JPH09160316A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfactorily measure the toner print density of an electrophotographic device from high to low density. SOLUTION: A laser beam is emitted to the surface of an intermediate transfer body 14 from a slanting position, and the position of the reflected laser beam is detected. Because the laser beam reflected from the intermediate transfer body 14 and a laser beam reflected from toner transferred to the intermediate transfer body 14 differ in position in proportion to the thickness of the toner, the thickness of transferred toner is detected from the positional change and this is converted into the print density. Because the print density is not read from the intensity of the reflection, it is not effected by the characteristic of an optical sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus for forming an image on printing paper by electrophotography.

[0002]

2. Description of the Related Art Currently, electrophotographic devices are used in laser printers, copying machines, facsimiles and the like. The electrophotographic apparatus forms an image on printing paper by an electrophotographic method.

That is, the surface of the photoconductor is uniformly charged by the discharge of the charging device, and the charged surface of the photoconductor is selectively discharged by the exposure of the exposure device to form an electrostatic latent image. This electrostatic latent image is developed with the toner supplied from the developing device, and this toner is transferred to the printing paper carried by the paper carrying mechanism by the potential of the transfer device. By fixing the toner transferred onto the printing paper by heating and pressurizing the fixing device, an image is formed on the printing paper by the fixed toner.

There is also a model of such an electrophotographic apparatus in which a transfer belt or a transfer roller is arranged as an intermediate transfer member between the photoconductor and the printing paper. In this case, the toner, which has developed the electrostatic latent image on the photoconductor, is transferred to an endless intermediate transfer member which is stretched by a plurality of supporting rollers in a circulating manner,
The toner attached to the intermediate transfer body is transferred to the printing paper. There is also a model in which the paper transport mechanism transports printing paper by a transport belt. In this case, an endless transport belt is stretched around a plurality of support rollers in a circulatory manner, and printing paper is sequentially transported by the circulating transport belt.

In the electrophotographic apparatus as described above, in order to maintain good quality of the image formed on the printing paper, the density of the toner is detected by the density sensor on the surface of the photoconductor, and the detected value is detected by the developing device or the developing device. There are also models that reflect the control of the exposure device and transfer device.

[0006]

In the electrophotographic apparatus described above, the toner density is detected on the surface of the photoconductor in order to improve the image quality.

As a density sensor for detecting the toner density, an optical sensor such as a photodiode is generally used, but such an optical sensor does not have good detection characteristic linearity. For this reason, it is difficult to accurately detect the toner density from a low density to a high density, and the detection accuracy is lowered particularly when the toner has a high density. Proposals aimed at solving such problems are disclosed in Japanese Patent Laid-Open Nos. 6-1861816 and 6-109643.

For example, in the electrophotographic apparatus disclosed in Japanese Patent Laid-Open No. 6-186816, the surface potential of the electrostatic latent image of the gradation density pattern formed on the photoconductor is detected by the potential sensor, and the developed gradation density is detected. The pattern is read by the optical sensor,
A relational expression between the surface potential of the photoconductor and the toner adhesion amount is obtained. When the toner concentration is low, the optical sensor detects the toner concentration, and when the toner concentration is high, the toner concentration is calculated from the surface potential and the relational expression.

Further, in the electrophotographic apparatus disclosed in Japanese Patent Application Laid-Open No. 6-109643, an optical sensor reads the surface of a photosensitive member when toner is attached and when toner is not attached, and these reading results are logarithmically compressed. The toner density is calculated by the difference between when toner is attached and when toner is not attached.

Although the accuracy of detecting the toner density can be improved by the above-described processing, it is difficult to accurately detect the toner density because the toner density is read by the optical sensor in each case.

[0011]

According to the first aspect of the present invention,
The surface of the photoconductor is uniformly charged by the discharge of the charging device, and the surface of the charged photoconductor is selectively neutralized by the exposure of the exposure device to form an electrostatic latent image, and the electrostatic latent image is developed. In an electrophotographic apparatus in which a toner supplied from a developing device is used for development, the toner is transferred to a printing paper by an intermediate transfer body, and the toner transferred to the printing paper is fixed by a fixing device, the surface of the intermediate transfer body is inclined. Then, a laser light source is arranged at a position facing each other, and a position detection element for detecting the position of the laser light emitted from this laser light source and reflected by the intermediate transfer member is provided. An adhesion amount detecting means for detecting the adhesion amount of the toner transferred to the transfer body is provided. Therefore, since the laser light emitted from the laser light source is incident on the surface of the intermediate transfer body from the inclined direction and is reflected, when the toner is transferred to the surface of the intermediate transfer body, the position of the reflected laser light is changed. Displace. Therefore, if the position detection element detects the position of the reflected laser light, the adhesion amount detection means can detect the adhesion amount of toner from the detection result.

