JP3264695B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus,
More specifically, the present invention relates to a transfer structure of a toner image formed on a photoconductor.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus such as a copying machine or a printer using an electrophotographic system, a color image is obtained by overlappingly transferring toner images of a plurality of colors. That is, this color copier, as one method, sequentially superimposes and transfers the toner images formed on the photoreceptor for each of the different color components onto an intermediate transfer body, and collectively transfers the superimposedly transferred toner images onto transfer paper or the like. By doing so, a color image is obtained.

In an image forming apparatus using an electrophotographic method including the above-described color copying machine, 100% of a toner image is formed on a photosensitive member or an intermediate transfer member.
In some cases, the toner is not transferred and remains as untransferred toner on the photoreceptor or the intermediate transfer member. Therefore, in such a case, there is a possibility that the load of the cleaning member in the cleaning step for the photoconductor or the intermediate transfer body performed after the transfer step may be increased. In this type of image forming apparatus, the initial setting of the transfer current and the like is performed at the time of factory shipment so that the efficiency of transferring the toner image from the photoconductor or the intermediate transfer body to the transfer paper is maximized. However, the transfer efficiency may change due to changes in environmental conditions during use of the apparatus, that is, humidity, temperature, paper used, and photoreceptor deterioration over time during use. Therefore, it is necessary to correct such a change in the transfer efficiency over time, but in reality, there is no firm method for such correction. In particular, the above-described transfer efficiency is a very important factor in performing faithful color reproduction from a color original in a color copying machine employing a method of superimposing and transferring a toner image for each color. Has the following problems with regard to the transfer efficiency in this copying machine. First
In addition, when transferring the toner image of each color from the photoreceptor to the intermediate transfer body, if the transfer rate differs for each color, the color balance on the intermediate transfer body deteriorates. Second, the first toner image formed on the photoreceptor is located at the lowest position during transfer to the intermediate transfer body, and is not 100% transferred during transfer from the intermediate transfer body to transfer paper. Then, a phenomenon occurs in which a part of the toner remains on the intermediate transfer member. This is because the surface energy between the lowermost toner and the intermediate transfer body and the surface energy between the toners are different, so that the lowermost toner located on the intermediate transfer body side is transferred. It is considered that it becomes difficult. Therefore, the amount of toner used for the visible image processing of the first color latent image formed on the photoconductor is smaller than the amount of the toner used for the visible image processing of the second and subsequent latent images on the transfer paper. As a result, the ratio of the amount of toner included in the toner image of each color developed on the photoconductor and the ratio of the amount of toner of each color on the transfer paper differ. For this reason, there is a possibility that the balance of each color is lost and the color difference is increased, so that it is impossible to faithfully reproduce the color of the document.

In order to solve such a problem, for example, for the first problem, a test pattern is formed on the surface of a photoreceptor, and the optical density of the test pattern image after development and the pattern image are developed. The transfer rate is determined by measuring the optical density after the transfer, and the transfer rate is compared with a reference value. It has been proposed to control a transfer voltage, which is one of the methods (for example, Japanese Patent Application Laid-Open No. 1-257978). In order to solve the second problem, the amount of toner attached to the visible image processing of the first color latent image formed first on the photoconductor should be larger than the amount of toner attached to the second and subsequent colors. (For example, Japanese Patent Application No. 3-199529).

[0005]

However, in the above-mentioned proposal, only one of the problems can be solved and the two problems cannot be solved together. Reproducibility issues still remain. In general, in a color copying machine, the color located at the lowest position is set to black which has little influence on the color balance. However, when such a toner transfer order is set, there is a restriction on the arrangement that the black developing device must be first in the arrangement order of the developing devices corresponding to the photoconductors. If the transfer rate changes for the reasons described above,
A subtle change occurs in the color tone, which may impair the color reproducibility.

Accordingly, an object of the present invention is to make the ratio of the amount of toner on a photoreceptor the same on transfer paper in view of the above-mentioned problems in the conventional image forming apparatus, especially in a color copying machine that performs overlap transfer. It is another object of the present invention to provide an image forming apparatus capable of ensuring color reproducibility faithful to a document.

