JP2003122066A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer capable of forming an inspection printed image of stable density. SOLUTION: The printer 10 is provided with a rotary developing part 40 for supplying developer to an electrostatic latent image formed on a photoreceptor drum 404d and forming a printed image, a fixing part 50 for heating the paper with the printed image transferred and fixing the printed image on the paper, and a detection part 502 for detecting the density of the printed image which is formed by the rotary developing part 40 and fixed by the fixing part 50, and after the prescribed number of papers is heated by the fixing part 50 whose temperature is elevated, a toner patch formed by the rotary developing part 40 is fixed on the paper by the fixing part 50, and then, the density of the toner patch fixed on the paper is detected by the detection part 502, and the density of the printed image formed by the rotary developing part 40 is adjusted based on the detected density of the toner patch.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus having a developing section for supplying a developer containing toner to an electrostatic latent image formed on an electrostatic latent image carrier to form a printed image.

[0002]

2. Description of the Related Art A printing density of an electrophotographic printing apparatus having a developing unit for supplying a developer containing toner to an electrostatic latent image formed on an electrostatic latent image carrier to form a printed image is adjusted. However, there are the following methods for obtaining an image with excellent gradation reproducibility. First, a toner patch, which is a print image for inspection, is formed in the same manner as the developing unit forms a print image on the electrostatic latent image carrier, and this toner patch is transferred to a sheet, and the fixing unit Fix on paper. Next, the density of the toner patch is detected, and the density of the print image is adjusted based on the detection result.

[0003]

However, the density of the toner patch changes depending on the printing condition, and when forming the toner patch on several sheets of paper, the density of the toner patch on the first sheet of paper is changed. And the density of the last toner patch may be different. Therefore, when adjusting the density of the printed image based on the density of the toner patch, it may not be possible to make an accurate adjustment. Further, in order to perform accurate adjustment, it is necessary to repeatedly print toner patches on a large number of sheets and repeat sampling, and there is a problem that a large number of sheets are used for sampling.

Therefore, a first object of the present invention is to provide a printing apparatus capable of forming a print image for inspection having a stable density. A second object is to provide a printing apparatus that can form a print image for inspection with a stable density and can efficiently use a sheet used for inspection.

[0005]

A printing apparatus according to the present invention comprises an image forming unit for forming an unfixed print image on a sheet and a sheet on which the print image is formed by the image forming unit to heat the sheet. A fixing unit that fixes the image on the sheet, and a detecting unit that detects the density of the print image fixed on the sheet by the fixing unit;
An image quality adjusting unit that makes settings for adjusting the image quality of a print image based on the detection result of the detecting unit, and a fixing unit for a sheet to be supplied to the fixing unit after the fixing unit heats a predetermined number of sheets. The control means detects the density of the printed image fixed by the detecting means, and controls the image quality adjusting means to set based on the result detected by the detection.

According to the present invention, since the fixing means heats a predetermined number of sheets of paper, the amount of heat generated by the fixing means and the amount of heat taken from the fixing means by the paper are in equilibrium, and the fuser included in the fixing means. The surface temperature of the heating means is stable. With the temperature of the fixing means stable,
Since the print image for inspection is formed, the density of the print image for inspection is stable. Since the image quality of the print image is adjusted based on the stable print image for inspection, the image quality can be adjusted more accurately.

The printing apparatus of the present invention is an image forming means for forming an unfixed print image on a sheet, and a fixing means for heating the sheet on which the print image is formed by the image forming means to fix the print image on the sheet. Means, a detecting means for detecting the density of the print image fixed on the paper by the fixing means, an image quality adjusting means for setting the image quality of the print image based on the detection result of the detecting means, and a heating means by the fixing means. The re-feeding unit that re-feeds the formed sheet to the image forming unit and the fixing unit, and the fixing unit heats a predetermined number of sheets, and the re-feeding unit re-feeds the heated sheet and And a control unit that controls the image quality adjusting unit to perform setting based on the result detected by the detection unit by detecting the density of the print image fixed by the fixing unit on the supplied sheet.

According to the present invention, since the fixing means heats a predetermined number of sheets of paper, the amount of heat generated by the fixing means and the amount of heat taken away from the fixing means by the paper are in equilibrium, and the fuser included in the fixing means. The surface temperature of the heating means is stable. With the temperature of the fixing means stable,
Since the print image for inspection is formed, the density of the print image for inspection is stable. Since the image quality of the print image is adjusted based on the stable print image for inspection, the image quality can be adjusted more accurately. Further, since the print image for inspection is formed on the paper heated by the fixing unit, the paper can be efficiently used.

