JP2002357932A - Electrophotographic printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a toner concentration detector that prevents a decrease in glossiness of a calibration plate used for low concentration measurement, has a simple structure and ensures accurate measurement of a toner concentration without a cost increase. SOLUTION: In order to calibrate the toner concentration sensor in setting a low concentration, a photoreceptor is used as the calibration plate for low concentration measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic printing apparatus.

[0002]

2. Description of the Related Art The toner density detecting device shown in FIG. 5 shows a trial example examined in the course of the invention of the electrophotographic printing device of the present invention. A similar toner density detecting device has been proposed in, for example, Japanese Patent Application Laid-Open No. 10-161416.

The outline of the toner density detecting device will be described with reference to FIG.

A density sensor 1 for measuring the toner density on the surface of the photoreceptor 7 based on the amount of light reflected, and a high-density measurement for calibrating the density sensor 1 and the measurement position facing the photoreceptor 7 A rotating unit 4 having a motor and the like for rotating and moving to a calibration position facing the calibration plate 3 and the calibration plate 5 for low concentration measurement is provided. The density sensor 1, the calibration plate for high-concentration measurement 3, the calibration plate for low-concentration measurement 5, and the rotating unit 4 are housed in a housing 2 (outer case).

[0005] This toner concentration detecting device calibrates the density sensor 1 before measuring the toner concentration. When the toner density setting is low density, the density sensor 1 is calibrated with the low density measurement calibration plate 5. Since the reflectance from the toner image is high when the toner density is low, the low-density measurement calibration plate 5 (the low-density reference value calibration light beam reflection unit of the reference value calibration light beam reflection unit) has a high reflectance. A glossy calibration plate is used.

When the toner density setting is high density, calibration is performed using a high density measurement calibration plate 3 (a high density reference value calibration light reflecting portion of a reference value calibration light reflecting means). When the toner density is high, the reflectance from the toner image is low, so a low-reflectance non-glossy calibration plate is used as the low-density measurement calibration plate 3. After calibration of the concentration sensor 1,
By measuring the density of the toner image formed on the photoreceptor 7 and correcting the density control according to the measured value of the density, development conditions and exposure conditions can be optimized.

[0007]

However, in the above-described toner density detecting device, the glossiness of the component plate for low density measurement using a glossy calibration plate may be reduced due to toner or paper dust. In addition, since two calibration plates are used, there is a problem in that the mounting structure becomes complicated and costs increase.

It is an object of the present invention to address such a problem and to realize a toner density detecting device capable of accurately measuring toner density without simplifying the structure and increasing the cost. Another object of the present invention is to prevent the glossiness of the calibration plate for low concentration measurement from decreasing.

[0009]

According to the present invention, there is provided a toner density detecting device for detecting a toner density of a toner image formed by toner, and a printing mechanism including a transfer device for transferring the toner image to a sheet. In the electrophotographic printing apparatus, the toner density detecting device includes a light emitting element that emits a light beam, a light receiving element that receives the reflected light beam, and a reference value calibrating light reflecting unit that calibrates a reference value of toner density detection. The reference value calibrating light reflecting means includes a high density reference value calibrating light reflecting portion that becomes a light reflection reference value of a high density toner, and a low density reference value that becomes a light reflection reference value of a low density toner. A calibration light reflecting portion is provided, and the low-density reference value calibration light reflecting portion is a surface of the photoconductor.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIGS.
This will be described with reference to FIGS.

An embodiment of the present invention will be described below with reference to the drawings. First, a schematic configuration of a mechanism of an electrophotographic printing apparatus to which the present invention is applied will be described with reference to FIG.

In FIG. 4, when the photoreceptor 7 starts rotating, a high voltage is applied to the charger 8 to uniformly charge the surface of the photoreceptor 7 with the printing mechanism 6 of the electrophotographic printing apparatus. Is done. When the laser beam 9 for exposing the print data is irradiated from the exposure unit, an electrostatic latent image is formed on the surface of the photoconductor 7.

When the photosensitive area holding the electrostatic latent image reaches a position facing the developing device 10, toner is supplied to the electrostatic latent image, and the charge on the photosensitive element 7 is lost by irradiation with the laser beam 9. The charged toner is attracted to the charged portion by the static electricity, and a toner image is formed on the photoconductor 7. Photoconductor 7
The toner image formed on the sheet 11 is attracted onto the sheet 11 by the action of the transfer unit 12 that applies a charge of a polarity opposite to that of the toner image to the back side of the sheet 11. The area of the photoconductor 7 that has passed the transfer position is cleaned by the cleaning device 13, and the toner adhered to the surface of the photoconductor 7 does not remain, and is completely removed. Thus, the next printing operation is prepared.

The configuration of the toner density detecting device and the optimization of the toner density will be described below with reference to FIGS. 1, 2, 3 and 4.

The toner concentration detecting device 14 provided so as to face the surface of the photosensitive member 7 includes a developing device 10 and a transfer device 12.
The reflection density of the toner image on the photoreceptor 7 is measured based on the measurement result in order to correct the change in the development characteristics due to the environment such as temperature and humidity and to always obtain a constant print quality. The voltage and the like applied to the developing device 10 are controlled.

The toner density detecting device is a density sensor 1 for measuring the toner density on the surface of the photoreceptor 7 based on the amount of light reflected, and the measurement position of the density sensor 1 facing the photoreceptor 7 and the density sensor 1 are calibrated. Rotating unit 4 having a motor or the like for rotating and moving to a calibration position facing a high-density measurement calibration plate 3 (a high-density reference value calibration light reflecting unit of a reference value calibration light reflecting unit) for measuring the density. Sensor 1,
It comprises a calibration plate 3 for high-concentration measurement and a storage container 2 for storing the rotating unit 4.