According to a second aspect of the present invention, the surface of the photoconductor is uniformly charged by the discharge of the charger, and the charged surface of the photoconductor is selectively neutralized by the exposure of the exposure device to form an electrostatic latent image. In the electrophotographic apparatus in which the electrostatic latent image is developed by the toner supplied from the developing device, and the toner is transferred to the printing paper and then fixed by the fixing device. A laser light source is arranged at a position that is inclined and opposed to the surface, and a position detection element that detects the position of the laser light emitted from this laser light source and reflected by the printing paper is provided, and from the detection result of this position detection element Adhesion amount detection means for detecting the adhesion amount of the toner transferred to the printing paper is provided. Therefore, since the laser light emitted from the laser light source is incident on the surface of the printing paper from an inclined direction and is reflected, when the toner is transferred to the surface of the printing paper, the position of the reflected laser light is displaced. . Therefore, if the position detection element detects the position of the reflected laser light, the adhesion amount detection means can detect the adhesion amount of toner from the detection result.

According to the third aspect of the present invention, the surface of the photoconductor is uniformly charged by the discharge of the charger, and the charged surface of the photoconductor is selectively discharged by the exposure of the exposure device to form an electrostatic latent image. In the electrophotographic apparatus in which the electrostatic latent image is developed by the toner supplied from the developing device, the toner is transferred to the printing paper, and then fixed by the fixing device. A laser light source is arranged at a position opposite to the surface inclined, and a position detection element for detecting the position of the laser light emitted from this laser light source and reflected by the photoconductor is provided, and from the detection result of this position detection element Adhesion amount detection means for detecting the adhesion amount of the toner transferred to the photoconductor is provided. Therefore, since the laser light emitted from the laser light source is incident on the surface of the photoconductor in an inclined direction and reflected, the position of the reflected laser light is displaced when toner is applied to the surface of the photoconductor. . Therefore, if the position detection element detects the position of the reflected laser light, the adhesion amount detection means can detect the adhesion amount of toner from the detection result.

According to a fourth aspect of the present invention, in the invention according to the first, second or third aspects, the developing device is composed of a plurality of toners which respectively store toners having different colors, and the laser light source has different colors. The laser light is reflected by the toner, and the position detecting element is composed of a plurality of corresponding laser light sources. Therefore, even if different color toners are transferred to the intermediate transfer member by the plurality of developing devices, at least one laser beam of the plurality of laser light sources is reflected by the toner, and the position of the reflected laser beam is changed. It is detected by the corresponding position detecting element.

According to a fifth aspect of the present invention, in the first, second or third aspect of the present invention, the developing device is composed of a plurality of toners each of which has a different color, and the laser light source has a different color. The laser light is tuned to a wavelength that is reflected by the respective toners. Therefore, even if toners of different colors are transferred to the intermediate transfer member by a plurality of developing devices, the laser light whose wavelength of the laser light source is variable is reflected by this toner, and the position of the reflected laser light is changed. It is detected by the detection element.

According to a sixth aspect of the present invention, in the first, second or third aspect of the invention, the laser light source emits infrared laser light, and the position detecting element detects the position of the laser light at two locations. The adhesion amount detecting means detects the adhesion amount of toner from the interval between the two detection positions. Therefore, since the laser light emitted from the laser light source is infrared light, this is reflected by both the surface of the toner and the surface of the intermediate transfer body when the toner is transferred to the position where the toner is transferred to the intermediate transfer body.
Since the positions of the two laser beams reflected in this way are detected by the position detection element, the adhesion amount detection means detects the adhesion amount of toner from the interval between the two detection positions.

