JPH08327331A - Apparatus for measuring adhering amount of toner and apparatus for controlling density of image - Google Patents

Abstract

PURPOSE: To measure the adhering amount of toners correctly and suitably to control the density by detecting a thickness of toners adhering onto an image carrier body. CONSTITUTION: The apparatus is provided with an illuminating means for projecting a spot light onto an image carrier body 1, an image formation means 23 for forming an image of a reflecting light of the spot light from a developed image 25 on the image carrier body 1 at a position corresponding to the thickness difference of toners adhering to an image-developing part, a detection means 34 for detecting difference of image formation positions by the image formation means 33, and a judging means 23 for judging the adhering amount of toners from the difference of the image formation positions. The image density is feedback controlled based on the judgement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner adhesion amount measuring device and an image density control device used in an electrophotographic image forming apparatus such as a copying machine, a laser printer and a facsimile.

[0002]

2. Description of the Related Art Even when an image is formed under the same setting conditions, the density of the formed image is not constant. This is because variations in various image density parameters such as variations in the toner concentration of the developer, stains on the optical system, and variations in the voltage of the power supply, and variations in environmental conditions such as humidity influence. Therefore, conventionally, the density of the developed image on the image carrier is detected, and based on the detection result, various image density parameters such as toner replenishment, charging potential, and developing bias potential are feedback-controlled.

For example, US Pat. No. 2,956,487 describes any of an exposed image on an image bearing member, a latent image formed by exposure on the image bearing member, and a developed image of the latent image. The image density is detected, the detected value at this time is compared with a reference value, and the image density is controlled according to the comparison result.

US Pat. No. 4,082,445 compares the difference between the amount of reflected light from a non-image area on an image carrier and the amount of reflected light from a visible image reference pattern with a reference value. It discloses that the toner is replenished according to the comparison result.

On the other hand, it is also required to suppress excessive consumption of toner while keeping the image density above a predetermined range, and the amount of toner adhering to the image carrier is based on the intensity of light reflected from the visible image. It is also controlled. However, the light absorptance does not change linearly with respect to the toner adhesion amount, and the change in the reflected light amount with respect to the toner adhesion amount change in the high adhesion region is slight. However, the amount of adhered toner used when forming an actual image belongs to the high adhered area, and even in such an area, the difference in the amount of reflected light with respect to the difference in the amount of adhered toner is small. It is difficult to accurately control the adhered amount of the. Further, since the toner itself also has a certain reflectance, this deteriorates the S / N for density detection.

In order to deal with this, the amount of toner adhered under a predetermined setting condition is formed by setting the image density as a paragraph below the set value, for example, by lowering the charging potential by about 150 V from the charging potential during normal image formation. The toner adhesion amount is determined based on the intensity of the reflected light from the so-called halftone visible image reference pattern.

[0007]

However, in the method of detecting the density of the visible image formed on the image bearing member as described in the above-mentioned US patent specification, the reflectance of the bare surface of the image bearing member is Since it is affected by changes in surface roughness, reduction in film thickness, occurrence of filming due to toner, etc., it is necessary to frequently deal with such changes.

Further, the spectral reflectance of the toner or the image carrier is easily affected, and the color toner or the like cannot be measured in combination with the color tone of the image carrier, or the accuracy is remarkably deteriorated.

Further, when the toner adhesion amount increases, the amount of reflected light becomes extremely small, the S / N ratio deteriorates, and it becomes impossible to take an effective dynamic range.

Further, as disclosed in the US patent specification, the density of the visible image formed on the image carrier is detected based on the image density relating to the latent image and the exposed image. There are problems other than those related to.

Therefore, in any case, it is impossible to stably guarantee the image formation with an appropriate density.

If the image density is determined based on the intensity of the reflected light from the halftone visible image reference pattern, the halftone and the image forming potential are different from each other, so that accurate measurement cannot be performed.