In the printing apparatus of the present invention, the image forming means is
A print image may be formed on each of a predetermined number of sheets. In addition to stabilizing the surface temperature of a heating unit such as a fuser, if additional information such as information regarding the adjustment state of the printing apparatus is added as a print image, the user can be notified of the additional information.

The printing apparatus of the present invention comprises an image forming means for forming an image on a sheet, a detecting means for detecting the density of the image formed by the image forming means, and an image forming means for detecting an image based on the detection result of the detecting means. Image quality adjusting means for making settings for adjusting the image quality, re-feeding means for re-feeding the paper on which the image is formed by the image forming means to the image forming means, and image formation on the paper re-supplied by the re-feeding means And a control unit that controls the image quality adjusting unit to perform setting based on the result detected by the detection unit.

According to the present invention, the density of the image for inspection is stabilized because the density of the image formed on the sheet re-supplied by the re-supply unit is detected by the image forming unit. . Since the image quality of the image is adjusted based on the stable image for inspection, the image quality can be adjusted more accurately. Further, since the inspection image is formed on the sheet re-supplied by the re-supplying unit, the sheet can be efficiently used.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. When possible, the same parts are designated by the same reference numerals, and overlapping description will be omitted. A printing apparatus 10 according to an embodiment of the present invention will be described with reference to FIG. 1 showing the configuration of the printing apparatus 10. The printing device 10 reads an image of an original placed on a copy glass (not shown) and converts it into an image signal, and a document reading unit 20 that fixes the image on a sheet based on the image signal from the original reading unit 20. An image forming unit (image forming unit, image quality adjusting unit) 40 that forms a print image for causing the image forming unit 40, a sheet feeding unit 30 that supplies a sheet to the image forming unit 40, and a print image formed by the image forming unit 40 An image transfer unit 61 that transfers the image to a sheet, an image fixing unit (fixing unit, image quality adjusting unit) 50 that heats the sheet on which the print image is transferred by the image transfer unit 61 to fix the print image on the sheet, and image formation. An image density control unit (control means) 8 that outputs a signal for adjusting the density of a print image formed by the unit 40.
0, and is comprised.

The document reading section 20 is provided with an image sensor (not shown) such as a CCD which receives reflected light of a fixed document illuminated by a light source (not shown) such as a halogen lamp through a lens (not shown), and this. An image processing processor unit (not shown) that performs predetermined image processing on information obtained by an image sensor (not shown).

The paper feed section 30 includes a plurality of paper feed trays 301-301.
It comprises 303. The paper feed trays 301 to 303 are for accommodating sheets in a stacked manner according to size or type, and are detachably mounted side by side vertically. Then, the paper is sent out from any one of these paper feed trays 301 to 303.
The sheet sent out in this manner is sent to the image forming unit 40 via a conveying unit (not shown) such as a pickup roll or a resist roll.

The image forming section 40 includes a photosensitive drum (electrostatic latent image carrier) 401 corresponding to each of four colors of cyan (C), magenta (M), yellow (Y) and black (K).
a to 401d and their photosensitive drums 401a to 40d
1d includes toner cartridges 402a to 402d for supplying toner for image formation. In the image forming unit 40, since the respective portions corresponding to the four colors of cyan (C), magenta (M), yellow (Y), and black (K) have substantially the same configuration, it corresponds to cyan (C). A description will be given by taking the part that has been done as an example.

A portion of the image forming unit 40 corresponding to cyan (C) includes a laser exposure unit 404 for emitting a laser beam modulated by an image signal from the image processing processor unit (not shown), and a charging trocolon. Charging unit 405,
The photoconductor drum 401a is charged by the charging unit 405 and is exposed by receiving the laser beam from the laser exposure unit 404, and the toner is supplied to and transferred to the photoconductor drum 401a, whereby the exposure is performed. Rotary developing unit 406 that visualizes or develops the electrostatic latent image formed on the photosensitive drum 401a as a color image.
And

The image forming section 40 further includes an intermediate transfer belt 60 onto which the developed print image is transferred onto the photosensitive drum 401a. The print image transferred to the intermediate transfer belt 60 is transferred to a sheet at the image transfer section 61. More specifically, the image transfer portion 61 is the transfer roll 6
This transfer roll 61a is configured to include 1a and the like.
And the intermediate transfer belt 60 are sandwiched between the intermediate transfer belt 60 and the intermediate transfer belt 60 by adjusting the paper posture and the transportation timing by the above-mentioned transporting means (not shown), so that the print image formed on the intermediate transfer belt 60 is formed. Transferred to paper.

