JPH09244401A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact type developing device constituted so that a high-resolution and high-developability image without a vertical stripe or developing irregularity is stably obtained. SOLUTION: The developing device 13 is constituted so that a developing sleeve 130 arranged by being faced to a photoreceptor drum 10 being an image forming body and set for carrying developer and a control electrode plate 80 provided with an electrode part 82 which is supported in a gap between the sleeve 130 by an insulating member 83 and on which a voltage can be applied are arranged and the non-magnetic one-component developer is used. In such a case, when the toner attachment quantity of the image forming body in the case that the plate 80 is not arranged is defined as M0 (mg/cm<2> ) and the maximum toner attachment quantity of the image forming body of a developing time in the case that the plate 80 is moved along the circumferential surface of the developer carrying body is defined as Mmax (mg/cm<2> ), a developing bias having such a vibration electric field that the relation of 0.1<=(M0 /Mmax )<=0.5 is obtained is set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for non-contact developing an electrostatic latent image by using a non-magnetic one-component developer in an image forming apparatus such as an electrophotographic copying machine.

[0002]

2. Description of the Related Art Conventionally, as one of developing methods used in an electrophotographic copying machine or the like, there is a one-component developing method using a non-magnetic toner. This developing method has a cylindrical sleeve rotatably supported with its surface roughened, the charged toner is supported on the surface of the developing sleeve, and the toner is conveyed to a developing area for developing.

In this developing method, since a toner particle having an average particle diameter of about 10 μm is used, there is a problem that it is difficult to obtain a high-quality image which reproduces delicate lines, dots, shading differences, and the like. In order to obtain such high quality images,
It is considered essential to make the toner particles finer. However, if the toner particles are fine particles having an average particle size of 10 μm or less, the influence of van der Waals force becomes relatively large with respect to the Coulomb force at the time of development.
Since the developability is likely to decrease and toner agglomeration is also likely to occur, charge control is difficult, and the side effects are more conspicuous and there is a problem that a clear image cannot be obtained. It was difficult to do so.

As a method of solving this problem, a plate-shaped member having an electrode in the upstream portion of the developing area is brought into contact with the developing sleeve which is the developer transporting body, and the electrode and the developing sleeve, and the developing sleeve and the image forming body. A method of forming an oscillating electric field such that the former is stronger during the period of time, and forming the toner in the developer into a cloud to perform development is disclosed in Japanese Patent Laid-Open No. 5-346736.
JP-A-6-175485.

[0005]

However, in the above-mentioned control electrode method, the distance between the developing sleeve and the electrode changes due to the waviness or warpage in the longitudinal direction of the control electrode plate, so that the developability is deteriorated. Non-uniformity causes vertical stripes, uneven development, etc., resulting in deterioration of image quality.

Further, since toner is deposited on the control electrode plate to stain the image on the image forming body, or the portion where the toner is deposited has a high dielectric constant by the thickness thereof, the developability is high. Therefore, there is a problem that a uniform image cannot be obtained.

The present invention solves the above-mentioned problems of the control electrode method and stabilizes a uniform and high-quality image having high resolution and developability without vertical stripes due to undulation and warpage of the control electrode plate, development unevenness, and the like. It is an object of the present invention to provide a developing device for performing non-contact development which is obtained as described above.

[0008]

SUMMARY OF THE INVENTION The above object is to support a developer carrier provided facing an image forming body, and to support a gap between the developer carrier and the image forming body by an insulating member.
Toner of the image forming body at the time of development in the case where a control electrode plate having an electrode portion to which a voltage can be applied is arranged and development is performed using a non-magnetic one-component developer when the control electrode plate is not provided. The adhesion amount is M ₀ (mg / cm ² ), the maximum toner adhesion amount of the image forming body when the control electrode plate is provided and the position of the control electrode plate is changed along the peripheral surface of the developer transport body. _Is defined as M _max (mg / cm ² ), a developing bias voltage having an oscillating electric field is set such that 0.1 ≦ (M ₀ / M _max ) ≦ 0.5. To be achieved.

When the toner adhesion amount at an arbitrary setting position is M (mg / cm ² ) using the control electrode plate, 0.5 ≦ (M / M _max ) ≦ 0.9, and M The developing device is characterized in that the control electrode plate is set at a position where> M ₀ .