An object of the present invention is to solve the above problems and to accurately measure the amount of toner adhering by detecting the thickness of the toner adhering to the image carrier, and to perform accurate density control. It is an object of the present invention to provide a toner adhesion amount measuring device and an image density control device capable of performing the above.

[0014]

In order to achieve the above object, the toner adhesion amount measuring apparatus of the present invention comprises an illuminating means for irradiating an image carrier with spot light and a developing means on the image carrier. An image forming means for forming an image of the reflected light of the spot light from the formed visible image at a position corresponding to the difference in the thickness of the toner adhering to the visible image portion, and an image forming means for the reflected light. It is characterized in that it is provided with a detecting means for detecting a difference in the image forming position and a determining means for judging the toner adhesion amount based on the difference in the image forming position.

Further, in the image density control device of the present invention, the illuminating means for irradiating the image carrier with the spot light and the reflected light of the spot light from the image carrier do not adhere to the toner on the image carrier. And an image forming means for forming an image at a position corresponding to a difference in the thickness of the adhered toner, a detecting means for detecting a difference in the image forming position of the reflected light, and a detecting means on the image carrier as necessary. Reference pattern forming means for forming an image reference pattern,
The image density of the image forming system is changed according to the difference between the image forming position of the reflected light from the non-developed portion on the image carrier and the image forming position of the reflected light from the visible image reference pattern on the image carrier. The image density parameter control means for controlling the parameters is provided.

[0016]

In the above structure of the toner adhesion amount measuring device of the present invention, the reflected light when the developed visible image on the image carrier is irradiated with the spot light is changed by the image forming means and the intensity of the light is changed. Irrespective of the color of the image or the difference in the degree of reflection or absorption of light, the image can be accurately formed at a position corresponding to the difference in the thickness of the toner adhering to the visible image portion. The position difference is detected by the detection unit in a good S / N state, and the determination unit determines the toner adhesion amount based on the detection result. Therefore, the toner adhesion amount is determined by the normal image forming conditions. It can be accurately measured from the image.

In the above-described structure of the image density detecting apparatus of the present invention, the reflected light of the spot light irradiated on the image carrier is formed on the image carrier by the image forming means as in the case of the toner adhesion amount measuring apparatus. An image is accurately formed at a position according to the presence / absence of toner adhesion and the difference in the thickness of the adhered toner, and this difference in image formation position is detected by the detection means in a good S / N state. An image forming position related to reflected light from a developed image reference pattern formed by the reference pattern forming means on the image carrier and a reflected image from a non-developed portion on the image carrier. The difference corresponds exactly to the toner adhesion amount of the visible image reference pattern, and the image density parameter control means controls the image density parameter of the image forming system in accordance with this difference, which is required under normal image forming conditions. Shaped according to From time to time of an image formed from the visible reference pattern it can be made to stably achieved in a predetermined amount of toner adhesion.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A toner adhesion amount measuring device and an image density control device according to a first embodiment of the present invention will be described below.

This embodiment is a case of a laser printer, and as shown in FIG. 2, a photosensitive drum 1 as an image carrier.
A charge charger 2 for uniformly charging the photosensitive drum 1 to a predetermined potential in accordance with the direction indicated by the arrow around which the photosensitive drum 1 is rotationally driven, and image exposure to the charged surface of the photosensitive drum 1 is performed. The laser oscillator 3, the developing device 4 for developing the image-exposed portion of the photoconductor drum 1, and the developed visible image on the photoconductor drum 1 are transferred to the recording paper 6 fed from the paper feed unit 5. A transfer charger 7, a cleaner 8 for removing the residual toner on the surface of the photosensitive drum 1 after the transfer, and an eraser 9 for removing the residual potential on the surface of the photosensitive drum 1 after the transfer are sequentially arranged. Are configured.

The photosensitive drum 1 includes a photosensitive member driving mechanism 10
However, a charging transformer 11 is provided in the charging charger 2, a laser controller 12 is provided in the laser oscillator 3 for modulating laser light emitted from the laser oscillator 3 according to an image signal, a developing bias power source 13 is provided in the developing device 4, and An eraser power source 14 is connected to the eraser 9, and these are connected to the central processing unit 2
The image formation is performed based on a predetermined image density parameter.

