JP2000253249A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an optimum image even if the lack of the residual amount of toner is detected. SOLUTION: When a toner end signal 208 is inputted, a counter 209 generates a carry signal whenever prescribed time passes and outputs it to a γ-conversion control part 202. The γ-conversion control part 202 selects a γ-conversion table 1 by which much toner is consumed when the first carry signal (after time t=T1 passes from a toner end signal 208) is inputted and γ-converts it. When the next carry signal (after time t=T2 passes from toner end signal 208) is inputted, a γ-conversion table 2 by which more toner is not consumed than by the γ-conversion table 1 is selected and it is γ-converted. When the next carry signal (after time t=T3 passes from tone end signal 208) is inputted, a γ-conversion table 3 by which a toner consumption amount is reduced is selected and it is γ-converted.

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 having a function of detecting the end of a recording material such as toner.

[0002]

2. Description of the Related Art In an image forming apparatus for forming an image on a sheet of paper by using a recording agent such as toner, image formation becomes impossible when the toner is exhausted. It is common to have a function such as notification.

However, if image formation is suddenly stopped when toner end is detected, a problem occurs.
As a conventional example which solves this problem, Japanese Patent Application Laid-Open No. H10-207
Japanese Patent Application Publication No. 319 proposes a method in which, when a shortage of the remaining amount of the recording material is detected, a warning of the shortage of the remaining amount is made, and the recording density is lowered to visually notify the user of the remaining amount.

Another conventional example is disclosed in Japanese Patent Laid-Open No. 6-3 / 1994.
No. 958 discloses that even if the remaining amount of the developing material falls below a predetermined amount, in order to effectively use the remaining developing material, the toner remaining amount when the detector detects that the remaining amount of the toner is small is reduced. A method has been proposed in which the number of printable sheets is set in advance according to the amount, and the printing operation is stopped when the set number of sheets is printed after the above detection.

[0005]

However, as disclosed in Japanese Patent Application Laid-Open No. 10-207319, if the recording density is reduced when the remaining amount of the recording material is detected, an optimum image cannot be formed. For this reason, there is a problem that the recording paper is wasted and that the printout has to be performed again.

The present invention has been made in consideration of the above-described problems of the related art, and has as its object to provide an image forming apparatus capable of forming an optimum image even when the remaining amount of the recording material is detected to be insufficient.

[0007]

According to a first aspect of the present invention, there is provided an image forming apparatus for forming an image on a sheet of paper by using a recording material to detect an insufficient amount of the recording material. Means, counting means for counting the elapsed time from when the remaining amount of the recording material is detected to be insufficient by the remaining amount detecting means, and the remaining amount of the recording material based on the elapsed time counted by the counting means. Gamma conversion means for correcting gamma conversion characteristics of an image so as to correct a decrease in image density on paper caused by the shortage.

[0008] The second means is to achieve the above object,
In an image forming apparatus that forms an image on a sheet by using a recording material, a remaining amount insufficient detecting unit that detects a remaining amount of the recording agent and a time period when the remaining amount of the recording agent is detected by the remaining amount detecting unit. Counting means for counting the number of pixels of the image data, and an image for correcting a decrease in image density on a sheet caused by a shortage of the remaining amount of the recording agent based on the number of pixels counted by the counting means. Γ conversion means for correcting the γ conversion characteristics of the above.

A third means is to achieve the above object.
In an image forming apparatus that forms an image on a sheet by using a recording material, a remaining amount insufficient detecting unit that detects a remaining amount of the recording agent and a time period when the remaining amount of the recording agent is detected by the remaining amount detecting unit. First counting means for counting elapsed time, second counting means for counting the number of pixels of image data from the time when the remaining amount of recording material is detected to be insufficient by the remaining amount detecting means, and Based on the elapsed time counted by the first counting means and the number of pixels counted by the second counting means, a decrease in image density on paper caused by a shortage of the remaining amount of the recording material is corrected. Gamma conversion means for correcting gamma conversion characteristics of an image.