[0010]

2 and 3 are schematic configuration diagrams showing an example of a color image forming apparatus provided with the developing device of the present invention as a suitable developing means.

In FIGS. 2 and 3, reference numeral 10 denotes a drum-shaped image forming body, that is, a photosensitive drum, which has a transparent conductive layer and an organic material on the outer periphery of a cylindrical substrate formed of a transparent member such as optical glass or transparent acrylic resin. A photosensitive layer (OPC) is applied.

In this image forming apparatus, in the photoconductor layer of the photoconductor drum, which is the image formation point of the exposure beam for image exposure, a proper contrast is obtained with respect to the light attenuation characteristics (photocarrier generation) of the photoconductor layer. It suffices to have an exposure light amount of a wavelength that can give Therefore, the light transmittance of the transparent substrate of the photosensitive drum does not need to be 100%, and may have a characteristic that some light is absorbed when the exposure beam is transmitted. The material of the translucent substrate is soda glass,
Various transparent resins such as fluorine, polyester, polycarbonate and polyethylene terephthalate used for Pyrex glass, borosilicate glass and general optical members can be used. The light-transmissive conductive layer is made of indium, tin oxide (ITO), tin oxide, lead oxide, indium oxide, copper iodide, or a metal such as Au, Ag, Ni, or Al that maintains the light-transmissive property. A thin film is used, and as the film forming method, a vacuum vapor deposition method, an active reaction vapor deposition method, various sputtering methods, various CVD methods, dip coating methods, spray coating methods and the like are used. As the photoconductor layer, an amorphous silicon (a-Si) alloy photosensitive layer, an amorphous selenium alloy photosensitive layer, or various organic photosensitive layers (OPC) can be used.

A flange 10A at one end of the photosensitive drum 10 is bearing-supported by a guide pin 30P provided in a cartridge 30 described later, and a flange 10B at the other end is a plurality of guide rollers provided on a substrate 40 of the apparatus main body. 40R and the outer gear 10G is fitted to the drive gear 40
G is rotated in a clockwise direction with the transparent conductive layer grounded by its power.

Reference numeral 11 denotes a scorotron charger (hereinafter also simply referred to as a charger), which charges the organic photosensitive layer of the photosensitive drum 10 by a grid held at a predetermined potential and a corona discharge by a discharge wire. Then, a uniform potential is applied to the photosensitive drum 10.

Reference numeral 12 denotes FL, EL, P in which light emitting elements arranged in the axial direction of the photosensitive drum 10 are arranged in a line in an array.
L, LED, LISA, PLZT, LCS in which a light emitting element and an element having an optical shutter function are arranged in a line, and an exposure optical system composed of a SELFOC lens as an equal-magnification imaging element, and a separate image reading The image signals of the respective colors read by the apparatus are sequentially taken out from the memory and input to the respective exposure optical systems 12 as electric signals.

Each of the exposure optical systems 12 is mounted on a columnar support member 20 which is fixed to the substrate 40 of the apparatus main body using guide pins 40P1 as guides, and is housed inside the base body of the photosensitive drum 10. .

Reference numerals 13 (Y) to 13 (K) are developing devices for accommodating yellow (Y), magenta (M), cyan (C), and black (K) developers, respectively, and are located around the photosensitive drum 10. A developing sleeve 130 is provided which rotates in the same direction while maintaining a predetermined gap with respect to the surface.

Each of the developing devices 13 does not contact the electrostatic latent image formed on the photosensitive drum 10 by the charging by the charger 11 and the image exposure by the exposure optical system 12 by applying the developing bias voltage. Reverse development in the state.

Next, the process of the color image forming apparatus in this apparatus will be described.

In an image reading apparatus separate from this apparatus, image data of an original image read by an image sensor or image data edited by a computer is
The image signals are temporarily stored in a memory as image signals for respective colors of Y, M, C and K.

When the image recording is started, the drive gear 40G is rotated by the start of the photoconductor drive motor to rotate the photoconductor drum 10 in the clockwise direction, and at the same time, the charger 11 is driven.
The application of the potential to the photosensitive drum 10 is started by the charging action of (Y).

After a potential is applied to the photosensitive drum 10, the exposure optical system 12 (Y) starts exposure by an electric signal corresponding to a first color signal, that is, a yellow (Y) image signal, and the photosensitive drum 10 is exposed. By rotating and scanning, an electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface thereof.

