JPH08194371A - Image forming method and device therefor - Google Patents

Abstract

PURPOSE: To eliminate the sticking of carriers to an image carrier, to make a deterioration in the carriers slow and to reduce the consumption of toner by making speed for rotating a developing sleeve lower, when an image region does not pass in front of the developing sleeve. CONSTITUTION: The number of rotations of a developing sleeve 41 and the driving shafts of stirring screws 43A-43C is changed by the control of a developing unit driving system capable of consecutively changing the speed. The operation control of the developing unit driving system is executed by a process CPU. When the image region does not pass through a part where a photoreceptor drum 1 faces the developing sleeve 41, the number of rotations of the sleeve 41 is set to 100rpm for instance and when the image region passes through the part where the photoreceptor drum 1 faces the sleeve 41, the number of rotations of the sleeve 41 is set to 250rpm for instance. Thus, the image region does not pass in front of the sleeve 41, the speed for rotating it is made slower than that when the image region passes in front of the sleeve 41, while a voltage is applied thereto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image forming method and an image forming apparatus. In particular, the present invention is suitable for an image forming method and an image forming apparatus by electrophotography. Further, the present invention can be applied to a copying machine and a non-impact printer of plain paper.

[0002]

2. Description of the Related Art A photoconductor is charged, an electrostatic latent image is formed on the photoconductor by imagewise exposure of a laser optical system, and a predetermined voltage is applied to a developing sleeve provided facing the photoconductor. By rotating the photoconductor and the developing sleeve at a predetermined speed while applying the voltage, the electrostatic latent image of the photoconductor is developed to form a toner image on the photoconductor. Two-component contact between carrier and toner In the image forming method by the electrophotographic method of the reversal development method, a technique of detecting the light amount of the laser optical system other than when the electrostatic latent image of the image is formed and controlling the light amount of the laser optical system at the time of the imagewise exposure. There is. However, an electrostatic latent image is formed by the laser light for detecting the light amount of the laser optical system, and therefore the toner develops the electrostatic latent image (hereinafter also referred to as a test image) at the time of controlling the light amount. Was wasted.

Therefore, by stopping the rotation of the developing sleeve when the image area electrostatically formed on the image carrier does not pass in front of the developing sleeve, the electrostatic latent image is developed by the toner when the light amount is controlled. There are techniques that we do not do.

[0004]

However, actually, if the rotation of the developing sleeve is stopped when the image area does not pass in front of the developing sleeve, the toner in the portion of the developing sleeve in contact with the photoconductor becomes the above-mentioned. After adhering to the electrostatic latent image part by the laser beam to detect the light quantity of the laser optical system, the carrier in the part where the developing sleeve and the photoconductor are close to each other sticks to the photoconductor and scratches the photoconductor. It turned out that the problem of putting on. As a result, the toner density on the developing sleeve is reduced, and the density of the beginning portion of the image area when the image area passes in front of the developing sleeve is reduced by the carrier adhering on the photosensitive member, and the developed toner image becomes uneven. Was found to occur. In such a case, further, in the image forming method or apparatus for collecting the toner not transferred from the image carrier to the transfer sheet,
It has been found that the carrier that is collected with the toner is also stressed on the collection path, and the carrier deteriorates faster than the image forming method or apparatus that collects the toner, and that the toner easily deteriorates.

Further, an electrostatic latent image is formed on the image carrier, and a voltage is applied to a developing sleeve provided opposite to the image carrier while the image carrier and the developing sleeve are moved at a predetermined speed. The electrostatic latent image on the image bearing member is developed by rotating the image bearing member to form a toner image on the image bearing member. If the image carrier is discharged and the charge level is lowered when it is not used, the portion between the developing device and the charging unit is developed, toner is wastefully consumed, and the carrier deteriorates quickly. I knew that.

Therefore, a method was studied in which no voltage was applied to the developing sleeve when the image area did not pass in front of the developing sleeve. Even in that case, some toner adhered to the photosensitive body and then the carrier adhered to the photosensitive body. I found out that It was also found that the problem of scratching the image carrier also occurs.

Further, it has been found that the above-mentioned problems are remarkable due to the thinning of the image bearing member, the smaller particle size of the carrier, the smaller size of the magnet roller and the like.

A first object of the present invention is to prevent the carrier from adhering to the image carrier, to prevent uneven density of the toner image, to delay the deterioration of the carrier and to reduce the waste of toner.

A second object of the present invention is to collect the toner, which does not cause the carrier to adhere to the image carrier, does not cause uneven density of the toner image, has a slow deterioration of the carrier, and has a slow deterioration of the toner. is there.

A third object of the present invention is to carry out two-component contact reversal development in which the carrier is not attached to the image carrier, density unevenness of the toner image does not occur, carrier deterioration is slow, and toner is not wasted. Is to provide.

A fourth object of the present invention is to provide a toner recovery / development system in which the carrier is not attached to the image carrier, the density of the toner image is not uneven, and the deterioration of the carrier is slow, and the deterioration of the toner is slow. It is to provide two-component contact reversal development.

A fifth object of the present invention is to control the amount of energy of a source for forming an electrostatic latent image without causing density unevenness of the toner image, reducing toner waste.

A sixth object of the present invention is to control the amount of energy of a source for forming a latent electrostatic image by recovering the toner with a slow deterioration of the toner without causing uneven density of the toner image. is there.

The seventh object of the present invention is to achieve the fifth or sixth object of the present invention in which the carrier does not adhere to the image bearing member and deterioration of the carrier is slow even in the two-component developing system. That is.

[0015]

SUMMARY OF THE INVENTION The present invention solves these problems when the image area of the latent image formed on the image carrier passes in front of the developing sleeve. The present invention has been made by finding that the problem can be solved by lowering the rotating speed of the developing sleeve when it does not pass in front of the above, and further by finding that this technique can be used for various image forming techniques. is there.

That is, the image forming method according to claim 1 is
While the electrostatic latent image is formed on the image carrier and a voltage is applied to a rotatable developing sleeve that has a magnet body inside and is provided so as to face the image carrier, the image carrier and the developing sleeve are connected to each other. Is rotated at a predetermined speed to develop the electrostatic latent image on the image carrier to form a toner image on the image carrier.
In the image forming method by the electrostatic method of two-component developing method of carrier and toner, when the image area electrostatically formed on the image carrier does not pass in front of the developing sleeve, a voltage is applied to the developing sleeve. However, the speed at which the developing sleeve is rotated is lower than when the image area passes in front of the developing sleeve.

The image forming method described in claim 5 is
An electrostatic latent image is formed on the image bearing member by charging an image bearing member, which is an electrophotographic photoreceptor, imagewise exposure by a laser optical system, and a predetermined amount is provided on a developing sleeve provided opposite to the image bearing member. By rotating the image bearing member and the developing sleeve at a predetermined speed while applying the voltage of, the electrostatic latent image of the image bearing member is developed to form a toner image on the image bearing member. In the image forming method by a photographic method, the amount of light of the laser optical system is detected and controlled by emitting a laser beam to the outside of the image area on the image carrier, except during the imagewise exposure, and the image carrier When the charged area of passes through the developing sleeve, a voltage is applied to the developing sleeve to rotate the developing sleeve,
In addition, when the image area electrostatically formed on the image carrier does not pass in front of the developing sleeve, the image area passes in front of the developing sleeve while applying a voltage to the developing sleeve. The developing sleeve is rotated at a low speed.