The fourth means is as follows. In the first to third means, when the remaining amount of recording material is detected by the remaining amount detecting means to be insufficient, the user is further provided with a means for warning the user of the fact.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an image processing system of a digital copying machine as an embodiment of an image forming apparatus according to the present invention, FIG. 2 is a block diagram showing a control system of the digital copying machine of FIG. 1, and FIG. FIG. 4 is a block diagram showing the write control unit and the LD modulation unit in detail. FIG.
FIG. 4 is an explanatory diagram showing a conversion table.

A digital copying machine 1 shown in FIG. 1 schematically includes an image reading section 2 for reading a document (not shown), and a signal for performing various processes on the image data read by the image reading section 2. The image processing unit 3 includes a processing unit 3 and an image printing unit 4 that prints an image on printing paper (not shown) by a known electrophotographic method using toner based on image data processed by the signal processing unit 3.

More specifically, in the image reading section 2, a document placed on the contact glass 5 is illuminated by a light source 6 which is elongated in the main scanning direction, and reflected light thereof is reflected by a first mirror 7, a second mirror 9, and a second mirror 9. The light is sequentially reflected by the three mirrors 10 and then imaged by the imaging optical system 12 so that the CCD (Ch
(Arge Coupled Device) sensor 13 performs photoelectric conversion. In this case, the light source 6 and the first mirror 7 constitute a first scanning unit 8, the second mirror 9 and the third mirror 10 constitute a second scanning unit 11, and the first scanning unit 8 and the second
The original is scanned in the sub-scanning direction by the scanning unit 11 moving at a speed ratio of 2: 1.

In the signal processing section 3, an analog image signal photoelectrically converted by the CCD sensor 13 is amplified by an amplifier 14, and then converted into a digital image signal by an A / D converter (ADC) 15. Next, the digital image signal is subjected to image processing such as brightness correction processing, scaling processing and editing processing by the image processing section 16, and then the image processing section 1
The raster image data subjected to the image processing by 6 is sent to the writing control unit 18 via the buffer memory 17 and subjected to smoothing processing and the like. The LD modulator 19 modulates the beam of the semiconductor laser array (LD) of the LD unit 20 based on the image data.

In the image printing unit 4, the beam emitted from the LD unit 20 is converged by the cylinder lens 22 and then deflected by the polygon mirror 23 at a constant angular velocity. The beam deflected at the constant angular velocity is applied to the fθ lens 24.
Then, the light is corrected to have a constant velocity deflection, is reflected by the mirror 25, is irradiated on the photosensitive drum 26 to form a latent image, and is detected by the photodetector 27. Light detector 27
Is arranged in front of the effective writing area in the main scanning direction, receives the beam, and feeds back the synchronization detection pulse signal XDETP to the writing control unit 18.

As shown in FIG. 2, the control system of the copying machine includes a scanner unit 101 and a scanner drive control unit 102 for controlling the image reading unit 2, a key input unit 103, a main control unit 104, and a memory unit 105. And a printer drive control unit 106 and a printer unit 107 for controlling the image printing unit 4. The scanner drive control unit 102 controls each component of the scanner unit 101, and the printer drive control unit 106 controls each component of the printer unit 107. The key input unit 103 has various numbers of copies (number of prints), paper size, enlargement / reduction, and other various settings, and various keys for clearing a setting mode and starting / stopping operation. Necessary components are controlled according to a signal from the input unit 103. The memory unit 105 is used for storing image data.

The write controller 18 also arbitrates the input speed of the image data input from the image reading unit 2 and the output speed of outputting the image data to the image printing unit 4. That is, the image reading unit 2 scans the original on the contact glass 5 with the first and second scanning units 8 and 1.
1 scans in the sub-scanning direction and is read by the CCD sensor 13. The CCD sensor 13 outputs the dot matrix image data of a plurality of main scanning lines continuous in the sub-scanning direction to the signal processing unit 3 line by line. At this time, since the CCD sensor 13 outputs one line of image data for one line in the main scanning direction at every pixel clock after the address is reset by the line synchronization signal LSYNC, the signal processing unit 3 (write control unit) 18), one line at a time is output at a predetermined line cycle based on the scanning speed of the first and second scanning units 8, 11 and the reading cycle of the CCD sensor 13.