According to a seventh aspect of the present invention, in the first, second or third aspect of the invention, the operation of the movable portion that affects the position detection of the position detection element is temporarily stopped in synchronization with the detection timing of the position detection element. An operation control means for controlling the operation is provided.
Therefore, when the position detecting element detects the laser light, the laser light does not vibrate.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. First, a digital copying machine 1 exemplified here as an electrophotographic apparatus has an image reading unit 2 and an image forming unit 3, as shown in FIG.
The image reading unit 2 is formed by connecting an image processing circuit 5 to an image scanner 4, and the image processing circuit 5 is connected to a laser scanner 6 which is an exposing device of the image forming unit 3.

The image forming section 3 has a rotatable photosensitive drum 7 as a photosensitive member. On the outer peripheral surface of the photosensitive drum 7, a drum cleaner 8, a discharging lamp 9, a charging device 10, the laser scanner 6, a potential sensor 11, a developing device 12, an optical sensor 13, and a transfer belt 1 which is an intermediate transfer member.
4 are arranged facing each other in order. This transfer belt 14
Is formed endlessly and is stretched by a plurality of support rollers 15 so as to be able to circulate, and a belt cleaner 16 and a transfer device 17 are arranged to face each other on the outer surface thereof.

A paper transport path 18 communicates with a gap between the transfer device 17 and the transfer belt 14, and the paper transport path 18 communicates from a paper feed cassette 19 to a paper discharge tray 20. At a position facing the paper feed cassette 19,
A paper feed mechanism 22 is provided as part of the paper transport mechanism 21, and a part of the paper transport mechanism 21 is provided at a position where the paper feed mechanism 22 communicates from the gap between the transfer device 17 and the transfer belt 14 to the paper discharge tray 20. Belt transport mechanism 23 and fixing device 2
4 are sequentially arranged. The belt transport mechanism 23
Has an endless conveyor belt 25, and the conveyor belt 25 is stretched around a plurality of support rollers 26 in a circulatory manner.

The digital copying machine 1 illustrated here is used.
Then, the adhesion amount measuring unit 27 is arranged opposite to the portion where the transfer belt 14 circulates from the position of the photosensitive drum 7 to the position of the paper transport path 18. This adhesion amount measurement unit 2
As shown in FIG. 2, reference numeral 7 denotes a visible light laser 28 which is a laser light source and a PSD (Position Sensitit) which is a position detecting element.
ive Device) 29. The visible light laser 2
8 is disposed via a condenser lens 30 at a position facing the surface of the transfer belt 14 in an inclined manner.
The D 29 is arranged via a condenser lens 30 at a position where the laser light emitted from the visible light laser 28 and reflected by the transfer belt 14 is detected. At the position where the visible light laser 28 and the PSD 29 of the transfer belt 14 face each other, one of the support rollers 15 is arranged on the back side thereof.

A rotary encoder (not shown) is connected to one of the support rollers 15 around which the transfer belt 14 is stretched, and a rotation amount detector 31 is connected to the rotary encoder. . Further, FIG.
, The potential sensor 11 and the optical sensor 1
3, the adhesion amount measuring unit 27, the rotation amount detecting unit 31, the driving unit 32 of the photosensitive drum 7, the driving unit 33 of the transfer belt 14, the driving unit 34 of the conveying belt 25, the driving of the paper feeding mechanism 22. Unit 35, drive unit 36 of the transfer unit 17
Are connected to an I / O (Input / Output) control unit 37, and an information processing unit 38 is connected to the I / O control unit 37. Since the control circuit 39 is connected to the visible light laser 28 and the data processing circuit 40 is connected to the PSD 29 in the adhesion amount measuring unit 27, these circuits 39 and 40 are connected to the I / O. It is connected to the control unit 37.

The information processing unit 38 is composed of a micro computer, and includes a CPU (Central Processing Unit) and an RO.
M (Read Only Memory) and RAM (Random Access Memory)
Having. By performing various data processing based on various data input from the potential sensor 11, the optical sensor 13, the adhesion amount measuring unit 27, and the rotation amount detecting unit 31, and by performing various data processes, It controls the operation of the drive units 32-36 and the like.

The digital copying machine 1 of the present embodiment has a pattern forming means, a circulation detecting means, a first position detecting means, a second position detecting means, a first storing means, a second storing means, an adhesion amount detecting means, and an operation. Control means. The pattern forming unit drives the image forming unit 3 in correspondence with a preset test pattern, and an electrostatic latent image of the test pattern formed on the photosensitive drum 7 by the laser scanner 6 is output from the developing device 12. The toner 41 supplied is developed and then transferred to the transfer belt 14. The circulation detection means uses the rotation amount detection unit 31 to transfer the transfer belt 1
The position of the toner 41 of the test pattern transferred to the surface is detected by recognizing the circulation position of No. 4.

