JP2991255B2 - Method for determining suitability of image formation in image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner carrier having a developer carried thereon, and an exposure means disposed on the rear surface of the photoconductor, and a developer slide between the photoconductor and the toner carrier. In an image forming apparatus, a rubbing area is provided, and a photosensitive member is charged on the rubbing area, and an image is formed while performing exposure and development.
The appropriateness of the image formation .

[0002]

2. Description of the Related Art Conventionally, for example, a photosensitive drum formed by laminating a light transmitting conductive layer and a photoconductive layer on a light transmitting support,
Exposure means for generating a light output corresponding to the image information is interpolated, and the light output of the exposure means is converged to form a latent image on the photoconductor layer at the same time or immediately after that, and the photoconductor drum is opposed to the photosensitive drum. An image forming apparatus is known in which the latent image is converted into a visible image (toner image) via a toner carrier that has been made, and the toner image can be transferred to plain paper via a transfer roller or other transfer means. is there. (JP-A-58-15395)
No. 7, etc.)

In this type of image forming apparatus, in order to further simplify the structure and prevent ozone generation and the like, and to prevent ground fogging, the image forming apparatus faces the photosensitive drum without providing an independent charger. and with supporting the conductive magnetic toner on the arranged developing sleeve which is provided with a toner sliding Kosuiki called magnetic brush by using a fixed magnetic pole and other magnetic energy that is contained in the sleeve to a developing position immediately before the position, the After the surface of the photosensitive drum is rubbed by the rubbing region, a charge is injected by injecting a charge into the photoconductive layer of the drum through the rubbing region using a developing bias applied to the developing sleeve side. Immediately after the charging, an exposure image is formed by using an exposure head included in the drum, development is performed, and a predetermined image is formed.

[0004]

Therefore, it is premised that the toner used in the above-mentioned apparatus is a conductive toner in order to inject electric charge from the developing sleeve side. As described above, it is not possible to employ an electrostatic transfer means by corona discharge. Therefore, generally, a transfer roller is used, and a transfer bias, heat, a magnetic force, or the like is applied to the transfer roller to increase transfer efficiency. , The resistance value of the recording paper is likely to fluctuate due to moisture and other environmental factors,
For this reason, stable and smooth transfer cannot be performed, and it is difficult to form a high-quality image.

In order to solve such a drawback, a device using a two-component developer comprising a combination of an insulating toner and a conductive carrier (Japanese Patent Laid-Open No. 60-22145), a device using a combination of a conductive toner and an insulating toner, etc. However, none of them have been put to practical use because it is difficult to uniformly charge the photosensitive drum side.

[0006] The Applicant has therefore, although the points using a high-resistance or a combination of insulating toner and a conductive carrier two-component developer is the same as the prior art, in particular the conductive carrier, Figure 5 As shown in (1), a developer in which conductive fine particles are fixed to the surface of particles in which a magnetic material is dispersed in a binder resin, and the diameter of the carrier is set to 1 to 5 times the toner diameter (hereinafter referred to as the prior application) has proposed a) that the developer earlier.

[0007] The present invention highly resistive or two-component developer composed of a combination of insulating toner and a conductive carrier, in particular in the device using the prior application developer, accurately and easily image before performing the image forming operation formation of suitability judging, especially pos- sibly presence or absence of an electrical abnormality in the photosensitive member from the developing container, and further a developer, deterioration of the carrier, the presence or absence of abnormality of the site of the image formation on the influence of the dielectric breakdown of the photosensitive member Suitability of image formation in an image forming apparatus that can be performed accurately and easily
The purpose is to provide a judgment method.