The latent image is reversal-developed by the developing device 13 (Y) with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is further given a potential on the yellow (Y) toner image by the charging action of the charger 11 (M), and the second color signal of the exposure optical system 12 (M), that is, Exposure with an electric signal corresponding to the magenta (M) image signal is performed, and non-contact reversal development by the developing device 13 (M) causes a magenta (M) toner image on the yellow (Y) toner image. Are sequentially stacked and formed.

By the same process, the charger 11 (C),
The exposure optical system 12 (C) and the developing device 13 (C)
Further, a toner image of cyan (C) corresponding to the third color signal is formed by the charger 11 (K), the exposure optical system 12 (K), and the developing device 13 (K). The toner images of (K) are sequentially superimposed, and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 10.

Photoreceptor drum 1 by each of these exposure optical systems
The exposure of the organic photosensitive layer of No. 0 is performed from the inside of the drum through the transparent substrate described above. Therefore, the exposure of the images corresponding to the second, third and fourth color signals is performed without any influence from the previously formed toner image, and the first exposure is performed.
It is possible to form an electrostatic latent image equivalent to an image corresponding to the color signal. In order to stabilize the temperature inside the photoconductor drum 10 and prevent the temperature rise due to the heat generation of each exposure optical system 12, a material having good thermal conductivity is used for the supporting member 20,
When the temperature is low, the heater 201 is used, and when the temperature is high, the heat is radiated to the outside through the heat pipe 202. Further, during the developing action by each developing device 13, a developing bias in which a direct current or an alternating current is applied to the developing sleeve 130 is applied, jumping development by the one-component developer accommodated in the developing device 13 is performed, and the transparent conductive material is obtained. A non-contact reversal development is performed in which a DC bias having the same polarity as the toner is applied to the photoconductor drum 10 that grounds the layer to attach the toner to the exposed portion.

In this way, the color toner image formed on the peripheral surface of the photosensitive drum 10 is transferred to the transfer paper which is conveyed from the paper feed cassette 15 in the transfer device 14A and is fed synchronously by the driving of the timing roller 16. It

The transfer paper on which the toner image has been transferred is removed from the charge by the static eliminator 14B and separated from the peripheral surface of the drum. After the toner is fused by the fixing device 17, the transfer paper is transferred to the upper portion of the device via the paper discharge roller 18. Will be ejected onto the tray.

On the other hand, the photosensitive drum 10 from which the transfer paper is separated
The cleaning device 19 removes and cleans residual toner to continue forming a toner image of a document image, or temporarily stops to form a toner image of a new image.

The photosensitive drum 10, each charger 11,
Each developing device 13 and further the cleaning device 19 are housed in the cartridge 30 and can be attached to and detached from the main body of the apparatus while leaving the supporting member 20 having the optical system 12 without giving a load or a shock to the image exposure means. Is configured. The structure in which the supporting member 20 is left at the time of attachment / detachment is such that the heater 201, the heat pipe 202, the lead wire 203 for operating the LED, and the optical system 12 are supported by the supporting member 20 despite the rotation of the photosensitive drum 10 and the attachment / detachment of the photosensitive drum 10. It has a feature that can be fixed to. It can also be used to determine the axis of the photosensitive drum 10.

FIG. 1 is a schematic sectional view showing an example of the developing device of the present invention. Details of the developing device will be described later. FIG. 1 also shows a state in which the exposure position of the exposure optical system 12 on the photosensitive drum 10 is provided on the upstream side of the developing sleeve 130 in the developing casing 138 of the developing device 13.

In this color image forming apparatus, the exposure optical system 12 using LEDs or the like is arranged inside the photosensitive drum 10, and the image exposure position by the exposure optical system 12 is located inside the developing casing 138 on the upstream side of the developing sleeve 130. In the
Assuming that a center line connecting the center of the photosensitive drum 10 and the center of the developing sleeve 130 is a center line p, the distance between the photosensitive drum 10 and the developing sleeve 130 on the center line p is the shortest, and the development is performed on the center line p. There is a center P. The photosensitive drum 1 from the development center P to the end surface of the upstream development casing 138
0, L ₁ , the distance of the photosensitive drum 10 from the developing center P to the image exposure position is L ₂ , and the width of the developing area where the developing is performed from the developing center P (in the circumferential direction of the photosensitive drum 10). length) w _1, T the reduction time potential of the organic photosensitive material coated on the photosensitive drum 10, when the peripheral speed of the process speed i.e. the photosensitive drum 10 was set to v, of _{L 1> L 2> vT +} w 1 Set in a relationship.