Next, the write controller 18 and the LD modulator 19 will be described in detail with reference to FIG. First, in the input image data, when a white spot (trim) mode is set, a designated area is trimmed by the area control unit 201. The area control unit 201 also includes a plurality of test patterns, and can replace input image data with test patterns. The image data processed by the area control unit 201 is converted into an optimum density by the γ conversion control unit 202 in accordance with the photosensitive drum 26, or density is converted in accordance with the remaining amount of toner as described later. The image data at this time is generally 4-bit or 8-bit multi-value data. The image data processed by the γ-conversion control unit 202 is sent to the LD 206 by the LD driver I / F control unit 204.
It is processed to turn on / off and other control of
Next, the LD driver 206 turns on / off the LD 206 based on the processing data.

In the image forming section 207, the photosensitive drum 26
The upper portion is uniformly charged, and then a latent image is formed in accordance with turning on / off of the LD 206. Then, the latent image is developed with toner, and then the toner image is transferred to a sheet. When the toner is consumed and the remaining amount becomes equal to or less than a predetermined amount, the toner output unit 208 outputs a toner end signal 208 to the main control unit 104 and the counter 209. When receiving the toner end signal 208, the main control unit 104 displays a message indicating a decrease in the remaining amount of toner on the key input unit 103 to notify the user of toner supply.

The counter 209 outputs a toner end signal 208
, The count of this clock is started, and a carry signal is generated and output to the γ-conversion control unit 202 every time a predetermined time elapses. Here, the counter 209 is, for example, 4
When the counter clock is 1 kHz, the count value is “0”.
The time from the start of counting to the generation of the carry signal after the full count value “15” is 16 × 1/1 kHz = 16 ms.

The gamma conversion control unit 202 includes a gamma conversion table (not shown) for converting the density to an optimum density according to the photosensitive drum 26, and a gamma conversion table that consumes a large amount of toner as shown in FIG. And a γ conversion table that consumes less toner than the γ conversion table, a γ conversion table that reduces toner consumption, and a γ conversion table (not shown) that further reduces toner consumption.

Then, when the first carry signal (after the time t = T1 has elapsed from the toner end signal 208) is input, a γ conversion table which consumes a large amount of toner is selected and γ converted, and the next carry signal (toner end signal 208) When a time t = T2 elapses after the input, a γ conversion table that does not consume much toner is selected from the γ conversion table and γ converted, and the next carry signal (toner end signal 208
When a time t = T3 elapses), a gamma conversion table for reducing the toner consumption is selected and gamma converted, and a gamma conversion table (not shown) for further reducing the toner consumption is selected in the same manner. Perform gamma conversion.

It should be noted that gamma conversion may be performed so that the converted black data becomes a larger value as the time t increases, thereby compensating for the unclear density due to the thinned toner.

Next, a second embodiment will be described with reference to FIGS. In the second embodiment, a pixel number counting unit 203 is provided instead of the counter 209. Other configurations are the same as those of the first embodiment. When the toner end signal 208 is input, the pixel number counting unit 203 starts counting the number n of pixels of the image data processed by the area control unit 201. At this time, for example, a gate signal in the sub-scanning direction of the image is used as a control signal indicating an effective period for counting the number n of pixels. Then, when the number n of pixels is a predetermined value N1, N
2. The table selection signal is notified to the γ-conversion control unit 202 every time the number becomes N3.

As shown in FIG. 5, the gamma conversion control unit 202
A γ conversion table that consumes a very large amount of toner, a γ conversion table that consumes a little toner, a γ conversion table that consumes a little but a little more than the γ conversion table, and a γ conversion table that further reduces toner consumption ( (Not shown). Then, when n = N1, a γ conversion table is selected, when n = N2, a γ conversion table is selected, and when n = N3, a γ conversion table is selected. A gamma conversion table (not shown) to be reduced is selected and gamma converted.