[0008]

SUMMARY OF THE INVENTION The present invention provides a method for supporting a developer.
The exposed toner carrier is placed on the surface of the photoreceptor,
Placed on the back side of the photoconductor, at least before exposure starts
Formed between the photoreceptor and the toner carrier
Charge of the photoreceptor, exposure and development on the rubbing area
Formation in an image forming apparatus that performs image formation while performing
In the method of judging whether or not the developer is
Carrier whose surface is conductively treated
And a developer containing the developer.
Detects the toner concentration in the developing container
The first to output a detection signal when it is out of the standard range
Signal output means, and the photosensitive member through the developer rubbing area
To applying a constant voltage between the toner carrying member and, between the both members
The voltage drop between the constant voltage and the voltage drop is detected.
LOW signal when voltage is below reference value, exceeds reference value
And a second signal output means for outputting an HI signal in this case.
If the first signal output is present, the second signal
When the output is HI, the toner concentration in the developer rubbing area decreases.
Judge, and when there is no said first signal output , said second signal
When the signal output is HI, it is determined that the photoconductor has dielectric breakdown.
When the second signal is LOW, it is determined that the carrier has deteriorated.
It is characterized by doing.

The process leading to the present invention will be described step by step. First, as described above, the present invention is based on the premise that a carrier composed of a carrier having at least a surface subjected to a conductive treatment and a high-resistance or insulating toner is used. In other words, stable and smooth transfer is possible by using a high-resistance or insulating toner, and the conductivity of the carrier is set low irrespective of the transfer side because charge is injected using a conductive carrier. Therefore, the charging time can be shortened.

Further, by applying conductive fine particles to the surface of the carrier as in the prior application, the conductivity can be maintained irrespective of the material constitution in the carrier, and the stability of charging and exposure can be achieved. Since the magnetic substance is dispersed and arranged in the binder, strong magnetism can be imparted, and thereby, the developer rubbing area (toner accumulation) can be smoothly formed, which is preferable.

However, when the carrier on which the conductive fine particles are adhered is rubbed as described above, if the fine particles are peeled off, the resistance value increases and smooth charging becomes impossible. Further, even in the case of a carrier which does not adhere fine particles and has conductivity itself, the carrier itself is rubbed and easily deteriorates, and it is preferable to detect this every time an image is formed.

Further, since the development is also performed in the developer rubbing area, only the toner is consumed at the development position and the carrier remains, so that the developer is not sufficiently supplied. There is a possibility that the toner distribution ratio at the developing position is out of order and the image forming density is reduced. Furthermore, if the surface of the photoconductor is always rubbed with the developer as described above, there is a possibility that dielectric breakdown may occur due to abrasion of the surface of the photoconductor or leakage of a developing bias.

If it is attempted to perform an abnormality check on each of these check items by an independent circuit, the circuit configuration becomes complicated, which is not only undesirable, but also liable to malfunction. Further, since there is a developer rubbing area between the photoreceptor and the toner carrier, it is also difficult to check the area.
Accordingly, the present invention is intended to perform the above-described various abnormality determinations accurately and easily with a single circuit by effectively utilizing the developer rubbing area.

That is, the feature of the present invention is that, as described above, a developer comprising a carrier having at least a surface subjected to conductive treatment and a high-resistance or insulating toner is used as the developer. In particular, as shown in FIG. 1, at least before the start of exposure, the photoconductor 1 and the toner carrier 20 are rotated to form the rubbing area 10, and the toner carrier 20 and the photoconductor 1 are interposed via the rubbing area 10. A constant voltage is applied in between, and the current or / and voltage flowing between the two members 1/20 are detected, and based on these detection signals, the above-mentioned respective detection items are checked by the detection circuit 50 to determine whether image formation is appropriate. Is determined. In this case, it is preferable to simplify the circuit configuration by using the developing bias Vi as shown in FIG. 1 without using a special detection power source for the constant voltage. It is necessary to include at least a DC component of a constant voltage, and unless the detection voltage to be taken out by application of the bias Vi is taken out from the photoconductor 1 side, the above-mentioned detection items cannot be checked.

Therefore, in the present invention, the rubbing area 1
0 was applying a developing bias comprising at least a constant voltage direct current component to the photosensitive member 1 side of the toner carrying member 20 through, that determines the propriety of the image formed based on the detection voltage taken out from the photosensitive member 1 side It is a feature.