Here, in this embodiment, L ₁ and L ₂ are set between 3 and 30 mm. Also the process speed v
Is between 30 and 300 mm / sec. The potential reduction time T of the organic photoreceptor used in this embodiment can be easily obtained experimentally, but is 0.1 sec or less. The width w1 of the development area is usually between _{1 and} 2 mm.

Therefore, the process speed v is 30 to 300.
When the potential drop time T is 0.1 sec in mm / sec, vT + w ₁ = 4 to 32 mm, and the process speed v is 30 to 300 mm / se.
When the potential decrease time T is 0.05 sec in c, vT + w ₁ = 2.5 to 17 mm, and L ₂ > 3 to 32 mm or L ₂ > 2.5 to 17 mm.
By performing the image exposure at the position satisfying the condition of 1, the potential of the photosensitive member is sufficiently lowered as shown in FIG. 4, and the previously developed toner image is stably attached on the image forming body. Then, the next development is performed on it.

Further, the developing devices 13 (Y) to 1 shown in FIG.
3 (K) is a developing device that contains a non-magnetic one-component developer and has the same configuration, so the reference numeral is simply 13.

FIG. 1 is a sectional view showing the construction of one set of the developing device 13 taken out. In FIGS. 1A and 1B, reference numeral 130 denotes a developing sleeve which is a developer carrier.
It is made of a non-magnetic material such as aluminum and has a roughened surface so that it can rotate in the direction of the arrow in the figure. The developer moves in the same direction by the rotation of the developing sleeve 130 and is transported to the developing area. 136 is a regulating blade which is provided on the upstream side of the developing area of the rotating developing sleeve 130 and regulates the amount of the developer conveyed to the developing area. 133 is a scraping blade which scrapes off the developer D adhering to the developing sleeve 130 after finishing the development. The removing member 134 is a supply member including a fur brush or the like for supplying the developer D to the developing sleeve 130 while stirring the developer D.
Reference numeral 35 is a stirring screw that stirs the developer D to uniformly charge the toner that is the developer, and 136 is a regulating blade that regulates the thickness of the developer layer, and the toner is rubbed against the developing sleeve 130 to charge the toner. Therefore, an elastic blade type made of elastic rubber such as urethane rubber or silicon rubber is preferable. Reference numeral 138 is a developing casing, 139 is a supporting portion provided on the developing casing 138 for fixing the base portion of the supporting member 81 of the control electrode plate 80 to the developing casing 138, and 88 and 89 are supporting portions 81 for supporting the supporting member 81 of the control electrode plate 80. A pressing plate and a set screw for fixing to 139.

An insulating member 83 made of an electrically insulating material is provided on the upstream side of the developing area so as to be in contact with the layer of the developer D.
A control electrode plate including an electrode portion 82 to which a voltage can be applied and a support member 81 coupled to support the insulating member 83 on the upstream side of the electrode portion 82 will be described in detail later. The electrode portion 82 is made of a conductive material such as a metal, and is linearly provided integrally on the distal end portion of the insulating member 83.

A developing bias voltage in which a direct current and an alternating current are superimposed is applied to the developing sleeve 130, and the photosensitive drum 10
The reversal development is performed in a non-contact state in the development region closest to the above.

The contact force / gap between the developing sleeve 130 and the regulating blade 136 and the developing sleeve 130 and the photoconductor so that the developer layer formed on the developing sleeve 130 does not contact the surface of the photoconductor drum 10 and maintains a gap. The closest distance g ₀ of the drum 10 is adjusted.

The developing sleeve 130 has a DC power source E.
An AC bias voltage in which an AC component is superimposed on a DC component is applied by a ₁ and an AC power source E ₂ via a protective resistor R ₁ . Furthermore, the electrode portion 82 a bias voltage of only a DC component from the DC power source E ₃ is applied through the protective resistance R _2. It is preferable to apply a DC voltage having the same polarity as the toner in the developer to the electrode portion 82 from the viewpoint of preventing toner adhesion.