As shown in FIG. 2A, the first position detecting means causes the visible light laser 28 to emit laser light to a position on the surface of the transfer belt 14 where the toner 41 is not transferred, and The PSD 29 detects the position of the laser beam reflected on the surface of the transfer belt 14, and outputs it to the information processing section 38 as first position data. As shown in FIG. 2B, the second position detecting means emits the laser beam of the visible light laser 28 to the position on the surface of the transfer belt 14 where the toner 41 is transferred, and the surface of the toner 41 is discharged. The position of the laser light reflected by the PSD
29, and outputs this to the information processing unit 38 as second position data.

The first storage means stores the first position data by the information processing section 38, and the second storage means
The second position data is stored by the information processing unit 38.
The adhesion amount detecting means subtracts the first position data from the second position data by the information processing unit 38, and multiplies the calculation result by a predetermined constant to transfer the transfer belt 1.
The amount of adhered toner 41 transferred to No. 4 is detected.

The operation control means suspends the operation of the movable part which influences the position detection of the PSD 29 in synchronization with the detection timing of the PSD 29. More specifically, since the adhesion amount measuring unit 27 detects the adhesion amount of the toner 41 on the surface of the transfer belt 14, if the transfer belt 14 is circulating at this time, the detection result is affected. Since the transfer belt 14 is provided so as to be pressed against the photosensitive drum 7 and circulate integrally therewith, the operation control means synchronizes with the detection timing of the PSD 29 and causes the information processing section 38 to move the photosensitive drum 7 to the photosensitive drum 7. The drive unit 32 and the drive unit 33 of the transfer belt 14 are temporarily stopped.

In such a configuration, the digital copying machine 1 of the present embodiment reads the image of the document 42 by the image reading section 2 and copies the image on the printing paper 43 by the image forming section 3.

More specifically, in the image reading section 2, the document 4
Since the image 2 is optically scanned by the image scanner 4 and converted into image data, this image data is transmitted from the image processing circuit 5 to the laser scanner 6 of the image forming unit 3. At this time, in the image forming portion 3, the rotating photosensitive drum 7
Since the surface of the photosensitive drum 7 is uniformly charged by the discharge of the charger 10, the surface of the photosensitive drum 7 that is charged and rotated is exposed by the laser scanner 6 that operates according to the image data. By this exposure, the charged surface of the photosensitive drum 7 is selectively neutralized and an electrostatic latent image is formed, so this electrostatic latent image is developed by the toner 41 supplied from the developing device 12 and measured. The toner 41 is transferred to the transfer belt 14.

At this time, the printing paper 43 is fed from the paper feed cassette 19 to the paper conveyance path 18 by the paper feed mechanism 22, so that the toner 41 transferred onto the transfer belt 14 is transferred to the transfer device 1.
It is transferred to the printing paper 43 by the potential of 7. The printing paper 43 to which the toner 41 is transferred is conveyed to the fixing device 24 by the conveying belt 25, so that the toner 41 is pressed and heated by the fixing device 24 to be printed.
Settles in 3. Printing paper 43 with this toner 41 fixed
Is discharged onto the paper discharge tray 20, and the copying operation of the digital copying machine 1 is completed. The toner 41 remaining on the surface of the rotating photosensitive drum 7 is removed by the drum cleaner 8
The toner 41 remaining on the surface of the circulating transfer belt 14 is removed by the belt cleaner 16.

As described above, an image is formed on the printing paper 43 with the toner 41 by the electrophotographic method.
The print density of No. 1 changes due to changes in the electrostatic characteristics of the photosensitive drum 7 over time, environmental changes, and the like. However, the digital copying machine 1 exemplified here has the toner 4 in the initial setting at the time of startup.
By detecting the print density of No. 1 and controlling the drive voltage of the charging device 10, the developing device 12, and the transfer device 17 in accordance with the detected print density, the print density of the toner 41 is constantly corrected.

Therefore, the processing operation for detecting the print density of the toner 41 in order to execute such a correction operation will be sequentially described. First, with all movable parts such as the photosensitive drum 7 and the transfer belt 14 stopped, as shown in FIG. 2A, the visible light laser is first applied to the surface of the transfer belt 14 where the toner 41 is not transferred. 28 laser light is emitted, and the position of the laser light reflected on the surface of the transfer belt 14 is detected by the PSD 29.