As a specific detecting means, it is detected whether or not the toner concentration is within an appropriate range based on the detection voltage and a sensor 26 for detecting the toner concentration in the developing container 21 containing the developer. The path from the inside of the developing container 21 to the photosensitive member 1 by comparing with the detection voltage, specifically, the toner concentration in the developing container 21, the toner concentration in the rubbing area, the deterioration state of the carrier, and the dielectric breakdown of the photosensitive member etc. comes out detection.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Not just.

FIG. 2 is a schematic diagram showing the configuration of a printer according to an embodiment of the present invention. . Reference numeral 1 denotes a photosensitive drum, which is formed by laminating a light-transmitting conductive layer 1b and a photoconductor layer 1c on a drum-shaped light-transmitting support 1a, and a developing sleeve described later as the light-transmitting conductive layer 1b. A developing bias is applied in between, and the motor can be rotated clockwise by a drive motor (not shown).

Next, each part will be described in detail.
The translucent support 1a is made of a transparent inorganic material such as glass, quartz, sapphire, fluorine resin, polyester, polycarbonate, polyethylene, polyethylene terephthalate, or the like.
There are transparent resins such as vinylon, epoxy, and mylar, and they are formed in a drum shape. The translucent conductive layer 1b is made of ITO
(Indium, tin, oxide), lead oxide, indium oxide, copper iodide, etc.
A metal such as i or Au may be formed thin enough to be translucent.

The photoconductor layer 1c is made of a photoconductor made of a-Si: H. When the developing bias is positive, a non-doped or Va group element is contained in order to increase electron mobility. When the bias is negative, a group IIIa element is preferably contained in order to increase the mobility of holes. Also, if necessary, to obtain desired characteristics such as electrical characteristics such as dark conductivity and photoconductivity, and optical band gap,
Elements such as C, O, and N may be contained. Further, the photoconductor layer 1c is formed of two layers, a photoexcitation layer region having a function of generating photocarriers from the back side and a layer region having a function of transporting carriers, thereby improving photosensitivity and withstand voltage. I can do it.

Reference numeral 2 denotes a developing device, which comprises a toner container 22, a container body 21 containing a carrier and toner, and includes a fixed magnet assembly 23 on the side of the container body 21 facing the photosensitive drum 1. A developing sleeve 20 is provided, and the developing sleeve 20 is placed on a side facing the photosensitive drum 1.
To be rotatable clockwise in the opposite direction .

The toner accommodating portion 22 and the container body 21 are separated by a partition wall 24, a supply roller 25 is disposed in a slit opening provided at the center of the partition wall 24, and the inside of the container body 21 is provided based on a signal from a sensor 26. The supply roller 25 rotates each time the carrier / toner mixture ratio (toner density) decreases, and is always maintained at an appropriate density ratio. Further, a pair of mixers 27 each formed of a magnet roll is disposed in the container main body 21 to maintain the carrier / toner mixture ratio in the container main body 21 at a uniform concentration. Developing sleeve 20
A doctor blade 28 is attached to the entrance end of the container 21 on the lower surface side, so that the developer guided to the developing position can be regulated to a thin film. Next, the composition of the developer will be described.

FIG. 5 is a schematic view showing an embodiment of the carrier used in the developer of the present embodiment. The conductive fine particles 17 are formed on the surface of carrier base particles 13 in which a magnetic substance 15 is uniformly dispersed in a binder resin. Are fixed to form the carrier 11.

The carrier 11 has a volume resistivity of 10 ^4.
Ω · cm or less, more preferably 1 Ω · cm or less.
0 ⁸ to 10 ⁴ · Ω · cm. If the volume resistivity is too large, the characteristics as a conductive carrier are impaired. For example, when used in a back exposure method, charge injection is not performed promptly, and the photoconductor becomes insufficiently charged. The conductivity of the carrier 11 is mainly given by the conductive fine particles 17.