In the developing device 13 described above, the control electrode is applied together with the oscillating electric field (which will be referred to as a second oscillating electric field) formed between the photosensitive drum 10 and the developing sleeve 130 by applying the AC bias voltage. A first oscillating electric field is generated between the electrode portion 82 of the plate 80 and the developing sleeve 130. At this time, since the AC bias voltage is applied only to the developing sleeve 130, the first oscillating electric field and the second oscillating electric field have the same phase, and the toner particles are changed from the first oscillating electric field to the second oscillating electric field. Make a smooth transition.

Further, since the electrode portion 82 is provided closer to the developing sleeve 130 than the photosensitive drum 10, the strength of the first oscillating electric field is larger than the strength of the second oscillating electric field.

Since the toner particles of the developer reaching the vicinity of the electrode portion 82 are vibrated by the first oscillating electric field in the direction perpendicular to the lines of electric force, the toner becomes cloud haze-like and the so-called toner cloud is sufficiently formed. Can be generated.
This toner cloud is assisted by the second oscillating electric field to fly toward the latent image on the photoreceptor drum 10, and highly efficient and uniform development is performed.

The waveform of the AC component is not limited to a sine wave.
A rectangular wave or a triangular wave may be used. Although the frequency is also related, the higher the voltage value is, the more the developer D is vibrated, so that the toner particles are easily separated and fly, but on the other hand, the dielectric breakdown such as fogging and lightning is likely to occur. Become. The generation of fog can be prevented by a DC component, and the dielectric breakdown can be prevented by coating the surface of the developing sleeve 130 with insulation or semi-insulation with a resin or an oxide film.

The frequency of the AC component of the bias voltage applied to the developing sleeve 130 is 100 Hz to 20 kHz,
Particularly, the frequency is preferably 1 kHz to 10 kHz.

In the color image forming apparatus using the developing device 13, reversal development is performed using an OPC photosensitive member that is negatively charged as the photosensitive member of the photosensitive drum 10, and the photosensitive member is charged to, for example, -850V. Assuming that the potential of the image maximum density portion is −50 V, the electrode portion 83a has −750.
V, the developing sleeve 130 is preferably applied with an AC bias voltage obtained by superimposing an AC voltage on a DC voltage of -750V. Here, the AC bias voltage applied to the developing sleeve 130 is M ₀ (mg / cm ² ) as the toner adhesion amount on the photosensitive drum 10 at the time of development when the control electrode plate 80 is not provided, and the control electrode plate 80 is provided. M of the toner adhesion amount on the photoconductor drum 10 at the time of development by setting the control electrode plate 80 at an arbitrary position.
(Mg / cm ² ), the control electrode plate 80 is attached to the developing sleeve 13.
When the maximum toner adhesion amount on the photosensitive drum 10 at the time of development when moved along the peripheral surface of 0 is M _max (mg / cm ² ), the ratio of M ₀ and M _max is as follows. It is preferable to set a developing bias voltage having an oscillating electric field that

In the case of 0.1 ≦ (M ₀ / M _max ) ≦ 0.5 M ₀ / M _max <0.1, the effect of the control electrode plate 80 is too large, and the electrode portion 82 becomes dirty and the control electrode Vertical streaks and uneven density due to warpage and waviness of the plate 80 are likely to occur.

When 0.5 <M ₀ / M _max , the clouding due to the electrode is small and the developability is insufficient.

5 to 7 show the setting positions of the control electrode plate 80 and the photosensitive drum 10 when the developing bias voltage is changed.
6 is a graph showing the relationship with the toner adhesion amount at the time of development.
In the figure, d is the distance (m between the center line p between the photosensitive drum 10 and the developing sleeve 130 and the downstream end of the control electrode plate 80.
m) is represented.

FIG. 5 shows that the developing bias voltage is set to be proper and M ₀
= 0.3 (mg / cm ² ), M _max = 0.8 (mg / cm 2
² ), that is, a graph when M ₀ / M _max = 0.38 is selected, showing a case where the bias voltage is good.

In FIG. 6, the developing bias voltage is made excessively high, M ₀ = 0.5 (mg / cm ² ), M _max = 0.9 (m
g / cm ² ), that is, a graph when selected so that M ₀ / M _max = 0.56, in this case, the control electrode plate 8
The discharge to 0 is likely to occur, and the image disorder is likely to occur, which is inappropriate.