[0007]

According to the first aspect of the present invention,
A toner image is formed for each color component on the photoreceptor, and the toner image for each color component is sequentially superimposed and transferred on the intermediate transfer member.
In an image forming apparatus capable of forming a multi-color image by performing a process of batch-transfer onto transfer paper, a sensor capable of detecting the density of a pattern image of a fixed size formed on the photoconductor, Of a certain size
Transfer onto the transfer paper on the intermediate transfer body on which the turn image has been transferred
A sensor capable of detecting the density of untransferred toner remaining without being transferred, and a drive unit and a transfer bias, wherein each of the sensors is connected to an input side and capable of changing a development potential that affects the amount of toner adhered on the photoconductor. A control unit connected to the output side, wherein the control unit is configured to control a pattern image of a color that is first transferred to the intermediate transfer body .
Detects toner density and transfers to the transfer paper based on the density
The amount of toner remaining without being calculated is calculated.
The amount of toner that can compensate for the amount of toner
Exposure intensity and charge amount for the photoreceptor to increase the amount
Alternatively, reduce the development bias and toner concentration.
Change one or more and form on the photoreceptor
Density and photoreceptor of the pattern image for each color
The toner density of the pattern image transferred to the intermediate transfer member.
Each is detected and calculated based on the detected toner concentration.
To be the same as the transfer rate selected among the transfer rates,
Used when the image of each color is transferred to the intermediate transfer body
It is characterized by adjusting the transcription voltage that.

[0008]

[0009] According to a second aspect of the invention, the control unit includes an upper
The toner density of the pattern image for each color formed on the photoreceptor
And the pattern image transferred from the photoconductor to the intermediate transfer body
The toner density of each is detected, and the detected toner density
Of the transfer rates calculated by the above, the transfer rate between the photoreceptor and the intermediate transfer body for the other color image is set so that the transfer rate is the same as the pattern image of the color in which the lowest transfer rate is obtained. of
It is necessary to control the conditions for applying the transfer voltage used during transfer.
It is characterized by.

[0010] According to a third aspect, the optical density of the detecting means, is characterized in that it comprises an arrangement for detecting the optical density at two or more toner image carrying member in a single one.

[0011] The invention of claim 4, wherein, the said detection means used is a reflective photosensor, the photosensor,
It is characterized in that a first position facing the photoreceptor and a second position facing the intermediate transfer member can be selected so as to be rotatable.

[0012] According to a fifth aspect, the above detection means,
Position and angle facing photoconductor and intermediate transfer body
As a feature of the concentration detection signal from these two members are arranged is set to the position and angle obtained at most a maximum output

[0013]

According to the first aspect of the present invention, the intermediate transfer member is
The toner density in the pattern image of the first color to be transferred.
By detecting, the intermediate transfer body is not transferred to the transfer paper
The amount of toner that remains on the
Increase the amount of toner on the photoconductor to match the amount of toner adhered
Can be compensated for by the transfer from the intermediate transfer body to the transfer paper.
The toner delivery amount is satisfied. Moreover,
Toner density and sensitivity of pattern image formed on photoreceptor
The toner density of the pattern image transferred from the optical body to the intermediate transfer body
Calculates the transfer rate for each color based on the results of detecting the degrees
And the same as the selected transfer rate
Adjust the transfer voltage used when transferring images of each color
The ratio of the amount of toner adhering to each color is the same.
Thus, it is possible to prevent the color balance from changing.

[0014]

According to the second aspect of the present invention, on the photosensitive member
Toner density and photosensitivity of the formed pattern image for each color
Density of the pattern image transferred from the toner to the intermediate transfer member
Are calculated and calculated based on the detected toner concentration.
Of transfer rate which, as the lowest transfer rate of the resulting color pattern image and the transfer rate of the same, other images of the color
Used for transfer between photoreceptor and intermediate transfer member
Since the transfer voltage application conditions are controlled,
Transfer rate between the two to ensure the same
Can be stopped.

According to the third aspect of the present invention, it is possible to detect the optical density on the intermediate transfer body after the development and after the transfer to the transfer paper by only a single detecting means.

According to the fourth aspect of the present invention, the optical density on the intermediate transfer body after development and after transfer to the transfer paper is detected by selecting the first and second positions in the detection means. be able to.