The image forming apparatus according to claim 11 is
Image carrier for carrying an electrostatic latent image, electrostatic latent image forming means for forming an electrostatic latent image on the image carrier, two-component development of carrier and toner provided facing the image carrier A developing sleeve that conveys the agent, a developing sleeve voltage applying unit that applies a voltage to the developing sleeve, an image carrier driving unit that moves the image carrier, a developing sleeve driving unit that rotates the developing sleeve, and the voltage. While moving the image carrier by the image carrier driving unit with respect to the applied developing sleeve, the developing sleeve driving unit rotates the developing sleeve to develop the electrostatic latent image on the image carrier. In an image forming apparatus having a control means for forming a toner image on the image carrier, the control means is configured to: when the image area electrostatically formed on the image carrier does not pass in front of the developing sleeve. Control means for reducing the speed at which the developing sleeve is rotated by the developing sleeve drive means with respect to the time when the image area passes in front of the developing sleeve, while applying a voltage to the developing sleeve by the image sleeve voltage applying means. It was characterized by

The image forming apparatus according to claim 15 is
An electrophotographic photosensitive member which is an image bearing member carrying an electrostatic latent image,
Electrophotographic photosensitive member charging means for charging the electrophotographic photosensitive member, and a static image forming electrostatic latent image by performing imagewise exposure with a laser optical system on the electrophotographic photosensitive member charged by the electrophotographic photosensitive member charging means. An electro-latent image forming means, a developing sleeve which is provided to face the electrophotographic photosensitive member and which carries a two-component developer of a carrier and toner, and a developing sleeve voltage applying means which applies a predetermined voltage to the developing sleeve. An electrophotographic photosensitive member driving unit that moves the charged electrophotographic photosensitive member with respect to the developing sleeve; a developing sleeve driving unit that rotates the developing sleeve at a predetermined speed; and a developing sleeve to which the voltage is applied. While the electrophotographic photosensitive member is moved by the electrophotographic photosensitive member driving unit, the developing sleeve is rotated at a predetermined speed by the developing sleeve driving unit to move the electrophotographic photosensitive member. And control means for forming a toner image on the electrophotographic photoconductor by developing the electrostatic latent image on the photosensitive member,
In an image forming apparatus having a light amount control means for emitting a laser beam outside the image area of the electrophotographic photosensitive member to detect the light amount of the laser optical system except during the imagewise exposure, the electrophotographic photosensitive member is charged. When the area passing through the developing sleeve passes through the developing sleeve, the developing sleeve driving means rotates the developing sleeve while applying a voltage to the developing sleeve by the developing sleeve voltage applying means, and the developing sleeve driving means rotates the developing sleeve on the image carrier. When the electrostatically formed image area does not pass in front of the developing sleeve, the voltage is applied to the developing sleeve by the developing sleeve voltage applying means while the image area passes in front of the developing sleeve. The speed at which the developing sleeve is rotated by the developing sleeve driving means is reduced.

In the present invention, the image bearing member is a bearing member that holds an electrostatic latent image which is a latent image of electric charges distributed in an imagewise manner. It is an electrostatic recording sheet in an electrostatic recording method in which an electrostatic latent image is formed on a recording sheet by an electrode or a special electron tube, or a heat sensitive body in a method in which heat is used to charge a heat sensitive body to form an electrostatic latent image. May be. The image carrier is preferably formed on the image carrier support. Also,
The shape of the image carrier support is preferably cylindrical or belt-like. The toner image formed on the image carrier may be fixed on the image carrier as it is, but it is preferable that the toner image is transferred from the image carrier to a transfer material and fixed on the transfer material. This is preferable because the utility value of the effect is high. The transfer material is a material for transferring and holding the toner image formed on the image carrier, and is preferably a sheet-shaped material such as paper or plastic film.

In the present invention, the image area means an area where an electrostatic latent image is imagewise formed on the image carrier.
However, the image does not include the test image. Then, the present invention, except when the image area passes in front of the developing sleeve, applies the voltage to the developing sleeve while controlling the speed at which the developing sleeve is rotated with respect to the time when the image area passes in front of the developing sleeve. To lower it.

[0022]

[Action]

(1) An electrostatic latent image is formed on an image carrier, and a voltage is applied to a rotatable developing sleeve provided inside the image carrier to have a magnet body inside, while the electrostatic latent image is applied to the image carrier and the image bearing member. An image by an electrostatic method of a two-component developing method of carrier and toner, which develops the electrostatic latent image of the image bearing member by rotating the developing sleeve at a predetermined speed to form a toner image on the image bearing member. In the forming method, when the image area electrostatically formed on the image carrier does not pass in front of the developing sleeve,
By applying a voltage to the developing sleeve and lowering the speed at which the developing sleeve is rotated with respect to the time when the image area passes in front of the developing sleeve, a toner image can be obtained without attaching a carrier to the image carrier. The density deterioration of the carrier can be prevented, the deterioration of the carrier can be delayed, and the waste of the toner can be reduced.

(2) Since the two-component developing method is the two-component contact reversal developing method, the carrier does not adhere to the image carrier, uneven density of the toner image does not occur, and deterioration of the carrier is slow, Waste of toner can be reduced.

(3) The toner image formed on the image carrier is transferred to a transfer material, the remaining toner on the image carrier is recovered, and the recovered toner is returned into the developing device housing. As a result, it is possible to collect the toner without causing the carrier to adhere to the image carrier, without causing the density unevenness of the toner image, the deterioration of the carrier being slow, and the deterioration of the toner being slow.

In the above cases (1) to (3), the image bearing member is an electrophotographic photosensitive member, and after charging the image bearing member,
The electrostatic latent image may be formed by performing imagewise exposure on the image bearing member, or the image bearing member may be a heat sensitive member to form the electrostatic latent image. Before, the heat sensitive body may be charged and heat may be used to form the electrostatic latent image (the charge disappears where heat is applied).

(4) When the image carrier is a photoconductor, a laser optical system or a laser optical system may be used for the imagewise exposure, whether it is overall exposure or slit exposure. Scanning exposure such as solid-state scanning exposure system such as LED may be performed.

(5) An electrostatic latent image is formed on the image bearing member by charging the image bearing member, which is an electrophotographic photoreceptor, and by imagewise exposure with a laser optical system. By rotating the image carrier and the developing sleeve at a predetermined speed while applying a predetermined voltage to the developed developing sleeve, the electrostatic latent image on the image carrier is developed and toner on the image carrier is developed. To form an image, in the image forming method by electrophotography, except during the imagewise exposure, by detecting and controlling the light amount of the laser optical system by emitting a laser beam outside the image region on the image carrier, Further, when the charged area of the image carrier passes through the developing sleeve, a voltage is applied to the developing sleeve to rotate the developing sleeve, and an electrostatic latent image is formed on the image carrier. Area is above The density of the toner image is reduced by applying a voltage to the developing sleeve when not passing in front of the image sleeve, and lowering the speed at which the developing sleeve is rotated with respect to when the image area passes in front of the developing sleeve. It is possible to control the amount of energy of the source for forming the electrostatic latent image without causing unevenness, waste of toner, and the like.

(6) The toner image developed on the image carrier is transferred to a transfer material, the remaining toner on the image carrier is recovered, and the recovered toner is returned into the developing device housing. With this, it is possible to collect the toner having a slow deterioration of the toner and to control the energy amount of the source for forming the electrostatic latent image without causing the density unevenness of the toner image.

In the cases of (5) and (6), especially when the energy amount of the source for forming the electrostatic latent image is detected except when the electrostatic latent image in the form of image is formed, When the energy of directly affects the image carrier,
The effect is remarkable.

(7) In the cases (5) and (6), the electrostatic method may be a two-component developing method of carrier and toner, or a one-component developing method of only toner. Also, if
Even if the electrostatic method is a two-component developing method of carrier and toner,
The carrier does not adhere to the image carrier, and the deterioration of the carrier is slow.

In addition, in the cases of (5) and (6), the image bearing member is a photoconductor, and the photoconductor is charged before the electrostatic latent image is formed to form the electrostatic latent image. Imagewise exposure to, the amount of energy of the source for forming the electrostatic latent image may be the amount of light, the image carrier is a heat sensitive body,
The photoconductor may be charged before forming the electrostatic latent image, heat may be used to form the electrostatic latent image, and the amount of energy of the source for forming the latent image may be heat. When the image bearing member is a photoconductor, solid-state scanning exposure of a laser optical system, an LED, or the like, regardless of whether the imagewise exposure is full-surface exposure or slit exposure. Scanning exposure of a system or the like may be performed.
In particular, when a laser optical system is used for imagewise exposure, since the fluctuation of the light quantity is large, it is often necessary to emit light for controlling the energy quantity, which is optimal. Furthermore, when the light emission source of the laser optical system is a laser diode, it is preferable to emit light for controlling the amount of energy for each image, which is extremely suitable.

(8) In any one of the above (1) to (7), when the developing method is the magnetic brush contact developing method, the developing sleeve is stopped when the developing sleeve is stopped. When a voltage is applied, the phenomenon that the carrier attaches to the image carrier after the toner attaches to the non-charged portion occurs, but this phenomenon can be prevented by the above configurations (1) to (7). preferable.

(9) Further, the above (1) to (4) and (7),
In any case of (8), when the carrier is a binder carrier, a thin resin film on the surface of the carrier for improving triboelectric charging property, environmental stability, durability, etc. causes unnecessary development sleeve rotation. This is preferable because it prevents loss.

(10) Similarly, when a matting agent or a lubricant is present on the surface of the carrier, a matting agent or a lubricant for improving triboelectricity, fluidity and the like is added to the developing sleeve. The rotation is preferable because loss can be prevented.