In FIG. 7, the developing bias voltage is lowered and M ₀
= 0.05 (mg / cm ² ), M _max = 0.65 (mg /
cm ² ), that is, a graph when M ₀ / M _max = 0.07 is selected. In this case, the effect of the control electrode plate 80 is too large, and image density unevenness such as streaks and unevenness easily occurs. Inappropriate.

For reverse development, the preferred bias voltage is
Voltages e ₁ (voltage of E ₁ ) and e ₂ (E ₂ of each power supply in FIG. 1A)
, And e ₃ (voltage of E ₃ ) are e ₁ : the same polarity as the toner and an absolute value of 300 to 2,500.
V, preferably 400 V to 2,000 V e ₂ (V _0-P ): 200 V to 2,000 V, frequency is 10
0 Hz to 20 kHz, preferably 300 V to 1,500
V, frequency is 1 to 10 kHz e ₃ : 0.5 e ₁ with the same polarity as toner and absolute value e ₁
The range of <e ₃ <1.5e ₁ is preferable from the viewpoint of securing the developability and preventing the toner from adhering to the electrode portion 82.

The control of M _max changes e ₂ as well as e ₁ , e ₃
Can also be adjusted.

By setting the bias voltage as described above, it is possible to optimize the effect of the control electrode plate 80 and prevent vertical stripes, uneven density, discharge, and the like.

Toner adhesion amount M, M on the photosensitive drum 10
₀ and M _max are measured as follows.

The highest density image portion (photoconductor surface potential-
A solid image of 50 V) is formed. This toner
The area (cm ² ) and the weight (mg) are peeled off from the photoconductor with an adhesive tape whose weight is previously measured, and the weight is measured. When the weight difference of the adhesive tape before and after the toner peeling is dM (mg) and the area of the adhesive surface of the adhesive tape is A (cm ² ), the toner adhesion amount M (mg / cm ² ) = dM (mg) / A
It can be calculated from (cm ² ).

For the above measurement, for example, a jig 801 as shown in FIG. 13 is prepared, and the jig 801 and the thickness gauge 802 are used to move the control electrode plate 80 in the circumferential direction of the developing sleeve 130 while d The position was adjusted in units of 0.5 mm, and the above measurement was repeated. The _maximum toner adhesion amount was M _max , and the toner adhesion amount when the control electrode plate 80 was not attached was M ₀ .

The installation position of the control electrode plate 80 is shown in FIG.
As shown in (b), 0.5 ≦ (M / M _max ) ≦ in the developing area or in the upstream area of the developing area with respect to the rotation of the developing sleeve 130 and the same developing bias voltage is applied. It is preferable to install the control electrode plate 80 in a range shown by a dotted line in FIG. 5 where 0.9 and M> M ₀ , that is, a range of C and D.

At the set position where M ≦ M ₀ , the control electrode plate 80 portion excessively covers the development area, and the development is excessively suppressed, so that it cannot be used.

At the set position where M = M _max , the control electrode plate 80 has a large contribution to the development, so the electrode portion 82
The density unevenness of the image due to the toner stain becomes large, and the image density is greatly affected by the setting accuracy, which is not preferable. The setting position of the control electrode plate 80 is preferably set to a position where the developing property becomes insensitive to the position of the electrode portion 82.

Particularly, when the toner adhesion amount M of the photosensitive drum 10 at the time of development is set to a region where M = (0.6 to 0.9) × M _max , the influence of the electrode portion 82 on the developability becomes appropriate. Therefore, unevenness in image density and vertical stripes due to stains on the electrode portion 82 do not occur.

In particular, the toner adhesion amount M at the time of developing the photosensitive drum 10 has a region in which it decreases from M _max to M ₀ as the control electrode plate 80 is arranged on the upstream side in the developer conveying direction. It is preferable to set the control electrode plate 80a in this area. Downstream from the position of M _max , M ₀ → M _max
Since the control electrode plate 80 is too much in the developing region in the region where the above, the control electrode plate 80 has a large influence on the development when the development is continued for a long period of time, and uneven development and vertical streaks are likely to occur. Therefore, the most preferable area is the area D in FIG.

Next, the structure of the control electrode plate 80 used in the developing device 13 of this embodiment will be described.

As shown in FIG. 8A, the control electrode plate 80 is composed of an insulating member 83 made of an insulating member such as ceramic that supports the electrode portion 82, and a supporting member 81 that supports the insulating member 83. . The insulating member 83 and the supporting member 81 are integrally bonded by bonding a part of each with an adhesive or the like.