According to the fifth aspect of the invention, the optical density from the detecting means can be output most efficiently.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a schematic diagram illustrating the transfer principle in the image forming apparatus of the present invention. Hereinafter, this transfer principle will be described for multicolor copying such as full color. Now, as shown in FIG. 1A, the same amount (1 mg / cm ² ) is used as the toner used to process the electrostatic latent image for each color component formed on the photoreceptor into a visible image. In this case, if the toner transferred from the photoreceptor to the intermediate transfer member is, for example, the first color toner to which yellow (hereinafter, represented by Y) toner is first transferred, as shown in FIG. On the intermediate transfer member, the Y toner is located at the lowermost side, and subsequently, toner of another color is sequentially transferred onto this. At this time, black (BK), cyan
(C), magenta (M), and yellow (Y)
K, ηC, ηM, ηY (where 0 ≦ η ≦ 1),
In FIG. 1B, the amount of toner adhered on the intermediate transfer member is (1 * ηBK) mg / cm ² , (1 * ηC) mg / cm ² , (1 * ηM) mg / c
m ² , (1 * ηY) mg / cm ² . On the other hand, when the toner on the intermediate transfer member is transferred to transfer paper, in FIG.
Assuming that the transfer rate of the toner (Y) first transferred to the intermediate transfer member is η2, the amount of toner attached on the transfer paper is (1 * ηBK) mg / cm ² , (1 * ηC) mg / cm ² , (1 * ηM)
mg / cm ² , and (1 * ηY * η2) mg / cm ² . The transfer rate of the Y toner at this time is a value obtained from the difference between the surface energy between the intermediate transfer member and the surface energy between the toners. Accordingly, when the Y toner first transferred to the intermediate transfer member is transferred from the intermediate transfer member to the transfer paper, the amount of the toner adhered on the transfer paper is smaller than that of the toners of other colors. The ratio of the amount of toner between the colors on the body, the ratio of the amount of toner on the transfer paper, and the transfer rate do not match, resulting in a change in color balance.

Therefore, in the present invention, the toner of the color first transferred from the photoreceptor to the intermediate transfer member, in other words, the toner of the lowest color on the intermediate transfer member is transferred to the transfer paper. When developing on the photoconductor, the amount of toner remaining on the photoconductor is increased according to the amount that remains untransferred, and the transfer rate of each color toner transferred from the photoconductor to the intermediate transfer body is the same. Value. This is because, in advance, a large amount of toner corresponding to the untransferred toner remaining on the intermediate transfer member without being transferred onto the transfer paper is deposited on the photoreceptor in advance, and the transfer ratio of each color to the increased amount of toner is the same. Thus, even if the lowest color toner on the intermediate transfer member remains untransferred on the intermediate transfer member, the increased amount of toner is transferred onto the transfer paper, and This is to make the ratio of the toner amount on the transfer paper equal to the ratio of the toner amount on the transfer paper.

The order of increasing the amount of adhered toner and equalizing the transfer rate may be changed. The first is to make the transfer rate the same, and the second is the amount of untransferred toner not transferred to the transfer paper. May be supplemented.

The amount of toner to be transferred first among the toners transferred onto the intermediate transfer member, which is increased on the photosensitive member, is, for example, Y in the above example.
The toner is set to 1 * (1−η2), which is a value that compensates for the amount of toner remaining untransferred on the intermediate transfer member. This makes it possible to compensate in advance for the amount of toner whose transfer amount on the transfer paper is reduced, thereby making it possible to make the ratio of the toner amount on the photoreceptor equal to that on the transfer paper.

In the present invention, the amount of the untransferred toner remaining on the intermediate transfer member is determined by a photosensor described in detail later.
(Hereinafter, referred to as a P sensor) to detect the density of the toner on the photoreceptor so as to compensate for the shortage of the toner when transferred onto the transfer paper according to the amount of the untransferred toner. In order to increase the amount of adhesion, at least one of the developing potentials such as the charging potential of the photoconductor, the developing bias, and the exposure intensity, which affect the amount of toner attached, is adjusted.