The volume specific resistance of the carrier 11 was determined by placing 1.5 g of the carrier 11 in a Teflon cylindrical body having an inner diameter of 20 mm and having an electrode at the bottom, inserting an electrode having an outer diameter of 20 mmφ, and applying a load of 1 kg from the top. It is the value when measured.

The magnetic force of the carrier 11 needs to be larger than a certain level. Preferably, the maximum magnetization in a magnetic field of 5 KOe (Oersted) is 55 emu / g or more, more preferably 55 to 80 emu / g. Also, 1 KO
The maximum magnetization in the magnetic field of e is preferably 45 emu / g or more, more preferably 45 to 60 emu / g. When the magnetic force of the carrier 11 becomes too small, the transportability of the developer deteriorates, and the carrier 11 is developed together with the toner.

The average particle size of the carrier 11 is 10 to 100.
μm is suitable, and more preferably 15 to 50 μm. If the carrier 11 becomes too large, it becomes difficult to uniformly charge the photosensitive member, and it becomes impossible to increase the toner concentration T / C. On the other hand, if it is too small, the transportability of the developer on the developing sleeve deteriorates, and it becomes difficult to apply a constant potential.

The true density of the carrier 11 is 3.0 to 3.0.
A range of 4.5 g / cm ³ is preferred. As a magnetic material,
Magnetite (Fe ₃ O ₄ ), ferrite (Fe
₂ O ₃ ) and the like are used, and magnetite is particularly preferable, but is not limited thereto.

As the conductive fine particles 17, carbon black, tin oxide, conductive titanium oxide (a titanium oxide coated with a conductive material), silicon carbide and the like are used, and the conductivity is increased by oxidation with oxygen in the air. Those that do not lose are desirable.

As the binder resin used for the carrier base particles 13, vinyl resins represented by polystyrene resins, polyether resins, nylon resins, polyolefin resins and the like are used.

The adhesion of the conductive fine particles 17 to the surface of the carrier base particles 13 is performed, for example, by fixing the carrier base particles 13 to the magnetic material.
15 and the conductive fine particles 17 are adhered to the surface of the carrier base particles 13, and then a mechanical / thermal impact force is applied to drive the conductive fine particles 17 into the carrier base particles 13 and fixed. It is done by doing. The conductive fine particles 17 are not completely embedded in the carrier base particles 13, but are fixed so that a part thereof protrudes from the carrier base particles 13.

By fixing the conductive fine particles 17 on the surface of the carrier 11 in this manner, the carrier 11 can be efficiently made.
High conductivity. Further, the carrier base particles 13
Since it is not necessary to mix the conductive fine particles 17 therein, as many magnetic substances 15 can be compounded in the carrier base particles 13 and the magnetic force of the carrier 11 can be increased.

The above-mentioned carrier and toner are mixed to form a developer. As the toner, a normal insulating toner is used, and preferably has a volume resistivity of 10 ¹⁴ Ω · cm or more, more preferably 10 ¹⁶ Ω · cm or more. This value is measured as in the case of the carrier.

As the toner, those having the same constitution as in the prior art are used. For example, a binder resin, a coloring agent, a charge controlling agent, an offset preventing agent and the like can be compounded.
Also, a magnetic substance can be added to form a magnetic toner,
This is effective for preventing toner from scattering inside the machine.

On the other hand, the developing sleeve 2
The exposure head 3 is fixedly arranged on the inner peripheral surface side of the drum 1 facing 0. The exposure head 3 is formed by an LED or EL head array 31 for generating an optical output corresponding to image information and a converging lens 32 (trade name: Selfoc lens), and the image forming position of the lens 32 is determined by the photosensitive drum 1. Slightly from the focal line connecting the axis of the developing sleeve 20 and the drum 1
Is deflected to the downstream side in the rotation direction, and forms an image on the photoconductor layer 1c in the drum 1.