Further, in any of the above (1) to (6), the image bearing member is charged before the electrostatic latent image is formed on the image bearing member, and the electrostatic latent image is formed. By applying imagewise energy to the image carrier to form,
When an electrostatic latent image is formed on the image carrier, when a charged area of the image carrier passes through the developing sleeve, a voltage is applied to the developing sleeve and the developing sleeve can be rotated. Are prevented from adhering to the image carrier, which is preferable. Then, at that time, from a time point slightly before the charged area of the image carrier reaches the developing sleeve,
It is preferable to apply a voltage to the developing sleeve and control the developing sleeve to rotate so that the influence of time lag in the developing sleeve and the influence of instability of the developing sleeve can be eliminated. Further, in any of the above cases (1) to (6), the developing sleeve is moved at a predetermined speed from a time point slightly before the leading edge reaches the developing sleeve when the image area passes in front of the developing sleeve. It is desirable to control the rotation so that the image density formed on the image carrier is stabilized and a high quality image is obtained. Similarly,
From the time when the trailing edge reaches the developing sleeve when the image area passes in front of the developing sleeve or slightly after that,
It is desirable to control the developing sleeve to rotate at a speed lower than the speed at which the image area passes in front of the developing sleeve.

(11) An image bearing member carrying an electrostatic latent image, electrostatic latent image forming means for forming an electrostatic latent image on the image bearing member,
A developing sleeve provided to face the image carrier to convey a two-component developer of a carrier and toner, developing sleeve voltage applying means for applying a voltage to the developing sleeve, and an image carrier for moving the image carrier. Driving means, developing sleeve driving means for rotating the developing sleeve, and the developing sleeve driving means for moving the image carrier with respect to the developing sleeve to which the voltage is applied, while the developing sleeve driving means drives the developing sleeve. In an image forming apparatus having a control unit for developing an electrostatic latent image on the image carrier to form a toner image on the image carrier, the control unit electrostatically forming on the image carrier. When the developed image area does not pass in front of the developing sleeve, the developing area voltage applying means applies a voltage to the developing sleeve while An image forming apparatus is characterized in that it is a control means for lowering the speed at which the developing sleeve is rotated by the developing sleeve driving means when passing in front of the developing sleeve. In addition, it is possible to suppress the deterioration of the carrier and the waste of toner without causing uneven density of the toner image.

(12) Further, in the image forming apparatus characterized in that the control means forms a toner image on the image carrier by the two-component contact reversal development, the toner is not adhered to the image carrier and the toner image is formed. It is possible to reduce the deterioration of the carrier and the waste of the toner without causing the density unevenness of the image.

(13) Further, a toner image transfer means for transferring the toner image formed on the image carrier to a transfer material, and a toner remaining on the image carrier without being transferred to the transfer material. Then, the image forming apparatus characterized by having a toner collecting means for returning the collected toner into the developing device housing, without causing the carrier to adhere to the image carrier, without causing uneven density of the toner image, The deterioration of the carrier is slow, and the toner with the slow deterioration of the toner can be collected.

In the cases (11) to (13), the image carrier is a photoconductor and the electrostatic latent image forming means is
It may have a photoconductor charging unit that charges a photoconductor before forming the electrostatic latent image, and an exposing unit that performs imagewise exposure to form the electrostatic latent image. The image bearing member is a heat sensitive member, and the electrostatic latent image forming unit is
It may have a photoconductor charging unit that charges a photoconductor before forming the electrostatic latent image, and an imagewise heating unit that uses heat to form the electrostatic latent image.

(14) In the case of (11), the exposure means is
The whole surface exposure, the slit exposure, or the scanning exposure such as a laser optical system or a solid scanning exposure system such as an LED may be performed. In particular, when a laser optical system is used for imagewise exposure, the amount of light varies greatly, so it is often necessary to emit light for controlling the amount of energy. In this case, it is preferable that the energy amount control means detects the light amount of the laser optical system before image formation and controls the light amount of the laser optical system during the imagewise exposure.

(15) An electrophotographic photosensitive member which is an image bearing member carrying an electrostatic latent image, an electrophotographic photosensitive member charging means for charging the electrophotographic photosensitive member, and the electrophotographic photosensitive member charging means. An electrostatic latent image forming means for forming an electrostatic latent image on the electrophotographic photosensitive member by imagewise exposure with a laser optical system; and a two-component development of a carrier and a toner provided facing the electrophotographic photosensitive member. A developing sleeve that conveys a developing agent, a developing sleeve voltage applying unit that applies a predetermined voltage to the developing sleeve, an electrophotographic photosensitive member driving unit that moves the charged electrophotographic photosensitive member with respect to the developing sleeve, and the developing unit. Developing sleeve driving means for rotating the sleeve at a predetermined speed, and the developing sleeve driving means for moving the electrophotographic photosensitive member with respect to the developing sleeve to which the voltage is applied. Control means for rotating the developing sleeve at a predetermined speed by a leave driving means to develop an electrostatic latent image on the electrophotographic photosensitive member to form a toner image on the electrophotographic photosensitive member; In addition, in an image forming apparatus having a light amount control means for emitting a laser beam outside the image region of the electrophotographic photosensitive member to detect the light amount of the laser optical system, the charged region of the electrophotographic photosensitive member is the developing unit. When passing through the sleeve, the developing sleeve driving means rotates the developing sleeve while applying a voltage to the developing sleeve by the developing sleeve voltage applying means, and an image electrostatically formed on the image bearing member. When the area does not pass in front of the developing sleeve, the image area is covered by the developing sleeve while the developing sleeve voltage applying unit applies a voltage to the developing sleeve. With the image forming apparatus characterized in that the speed at which the developing sleeve of the developing sleeve driving means is rotated is made lower than that when passing through before the leave, particularly when a laser optical system is used for imagewise exposure, Since there is a large variation, it is often necessary to emit light for controlling the amount of energy, but without causing density unevenness in the toner image, less toner is wasted, or toner is collected with a slow deterioration of toner, and the The amount of light for forming a latent image can be controlled.

In this case, the energy of the source is detected by the image carrier when the amount of energy of the source for forming the electrostatic latent image is detected except when the electrostatic latent image is formed. It is especially suitable for direct influence.

(16) Further, toner image transfer means for transferring the toner image formed on the electrophotographic photosensitive member to a transfer material, and toner remaining on the image bearing member without being transferred to the transfer material. With the image forming apparatus characterized by having a toner collecting means for returning the collected toner into the developing device housing, without attaching the carrier to the image carrier,
It is possible to collect the toner with a slow deterioration of the toner without causing the density unevenness of the toner image and the deterioration of the carrier.

Further, in the cases (11) to (15) described above, the developing sleeve voltage applying means is arranged to develop the electrostatic latent image on the image carrier to form a toner image on the image carrier. It is preferable to have image forming control means for controlling the image carrier driving means and the developing sleeve driving means, and in this case, the image area is controlled by the image forming control means when the image area passes in front of the developing sleeve. It is preferable to control the rotating speed of the developing sleeve driving means to be low except when passing in front of the developing sleeve.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the essential structure of an embodiment of an image forming apparatus of the present invention.

The image forming apparatus of the present embodiment is a pulse width modulation (PW) for gradation recording by changing the light emission time of the semiconductor laser as the exposure process of the electrophotographic method.
M) was adopted. Further, the printer characteristic detection means for detecting the actual printer characteristics and the maximum image density, the gradation control means for correcting the gradation of the recording signal, and the developing property fixing means for stabilizing the maximum image density at a predetermined value are provided.

The printer characteristic detecting means has a patch detecting sensor C, a data calculation section D, and a RAM in which the test pattern signal S _G is written, and detects the actual printer characteristic. The printer characteristic detection means detects the maximum image density from the detected actual printer characteristic. The printer characteristic detecting means corresponds to the maximum image density converting means.

The writing unit A is an exposure device for irradiating the image carrier B with exposure light so as to form an electrostatic latent image. In this embodiment, the writing unit A is an exposure device having a laser optical system.

An electrostatic latent image is formed on the image carrier B by the energy emitted from the writing unit A. In this embodiment, the image carrier B is an electrophotographic photoreceptor corresponding to the writing unit A being an exposure device.

The patch detection sensor C sends to the data calculation unit D a luminance signal corresponding to the light intensity reflected from the test pattern showing 256 gradations developed on the image carrier B based on the test pattern signal S _G. Send out. Here, the test pattern signal S _G is a signal that expresses 256 gradations according to the printer characteristics in the initial room temperature and normal humidity. The test pattern signal S _G is written in advance in the RAM forming the image processing unit E, and is read by, for example, a copy start command signal. The schematic mechanism of the patch detection sensor C will be described later.