FIG. 2 shows the overall configuration of a digital color copying machine as an example of an image forming apparatus using the above-described transfer principle. This digital color copying machine has an exposure lamp, a mirror, and an image forming optical system. , Color filter, CC
A scanner unit 250 for reading a document image, an image processing unit (not shown) for performing image processing based on information from the image read by the scanner unit 250, a laser light source, A writing unit 300 including an image optical system, a deflection scanner, and the like, and performing writing with laser light in accordance with a signal from the image processing unit; a photosensitive drum 100, a charging unit 200, and a color developing unit 40
1, 402, 403, 404, an intermediate transfer belt 610 on which a toner image from the photosensitive drum 100 is overlaid and transferred, a transfer roller 600, a pressing roller 650, a fixing unit 800, a cleaning device 550, and a paper feeding unit 60, 61, 62. , 63
And a control unit connected to a sensor, which will be described later.

Hereinafter, an image forming process of the digital color copying machine will be described.

In FIG. 2, when the image forming process of the copying machine is started, the photosensitive drum 100 is uniformly charged by the charging unit 200, and the original image is read by the scanner unit 250 and read by the scanner unit 250. The original image is image-processed by an image processing unit (not shown) and stored in a memory as image information for each color component. Then, in response to a signal from the image processing unit, the writing unit 300 controls the photosensitive drum 1
00 is exposed to laser light, and an electrostatic latent image is formed on the photosensitive drum 100 for each color component. Photoconductor drum 100
The electrostatic latent image formed for each color component is a developing unit corresponding to each color, that is, four color developing units 401 of yellow (Y), magenta (M), cyan (C), and black (B). , 402, 403, and 404, the toner images are sequentially transferred onto the intermediate transfer belt 610, and four color toners are superimposed on the intermediate transfer belt 610. Then, the transfer paper fed from the designated paper feeding unit among the paper feeding units 60, 61, 62, 63 passes between the transfer roller 600 and the pressing roller 650 pressed against the roller. The toner image on the intermediate transfer belt 610 is transferred to transfer paper by the pressure of the roller and the transfer bias applied from the pressing roller 650 side. Thereafter, the transfer sheet is conveyed to the fixing unit 800, is fixed in the fixing unit 800, and is discharged to a discharge tray.

After the first color toner image is transferred to the transfer belt, the photosensitive drum 100 is neutralized by the pre-cleaning neutralization unit 850, and the untransferred toner is cleaned by the cleaning device 9.
00 removed. Then, it is charged again by the charging unit 200, and exposure, development, transfer, cleaning, and charge removal for the second and subsequent colors are repeated. The untransferred toner remaining on the intermediate transfer belt after the transfer to the transfer paper is removed by the transfer belt cleaning device 550 to prepare for the next image forming process.

When an image is formed by superimposing four colors of toner in order to obtain a copy from a color original, as shown in FIG. 2, the image is developed by the developing unit 401 as the first color on the photosensitive drum 100. The color toner (for example, yellow (Y) toner) on the intermediate transfer belt 610, the developing units 402, 403 and 4
04 is the bottom of the color toner developed. Therefore, when the toner layer is transferred from the intermediate transfer belt 610 to the transfer paper, a part of the Y toner remains on the intermediate transfer belt 610. Due to the untransferred toner, the amount of the image transferred to the transfer paper is reduced in the first color (Y toner),
The color balance of the image becomes worse.

Accordingly, in the present invention, the intermediate transfer belt 61
The shortage of untransferred toner on the transfer paper due to untransfer is compensated by detecting the amount of untransferred toner remaining on the transfer paper and changing one or more conditions of exposure intensity, charging potential, toner concentration, and developing bias. For this reason, the amount of toner of the first color located at the lowest position on the intermediate transfer belt 610 is increased from the amount of toner adhered to the second and subsequent colors on the photoreceptor, and the amount of toner of the first color when transferred onto transfer paper is increased. The toner density and the toner density of the second and subsequent colors are balanced. For this reason, in the present embodiment, a photosensor (hereinafter abbreviated as P sensor) S, which includes a light emitting element and a light receiving element and detects the reflection density of toner, is connected to an intermediate transfer belt as shown in FIG. 610, the P sensor S is used to detect the amount of untransferred toner remaining on the intermediate transfer belt by the reflected light intensity of the untransferred toner, that is, the so-called optical density. In the present embodiment, the P sensor S described above detects the amount of untransferred toner on the intermediate transfer belt 610 (see FIG. 3A) and the P sensor S
A sensor for detecting the amount of toner at 0 (see FIG. 4) is provided. A P sensor S for detecting the amount of toner of the first color remaining on the intermediate transfer belt 610 includes: As shown in FIG. 5, an output voltage corresponding to the toner adhesion amount is output to the control unit 1000 shown in FIG.