Next, as described above, the image forming unit 3 is driven to transfer the toner 41 to the surface of the transfer belt 14 in the shape of the test pattern, and the toner 41 is attached as shown in FIG. 2B. When moving to a position facing the amount measuring unit 27, all the movable parts such as the photosensitive drum 7 and the transfer belt 14 are temporarily stopped. In this state, the laser light of the visible light laser 28 is emitted to the toner 41 of the test pattern transferred onto the surface of the transfer belt 14, and the position of the laser light reflected on the surface of the toner 41 is detected by the PSD 29.

Since the displacement of the position of the laser beam reflected on the surface of the transfer belt 14 is detected depending on the presence or absence of the toner 41, the amount of toner 41 adhered is detected by multiplying this by a predetermined constant. . The amount of adhesion of the toner 41 detected in this way corresponds to the print density of the toner 41, and accordingly, the charging device 10, the developing device 12, and the transfer device 1 are correspondingly.
By controlling the driving voltage of No. 7, the print density of the toner 41 is constantly corrected.

Since the digital copying machine 1 of the present embodiment measures the print density of the toner 41 by the transfer thickness as described above, the detection accuracy is higher than that when the print density of the toner 41 is optically read. Is good, and the print density of the toner 41 can be measured with good characteristics from low density to high density. Moreover, as described above, all the movable parts are stopped in synchronization with the detection timing of the PSD 29, so that the print density of the toner 41 can be accurately detected on the surface of the transfer belt 14 where vibration easily occurs.

Since the transfer belt 14 is supported by the support roller 15 at the detection position, the detection accuracy is further improved. Further, as described above, when the test pattern of the toner 41 is transferred to the transfer belt 14 and the adhesion amount is detected, the image forming unit 3 needs to be driven, but the image scanner 4 and the paper transport mechanism 21 need to be driven. There is no. Therefore, in the operation of detecting the print density of the toner 41 as described above, the image scanner 4 and the paper transport mechanism 21 are operated.
The movable part of 1 is not driven from the beginning, and only the movable part of the image forming part 3 may be temporarily stopped at the detection timing.

In the digital copying machine 1 described above, it is assumed that the test pattern transferred to the transfer belt 14 in order to detect the adhesion amount of the toner 41 is a rectangular pattern having the highest density. The method is not limited to this, and it is also possible to form such a test pattern in stepwise multi-gradation. Further, here, one PSD2 is used as the position detecting element for detecting the reflection position of the laser beam.
By forming it with No. 9, the structure is simplified and the productivity is improved.
ce) It is also possible to form an array.

Further, in the above-mentioned digital copying machine 1, after the surface position of the transfer belt 14 is measured by the adhesion amount measuring unit 27, the transfer belt 14 is looped to transfer the toner 41 to the same position, and the surface thereof is transferred. The position is the adhesion amount measuring unit 27
It is assumed that the measurement is performed by. In this case, there is no need to worry about the uneven thickness of the transfer belt 14, and the toner 41
However, it is necessary to complete the transfer belt 14 once the surface of the transfer belt 14 is measured and before the surface of the toner 41 is measured. In other words, if the thickness of the transfer belt 14 is sufficiently uniform, it is not necessary to measure the adhesion amount of the toner 41 at the same position, and the surface measurement of the transfer belt 14 and the toner 41 is continuously performed to speed up the operation. Can be completed.

Further, in the digital copying machine 1 described above,
The adhesion amount measuring unit 27 is arranged opposite to the transfer belt 14 which is an intermediate transfer member, and the adhesion amount of the toner 41 transferred to the surface of the transfer belt 14 is detected, but the present invention is limited to the above method. It is not something that will be done. For example, as shown in FIG. 4 and FIG.
The toner 41 of No. 5 is placed on the upper surface for conveying the printing paper 43 on which the toner 41 of FIG.
It is also possible to detect the adhered amount of. Further, as shown in FIGS. 6 and 7, the adhesion amount measuring unit 27 is disposed opposite to a position where the transferred toner 41 of the photosensitive drum 7 as a photoconductor is conveyed, and the toner applied to the surface of the photoconductor 7 is disposed. It is also possible to detect the adhesion amount of 41.