The data calculator D performs a calculation for processing the luminance signal. That is, the processing calculation in the data calculation unit D is performed by A / D conversion of the luminance signal to obtain the maximum output of the patch detection sensor C with respect to the output voltage normalized to 256 gradations (in a portion where there is no patch image on the image carrier). The signal obtained by considering the difference between the density of the image carrier and the density of the transfer paper is obtained as a value obtained by logarithmically converting the ratio of the output). Further, in order to eliminate the detection error caused by the vibration occurring during the rotation of the image carrier B, the data calculation unit D uses the brightness signals obtained from a plurality of gray scales visualized on the image carrier B as described above. The signal of the averaged value is sent to the image processing unit E and the process CPU 90. As a result, the image processing unit E and the process CPU 90 can detect the printer characteristics and the maximum image density by eliminating the detection error caused by the vibration of the image carrier B.

The image processing section E corresponds to the above-mentioned gradation control means, and sends the recording signal in which the density signal is subjected to MTF correction, γ correction and gradation correction in an arbitrary order to the writing unit A. I decided. The MTF correction mentioned here is to correct variations in the MTF of the lens, the accuracy of the prism surface, and the scan speed in the optical system that constitutes the writing unit A, which directly affects the deterioration of resolution. In order to improve the reproducibility in the finest part of the image, MTF
A value of 30% or more is required, and the strength of MTF correction is determined by edge enhancement, smoothing, and anti-moire. γ
The correction and the gradation correction are to correct the gradation level based on the output signal representing the printer characteristic from the data calculation unit D.

The reading unit F is a scanner, and outputs a luminance signal read from an image on a document by, for example, 25
The density signal having 6 gradations is converted and sent to the image processing unit E. The density signal sent from the reading unit F is the MTF of the lens in the optical system constituting the reading unit F, the MTF correction of the influence of the accuracy of the CCD attachment and the vibration of the optical mirror in the scanning optical system, and the fluctuation of the scanning speed. Is.

The process CPU 90 is, for example, a microprocessor that controls the operation of the members that execute the electrophotographic process shown in FIG. A toner density control program having a function of controlling the toner density of the two-component developer loaded in the developing device 4, a development stability stabilizing program, a latent image condition control program, and a latent image by detecting a change in conditions in the electrophotographic process. A timing control program for determining the timing for driving the condition control program is provided.

The timing control program detects the turn-on of the main power source, the predetermined number of copies, the post-rotation after the end of the image, the change of the image forming mode, the idling time, the fixing temperature, the temperature and humidity of the environment, and the like to detect the image productivity. In consideration of the above, the control of the developing property and the gradation property is executed.

In the process CPU 90, the conditions for realizing the writing density of 400 dpi are written in the built-in RAM. In the process CPU 90 of this embodiment, the photosensitive member linear velocity 280 (m
m / s), sleeve rotation speed 250 (rpm), stirring screw shaft rotation speed 120 (rpm), polygon mirror 35 rotation speed 16
Each condition of 535 (rpm) is written.

The toner concentration control means is a magnetic permeability sensor MPS45 provided in the toner replenishing unit TH and the developing device 4.
Have. The toner concentration control program is a program for detecting the magnetic permeability of the developer loaded in the developing device 4 by the magnetic permeability sensor MPS45 and driving the toner replenishing unit by this to control the toner concentration substantially constant.

The process CPU 90 also has a program for controlling the developing property fixing means. The developing property fixing unit fixes the original developing property by controlling the toner density, which is closely related to the developing property, to a fixed value, and controls the rotation speed of the developing sleeve to adhere the toner to the developing area on the surface of the image carrier B. The maximum image density is adjusted by changing the amount of the developer to be used, which will be described in detail later. The developing property fixing means is provided with a mechanism and a control program for controlling the toner concentration in the developing tank to be constant when a two-component developer is adopted.

FIG. 2 is a sectional view showing a schematic mechanism of the image forming apparatus of this embodiment. Next, the electrophotographic process member of the image forming apparatus of this embodiment will be described with reference to FIG.

The photoconductor drum 1 relates to the image carrier of the present invention, and is one in which a photoconductive layer is formed on the surface of a conductive base material such as an aluminum material. The photosensitive layer has a coating type OPC of (-) charge with a film thickness of 15 to 30 μm and a dielectric constant of 2.0 to 5.0.
The conductive base material is grounded. The photoconductor drum 1 is a drum-shaped photoconductor having a diameter of 80 mm that rotates in the direction of the arrow, and an encoder 11 for detecting a phase is provided on the rotation shaft of the photoconductor drum 1. A phase signal indicating the phase is sent to the process CPU 90. The photoconductor drum 1 was rotated at a linear velocity of 280 (mm / s).

The motor 10M gives a rotational force to the photosensitive drum 1. The process CPU 90 controls the image carrier drive motor 10M (see FIG. 1) via a driver (not shown),
The number of rotations of the photosensitive drum 1 is controlled.

A charging device 2 is provided on the peripheral portion of the photosensitive drum 1.
An exposure device 3, a developing device 4, a transfer device 5, a separation device 6, and a cleaning device 7 are provided, and a paper feed tray (not shown),
A sheet feeding device 9 including a registration roller 91 and a conveyance roller 93 is provided.

The charging device 2 is, for example, a scorotron charger, and uniformly charges the photosensitive drum 1 to a predetermined voltage prior to the latent image forming process.

The exposure device 3 has a laser optical system and exposes the uniformly charged photosensitive drum 1 by a recording signal read from a page memory, for example. The exposure device 3 of the present embodiment is configured to expose the photosensitive drum 1 with two scanning bright lines formed of a laser beam. Details will be described later.

The developing device 4 is a developing sleeve 41 having an outer diameter of 40 (mm).
And a magnet roller 42 covered with a developing sleeve 41,
The two-component developer is conveyed to the developing area. The developing device housing 44 of the developing device 4 has an opening at a position facing the photoconductor drum 1. The rotating shafts of the developing sleeve 41 and the magnet roller 42 are fitted into the side wall of the developing device housing 44 so that the developing sleeve 41 is disposed near the opening of the developing device housing 44. The stirring screws 43A, 43B and 43C are stirring screws for stirring the two-component developer to adjust the charging potential of the developer. Each stirring screw 43A, 43B, 43C has a diameter of 16
(Mm), the driving shaft of each stirring screw is fitted in the side wall of the developing device housing 44 while being arranged in parallel with the rotating shaft of the developing sleeve 41. The developing device housing 44 includes a developing tank 4A for accommodating a stirring screw 43A having a diameter of 16 mm and a stirring tank 4B for accommodating stirring screws 43B and 43C having a diameter of 16 mm for supplying a new developer to the developing sleeve 41 including the magnet roller 42. Separated into. These developing sleeves 4
1. The drive shafts of the stirring screws 43A, 43B, 43C are controlled continuously by controlling the developing device drive system 30M.
The rotation speed can be changed. The process CPU 90 controls the operation of the developing device drive system 30M. In the image forming apparatus of this embodiment, this function is used to set the rotation speed of the developing sleeve 41 to 100 rpm, for example, when the image area does not pass through the opposing portion of the photosensitive drum 1 and the developing sleeve 41. The unnecessary toner adheres to the photosensitive drum 1 and the developing sleeve in the image area.
When passing through the facing part of 41,
It was set to 250 rpm. Not only 100 rpm and 250 rpm,
The maximum image density was controlled to be fixed by continuously changing between 200 and 300 rpm.

The stirring tank 4B extends laterally, and a toner supply port 441 and a recycling port 442 are formed on the top wall thereof.
The toner supply port 441 is a supply port for introducing the toner of the toner supply unit TH into the stirring tank 4B. Recycling mouth 442
Is formed on the top wall of the stirring tank 4B that houses the stirring screw 43C. With these configurations, new toner and waste toner are easily mixed.

The magnetic permeability sensor MPS45 is provided, for example, on the bottom wall below the stirring screw 43B. Further, the toner replenishing unit TH is provided in the opening formed on the top wall above the stirring screw 43C and replenishes the stirring chamber with new toner. A replenishing roller having a fine groove is provided at the replenishing port of the toner replenishing unit TH, and the motor speed of the developing device drive system 30 for driving the replenishing roller is controlled by the CPU 90.