The main part of the control unit 1000 is, for example, a microcomputer for controlling the sequence of a digital color copying machine. The P sensor S is connected to the input side and output to the output side. On the side, control units for setting the above-described charging potential, developing bias, exposure intensity, and toner density are connected via an I / O interface (not shown). By the way, the intermediate transfer belt 610 is detected by the P sensor S.
When the amount of untransferred toner remaining on the transfer paper is detected to compensate for the shortage of the transfer toner on the transfer paper, the P sensor S is made to face the intermediate transfer belt 610 as shown in FIG. However, the transfer rate from the intermediate transfer belt 610 to the transfer paper fluctuates due to temperature, humidity, the paper used, the deterioration of the intermediate transfer belt 610 with time, and the like. Is also fluctuated, the following method is used. That is, FIG.
As shown in (B), a pattern A is formed by superimposing four equal colors of toner single-color patterns Y, M, C, and Bk on a reference position provided on a transfer belt, and transferring the pattern to transfer paper. The reflection intensity of the untransferred A pattern remaining on the transfer belt after the detection is detected by the P sensor S, converted into a voltage value, and this voltage value is output to the control unit 1000 to measure the amount of untransferred toner. In the control unit 1000, the amount of the first color toner adhering to the remaining toner is increased on the photoconductor so as to balance the amount of toner adhering for the four colors. The control unit 1000 increases the charge potential, increases the developing bias, or increases the exposure intensity to increase the exposure energy in order to increase the toner adhesion amount on the photoconductor. In addition to setting the developing potential to a large value, a process for necessary control such as increasing the toner density is executed separately.

As shown in FIG. 7, when the developing potential is increased, the amount of adhered toner also increases. As a result, the amount of the first color toner transferred first on the intermediate transfer belt 610 is increased. Is increased from the amount of the second and subsequent colors, so that the color balance of the toner on the transfer paper can be obtained.

FIG. 8 is a flowchart showing a procedure performed by the control unit 1000 to increase the toner amount described above. The control unit 1000 calculates the residual toner amount based on the output voltage from the P sensor S. The first development potential at the time of color development is controlled.

On the other hand, as described above, the intermediate transfer belt 6
As the amount of the first color toner transferred first to the toner 10 increases, the transfer rate from the photosensitive drum 100 to the intermediate transfer belt 610 is the same for each color, as is clear from the above-described transfer principle. Is performed. This is because when the increased amount of the first color toner on the photoreceptor is transferred from the intermediate transfer member to the transfer paper, the transfer rate is reduced even if part of the first color toner remains untransferred. If they are the same, the increased amount compensates for the untransferred portion, so that the ratio of the amount of toner between the colors on the transfer paper is made the same so that the color balance can be achieved. . Therefore, the density of the pattern image of a fixed size formed on the photosensitive drum 100 and the density of the pattern image on the intermediate transfer belt 610 transferred from the photosensitive drum 100 are respectively detected by the P sensor. And
As the output from each P sensor, the output from the pattern image on the photosensitive drum 100 is V _SP , and the intermediate transfer belt 61
When the output from the pattern image on 0 is V _SB , the transfer rate η (%) of each color can be converted into the toner adhesion amount according to the relationship shown in FIG. The amount of adhesion (M / A) is determined, and the amount of adhesion on the photosensitive drum 100 side is M / A (P), and the amount of toner adhesion on the intermediate transfer belt 610 is M / A (B). Results. η1B _K = {M / A (BB _K )} / {M / A (PB _K )} × 100 η1C = {M / A (BC)} / {M / A (PC)} × 100 η1M = {M / A (BM)} / {M / A (PM)} × 100 η1Y = {M / A (BY)} / {M / A (PY)} × 100 By the way, when this transfer rate is to be the same, As shown by reference numerals A, B, and C in FIG. 9, the transfer rate fluctuates depending on the environmental conditions.
0, and the specific charge of the toner also varies depending on the environmental conditions. Since the transfer rate and the transfer voltage between the colors differ as shown in FIG. 11, the calculated transfer rate η ( %) Is, for example, η1B _K <η1C <η1M <η <1Y
In such a case, the transfer voltage of each color is adjusted so that the transfer rate is the same as the transfer rate (η1B _K ) of the black toner (B _K ) having the lowest value. Such a setting of the transfer rate is most easily performed when the transfer rate is set to the lowest one, and the transfer rate may not be obtained when the transfer rate is set to the highest transfer rate. This is to prevent