The image fixing unit 50 applies a predetermined process such as heating to the paper on which the print image formed by the image forming unit 40 is transferred to fix the print image on the paper, and the print image is fixed. This is a part for discharging the ejected paper. The image fixing unit 50 heats the paper on which the print image is transferred and fixes the print image on the paper, a detecting unit 502 that detects the density of the print image fixed by the fixing unit 501, and each unit. And a discharge unit 503 that discharges the sheet for which the processing of (1) is completed. The image fixing unit 50 further includes a branching unit 504. When printing on one side of a sheet, the sheet that has been processed by the fixing unit 501 is conveyed from the branching unit 504 in the direction of arrow B, and is ejected from the ejecting unit 503 to the outside of the printing apparatus 10. Also, when printing on both sides of the paper,
The sheet on the surface of which the fixing unit 501 has finished processing is conveyed from the branching unit 504 in the direction of arrow A, and is fed to the re-feeding path 70.
And is conveyed along the conveyance path 70a, and the front surface and the back surface are reversed in the paper reversing unit 70, and then the transfer device 6
At 1, the print image on the back side is transferred and conveyed to the fixing unit 501. The subsequent processing is the same as in the case of printing on one side.

The fixing section 501 comprises a fuser 501a and a pressure belt 501b. Fuser 50
1a is supplied with electric power by a power supply means (not shown) to raise the temperature. The temperature to be raised is set so that the toner forming the print image on the paper is melted and fixed to the paper. The pressure belt 501b sandwiches the sheet with the fuser 501a, and the fuser 501a
It is configured so that the paper comes into close contact with.

The temperature characteristic of the fuser 501a will be described with reference to FIG. FIG. 2 shows the fuser 501a.
FIG. 6 is a diagram showing a relationship between the number of sheets processed by and the surface temperature of a fuser 501a. The fuser 501a enters a steady state at t ₀ ° C as the power is supplied and the temperature rises. afterwards,
When the sheet on which the print image is formed is processed, the surface temperature of the fuser 501a decreases according to the number of processed sheets. In the case of the present embodiment, the surface temperature of the fuser 501a is in an equilibrium state when four sheets of paper are processed, and then the surface temperature becomes substantially constant at t ₁ ° C. This phenomenon is caused by heat being absorbed by the sheet when the fuser 501a processes the sheet.
This is due to the fact that the amount of heat generated by power supply to the fuser 501a and the amount of heat taken by the sheet are in an almost equilibrium state.

The detection unit 5 is provided in the conveyance path before the discharge unit 503.
02 is arranged. The detection unit 502 is an optical density sensor, and is a unit that detects the density of a print image for inspection called a toner patch formed on a sheet. The toner patch corresponds to each of cyan (C), magenta (M), yellow (Y), and black (K), and is composed of a plurality of regions whose densities are changed stepwise.
The toner patch may be formed on a single paper sheet or may be formed on a plurality of paper sheets. There is a correlation between the density of the toner patch and the surface temperature of the fuser 501a. The higher the temperature of the fuser 501a, the lower the density of the toner patch, and the lower the temperature, the higher the density. Therefore, when performing density adjustment such as adjusting the density of the print image formed by the image forming unit 40 based on the density of the toner patch detected by the detection unit 502, it is necessary to stabilize the surface temperature of the fuser 501a. In view of this, in the present embodiment, attention is paid to the fact that the surface temperature of the fuser 501a becomes stable when the fuser 501a processes a predetermined number of sheets, and the fuser 501a processes the predetermined number of sheets before the toner patch is formed, as described subsequently. Decided to let. Although the predetermined number of sheets is four in the present embodiment, it goes without saying that it changes depending on the size of the sheet and the characteristics of the fuser 501a.

The image density control unit 80 receives the density of the toner patch detected by the detection unit 502, and adjusts the density of the print image for the image forming unit 40 based on the received density of the toner patch. This is a part for outputting an instruction signal for instructing. More specifically, the image density control unit 8
0 holds the target density of the toner patch, and the detection unit 5
02 outputs an instruction signal for adjusting the density based on the difference between the density of the toner patch actually detected and the target density. Of the image forming unit 40 and the image fixing unit 50, the portion for setting the image quality adjustment adjusts the image density based on the instruction signal.