The transfer section provided with the transfer charger 7 is provided with a separation charger 15 for separating the recording paper 6 after transfer from the photosensitive drum 1, and the recording paper 6 after separation is sent to a fixing device 16 and fixed. It is processed and discharged to the outside of the machine. The operations of the paper feeding unit 5, the transfer charger 7, the separation charger 15, the fixing device 16, and the transport mechanism for the recording paper 6 are also controlled by the central processing unit 21.

Around the photosensitive drum 1, there is further provided a toner adhesion amount detecting element 22 for measuring the toner adhesion amount based on the thickness of the toner adhered by the development on the photosensitive drum 1. Toner adhesion amount detection element 22
An image density calculation device 23 is connected to the image density calculation device 23, and a predetermined calculation is performed based on the detection information from the toner adhesion amount detection element 22 to determine the toner adhesion amount. This determination result is transmitted to the central processing unit 21 so that the image density parameter is feedback-controlled according to the determination result. It goes without saying that the image density calculation device 23 may be an internal function of the central processing device 21.

The feedback control function in which the toner adhesion amount detecting element 22, the image density calculation device 23, and the central control device 21 function as an image density control device is executed in an image adjustment mode as required. In the image adjustment mode, the image forming system forms a partial visible image reference pattern 25 as shown in FIG. 2 on the photosensitive drum 1 under normal image forming conditions, and the image visible reference pattern 25 is detected. The feedback control is performed based on the toner adhesion amount. In this case, the recording paper 6 is not fed and the transfer charger 7 and the separation charger 15 are not activated. As a result, the image-exposed and developed visible image reference pattern 25 can pass through the transfer portion as it is and reach the position of the toner adhesion amount detection element 22, which is used for detection of the toner adhesion amount.

The image adjustment mode is set at a predetermined timing according to a preset program, for example, when the laser printer is turned on, when a predetermined number of recording operations or a predetermined number of recordings are satisfied, or after a trouble such as a jam has been dealt with. It may be executed at the time of rising or the like, or may be executed based on the input of a person as necessary. Depending on the case, both of them can be adopted.

The image density feedback control is performed in accordance with the toner adhesion amount determination information regarding the visible image reference pattern 25 from the image density calculation device 23, for example, the output of the charging charger 2, the laser output of the laser oscillator 3, and the developing device 4. Image density parameters such as the developing bias voltage, the output of the eraser 9 and the toner replenishment of the developing device 4 are controlled by the central controller 21.

The toner of the visible image reference pattern 25, which has been used for the detection of the toner adhesion amount, is cleaned by the cleaner 8 and the potential is removed by the eraser 9. After that, the normal image density density parameter is feedback-controlled to a normal value. Image formation is performed.

The toner adhesion amount detecting element 22 and the image density calculating device 23 have the structures shown in FIG.
To explain this, the toner adhesion amount detection element 22 detects a semiconductor laser 31 and a light projecting lens 32 that obliquely irradiate the photosensitive drum 1 with spot light and a reflected light from the photosensitive drum 1 to the photosensitive drum 1. It has a light-receiving lens 33 that forms an image at a position corresponding to the absence of toner on the top and a difference in the thickness of the adhered toner, and a light position detection element 34 that detects this difference in image formation position. There is.

When the spot light radiated onto the photosensitive drum 1 from an oblique direction is reflected by the photosensitive surface 1a of the photosensitive drum 1 in the non-developing portion where no toner adheres, the position B of the light position detecting element 34 is detected. Is imaged. In addition, the photosensitive drum 1
The visible image reference pattern 25 is formed on top of which toner is attached, and the toner surface 25a of the visible image reference pattern 25 is formed.
When reflected by, the image is formed at the position A of the optical position detecting element 34 according to the thickness of the attached toner.