Since the above-mentioned three methods have advantages and disadvantages, it is preferable to select them according to various conditions such as device specifications. For example, in the system in which the adhesion amount measuring unit 27 is arranged opposite to the conveyor belt 25, the adhesion amount of the toner 41 finally transferred to the printing paper 43 is detected, and this is the closest to the actual print density. However, on the other hand, the printing paper 43 is consumed for detecting the density of the toner 41. The adhesion amount measuring unit 27 is attached to the transfer belt 1
4 and the photosensitive drum 7, the printing paper 4
Although it is not necessary to consume 3, the adhered amount of the toner 41 measured at such a position may have a large error from the actual print density.

In the digital copying machine 1 described above, the toner 41 applied on the surface of the photosensitive drum 7 is transferred to the transfer belt 14.
However, there is also an electrophotographic apparatus (not shown) that directly transfers the toner 41 from the photosensitive drum 7 to the printing paper 43 without the transfer belt 14 as described above. In this case, the adhesion amount measuring section 27 detects the adhesion amount of the toner 41 on the surface of the photosensitive drum 7 or the printing paper 43. In other words, the method of disposing the adhesion amount measuring unit 27 so as to face the photosensitive drum 7 and the conveyor belt 25 as described above can also be applied to an electrophotographic apparatus having no transfer belt 14.

An electrophotographic device (not shown) in which the photosensitive member is not the photosensitive drum 7 but a photosensitive belt, or an electrophotographic device which does not have the conveyor belt 25 and conveys the printing paper 43 by a feed roller or a guide plate (see FIG. Although not shown), etc., even in such a case, the adhesion amount measuring unit 27 may be arranged at a corresponding position.

Further, the adhesion amount measuring unit 27 is connected to the photosensitive drum 7.
In the method in which the toner is scattered, the laser beam emitted from the adhesion amount measuring unit 27 may cause the photosensitive drum 7 to be exposed and the toner 41 may be scattered. Therefore, if this causes a problem, another method may be selected. preferable.

In the digital copying machine 1 described above, the toner 41 is one type of black because the image is expressed in black and white. For example, in a full color electrophotographic apparatus,
Four developing devices 12 are arranged to face the photosensitive drum 7, and YM
A color image is formed by CK (Yellow, Magenta, Cyanide, Black) toner. As described above, when the toners of a plurality of colors are used, the spectral reflectances are largely different depending on the colors, and there is a concern that the surface may not be well detected by one type of laser light. If this causes a problem, it is preferable to provide a plurality of laser light sources and position detecting elements corresponding to the types of toners and to favorably detect toners of all colors.

More specifically, when four types of toner, YMCK, are used, four laser light sources and four position detecting elements may be provided so as to individually detect the toner. As shown in FIG. 9, it is also possible to actually provide two visible light lasers 28 and two PSDs 29 so that YM toner can be satisfactorily detected on the one hand and CK toner can be satisfactorily detected on the other hand.

Further, the wavelength of the laser light of the laser light source is
If the wavelengths are variable and can be reflected by toners of different colors, one laser light source and one position detection element can satisfactorily detect a plurality of color toners such as YMCK.

In the digital copying machine 1 described above, the surface of the transfer belt 14 and the toner 41 are detected at the same position, so the transfer belt 14 is looped once to perform the measurement twice. The present invention is not limited to the above method. For example, as shown in FIG. 10, an infrared laser 51 is provided as a laser light source, a CCD array 52 is provided as a position detecting element, a transfer belt 14 and a toner 41 are provided.
It is also possible to detect the surfaces of and at the same time.

More specifically, when the infrared laser 51 irradiates the transfer belt 14 on which the toner 41 is transferred with infrared laser light, the laser light is reflected on the surface of the toner 41 and transmitted through the toner 41. It is also reflected on the surface of the transfer belt 14. Since the two laser beams reflected at the two points are incident on the two points of the CCD array 52, the parallel output of the CCD array 52 has two peaks at the two points, as shown in FIG. Since the peak interval is proportional to the toner 41 adhesion amount, the toner 41 adhesion amount can be detected by multiplying the peak interval by a predetermined constant.