In FIG. 2 , reference numeral 4 denotes a transfer roller, 5 denotes a registration roller, and 6 denotes a paper detection sensor. Transfer roller 4
Uses a conductive roller to increase the transfer efficiency, applies a transfer bias having a polarity opposite to the charging potential of the toner, and uniformly presses the peripheral surface of the photosensitive drum 1 to synchronize with the drum 1 It is configured to be rotatable. As for the material of the transfer roller 4, since the toner to be transferred is an insulating toner, it is not necessary to form a conductive toner, and a high-resistance or insulating toner can be used.

[0036] Next, the action of such an embodiment will be described with reference to FIG. First, the power is turned on, an initial check is performed, an alarm is displayed if there is a basic abnormality in the heater of the fixing unit, various control circuits and a display unit, and if there is no abnormality, the process proceeds to a pre-printing operation step. (STEP
1)

In the pre-print operation step, first, a drum motor (not shown) is turned on to rotate the drum, and a drive motor (not shown) on the developing unit 2 side is turned on, and the inside of the developing container is moved by the mixer 27. The toner density is controlled by the sensor 26 while rotating the developing sleeve 20 while stirring. (STEP 2) After the developer rubbing area 10 is formed between the developing sleeve 20 and the drum 1 by the rotation of the developing sleeve 20, the developing bias flowing to the drum 1 through the rubbing area 10 is checked on the detection circuit side. I do. (STEP3)

Next, the configuration of the detection circuit will be described in detail according to the operation procedure with reference to FIG. 51 is a DC power supply 56
A constant voltage circuit for maintaining the developing bias (Vi) composed of a constant voltage by the circuit 51. As shown in FIG. It is guided to the drum 1 side. (These members are collectively referred to as a load 52 hereinafter.)

The output side of the load 52 is connected to a voltage dividing resistor R.
1, the detection voltage between the load 52 and the voltage dividing resistor R1 is taken out to the detecting circuit 50 side, and the input voltage R
2, input to the window comparator 53 and the load current detection circuit 54 via R3.

The window comparator 53 has respective reference voltage setting circuits 5 for setting an upper reference voltage and a lower reference voltage.
The detected voltages are compared based on the reference voltages input from 5A and 55B.
The OW signal is configured to output a Hi signal when the voltage is equal to or higher than the upper limit reference voltage. On the other hand, in the developing container 21, a sensor 26 detects whether or not the toner density is within a predetermined reference range, and outputs a detection signal when the toner density is out of the predetermined reference range.

Therefore, when a detection signal is output from the sensor 26 and a LOW signal is output from the window comparator 53 (because the toner is insulative and the carrier is conductive), the development is performed together with the development container 21. It can be determined that the toner concentration in the agent rubbing region 10 is high. Therefore, the AND of the two signals is taken, and the signal output from the AND gate 61 determines that the toner concentration in the container 21 is high.

On the other hand, when the detection signal is output from the sensor 26 and the Hi signal is output from the window comparator 53, it is determined that the toner concentration in the developer rubbing area has decreased in the developing container 21 as well as in the developing container 21. Accordingly, the AND of the two signals is taken, and the signal output from the AND gate 62 determines that the toner density in the container 21 has decreased, and the supply roller 25 is driven to prompt toner supply.

Next, when the detection signal is not output from the sensor 26 and only the LOW signal is output from the window comparator 25, the conductive material adhering to the surface of the carrier 11 in the developer rubbing area 10 is output. It can be detected that the fine particles 17 have peeled off or the carrier 11 itself has deteriorated. Therefore, after the LOW signal is inverted by the inverter 68, it is determined that the carrier has deteriorated based on the signal output from the AND gate 63. I do.

On the other hand, when the detection signal is not output from the sensor 26 and only the Hi signal is output from the window comparator, a so-called leak state, more specifically, the photoconductive layer of the photosensitive drum is It can be determined that the insulation has been broken. Therefore, after the signal from the sensor 26 is inverted by the inverter 67, the AND gate 65
And prompts the user to replace the photosensitive drum based on the signal output.