It should be noted that the reflection on the toner surface 25a becomes irregular reflection and is not focused sharply on the light position detecting element 34.
Although it is detected with a broad intensity distribution, the position of B can be specified from this intensity distribution.

In short, the reflected light from the surfaces 1a and 25a of the photosensitive drum 1 and the visible image reference pattern 25 changes in the intensity of the spot light, the color of the photosensitive drum 1 and the visible image reference pattern 25, or the light. Irrespective of the difference in the degree of reflection or absorption, the presence or absence of the visible image reference pattern 25, and the respective positions on the light position detection element 34 depending on the difference in the thickness of the toner attached to the portion where the image reference pattern 25 is formed. An image can be accurately formed at a position, and the amount of adhered toner can be determined in a good S / N state from the difference in the image forming position of the detection element 34. This determination can be made only by the image forming position of the reflected light from the visible image reference pattern 25, but the image forming position of the reflected light from the surface of the photoconductor drum 1 without the image visible reference pattern 25 is used as a reference for the image formation. If the toner adhesion amount is determined based on the difference from the image formation position of the reflected light from the image reference pattern 25, even if the surface position of the photosensitive drum 1 changes, the toner adhesion amount can be accurately determined. Can be done.

Therefore, in the actual image adjustment mode, the detection of the image forming position by the optical position detecting element 34 is first performed on the surface of the photosensitive drum 1 on which the visible image reference pattern 25 is not formed, and then on the photosensitive drum 1. This is performed on the upper surface of the visible image reference pattern 25 to be formed, and the difference between the two is used for the determination.

The electric signal from the optical position detecting element 34 at the time of detecting the image forming position each time is output as an electric signal corresponding to the intensity of the reflected light imaged at each position for each image forming position. It is input to the image density calculation device 23 via 35. The image density calculation device 23 sequentially detects the input at each time of detecting the image forming position by switching the changeover switch 23a, samples each for an appropriate time and averages and uses the input, and connects the position showing the peak at that time. The toner adhesion amount is determined by calculating the toner adhesion amount based on the difference between the image forming positions, the toner adhesion amount is determined, the determination information is output to the central processing unit 21, and the image density based on the determination of the toner adhesion amount is performed. Feedback control of the central processing unit 21
To be done by.

In short, the difference between the image forming position of the reflected light from the visible image reference pattern 25 on the photosensitive drum 1 and the image forming position of the reflected light from the non-developing portion on the photosensitive drum 1 is apparent. Accurately corresponds to the toner adhesion amount of the image reference pattern,
Since the image density parameter is feedback-controlled according to this difference, the image formation from time to time is stably achieved with a predetermined toner adhesion amount from the visible image reference pattern formed as necessary under normal image forming conditions. You can

FIG. 3 shows a second embodiment of the present invention, in which the toner does not adhere to the photosensitive drum 1 of the spot light, and the image forming position varies depending on the thickness of the adhered toner. Imaging position detecting device 4 for detecting a difference by different methods
1 is shown.

As shown in the figure, the image forming position detecting device 41 forms a laser beam emitted from the semiconductor laser 41 into a spot light by a collimating lens 42 and an objective lens 43, and forms a spot light on the surface 1a of the non-developing portion of the photosensitive drum 1. And the surface 2 of the visible image reference pattern 25 formed on the photosensitive drum 1.
5a is irradiated to form an image on these surfaces 1a and 25a.

The reflected light from these surfaces 1a and 25a is
It passes through the objective lens 43 and the collimator lens 42 again, and returns to the half mirror 44, where it is reflected at a right angle and reaches the light receiving element 46 through a very small pinhole 45.

At this time, when the spot light is imaged on each of the surfaces 1a and 25a, the reflected light from these is imaged at the position of the pinhole 45, and the spot diameter becomes the minimum, so that the total amount of light is almost zero. Passes through the pinhole 45 and the light receiving element 4
6, the amount of light received by the light receiving element 46 becomes maximum.