In this case, the surfaces of the transfer belt 14 and the toner 41 can be detected at the same time, and the adhesion amount of the toner 41 can be measured at one time, so that the operation can be completed at high speed. In addition, since the infrared laser light has an extremely low degree of exposing the photosensitive drum 7, the adhesion amount measuring unit 53 as described above is most suitable for the system in which the photosensitive drum 7 is arranged to face the photosensitive drum 7.

The various modifications described above can be combined with each other within a range in which the contents do not conflict with each other.

[0051]

According to the first aspect of the present invention, the laser light source is arranged at a position which is inclined and opposed to the surface of the intermediate transfer member, and the position of the laser beam emitted from the laser light source and reflected by the intermediate transfer member. By providing a position detection element for detecting, and by providing an adhesion amount detection means for detecting the adhesion amount of the toner transferred to the intermediate transfer member from the detection result of the position detection element,
Since the print density of toner can be measured by the transfer thickness, the detection accuracy is better than when reading the print density of toner optically, and the print density of toner is good from low density to high density. It can be measured with various characteristics.

According to a second aspect of the present invention, a laser light source is arranged at a position that is inclined and opposed to the surface of the printing paper on which the toner has been transferred, and the laser light emitted from this laser light source and reflected by the printing paper is reflected. By providing a position detection element that detects the position and an adhesion amount detection unit that detects the adhesion amount of the toner transferred to the printing paper from the detection result of the position detection element, the print density of the toner can be determined by the transfer thickness. Therefore, the detection accuracy is better than in the case of optically reading the print density of the toner, and the print density of the toner can be measured with good characteristics from low density to high density.

According to a third aspect of the present invention, a laser light source is arranged at a position that is inclined and opposed to the surface of the photoconductor on which the toner has been transferred, and the laser light emitted from this laser light source and reflected by the photoconductor is reflected. By providing a position detection element that detects the position and an adhesion amount detection unit that detects the adhesion amount of the toner transferred to the photoconductor from the detection result of this position detection element, the print density of the toner can be determined by the transfer thickness. Therefore, the detection accuracy is better than in the case of optically reading the print density of the toner, and the print density of the toner can be measured with good characteristics from low density to high density.

In a fourth aspect of the present invention, the developing device is composed of a plurality of toners which respectively store toners of different colors, and the laser light source is composed of a plurality of lasers which are respectively reflected by the toners of different colors. The position detection element is
By consisting of a plurality of laser light sources,
Even if the toner has a plurality of colors and different spectral reflectances, at least one laser beam from a plurality of laser light sources is reflected, and therefore the amount of adhered toner of a plurality of colors can be satisfactorily detected.

In a fifth aspect of the invention, the developing device is composed of a plurality of toners each of which has a different color, and the laser light source emits a laser beam having a wavelength reflected by each of the toners having a different color. By varying, even if the toner has a plurality of colors and different spectral reflectances, the laser light of the laser light source is reflected by the variation of the wavelength, so that the adhered amounts of the toners of a plurality of colors can be favorably detected. .

In the invention described in claim 6, the laser light source is
Infrared laser light is emitted, the position detection element detects the position of the laser light at two locations, and the adhesion amount detection means detects the toner adhesion amount from the interval between the two detection positions. Since the adhesion amount can be detected at one time, the operation can be completed quickly.

According to the seventh aspect of the present invention, by providing the operation control means for temporarily stopping the operation of the movable part which influences the position detection of the position detection element in synchronization with the detection timing of the position detection element, the movable part of the movable part is provided. Since the operation does not affect the detection result of the position detection element, it is possible to improve the detection accuracy of the toner adhesion amount.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the overall structure of a digital copying machine which is a first embodiment of an electrophotographic apparatus of the present invention.

FIG. 2 shows a positional relationship between a transfer belt, a visible light laser that is a laser light source, and a PSD that is a position detection element, (a)
6B is a side view showing a state in which toner has not been transferred to the transfer belt, and FIG. 9B is a schematic view showing a state in which toner has been transferred to the transfer belt.

FIG. 3 is a block diagram showing a circuit structure of a main part of a digital copying machine.

FIG. 4 is a schematic diagram showing an overall structure of a digital copying machine in which an adhesion amount measuring unit is arranged to face a conveyor belt as a first modified example.

5A and 5B show a positional relationship among a conveyance belt, a visible light laser, and a PSD, FIG. 5A is a schematic diagram showing a state where the conveyance belt is not conveying the printing paper, and FIG. 5B is a printing paper on which toner is transferred. It is a schematic diagram which shows the state which is conveying.