On the other hand, the load current detection circuit 54 also converts the detected voltage taken out from the load outlet side into a current and compares the (inflow current) with a reference current 59. If the inflow current is lower than the reference current, a so-called disconnection is performed. Alternatively, it is determined that the switches (SW1, SW2, see FIG. 1) disposed in the transmission path of the developing bias are in an off state, or that the developing or the drum unit is not properly mounted and the developing gap is too open. Is set to be displayed on the display 60.

Returning to FIG. 4 , if there is no abnormality in all the gate outputs after the detection, the sheet is fed from the registration roller 5 and at the same time the exposure by the exposure head 3 is started to form the first image. (STEP 4) Then, after the transfer of the first sheet is completed, it is checked whether or not continuous printing is to be performed. If continuous printing is to be performed, the flow returns to (STEP 1) again to repeat the printing operation. On the other hand, when the continuous transfer is not performed, the developing bias, the developing drive system, and the drum motor are sequentially turned off to terminate the operation, and shift to a standby state.
(STEP5)

[0047]

As described above, according to the present invention, a combination of a high-resistance or insulating toner and a conductive carrier is used.
In the apparatus using the component developer, accurately and easily imaging suitability judging before performing an image forming operation, in particular pos- sibly presence or absence of an electrical abnormality in the photosensitive member from the developing container, and further a developer, a carrier, etc. It is possible to accurately and easily determine whether or not there is an abnormality in a portion that has an effect on image formation, such as deterioration of the photoconductor and dielectric breakdown of the photoconductor . And so on.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram according to an embodiment of the present invention .

FIG. 2 is a diagram illustrating a cross-sectional configuration of a printer according to an embodiment of the present invention .

FIG. 3 is a block diagram of a detection circuit used in the device of FIG. 2;
is there.

FIG. 4 is a composition diagram of a conductive carrier constituting a developer.
is there.

FIG. 5 is a flowchart showing an operation procedure of the embodiment.
It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Developing means 3 Exposure means 10 Developer rubbing area 50 Detection circuit 26 Sensor 21 Developing container (container main body)

Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI G03G 21/00 512 G03G 21/00 (56) References JP-A-60-22145 (JP, A) JP-A-59-219763 (JP, A JP-A-1-277870 (JP, A) JP-A-2-143269 (JP, A) JP-A-2-22672 (JP, A) JP-A-61-142456 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G03G 15/05 G03G 15/06 101 G03G 15/08 115 G03G 15/09 G03G 21/00 G03G 21/00 510

Claims (1)

(57) [Claims] An image forming apparatus according to claim 1, wherein a toner carrier carrying a developer is exposed
bodyofExposure means on the front sideOf the photoreceptorArranged on the back side
And putat leastBefore the start of exposure,SaidTona
ー Between carriersOn the formed developer rubbing area,Photoreceptor
Performs image formation while performing charging, exposure and development
Image formationAppropriateness of image formation in the deviceHow to smell
A carrier having at least a surface conductively treated,
Using a developer consisting of a high-resistance or insulating toner
Along withThe toner concentration in the developing container containing the developer is detected.
Detected when the toner concentration is out of the predetermined reference range.
First signal output means for outputting a signal; The photosensitive member and the toner carrying through the developer rubbing area
Apply a constant voltage between the body and detect the voltage drop between both members
And a difference voltage between the constant voltage and the drop voltage is equal to or less than a reference value.
In the case of, the LOW signal is output.
And second signal output means for outputting. The second signal output when there is the first signal output;
Is HI, it is determined that the toner concentration in the developer rubbing area has decreased.
And The second signal output when there is no first signal output
Is HI, it is determined that the photoconductor has dielectric breakdown,
When the second signal is LOW, it is determined that the carrier has deteriorated. Things
Characteristic image formationAppropriateness of image formation in the deviceOne
Law.