On the other hand, the spot light is reflected on the surfaces 1a and 25
When no image is formed on a, the reflected light from these does not form an image at the position of the pinhole 45, and only a very small amount of light passes through the pinhole 45 and reaches the light receiving element 46. Therefore, the amount of light received by the light receiving element 46 becomes extremely small.

Therefore, by adjusting the position of the objective lens 43 so that the amount of light received by the light receiving element 46 is maximized, the spot light can be imaged on each surface 1a or 25a.

Although the position of the objective lens 43 is adjusted by using the tuning fork 46 in this embodiment, when the image is obtained through the tuning fork position detecting sensor 47 which detects the position of the tuning fork 46. By detecting the position of the objective lens 43, it is possible to detect that the toner on the photosensitive drum 1 is not attached and the difference in the image forming position of the spot light according to the difference in the thickness of the attached toner. Therefore, the same operational effect as in the case of the first embodiment can be exhibited.
Moreover, it is superior to the case of the first embodiment in that it is not affected by the inclination and roughness of the reflecting surfaces 1a and 25a.

[0041]

According to the toner adhesion amount measuring apparatus of the present invention, the reflected light of the spot light from the developed image on the image carrier, which is irradiated with the spot light, is reflected by the image forming means.
Accurately image at a position according to the difference in the thickness of the toner adhering to the visible area, regardless of the variation in light intensity, the color of the visible image, or the difference in the degree of reflection or absorption of light. However, the difference in the image forming position is determined by the detecting means as a good S value.
In the / N state, the determination unit determines the toner adhesion amount based on the detection result, so that the toner adhesion amount can be accurately measured from the visible image formed under normal image forming conditions.

According to the image density detecting device of the present invention, the reflected light of the spot light irradiated on the image carrier is transferred to the toner on the image carrier by the image forming means as in the case of the toner adhesion amount measuring device. Is accurately imaged at a position according to the presence or absence of adherence of the toner and the difference in the thickness of the adhered toner, and the difference in the image formation position is detected by the detection means in a good S / N state. Difference between the image forming position of reflected light from the visible image reference pattern formed by the reference pattern forming means on the image carrier and the image forming position of light reflected from the non-developed portion on the image carrier. Accurately corresponds to the toner adhesion amount of the visible image reference pattern, and the image density parameter control means controls the image density parameter of the image forming system according to this difference, so that it is necessary under normal image forming conditions. Formed according to From time to time of an image formed from the image reference pattern it can be made to be achieved stably at a predetermined amount of toner adhesion.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a toner adhesion amount measuring device according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a printer that performs image density control using the apparatus of FIG.

FIG. 3 is a configuration diagram of a toner adhesion amount measuring device showing a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 3 Laser oscillator 21 Central processing unit 22, 40 Toner adhesion amount detection element 23 Image density calculation device 25 Visual image reference pattern 1a, 25a Surface 33 Light receiving lens 34 Optical position detection device 41 Semiconductor laser 43 Objective lens

Claims (2)

[Claims] 1. An illuminating means for irradiating an image carrier with spot light, and a reflected light of the spot light from a developed visible image on the image carrier, for the toner adhering to the visible image portion. An image forming unit that forms an image at a position corresponding to a difference in thickness, a detecting unit that detects a difference in the image forming position of the reflected light by the image forming unit, and a toner adhesion amount is determined based on the difference in the image forming position. A toner adhesion amount measuring device comprising: a determining unit. 2. An illuminating means for irradiating an image carrier with spot light and a reflected light of the spot light from the image carrier are used to determine whether toner is not adhered to the image carrier or the thickness of the adhered toner. Image forming means for forming an image at a position corresponding to the difference in height, a detecting means for detecting a difference in the image forming position of the reflected light, and a reference pattern for forming a visible image reference pattern on the image carrier as necessary. An image is formed according to the difference between the image forming position of the reflected light from the non-developing portion on the image carrier and the image forming position of the reflected light from the visible image reference pattern on the image carrier. An image density control device, comprising: an image density parameter control means for controlling an image density parameter of the system.