On the other hand, a P sensor S for detecting the amount of toner adhering to the photosensitive drum 100 and the intermediate transfer belt 610
As in the above-described embodiment, in addition to being provided independently at each portion, the number of the components can be reduced. FIG. 12 shows an embodiment in the case described above,
In this embodiment, the P sensor S is interlocked with a rotating member (not shown), as shown by a solid line in the figure, facing the photosensitive drum 100, and as shown by a two-dot chain line in the figure, An attitude facing the intermediate transfer belt 610 is selected. Then, as an installation condition of the P sensor S in this case, first, the facing angle (θ) with respect to the photoconductor drum 100 is set to 0 degree at which the relative photocurrent is obtained in the best state as shown in FIG. Further, the distance (d) from the detection surface is set to a distance at which the position where the relative photocurrent becomes highest is obtained as shown in FIG.

The conditions for installing the P sensor S are similarly set for the intermediate transfer belt 610, and the P sensor S is arranged at a position satisfying these conditions, and the photosensitive drum 100 and the intermediate transfer belt 610 are arranged. They are set to be able to face each other. For this reason, the above-described control unit 1000 can perform drive control on the rotating member in order to set each posture.

According to the present embodiment, a single photosensor can be used for the photoreceptor or the intermediate transfer member when detecting the amount of toner adhered, so that cost and space can be saved. Can be secured. Further, according to the present embodiment, when a single photo sensor is used, the amount of attached toner on each detection surface can be detected with the highest accuracy.

[0037]

As is apparent from the above embodiments, according to the present invention, after being transferred from the intermediate transfer member to the transfer paper ,
The amount of toner that has not been transferred can be compensated based on the density of the untransferred toner that has not been transferred to the transfer paper and remains on the intermediate transfer body.
The transfer for each color based on the toner density of the transferred pattern image
Determine the shading rate so that it is the same as the selected transfer rate
By adjusting the transfer voltage for each color, the toner for each color
The ratio of the adhesion amount is the same on the photoconductor side and the intermediate transfer body side.
When part of the toner is not transferred
However, using the replenished toner,
The change can be prevented. Further, according to the present invention, since the lowest transfer rate among the toner transfer rates of the respective colors is selected as the selected transfer rate, a simple process of merely lowering the transfer rates of the toners of other colors is performed. Thereby, the transfer ratio between the colors can be made the same. As a result, it is possible to secure a color balance faithful to the original on the photoconductor side and the transfer paper side.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a transfer principle of an image forming apparatus according to the present invention, and FIG.
(B) shows the state of toner adhesion on the intermediate transfer body, and (C) shows the state in which the toner is transferred from the intermediate transfer body to transfer paper.

FIG. 2 is a schematic layout diagram illustrating an overall configuration of an image forming apparatus according to the present invention.

FIGS. 3A and 3B are schematic diagrams illustrating a structure for detecting a toner adhesion state on an intermediate transfer member, wherein FIG. 3A illustrates an arrangement of a photosensor with respect to the intermediate transfer member, and FIG. 3 shows the state of the latent image pattern thus obtained.

FIG. 4 is a perspective view showing a structure for detecting a toner adhesion state on a photoconductor.

FIG. 5 is a diagram for explaining a relationship between an output voltage of a photo sensor and a toner adhesion amount.