The container 2 (outer case) of the toner concentration detecting device 14 has a light passage hole 20
Is formed. As shown in FIG. 2, the density sensor 1 placed in the storage container 2 (outer case) has a light emitting element 21 that emits a light beam and a light receiving element 22 that receives a reflected and returned light ray. The density sensor 1 is supported by the rotating unit 4 and faces the light passage hole 20 or the high-concentration measurement calibration plate 3 according to the rotation of the rotating unit 4. The light emitting / receiving direction of the element 22 can be selectively switched.

The low-density reference value calibration light beam reflecting portion that reflects the light beam that passes through the light passage hole 20 is defined as the surface of the photosensitive member. At the time of low-density setting printing, the density sensor 1 is opposed to the photoconductor 7, the reflectance of the photoconductor 7 is measured, the density sensor 1 is calibrated, and then the reflectance of the patch pattern formed on the photoconductor 7 is measured. I do.

The toner density is calculated from the reflectance, and the exposure condition and the development condition are controlled to be appropriate. The photoconductor 7
Has the same reflectance as that of a conventionally used calibration plate. Further, since the photoconductor 7 is cleaned by the cleaning device 13, a decrease in glossiness due to toner or paper dust is prevented. The description of the high density setting is omitted because it is the same as the prior art. As described above, by using the photoconductor to calibrate the density sensor 1 at the time of low-density printing, a toner density detecting device capable of accurately measuring the toner density even in any toner density setting can be manufactured at low cost without complicating the structure. Can be realized.

The light-emitting element 21, the light-receiving element 22, and the calibration plate 3 for high-concentration measurement are covered with the storage container 2 (outer case).
In addition, since the light beam passes through the light passage hole 20 in a closed configuration, toner does not easily enter the storage container 2, dirt due to toner does not easily occur, and the detection accuracy due to toner dirt is small.

In the above embodiment, the storage container 2 (outer case) is provided with the rotating density sensor 1.
It is also possible to adopt a configuration in which the outer case is turned without turning the density sensor 1.

[0022]

According to the present invention, the structure of the toner density detecting device capable of accurately measuring the toner density at any toner density setting by using the photoconductor for the calibration of the density sensor at the time of low density printing is complicated. Can be realized at low cost without inducing.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a toner concentration detecting device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a density sensor provided in the toner density detection device according to the embodiment of the present invention.

FIG. 3 is a diagram showing a flow of adjusting toner concentration to an appropriate value according to one embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of a printing unit according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a configuration of a toner concentration detecting device according to a trial example examined in a process leading to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Density sensor, 2 ... Storage container, 3 ... Calibration plate for high concentration measurement, 4 ... Rotating part, 5 ... Calibration plate for low concentration measurement, 6 ... Printing mechanism part, 7 ... Photoconductor, 8 ... Charger, 9 laser light, 10
... Developing device, 11 paper, 12 transfer device, 13 cleaning device, 14 toner concentration detecting device.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideho Yokokawa 1060 Takeda, Hitachinaka City, Ibaraki Prefecture Inside Hitachi Koki Co., Ltd. (72) Inventor Masaru Sawahata 1060 Takeda Hitachinaka City, Ibaraki Prefecture Inside Hitachi Koki Machinery (72 Inventor Susumu Edo 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd.Hitachi Research Laboratories Co., Ltd. F term in the laboratory (reference) 2G059 AA01 EE02 GG02 HH02 KK01 PP10 2H027 DA10 DA35 DD09 DE02 DE07 DE09 EA02 EA05 EC04 EC07 ED06 ED08 EE07 EF06 HA02 HA03 HA14 HB09 HB20 ZA07

Claims (3)

[Claims] A photoconductor having photoconductivity; a charger for charging the surface of the photoconductor; an exposure unit for forming an electrostatic latent image on the surface of the charged photoconductor; An electrophotographic printing apparatus provided with a developing device for adsorbing toner, a toner concentration detecting device for detecting a toner concentration of a toner image formed by toner, and a printing mechanism including a transfer device for transferring the toner image onto paper. A light-emitting element that emits a light beam;
A light-receiving element that receives the reflected light beam; and a reference-value-calibration light-reflecting unit that calibrates a reference value for toner-density detection. The high-density reference value calibration light reflection portion, and the low-density reference value calibration light reflection portion that becomes the light reflection reference value of the low-density toner, and the low-density reference value calibration light reflection portion of the photoconductor. An electrophotographic printing apparatus characterized by being a front surface. 2. A photoconductor having photoconductivity, a charger for charging the surface of the photoconductor, an exposure unit for forming an electrostatic latent image on the surface of the charged photoconductor, and An electrophotographic printing apparatus provided with a developing device for adsorbing toner, a toner concentration detecting device for detecting a toner concentration of a toner image formed by toner, and a printing mechanism including a transfer device for transferring the toner image onto paper. An outer case in which the toner density detecting device is provided is disposed so as to face the surface of the photoreceptor, and a density sensor having a light emitting element for emitting light and a light receiving element for receiving the reflected light in the outer case. And a high-density reference value calibration light beam reflection unit that becomes a light reflection reference value of the high-density toner. A light passing hole through which a returning light beam passes; and a low-density reference value calibration light beam reflecting portion that reflects the light beam passing through the light passing hole and reflecting the light beam is a surface of the photoconductor. Electrophotographic printing equipment. 3. The high-density reference value calibration light beam reflection device according to claim 2, wherein the density sensor is provided rotatably with respect to the outer case, and the light emitting / receiving direction of the density sensor is changed to the high-density reference value calibration light beam. And an electrophotographic printing apparatus characterized in that it is possible to selectively switch between a light-reflecting unit and a low-density reference-value calibration light-reflecting unit.