FIG. 6 is a schematic diagram showing an overall structure of a digital copying machine in which an adhesion amount measuring unit is arranged opposite to a photosensitive drum, which is a photosensitive member, as a second modified example.

FIG. 7 is a schematic diagram showing a positional relationship among a photosensitive drum, a visible light laser, and a PSD.

FIG. 8 is a schematic diagram showing a structure in which two visible light lasers and two PSDs are arranged to face each other on a transfer belt as a third modification.

FIG. 9 is a schematic diagram showing a structure in which two visible light lasers and two PSDs are arranged to face each other on a conveyor belt as a fourth modification.

FIG. 10 is a schematic diagram showing a structure in which an infrared laser which is a laser light source and a CCD array which is a position detection element are arranged to face each other on a transfer belt as a fifth modification.

FIG. 11 is a characteristic diagram showing a detection result of the CCD array.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrophotographic device 6 Exposure device 7 Photoconductor 10 Charging device 12 Developing device 14 Intermediate transfer body 21 Paper transport mechanism 24 Fixing device 28,51 Laser light source 29,52 Position detection element 41 Toner 43 Printing paper

Claims (7)

[Claims] 1. A surface of a photoconductor is uniformly charged by discharge of a charging device, and the surface of the charged photoconductor is selectively discharged by exposure of an exposing device to form an electrostatic latent image. In the electrophotographic apparatus, in which an electrostatic latent image is developed with toner supplied from a developing device, the toner is transferred onto a printing paper by an intermediate transfer body, and the toner transferred onto the printing paper is fixed by a fixing device. A laser light source is arranged at a position facing the surface of the body in an inclined manner, and a position detecting element for detecting the position of the laser light emitted from the laser light source and reflected by the intermediate transfer member is provided. An electrophotographic apparatus comprising an adhesion amount detecting means for detecting an adhesion amount of the toner transferred to the intermediate transfer member from a detection result. 2. The surface of the photoconductor is uniformly charged by the discharge of a charging device, and the charged surface of the photoconductor is selectively discharged by the exposure of an exposing device to form an electrostatic latent image. In an electrophotographic apparatus in which an electrostatic latent image is developed by a toner supplied from a developing device, the toner is transferred onto a printing paper and then fixed by a fixing device, the surface of the printing paper on which the toner is transferred is inclined and opposed. A laser light source is arranged at a position to be provided, and a position detection element for detecting the position of the laser light emitted from the laser light source and reflected by the printing paper is provided,
An electrophotographic apparatus comprising an adhesion amount detecting means for detecting an adhesion amount of the toner transferred to the printing paper based on a detection result of the position detecting element. 3. The surface of the photoconductor is uniformly charged by discharge of a charger, and the charged surface of the photoconductor is selectively discharged by exposure of an exposure device to form an electrostatic latent image. In an electrophotographic apparatus in which an electrostatic latent image is developed by a toner supplied from a developing device, the toner is transferred to a printing sheet and then fixed by a fixing device, the surface of the photoconductor on which the toner is transferred is inclined and opposed. Place the laser light source at the position
A position detecting element for detecting the position of the laser beam emitted from the laser light source and reflected by the photoconductor is provided, and the adhesion detecting unit detects the amount of toner transferred to the photoconductor from the detection result of the position detection element. An electrophotographic apparatus comprising a quantity detecting means. 4. The developing device is composed of a plurality of toners respectively containing toners of different colors, the laser light source is composed of a plurality of lasers of which the toners of different colors are reflected, and the position detecting element is 4. The electrophotographic apparatus according to claim 1, wherein the electrophotographic apparatus comprises a plurality of units each corresponding to the laser light source. 5. The developing device is composed of a plurality of toners each of which has a different color, and the laser light source varies the laser light to a wavelength reflected by the toners of different colors. The electrophotographic apparatus according to claim 1, 2, or 3. 6. The laser light source emits infrared laser light, the position detection element detects the position of the laser light at two positions, and the adhesion amount detection means detects the toner adhesion from the interval between the two detection positions. A quantity is detected, The quantity is detected.
Alternatively, the electrophotographic apparatus according to Item 3. 7. The operation control means for temporarily stopping the operation of the movable part, which affects the position detection of the position detection element, in synchronization with the detection timing of the position detection element. The electrophotographic apparatus according to 3.