In the developing tank 4A and the agitating tank 4B of the developing device 4, toner made of polyester material having an average particle diameter of 8.5 μm and ferrite resin coating carrier having an average particle diameter of 60 μm are controlled to have a toner concentration of 6%. After stirring the developer by rotating the stirring screws 43A, 43B, 43C at 120 rpm, the developer is placed outside the magnet roller 42.
250 rpm (when the image area passes in front of the developing sleeve 41)
Alternatively, a magnetic brush is formed on the outer circumference of the developing sleeve 41 that rotates at 100 rpm (when the image area does not pass in front of the developing sleeve 41), and the developing sleeve 41 has a predetermined bias voltage of −600.
By applying V, the latent image in the developing area facing the photoconductor drum 1 is visualized as a toner image.

As is well known, the transfer device 5 superimposes the transfer material P on the toner image electrostatically carried on the photosensitive drum 1 and discharges the electric charge from the back side of the transfer material P to transfer the transfer material P.
The toner image is transferred onto the surface, and a scorotron discharger is preferable, but the invention is not limited to this, and a toner image is electrostatically transferred onto a transfer material P such as a corotron charger or a charging roller. Anything can be used.

As is well known, the separating device 6 is a photosensitive drum 1.
By removing the charge from the transfer material P electrostatically adsorbed on the
The transfer material P is separated, and a scorotron charger,
A corotron charger, a charging roller, etc. are used.

The cleaning device 7 brings the blade 72 into contact with the surface of the photosensitive drum 1 to scrape off the toner and dust adhering to the surface of the photosensitive drum 1 and capture them in the cleaner box 71.

The toner recycling device will be described below with reference to FIG. FIG. 8 is a perspective view showing an embodiment of the toner recycling device.

An opening (not shown) is provided in the bottom wall of the cleaner box 71, and a transfer pipe 73 described later is attached to the opening. Thereby, the waste toner is carried out to the developing device 4. Further, the conveying pipe 73 is attached to the recycling port 442 of the developing device 4 so that the waste toner is recycled from the bottom wall of the cleaner box 71 to the recycling port 44 of the developing device 4.
It can be transported to 2.

The transport pipe 73 is, for example, a resin pipe into which a spiral screw is inserted, and a motor 30M (not shown) is provided at one end of the spiral screw.
It rotates in a predetermined direction.

As described above, by adopting the construction in which the waste toner is recycled from the cleaner box 71 to the developing device 4, the cleaner box 71 can be omitted or the volume of the cleaner box 71 can be reduced.

The description will be continued again with reference to FIG.

As is well known, the fixing device 8 is a device for permanently fixing the toner image on the transfer material P by applying heat or heat and pressure to the transfer material P carrying the toner image, and is a lower roller. 82 is made of, for example, LTV (abbreviation of Roten Paracher Vulcanizing) having a rubber hardness of 30 ° coated with PFA (abbreviation of tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) to a thickness of 70 μm. Yes, it contains a 200 W electric heater, and the upper roller 81 is made of a core metal material of, for example, A5056TD (aluminum) with a diameter of 50 mm and a total length of 324 mm.
A fixing temperature sensor TS1 is provided on the surface of the heating roller, which has a PFA coating on its surface and includes an electric heater (not shown) of 1100 W. Fixing temperature sensor TS1
Is composed of, for example, a thermistor or the like, and detects the surface temperature of the upper roller 81 including the electric heater as an output voltage of about 5 V at maximum, and the fixing temperature sensor TS1 controls the fixing temperature to 180 ° C., for example. It is used.

The paper discharge sensor 84 is provided in the path on the discharge side from the fixing device 8 and sends a detection signal for detecting the rear end of the transfer material P to the process CPU 90.

The humidity sensor HS outputs a maximum of 1.0 V according to humidity, for example, and amplifies it by about 4.9 times so as to approach the driving voltage of 5 V of the process CPU 90 through a noise removing capacitor and an input resistor. It is connected to a circuit (not shown). The humidity sensor HS is provided on the side wall of the apparatus housing to detect the humidity in the environment where the image forming apparatus is installed.

The fixing temperature sensor TS1 is composed of, for example, a thermistor or the like and is provided on the side wall of the apparatus housing to detect the temperature in the environment where the image forming apparatus is installed.

The structure of the exposure apparatus 3 will be described with reference to FIG. FIG. 3 is a plan view showing a schematic configuration of a laser beam type exposure apparatus according to an embodiment of the present invention.

The exposure apparatus 3 is an example of the writing unit A shown in FIG. 1 and has a laser optical system, for example, a recording signal read from a page memory or a test pattern signal S _G read from a RAM forming an image processing section E. Based on the above, the semiconductor lasers LD1 and LD2 are emitted to line-scan the photosensitive drum 1 dot by dot to form a latent image, and a so-called exposure process is performed.

The laser optical system oscillates the semiconductor laser elements LD1 and LD2 with a modulation signal obtained by performing pulse width modulation (PWM) on the recording signals for two continuous scanning lines in parallel, and oscillates the first optical axis adjusting prism 31 and the first optical axis adjusting prism 31. The two optical axis adjusting prism 32 and the combining prism 33 adjust the positions of the two in the sub-scanning direction and the main scanning direction. Then, the laser light is deflected by a polygon mirror 35 that rotates at a predetermined speed, and the fθ lens 36, the first cylindrical lens 34, and the second cylindrical lens 37 are focused on the photosensitive drum 1 to scan two minute spots. Yes, it can be applied to the pulse width modulation method in units of one pixel.

The scanning optical system constituting the laser optical system is provided with semiconductor lasers LD1 and LD2 as coherent light sources, collimator lenses 38 and 39 and prisms 31 to 33 as modulation optical system, and a polygon mirror 35 as deflection optical system.
Further, an fθ lens 36 is provided, and a first cylindrical lens 34 and a second cylindrical lens 37 are provided as a surface tilt correction optical system by the polygon mirror 35.

GaAlAs or the like is used for the semiconductor lasers LD1 and LD2, and the maximum output is 5 mW, the light efficiency is 25%, and the divergence angle is 8 to 16 ° parallel to the joint surface and 20 to 36 ° perpendicular to the joint surface. Since color toners may be sequentially superposed on each other, it is preferable to use light having a wavelength of 780 nm, which is less absorbed by the color toners.

The collimator lenses 38 and 39 are lenses for efficiently extracting the beam with a required diameter, and the numerical aperture N.V. A is 0.
33, which is composed of a lens having a transmissivity of 97% or more, and improves the spherical aberration and the cycondition.
The lens is a lens having a small refractive index.

The first optical axis adjusting prism 31, the second optical axis adjusting prism 32, and the combining prism 33 are prisms having a transmittance of 80 or more, and the first optical axis adjusting prism 31 subscans two adjacent beams. The pulse width modulation method for each pixel is performed by adjusting the position in the direction, the second optical axis adjusting prism 32 is for adjusting the position in the main scanning direction, and the first optical axis adjusting prism 31, The second optical axis adjusting prism 32 and the combining prism 33 compress the beam diameters from the semiconductor lasers LD1 and LD2 to 1/3. The deflection angle is finely adjusted by a screw or the like (not shown).

The deflection optical system reduces the Pepper sum and astigmatism in order to condense the beam and realize the flattening of the scanning surface.

The polygon mirror 35 is provided with eight polygonal surfaces and rotates at a rotation speed of 16535.4 (rpm) at a writing density of 400 dpi and 11023 (rpm) at a writing density of 600 dpi. To scan.

The fθ lens 36 reduces the Pepper sum and astigmatism in order to realize the flattening of the scanning surface, and eliminates the field curvature.

As the correction optical system, a first cylindrical lens 34 and a second cylindrical lens 37 are provided in front of and behind the polygon mirror 35 to reduce the unevenness of the scanning line pitch due to the surface tilt error of the polygon mirror 35. As a result, the polygon tilt angle is 120 seconds PP, and the tilt angle correction rate is 1'20 or more. The second cylindrical lens 37 forms an image of the beam on the photosensitive drum 1. The full width at half maximum of the spot size was 51.6 in the main scanning direction and 57.0 μm in the sub scanning direction. It is common to both 400dpi and 600dpi.

A control circuit (not shown) of the scanning optical system is provided with a modulation circuit, an index sensor (not shown) and an index detection circuit (not shown) as a synchronizing system, and a polygon driver (as a deflection optical system). (Not shown).