FIG. 6 is a block diagram illustrating a configuration of a control unit used in the image forming apparatus illustrated in FIG. 2;

FIG. 7 is a diagram for explaining a relationship between a development potential and a toner adhesion amount.

FIG. 8 is a flowchart for explaining the operation of the control unit shown in FIG. 6;

FIG. 9 is a diagram for explaining a relationship between a transfer voltage and a transfer rate based on a difference in environmental conditions.

FIG. 10 is a diagram for explaining a relationship between toner specific charge and transfer efficiency.

11 is a diagram for explaining a difference in a transfer rate with respect to a transfer voltage between colors of a developing toner used in the image forming apparatus shown in FIG. 2;

FIG. 12 is a schematic view showing another embodiment of a structure for detecting a toner adhesion state in the image forming apparatus of the present invention.

13A and 13B are diagrams illustrating one of the arrangement conditions of the photo sensor in another embodiment illustrated in FIG. 12, and FIG. 13A is a diagram illustrating an output state of the photo sensor from a facing angle with respect to a photoconductor. The diagram, (B), is a schematic diagram showing the facing angle between the photosensor and the photoconductor.

FIG. 14 is a view for explaining another one of the arrangement conditions of the photosensor in the other embodiment shown in FIG. 12;
(A) is a diagram for explaining an output state of a photosensor depending on a distance between the photoconductor and (B) is a schematic diagram illustrating a facing distance between the photosensor and the photoconductor.

[Explanation of symbols]

 100 Photoconductor drum 610 Intermediate transfer belt 1000 Control unit S Photo sensor (P sensor)

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G03G 15/00 G03G 15/01 G03G 15/16 G03G 21/00

Claims (5)

(57) [Claims] A toner image for each color component formed on a photoreceptor;
In an image forming apparatus capable of forming a multicolor image by sequentially transferring the toner images of the respective color components onto an intermediate transfer body and then performing a batch transfer process on transfer paper, forming the image on the photosensitive body A sensor capable of detecting the density of the formed fixed-size pattern image and the fixed-size pattern image formed on the photoreceptor are rotated.
Remain without being transferred to the transfer sheet in photographed intermediate transfer member
A sensor capable of detecting the density of the untransferred toner, a configuration in which each of the sensors is connected to an input side, and a drive unit capable of changing a development potential that affects the amount of toner adhered on the photoconductor and a transfer bias are adjusted. And a control unit connected to the output side. The control unit is configured to first transfer the image to the intermediate transfer body .
Of the color pattern image and detects the
Divide the amount of toner remaining on the transfer paper
To compensate for the amount of the toner thus determined.
To increase the amount of toner attached on the photoreceptor.
Exposure intensity, charge amount or developing bias and toner
-Change at least one of the concentrations
The toner of the pattern image of each color formed on the photoreceptor
Density and pattern transferred from photoconductor to intermediate transfer body
The toner density of the image is detected, and the detected toner density is detected.
Transfer rate selected from transfer rates calculated by degrees
Images of each color are transferred to the intermediate transfer body so that they are the same
Image forming apparatus characterized by adjusting a transcription voltage used when it is. 2. The image forming apparatus according to claim 1, wherein the control unit controls a pattern for each color formed on the photoconductor.
Transfer from the photoconductor to the intermediate transfer member
Detects and detects the toner density of the detected pattern image
The transfer rate is the same as the pattern image of the color for which the lowest transfer rate was obtained among the transfer rates calculated based on the determined toner density.
Between the photoreceptor and other color images.
Application of transfer voltage used for transfer to and from transfer body
Image forming apparatus characterized by control the condition. 3. An image forming apparatus according to claim 1, wherein said optical density detecting means has a structure for detecting optical densities of two or more toner image carrying members by a single unit. Image forming apparatus. 4. The image forming apparatus according to claim 3, wherein said detecting means is a reflection type photo sensor, and said photo sensor is provided rotatably and has a first attitude facing a photoreceptor. An image forming apparatus, wherein the user can select a second position facing the intermediate transfer member. 5. The image forming apparatus according to claim 4, wherein said detecting means obtains a density detection signal from each of said members at a maximum output as a position facing said photosensitive member and said intermediate transfer member and a facing angle. An image forming apparatus characterized by being set at a position and an angle.