give the operator a toner-free warning.

FIG. 8 shows the warning of the remaining amount of toner by the CPU 105.
6 is a flowchart showing a procedure when a program is executed and executed.

First, the brightness level output from the light source 102 is set according to the image density to be printed (step S81).

Next, when the detection signal is input from the reflected light detection section 103, it is taken in as a digital signal and compared with the level set in step S81 (step S81).
82). It is determined whether or not this difference is equal to or greater than a predetermined value (step S83), and if the determination is affirmative, the fluorescent lamp of the operation panel 113 is turned on as a person having no toner remaining amount (step S84).

As described above, the density detected by the image density detecting unit 101 is controlled by the developing bias, and the level of the input signal issued for density detection is compared with the level of the detected density signal. , The additional configuration for detecting the remaining amount of toner is suppressed to the level of a comparator,
Further, if the software is controlled by the CPU, the remaining toner amount can be warned without any additional configuration. [Second Embodiment] The present invention is not limited to the above-mentioned device and is also effective in the following cases.

In the color printer of the first embodiment, the absence of toner is detected by using the density detecting section. However, by using the conventional toner detector together with the present invention, finer control can be performed. You can

For example, when the toner is low, it is detected by a conventional toner detector, and a warning of no toner is issued,
Request toner replacement. After that, if the printing is continued, the printing cannot be performed at a predetermined density, and the print quality deteriorates for each print.

Here, it is also possible to use the image density detecting section in the first embodiment together and control the printing operation of the image forming apparatus to be stopped when the detecting section also detects the absence of toner.

Furthermore, by using both types together, the reliability of running out of toner is also improved. Further, although the laser beam printer is described as the first embodiment according to the present invention, the present invention is not limited to this, and may be applied to other color image forming apparatuses such as an inkjet printer, a dot matrix printer, and a facsimile. Applicable.

The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but can be applied to a single device (for example, a copier, a facsimile). Device).

Another object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and a computer (or CPU) of the system or apparatus.
And MPU) read and execute the program code stored in the storage medium.

[0054]

As described above, according to the present invention, it is possible to detect the toner remaining amount (no toner) without providing a dedicated circuit for detecting the toner remaining amount.
With such a configuration, cost and space can be reduced.

[0055]

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an image density detection unit according to an embodiment.

FIG. 2 is a schematic block diagram of an image forming apparatus according to an embodiment.

FIG. 3 is a diagram showing an outline of a printing process in the embodiment.

FIG. 4 is a schematic view showing a developing drum in the embodiment.

FIG. 5 is a block diagram showing a schematic configuration of an image processing unit in the embodiment.

FIG. 6 is a diagram showing an image density detection unit in the embodiment.

FIG. 7 is a graph showing the relationship between image density and transfer bias.

FIG. 8 is a flow chart when the remaining toner amount is detected by the CPU in the embodiment.

FIG. 9 is a block diagram showing a residual toner detector in a conventional example.

[Explanation of symbols]

 101 Image Density Detection Section 102 Emission Light Source Section 103 Reflected Light Amount Detection Section 104 D / A Converter 105 CPU Section 106 D / A Setting Section 107 D / A Capture Section 108 Density Conversion Section 109 Development Bias Setting Section 110 Development Bias Control Section 111 Developing device 112 Comparator 113 Operation panel

Claims (8)

[Claims] 1. An image forming means for forming an image by adhering a recording material onto a print medium, a detecting means for detecting the density of an image formed on the print medium by the image forming means, and the detecting means. A comparison unit that compares the detected density with the density of the image that is to be formed by the image forming unit, and a determination unit that determines the remaining amount of the recording material based on the comparison result by the comparison unit. An image forming apparatus characterized by the above. 2. The image forming apparatus according to claim 1, further comprising an output unit that outputs a notification when the determination unit determines that the remaining amount of the recording material is low. 3. The density of the image is detected by the detection means emitting light having a brightness corresponding to the density of the image formed by the image forming means, reflecting the light on the image and detecting the brightness. It detects, It is characterized by the above-mentioned.
An image forming apparatus according to claim 1. 4. The density control means according to claim 1, further comprising density control means for controlling the density of an image formed by the image forming stage based on the density detected by the detection means. The image forming apparatus described. 5. The image forming unit forms an image using toner as a recording material by an electrophotographic method, and the density control unit controls the amount of toner adhered when developing an electrostatic latent image with toner. The image forming apparatus according to claim 1, wherein: 6. The image forming apparatus according to claim 1, wherein the image forming unit forms a color image. 7. A control method for controlling an image density by an image forming apparatus which forms an image by attaching a recording material onto a print medium, and sets a signal level according to the density of an image to be printed. A setting step, a detecting step of detecting the density of an image on a formed print medium, a comparing step of comparing the signal level set by the setting step with the density detected by the detecting step, and the comparing step. And a determination step of determining the remaining amount of the recording material based on the comparison result of 1. 8. The detecting step detects the density based on the brightness of the light reflected on the image, and the brightness of the light reflected on the image whose density is to be detected by the detecting step is set by the setting step. The method of controlling an image forming apparatus according to claim 7, wherein the control method is based on the level.