The modulation circuit (not shown) compares the reference wave and the analog recording signal obtained by D / A converting the recording signal consisting of predetermined bits, and multivalues it. Usually, the writing density is 600 dpi or 2 pixels. If the unit pulse width modulation is selected, the recording signal is processed in parallel for two continuous scanning lines. The modulation signal thus obtained becomes a drive signal for an LD drive circuit (not shown).

An LD drive circuit (not shown) oscillates the semiconductor lasers LD1 and LD2 with a modulation signal, and a signal corresponding to the beam light amount from the semiconductor lasers LD1 and LD2 is fed back, and the light amount becomes constant. In this way, the selector means for selecting and oscillating only one of the semiconductor lasers LD1 and LD2 is provided, and the current conducted to the semiconductor lasers LD1 and LD2 can be changed. There is. Thereby, the latent image potential can be adjusted.

The synchronizing system enters the index sensor (not shown) via a mirror (not shown) that reflects the beam from the deflection optical system. The index sensor outputs a current in response to the beam, and the current is converted into a current / voltage by an index detection circuit and output as an index signal. The surface position of the polygon mirror 5 which rotates at a predetermined speed is detected by this index signal, and optical scanning is performed by a modulation signal in a raster scanning system at a cycle in the main scanning direction. The scanning frequency is 16.1133MHz at 400dpi,
The effective print width is 297 mm or more, and the effective exposure width is 306 mm or more. At 600dpi, the scanning frequency becomes 4/9.

The positions of the two laser beams are adjusted in the sub-scanning direction and the main scanning direction by the first optical axis adjusting prism 31, the second optical axis adjusting prism 32 and the synthesizing prism 33, and these laser beams are emitted. The light is deflected by a polygon mirror 35 that rotates at a predetermined speed, and the fθ lens 36, the first cylindrical lens 34, and the second cylindrical lens 37 focus on the photosensitive drum 1 to scan a minute spot.
In this case as well, two scanning lines are simultaneously scanned by the pulse width modulation method for each pixel for the purpose of improving the image productivity.

Next, the proper arrangement of the patch detection sensor C, its mechanism and circuit configuration will be described in detail with reference to FIGS. 4 to 7.

FIGS. 4 to 7 are views showing the structure of the patch detection sensor C employed in the image forming apparatus of this embodiment. FIGS. 4 (a), 5 (a), and 6 (a) are patches. It is a top view of a detection sensor, FIG.
6C and 6B are cross-sectional views of the patch detection sensor C. The structure and arrangement of the patch detection sensor C are also common in this specification.

The patch detection sensor C includes a light emitting diode LED (light emitting diode LN66, manufactured by Kagoshima Matsushita Electronics Co., Ltd.) and a phototransistor PT (phototransistor PN101, Kagoshima Matsushita) that emits infrared light as shown in FIGS. The center of the light-receiving surface with the Electronics Co., Ltd. is 0 °, 40 °, 80
A groove having an angle of ° is formed in the casing CK, and the light emitting diode LED and the phototransistor PT are formed in the groove.
Is inserted. Dust-proof glass BG in front of the groove
Is provided. A socket SK is provided on the fixing plate that supports the casing CK. The casing CK is provided in the vicinity of the cleaning unit 50 so as to be horizontal to the surface of the image carrier B via a fixing plate. Thereby, the light reflected from the toner image can be efficiently received. The patch detection sensor C may be of any type shown in FIGS. 4 to 6, but in terms of detecting the density of the patch toner image with high accuracy, the patch detection sensor C forms an angle of 40 ° and 0 °. Those that actively use are good. With such a configuration alone, vibration due to rotation of the image carrier B cannot be prevented. A method of removing the error due to this will be described later.

FIG. 7 is a circuit diagram showing the patch detection sensor C.

In FIG. 7, the light emitting diode LED and the phototransistor PT form a photocoupling.
The maximum output is 10 at the anode terminal of the light emitting diode LED.
A variable DC power supply V _ref of (V) is connected, and the cathode terminal of the light emitting diode LED has, for example, 1 k (Ω) and 2
A semi-fixed resistance element VR1 and a fixed resistance element R8 that can be switched to k (Ω) are connected. With such a configuration, the output voltage of the variable DC power supply V _ref is varied to adjust the light emission intensity of the light emitting diode LED. A 10 V DC power source is connected to the anode terminal of the phototransistor PT, and an output detection circuit composed of an operational amplifier IC and fixed resistance elements R5 to R7 is provided to the cathode terminal. With such a configuration, the voltage corresponding to the light intensity received by the phototransistor PT is detected. The maximum image density is fixed using such a configuration.

The data calculation unit D determines the signal level obtained from the two test patterns visualized on the image carrier B as described above, for example, when the sensor output at a certain signal level is 5.
At 8 (V), the maximum output of the sensor without toner image is 7 (V)
Then, the density of the transfer paper is 0.08 minutes, and the image density is calculated as −log5.8 (V) / 7 (V) +0.08.
The 256-level density signal is applied to the two test patterns, and an average 256-level image density signal is sent to the image processing unit E and the process CPU 90. In this way, the detection error due to the slight vibration of the image carrier B and the error due to the difference between the reflection density of the image carrier and the reflection density of the transfer paper are reduced. In this embodiment, the image density averaging process is performed after conversion to the transfer paper density, but the image density averaging process is performed after the image density averaging process is performed to reduce the rounding error due to the calculation process. May be added. As a result, in this embodiment, the minimum image density is also fixed to the image density of the transfer paper.

FIG. 9 is a flow chart for explaining the developing stability control operation of the first embodiment of the image forming apparatus of the present invention.

The operator sends a copy start command from the operation panel 100 to the process CPU 90. Process CPU
Reference numeral 90 detects the phase of the photoconductor drum 1 based on the phase signal output from the encoder 11, and rotates the photoconductor drum 1 in the arrow direction (see FIG. 2) from the detected phase. Process CP
U90 applies a predetermined output voltage from a high voltage power source (not shown) to the charging device 2, whereby the charging device 2 starts discharging and uniformly charges the image forming area of the photosensitive drum 1 (S).
1). On the other hand, the process CPU 90 sends the first timing signal to the image processing unit E. The image processing unit E waits for R after a predetermined time has elapsed after receiving the first timing signal.
The test pattern signal S _G is sent from the AM to the modulation circuit (S2). The modulation circuit sends out to the LD drive circuit a modulation signal obtained by pulse-width-modulating the test pattern signals S _G for two consecutive scanning lines in parallel (S3). The LD driving circuit irradiates two laser beams by oscillating the semiconductor lasers LD1 and LD2 with a modulation signal. The two laser beams are the first optical axis adjusting prism 31 and the second optical axis adjusting prism 32.
The position of the two laser beams in the sub-scanning direction and the main scanning direction is adjusted by the combining prism 33, these laser lights are deflected by the polygon mirror 35 rotating at a predetermined speed, and the fθ lens 36, the first cylindrical lens 34, and the second cylindrical lens 34 The cylindrical lens 37 narrows and scans a minute spot on the photosensitive drum 1 (S4). In this way, the spots scanned on the photosensitive drum 1 are two scanning line simultaneous scans by the pulse width modulation method in units of one pixel for the purpose of improving the image productivity.

The laser optical system A repeats the operations of step 3 (S3) to step 4 (S4) a predetermined number of times to form an electrostatic latent image of 256 surface potential levels on the surface of the photosensitive drum 1. For example, they are formed in series. The beam from the deflection optical system is incident on the index sensor through the reflecting mirror, and the index signal is obtained from this, so the process CPU 90 detects the end of the latent image forming operation from the number of times the index signal is detected. can do. When the process CPU 90 detects the end of the latent image forming operation, it detects the phase of the photosensitive drum 1 from the phase signal sent from the encoder 11 and then decreases the rotation speed of the developing device 4 at a position synchronized with the electrostatic latent image. Yes (S5).

The process CPU 90 obtains the maximum image density from the 256-level image density signal, and compares the maximum image density with, for example, the maximum image density 1.3 stored in advance (S8). If the maximum image density is smaller than the value stored in advance by this comparison operation, the rotational speed of the sleeve is changed to increase (S9). This allows
By controlling the toner density, which is closely related to the developing property, to a constant value, the rotation speed of the sleeve is controlled to change the amount of the developer adhering to the developing area on the surface of the image carrier B to bring the maximum image density to 1.3. After adjustment, the process CPU 90 stores the sleeve rotation speed in the RAM. In this way,
The process CPU 90 of this embodiment sets the maximum image density of the control target.