Subsequently, a procedure for adjusting the density of the printing apparatus 10 will be described with reference to FIGS. Figure 3
3 is a flowchart illustrating a procedure for performing density adjustment. When a density adjustment command is input from an operation unit (not shown) of the printing apparatus 10, the image forming unit 40 forms a dummy patch on the paper supplied from the paper supply unit 30.
The dummy patch is a print image having the same print pattern as the toner patch, but the detection unit 502 does not detect the density. In addition, instead of the dummy patch, additional information such as information regarding the adjustment state of the printing apparatus 10 may be printed. The sheet on which the dummy patch has been formed by the image forming section 40 is conveyed to the image fixing section 50 and heated by the fuser 501a of the fixing section 501, so that the dummy patch is fixed on the sheet. The sheet that has been processed by the fuser 501a is discharged to the outside from the discharge unit 503 (step S0).
1).

The number of sheets for printing the dummy patch is four
Since it is set to, the operation of step S01
It is continuously executed (step S02). Dummy patch
If the number of printed sheets exceeds 4, the fuser 501
When the surface temperature of a is at equilibrium t ₁Estimated to be ℃
Therefore, the image forming unit 40 does not touch the succeeding paper.
Form the ner patch. Toner by the image forming unit 40
The sheet on which the patch is formed is conveyed to the image fixing unit 50,
By being heated by the fuser 501a of the fixing unit 501,
The nap patch is fixed on the paper. In the fuser 501a
The processed paper is conveyed to the detection unit 502 (step
S03).

The density of the toner patch formed on the sheet conveyed to the detecting section 502 is detected by the detecting section 502 (step S04). The paper for which the density of the toner patch is detected is discharged from the discharge unit 503 to the outside. In the present embodiment, since the number of sheets for forming the toner patch and measuring the density thereof is set to eight, the operations of steps S03 to S04 are repeated for eight sheets (step S05). When the number of sheets for which the toner patch is printed and the density is measured exceeds eight, the image density control unit 80 outputs a signal for adjusting the image density based on the measurement result, and the image forming unit 40 The density of the image is adjusted based on the signal (step S06).

Next, another embodiment for adjusting the density of the printing apparatus 10 will be described with reference to FIGS. 1 and 4. FIG. 4 is a flowchart illustrating a procedure for performing density adjustment. When a density adjustment command is input from an operation unit (not shown) of the printing device 10, the fuser 50
1a is heated to t ₀ ° C shown in FIG. 2 (step S1
1). When the temperature of the fuser 501a is raised to t ₀ ° C, the paper is conveyed from the paper feeding section 30 and heated between the fuser 501a and the pressure belt 501b (S12).
The sheet that has passed between the fuser 501a and the pressure belt 501b is guided to the sheet re-feeding path 70, and is conveyed along the conveying path 70a toward the sheet reversing unit 70b.

In this embodiment, the number of sheets heated by the fuser 501a is set to eight, so the operation of step S12 is repeated for eight sheets (step S1).
3). In this case, the surface temperature of the fuser 501a is t ₁ ° C.
It is estimated that The eight sheets conveyed in the re-feeding path 70 are conveyed to the transfer device 61 of the image forming unit 40 with the front surface and the back surface reversed. This fuser 501
A toner patch is formed by the image forming unit 40 on each of the eight sheets that have passed a (step S14).
The sheet on which the toner patch is formed is conveyed to the image fixing section 50, and after the fixing section 501 fixes the toner patch, the sheet is sent to the detecting section 502. The detection unit 502 detects the density of each toner patch on each sheet (step S15).

In the present embodiment, since the number of sheets for forming the toner patch and measuring the density thereof is set to eight, the operations of steps S14 to S15 are repeated for eight sheets (step S16). When the number of sheets for which the toner patch is printed and the density is measured exceeds eight, the image density control unit 80 outputs a signal for adjusting the image density based on the measurement result, and the image forming unit 40 The density of the image is adjusted based on the signal (step S17).

In the present embodiment, an example has been shown in which the front and back sides of the paper are reversed by the paper reversing section 70b. However, in the case of paper such as coated paper having different characteristics on the front and back sides, the image forming section 40 is not reversed. It may be transported to the.

As still another mode, an example of adjusting the image density using six sheets will be described. The sheet up to the fourth sheet is heated without passing through the fuser 501a and the pressure belt 501b without forming a toner patch, and is then guided to the re-feeding path 70. Toner patches are formed on the succeeding fifth and sixth sheets, and the density of the toner patches is detected by the detection unit 502, and then the fifth and sixth sheets are re-fed. It is guided to the paper path 70. The six sheets of paper guided to the re-feeding path 70 are conveyed to the image forming unit 40 with the front surface and the back surface thereof being reversed by the paper reversing unit 70b. In the image forming section 40, toner patches are formed on the back surfaces of all the first to sixth sheets, the density of the toner patches is detected by the detecting section 502, and then all six sheets are discharged. . The image density control unit 80 determines the image density from the detection results of the toner patches on the front surface of the fifth sheet and the sixth sheet and the toner patches formed on the back surfaces of the first to sixth sheets. Outputs a signal for adjustment.