As shown by a broken line in FIG. 3, a pixel counting section 203 is added, and the elapsed time t after the toner end signal 208 is input and the image data of the image data are output by both the counter 209 and the pixel counting section 203. A γ conversion table may be selected according to both the number n of pixels to perform γ conversion.

[0027]

As described above, according to the first aspect of the present invention, the recording medium is generated in accordance with the shortage of the remaining amount of the recording material based on the elapsed time from when the shortage of the remaining recording material is detected. Since the gamma conversion characteristic of the image is corrected so as to correct the decrease in the image density on the paper, an optimum image can be formed even when the remaining amount of the recording material is detected to be insufficient.

According to the second aspect of the present invention, based on the number of pixels of the image data from when the remaining amount of the recording material is detected, an image on a sheet generated due to the remaining amount of the recording material is generated. Since the γ-conversion characteristic of the image is corrected so as to correct the decrease in density, an optimum image can be formed even when the remaining amount of the recording material is detected to be insufficient.

According to the third aspect of the present invention, based on the elapsed time since the detection of the lack of the remaining amount of the recording material and the number of pixels of the image data, the paper generated due to the lack of the remaining amount of the recording material. Since the γ-conversion characteristic of the image is corrected so as to correct the decrease in the image density, an optimum image can be formed even when the remaining amount of the recording material is detected to be insufficient.

According to the fourth aspect of the present invention, since a means for warning the user when a shortage of the remaining amount of the recording material is detected is further provided, an optimum image can be formed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an image processing system of a digital copying machine as an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram showing a control system of the digital copying machine shown in FIG.

FIG. 3 is a block diagram illustrating a write control unit and an LD modulation unit of FIG. 1 in detail;

FIG. 4 is an explanatory diagram illustrating a γ conversion table of a γ conversion control unit in FIG. 3;

FIG. 5 is a block diagram illustrating a write control unit and an LD modulation unit according to a second embodiment in detail.

FIG. 6 is an explanatory diagram showing a γ conversion table of a γ conversion control unit in FIG. 5;

[Description of Signs] 202 γ Conversion Control Unit 203 Pixel Count Unit 207 Image Forming Unit (Toner Remaining Detecting Means) 208 Toner End Signal 209 Counter

Claims (4)

[Claims] An image forming apparatus for forming an image on a sheet of paper using a recording material, comprising: a remaining amount insufficient detecting unit for detecting a remaining amount of the recording agent; Counting means for counting the elapsed time from the time of detection; and, based on the elapsed time counted by the counting means, correcting a decrease in image density on a sheet caused by a shortage of the remaining amount of the recording material. And a gamma conversion unit for correcting the gamma conversion characteristics of the image. 2. An image forming apparatus for forming an image on a sheet by using a recording material, comprising: a remaining amount detecting device for detecting a remaining amount of the recording material; Counting means for counting the number of pixels of the image data from the time of detection; and, based on the number of pixels counted by the counting means, a reduction in image density on a sheet caused by a shortage of remaining recording material. Γ conversion means for correcting γ conversion characteristics of an image so as to perform correction. 3. An image forming apparatus for forming an image on a sheet of paper using a recording material, comprising: a remaining amount insufficient detecting device for detecting a remaining amount of the recording material; First counting means for counting the elapsed time from the detection, and second counting for counting the number of pixels of the image data since the shortage of the remaining amount of the recording material is detected by the remaining amount detection unit. Means, based on the elapsed time counted by the first counting means and the number of pixels counted by the second counting means, a decrease in image density on a sheet caused by a shortage of the remaining amount of recording material. An image forming apparatus comprising: a γ conversion unit that corrects a γ conversion characteristic of an image so as to correct the image. 4. The apparatus according to claim 1, further comprising: a unit that warns a user when a shortage of the remaining amount of the recording material is detected by the remaining amount detection unit. Item 10. The image forming apparatus according to item 1.