As a result, the latent image formed on the photosensitive drum 1 is, for example, a 20 × 30 mm square toner image at intervals of about 5 mm.
2 test patterns that change the toner adhesion amount in 256 steps
It will be visualized continuously. The test pattern is
Since it is desired to directly obtain the printer characteristics, the image forming region is formed on the photosensitive drum 1, but the present invention is not limited to this and may be formed in the non-image region. Further, in the present embodiment, only two test patterns are visualized in view of the processing time, but the present invention is not limited to this, and the photoconductor drum 1
It is preferable to form a proper number corresponding to the change with time. As a result, the latent image formed on the photoconductor drum 1 is not overdeveloped even if it passes through the development area, which is the opposing portion of the photoconductor drum 1 and the developing device 4, and therefore toner is wasted. Can be prevented.

Next, the timing control program will be described by focusing on the fixing temperature.

First, the process CPU 90 uses the main power source M
By inputting / S, the initialization program is started, and then the fixing temperature control program is started.

The process CPU 90 is the fixing temperature sensor TS1.
The temperature of the upper roller 81 is detected by the output signal from the electric roller.
Heat up to This period is the so-called warm-up time. During this time, the charging characteristic of the photosensitive drum 1 and the charging characteristic of the developer are not sufficient.

The process CPU 90 activates the toner density control program, detects the toner density from the output signal from the fixing temperature sensor TS1, determines whether the control target density is 6%, and replenishes the toner as necessary. To do. Further, in parallel with the toner concentration control operation described above, the process CPU 90 sets the rotation speed of the stirring screws 43A, 43B, 43C to 120 (rp).
m) Change the above to adjust the charging performance of the developer.

The process CPU 90 forcibly raises the surface potential of the photosensitive drum 1 to -700 by increasing the current discharged from the charging device 2 within the warm-up time.
The charge is uniformly charged to (V), and subsequently, the charge is removed from the photoconductor drum 1 by the charge removing unit provided in the cleaning device 7. The process CPU 90 adjusts the charging characteristics of the photosensitive drum 1 by repeatedly executing the charging and discharging operations within the warm-up time.

Subsequently, the process CPU 90 executes the developing property stabilizing program and the latent image condition controlling program. As a result, the developability and gradation control can be executed without affecting the image productivity.

The warm-up time is compared with the time for controlling the developability and gradation, and when the latter time is longer than the former time, it is not preferable in terms of productivity. Therefore, in the fixing device 8 of the embodiment as described in FIG. 2, the fixing temperature is preferably 50 ° C. or lower in order to satisfy (warm-up time)> (control of developing property and gradation).

Although the fixing temperature at the time of turning on the power source has been described in the above-mentioned embodiment, the present invention is not limited to this.
Since the fixing temperature has decreased due to the energy saving mode that controls the temperature to a low temperature of about 50 ° C, continuous copying, etc., the same control is executed for the idling time during the temperature increase. Also by this, the developing property and gradation control can be executed without affecting the image productivity. In addition, the process CPU 90
A counter counts the ON state of the output signal from the paper discharge sensor 84, and the timing control program executes the developability stabilization program and latent image condition control program when the value written in the counter changes by, for example, 1,000. To do. As a result, it is possible to improve the image productivity as compared with the case where it is executed for each copy.

The process CPU 90 uses the fixing temperature sensor TS.
1. The temperature and humidity in the environment are detected from the output signals from 1 and the humidity sensor HS. For example, when the normal temperature and normal humidity is changed to a low temperature and low humidity of 10 ° C. and 30% RH, the mode change from the writing density switching means G In any case where the designated signal is detected, it is necessary to adjust the developability and gradation. However, in the case where the timing control program of this embodiment is activated, if all of these conditions are met,
Alternatively, if the development stability program and the latent image condition control program are started only when either the predetermined number of copies or the post-rotation time is detected, the image productivity is not affected. .

Next, an embodiment in which the rotation speed of the developing sleeve 41 is changed will be described with reference to Table 1.

Table 1 is a summary of the results of experiments conducted by using various developers in the electrostatic copying machine according to the image forming apparatus of the present invention. In the first to ninth embodiments, the number of rotations of the developing sleeve 41 is set to the image area of the developing sleeve as in the previous embodiment.
When passing in front of 41, the speed is set to 250 rpm, and when the image area does not pass in front of the developing sleeve 41, it is set to 100 rpm. In Comparative Examples 1 to 4, the rotation speed of the developing sleeve 41 was set to 250 rpm regardless of whether the image area passes in front of the developing sleeve 41 or not. Each item will be described below.
In Table 1, KC represents the number of copies, and 1000 copies were 1 KC (1 kilocopy).

[0119]

[Table 1]

In Table 1, the number of copies in which a cleaning failure occurs is the cumulative number of copies until a cleaning failure occurs due to repeated copying by the electrostatic copying machine of the image forming apparatus of the present invention. Is. That is, this experiment
The cleaning failure determination chart is continuously copied twice (2 screens) every 5KC, and the second copy of the two consecutive copies has a white background, which is contaminated by the toner passing through the cleaning blade. Whether or not it was visually confirmed. However, the cleaning failure determination chart refers to a document whose front 100 mm is black with respect to the feeding direction and the rest is white.

The number of copies in which white spots occur is the cumulative number of copies until the white spots are generated by making copies with the electrostatic copying machine of the image forming apparatus of the present invention. That is, in this experiment, the black chart on the entire surface was copied every 5 KC, and the occurrence of white spots was visually confirmed.

The toner scattering state was evaluated by visually observing the toner scattering around the sleeve of the developing device after 50 KC. The visually confirmed evaluation was based on the following five levels. In the five-level evaluation, the image has stains, the edge of the image has stains, and the image has no stains, but the toner is accumulated around the sleeve, the toner is slightly accumulated, and the fluidity of the recycled toner is good. The static bulk density (g / cc) of the toner in the conveying pipe 73 at 25KC and 50KC was measured by a Kawakita type static bulk density measuring device.

The amount of spent on the carrier surface is 25 KC and 50
The developer is collected by KC, the toner is removed (washed with a surfactant or water), and then dried, and about 3.0 g is precisely weighed to obtain a sample. The obtained sample is dipped in methyl ethyl ketone and stirred to dissolve the coating resin and the spent toner on the carrier surface. Repeat this operation until the dissolved solution becomes 100 cc in the volumetric flask. Then, carbon black is eluted from the toner and the solution becomes cloudy.

The transmittance of this cloudy solution was measured with a spectrophotometer for the spectral transmittance with a light beam having a wavelength of 500 nm, and it was determined that the lower the value, the more the toner spent was progressing. However, although not used for image formation, the transmittance of the carrier after stirring was 98% because of triboelectrification.

In Table 1, toner Nos. A-1 to 6 and B-1 to 3
Are toners as described below. No.A-1 to 6
Is a Konica 6192 toner to which zinc stearate (hereinafter referred to as Zn-St) was added during the experiment. Konica 619
2 Toner N is added with Zn-St as 100%, and toner N
o.A-1 had a Zn-St content of 0.02% by weight. Toner No.
A-2 had a Zn-St content of 0.04% by weight. Toner No. A
-3 had a Zn-St content of 0.06% by weight. Toner No. A-
No. 4 had a Zn-St content of 0.08% by weight. Toner No. A-5
Has a Zn-St content of 0.10% by weight. Toner No. A-6
The Zn-St content was 0.12% by weight. In addition, Konica 6192 toner (trade name, manufactured by Konica Corporation) is a product composed of about 90% by weight of polyester resin (non-linear crosslinking) and about 10% of carbon black.

Toners Nos. B-1 to No. B-1 to No. 3 were adjusted in the experiment, and the weight percentage was about 90% of polystyrene resin, about 10% of carbon black, and Zn-St0.02 ~.
Toner No. B-1 has a Zn-St content ratio of 0.06%.
It was set to 02% by weight. Toner No. B-2 has a Zn-St content of 0.
It was set to 04% by weight. Toner No. B-3 has a Zn-St content of 0.
It was set to 06% by weight.

The toners A-1 to 6 were used as a two-component developer in combination with C-16V (trade name, manufactured by Konica Corporation) as a carrier, while the toners B-1 to 3 were used. , Was used as a two-component developer in combination with C-16 (trade name, manufactured by Konica Corporation) as a carrier.

[0128]

As described above, according to the image forming method of the first aspect of the present invention, the carrier does not adhere to the image carrier, the density unevenness of the toner image does not occur, and the carrier deteriorates. It is slow and the consumption of toner can be reduced.

According to the image forming method of claim 5,
Toner density is not unevenly generated, less toner is wasted,
The amount of energy in the source to form the electrostatic latent image can be controlled.