The operation and effect of this embodiment will be described. The fuser 501a of the fixing unit 501, which has been heated, heats a predetermined number of sheets, so that the fuser 50
1a and the amount of heat taken from the fuser 501a by the sheet are in equilibrium, and the fuser 501a
Surface temperature is stable. Since the toner patch is formed while the temperature of the fuser 501a is stable, the density of the toner patch is stable. Since the density of the print image formed by the image forming unit 40 is adjusted based on the toner patch having a stable density, the adjustment can be performed more accurately.

Since the toner patch is formed on the sheet heated by the fuser 501a, the sheet can be used efficiently.

Since the sheet is sent to the fuser 501a before the toner patch is formed on the sheet, the fuser 501a
The surface temperature can be stabilized, and if additional information such as information regarding the adjustment state of the printing apparatus 10 is added as a print image, the user can be notified of the additional information.

[0034]

According to the present invention, the fixing means heats a predetermined number of sheets of paper, so that the inspection print image can be formed in a state where the temperature of the fixing means is stable, and the inspection print image can be formed. The concentration of is stable. Since the density of the print image formed by the developing unit is adjusted based on the stable print image for inspection, the adjustment can be performed more accurately. Therefore, it was possible to provide the printing apparatus capable of forming a print image for inspection with stable density, which is the object of the present invention. Furthermore, it is possible to provide an apparatus that efficiently uses the paper spent for inspection.

[Brief description of drawings]

FIG. 1 is a diagram showing a printing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the surface temperature of the fuser of FIG. 1 and the number of processed sheets.

FIG. 3 is a flowchart showing a procedure for performing density adjustment of the printing apparatus of FIG.

FIG. 4 is a flowchart showing a procedure for performing density adjustment of the printing apparatus of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Printing device, 20 ... Original reading section, 30 ... Paper feeding section, 4
0 ... Image forming unit, 50 ... Image fixing unit, 70 ... Paper reversing unit, 301-303 ... Paper feed tray, 401a-404a
Photoreceptor drums 402a to 402d Toner cartridge 404 Laser exposure unit 405 Charging unit 406
... rotary developing section, 60 ... intermediate transfer belt, 61 ... transfer device, 501 ... fixing section, 501a ... fuser, 501
b ... Pressure roll, 502 ... Detection unit, 503 ... Ejection unit, 5
04 ... Branching part.

Claims (4)

[Claims] 1. An image forming unit that forms an unfixed print image on a sheet, a fixing unit that heats the sheet on which the print image is formed by the image forming unit, and fixes the print image on the sheet. A detection unit that detects the density of the print image fixed on the paper by the fixing unit; an image quality adjustment unit that makes settings to adjust the image quality of the print image based on the detection result of the detection unit; The density of the print image fixed by the fixing unit on the paper supplied to the fixing unit after heating a predetermined number of sheets is detected by the detecting unit,
And a control unit that controls the image quality adjustment unit to perform the setting based on a result detected by the detection. 2. An image forming unit that forms an unfixed print image on a sheet, a fixing unit that heats the sheet on which the print image is formed by the image forming unit, and fixes the print image on the sheet. A detection unit that detects the density of the print image fixed on the sheet by the fixing unit, an image quality adjustment unit that sets the image quality of the print image based on the detection result of the detection unit, and a heating unit that heats the image by the fixing unit. The re-feeding unit that re-feeds the formed sheet to the image forming unit and the fixing unit, and the fixing unit heats a predetermined number of sheets, and the re-feeding unit re-feeds the heated sheet. Then, the density of the print image fixed by the fixing unit on the re-supplied paper is detected by the detecting unit, and the image quality adjusting unit makes the setting based on the result detected by the detecting. Printing device comprising a control for controlling means, a so. 3. The printing apparatus according to claim 1, wherein the image forming unit forms a print image on each of the predetermined number of sheets. 4. An image forming means for forming an image on a sheet, a detecting means for detecting a density of an image formed by the image forming means, and an image quality of the image is adjusted based on a detection result of the detecting means. Image quality adjusting means for setting, re-feeding means for feeding again the paper on which the image is formed by the image forming means to the image forming means, and the image forming for the paper re-feeded by the re-feeding means And a control unit that controls the image quality adjusting unit to perform the setting based on a result detected by the detection, the density of an image formed by the unit being detected by the detection unit.