According to the image forming apparatus of claim 11,
The carrier is not attached to the image carrier, the density of the toner image is not uneven, the deterioration of the carrier is slow, and the toner waste can be reduced.

According to the image forming apparatus of claim 15,
Toner density is not unevenly generated, less toner is wasted,
Alternatively, the amount of light for forming the electrostatic latent image can be controlled by collecting the toner having a slow toner deterioration.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of an image forming apparatus according to an embodiment.

FIG. 2 is a cross-sectional view showing a schematic mechanism of an embodiment of the image forming apparatus.

FIG. 3 is a plan view showing a schematic configuration of a laser beam type exposure apparatus.

FIG. 4 is a plan view and a cross-sectional view of an embodiment of a patch detection sensor.

5A and 5B are a plan view and a sectional view of another embodiment of the patch detection sensor.

6A and 6B are a plan view and a sectional view of another embodiment of the patch detection sensor.

FIG. 7 is a circuit diagram showing an example of a circuit of a patch detection sensor.

FIG. 8 is a perspective view showing an embodiment of a toner recycling device.

FIG. 9 is a flowchart illustrating a toner density control operation.

[Explanation of symbols]

A writing unit B image carrier C patch detection sensor D data calculation unit E image processing unit F reading unit S _G test pattern signal 1 photoconductor drum 2 charging device 3 exposure device 4 developing device 5 transfer device 6 separation device 7 cleaning device 9 Feeder 11 Encoder 41 Development sleeve 42 Magnet rollers 43A, 43B, 43C Stirring screw 44 Developer housing 90 Process CPU 441 Toner supply port 442 Recycle port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Nishida 2970 Ishikawa-cho, Hachioji City, Tokyo Konica Stock Company

Claims (16)

[Claims] 1. An image bearing member, wherein an electrostatic latent image is formed on the image bearing member, and a voltage is applied to a rotatable developing sleeve having a magnet body inside, which is provided so as to face the image bearing member. By rotating the developing sleeve and the developing sleeve at a predetermined speed,
In an image forming method by an electrostatic method of a two-component developing method of carrier and toner, which develops an electrostatic latent image of the image carrier to form a toner image on the image carrier, an electrostatic image is formed on the image carrier. When the formed image area does not pass in front of the developing sleeve, the speed at which the developing sleeve is rotated is lower than that when the image area passes in front of the developing sleeve while applying a voltage to the developing sleeve. An image forming method comprising: 2. The image forming method according to claim 1, wherein the two-component developing method is a two-component contact reversal developing method. 3. A toner image formed on the image bearing member is transferred to a transfer material, the remaining toner on the image bearing member is collected, and the collected toner is returned into the developing device housing. The image forming method according to claim 1, which is characterized in that 4. The image bearing member is an electrophotographic photosensitive member,
When the electrostatic latent image is formed by exposing the image bearing member imagewise after charging the image bearing member, and when the charged region of the image bearing member passes through the developing sleeve. 4. The image forming method according to claim 1, wherein a voltage is applied to the developing sleeve to rotate the developing sleeve. 5. An image bearing member which is an electrophotographic photoreceptor is charged, an electrostatic latent image is formed on the image bearing member by imagewise exposure by a laser optical system, and the electrostatic latent image is provided so as to face the image bearing member. By applying a predetermined voltage to the developing sleeve and rotating the image carrier and the developing sleeve at a predetermined speed, the electrostatic latent image on the image carrier is developed and a toner image is formed on the image carrier. In the image forming method by electrophotography, forming and forming, except for the imagewise exposure, detecting and controlling the light amount of the laser optical system by emitting laser light outside the image area on the image carrier, and When the charged area of the image carrier passes through the developing sleeve, a voltage is applied to the developing sleeve to rotate the developing sleeve, and an image area electrostatically formed on the image carrier. Is the current When not passing in front of the sleeve, while applying a voltage to the developing sleeve, an image forming method is characterized in that the speed at which the developing sleeve is rotated is made lower than when the image area passes in front of the developing sleeve. . 6. The toner image developed on the image carrier is transferred to a transfer material, the remaining toner on the image carrier is recovered, and the recovered toner is returned to the developing device housing. The image forming method according to claim 5, which is characterized in that. 7. The electrophotographic method comprises a carrier and a toner.
The image forming method according to claim 5, which is a component developing method. 8. The image forming method according to claim 1, wherein the developing method is a magnetic brush contact developing method. 9. The image forming method according to claim 1, 2, 3, 4, 7, or 8, wherein the carrier is a binder carrier. 10. The image forming method according to claim 1, wherein the carrier has a matting agent or a lubricant present on the surface thereof. 11. An image bearing member carrying an electrostatic latent image, an electrostatic latent image forming means for forming an electrostatic latent image on the image bearing member, and a carrier provided facing the image bearing member. A developing sleeve that conveys a two-component developer of toner, a developing sleeve voltage applying unit that applies a voltage to the developing sleeve, an image carrier driving unit that moves the image carrier, and a developing sleeve driving unit that rotates the developing sleeve. While moving the image carrier by the image carrier driving means with respect to the developing sleeve to which the voltage is applied, while rotating the developing sleeve by the developing sleeve driving means,
In an image forming apparatus having control means for developing an electrostatic latent image on the image carrier to form a toner image on the image carrier, the control means is an image area electrostatically formed on the image carrier. Is not passing in front of the developing sleeve, a voltage is applied to the developing sleeve by the developing sleeve voltage applying means, and the developing sleeve driving means of An image forming apparatus comprising: a control unit that lowers a speed at which the developing sleeve is rotated. 12. The image forming apparatus according to claim 11, wherein the control unit forms a toner image on the image carrier by two-component contact reversal development. 13. A toner image transfer means for transferring a toner image formed on the image carrier to a transfer material, and a toner remaining on the image carrier without being transferred to the transfer material. 13. The image forming apparatus according to claim 11, further comprising: a toner collecting unit that returns the collected toner into the developing device housing. 14. The image bearing member is an electrophotographic photosensitive member, the electrostatic latent image forming unit charges the image bearing member, and the image bearing member charging unit uses the image bearing member charging unit. Imagewise exposure means for performing imagewise exposure after charging, and when the charged area of the image carrier passes through the developing sleeve, a voltage is applied to the developing sleeve by the developing sleeve voltage applying means. 14. The image forming apparatus according to claim 11, 12 or 13, wherein the developing sleeve driving unit rotates the developing sleeve while applying the voltage. 15. An electrophotographic photosensitive member that is an image bearing member that carries an electrostatic latent image, an electrophotographic photosensitive member charging unit that charges the electrophotographic photosensitive member, and an electron charged by the electrophotographic photosensitive member charging unit. An electrostatic latent image forming means for forming an electrostatic latent image on a photographic photosensitive member by imagewise exposure with a laser optical system; and a carrier and toner two-component developer provided facing the electrophotographic photosensitive member. A developing sleeve that conveys the developing sleeve, a developing sleeve voltage applying unit that applies a predetermined voltage to the developing sleeve, an electrophotographic photosensitive member driving unit that moves the charged electrophotographic photosensitive member with respect to the developing sleeve, and the developing sleeve Developing sleeve drive means for rotating at a predetermined speed, while moving the electrophotographic photosensitive member by the electrophotographic photosensitive member driving means with respect to the developing sleeve to which the voltage is applied, Control means for rotating the developing sleeve at a predetermined speed by an image sleeve driving means to develop the electrostatic latent image on the electrophotographic photosensitive member to form a toner image on the electrophotographic photosensitive member; and the imagewise exposure. In an image forming apparatus having a light amount control means for emitting a laser beam outside the image region of the electrophotographic photosensitive member to detect the light amount of the laser optical system other than the time, the charged region of the electrophotographic photosensitive member is When passing through the developing sleeve, the developing sleeve driving means rotates the developing sleeve while applying a voltage to the developing sleeve by the developing sleeve voltage applying means, and electrostatically formed on the image carrier. When the image area does not pass in front of the developing sleeve, the developing area voltage applying means applies a voltage to the developing sleeve while the image area is Image forming apparatus characterized by lowering the speed to turn the developing sleeve of the developing sleeve driving means with respect to when it passes in front of the statue sleeve. 16. A toner image transfer means for transferring a toner image formed on the electrophotographic photosensitive member to a transfer material, and a toner left on the image carrier without being transferred to the transfer material. 16. The image forming apparatus according to claim 15, further comprising a toner collecting unit that returns the collected toner into the developing device housing.