(Material of Support Member 81) The material of the support member 81 is preferably a thin metal plate having high linearity and elasticity. For example, the metal or alloy used for the linear electrode can be used, and of these, it is particularly preferable to use a thin plate of stainless steel (SUS) from the viewpoint of cost and flexibility.

The thickness of the support member 81 depends on the material,
Considering the ease of connection with the insulating member 83, 0.05 m
m to 1 mm is preferred. If the thickness is less than 0.05 mm, wrinkles and distortions are liable to occur when joining with the insulating member 83.
If the thickness is more than 1 mm, the elasticity is lost and the control electrode plate 80
The degree of freedom of setting is reduced.

When the above-mentioned thin metal plate is used for the supporting member 81, in order to prevent the bias voltage applied to the developing sleeve 130 and the leak of the photosensitive member potential, it is preferable that the thin metal plate is insulatingly coated with a fluorine resin or the like.

The insulating member 83 is thin so that it can be installed in a space of a narrow developing area, and in order to maintain the linearity of the entire control electrode plate 80 (in particular, the electrode portion 82), the insulating member 83 is made of the following materials. It is preferable that

(Material of Insulating Member 83) Examples of the insulating member 83 include polyester, polyimide, glass epoxy, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-6-fluoropropylene copolymer, poly-4 fluoride. Ethylene, polyamide imide, polysulfone, triazine resin, polyethylene terephthalate, insulating resin such as polyurethane, or other composite materials reinforced with glass fiber or the like, paper, paper phenol, varnish, silicon rubber, etc. materials, As a ceramic material, alumina (Al ₂ O ₃ ) material, single crystal sapphire (Al ₂ O ₃ ) material, forsterite (2MgO / SiO ₂ ) material, steatite (MgO / SiO ₂ ) material, zircon (ZrO ₂ ·. Si
O ₂ ) cordierite (2MgO.2Al ₂ O ₃ .5S)
Ceramics of io ₂ ) type, titania type, silicon carbide (SiC) type, silicon nitride (Si ₃ N ₄ ) type, zirconia (ZrO ₂ ) type, and cermet type can be used.

In order to impart appropriate elasticity to the insulating member 83, the ceramic may contain 5 to 20% by weight of resin. Further, in order to reduce the surface roughness of the surface on the developing sleeve 130 side, the surface of the insulating member 83 is preferably polished.

(Method of forming electrode portion 82) The insulating member 8 described above.
3 is attached with electrolytic copper foil, annealed electrolytic copper foil, beryllium copper foil, etc. by an adhesive, and is required on the insulating member 83 by a photoetching method using a conventionally known photopolymer and an etching resist forming method by screen printing. The electrode portion 82 is formed. In addition, a method of printing the conductive ink by letterpress, stencil, intaglio, or planographic printing corresponding to the electrode portion 82 or a method of evaporating metal can be used.

FIG. 8B shows an example in which the downstream tip of the electrode portion 82 and the downstream tip of the insulating member 83 are aligned with each other, and FIGS. 8C and 8D.
Shows an example in which an eaves member 84 made of an insulating material such as a glass epoxy plate is adhered to the tip of the insulating member 83 with an adhesive or the like, and an electrode portion 82 is formed between the insulating member 83 and the eaves member 84. Further, FIG. 8E shows the eaves member 84.
2 shows an example in which the electrode portion 82 is formed on the lower surface of the tip of the.

The control electrode plate 80 is also shown in FIG.
As shown in (b), (c) and (d), an electrode portion 82 is formed by bonding a linear electrode having a circular or quadrangular cross section to the tip of the insulating member 83 using an adhesive or the like. Can be used. Further, as shown in FIG. 9E, a notch 83a may be provided at the tip of the insulating member 83, and a linear electrode may be embedded therein to form the electrode portion 82. Further, as shown in FIGS. 9F and 9G, an eaves member 84 is provided at the tip of the insulating member 83, and a linear electrode is adhered to the lower surface of the tip of the eaves member 84 to provide the electrode portion 82. May be

(Material of linear electrode) The material of the linear electrode is copper, copper-zinc, copper-cadmium, phosphor bronze, copper-beryllium, Corson alloy, aluminum, aluminum alloy, tantalum, tungsten, nickel, molybdenum. , Stainless steel, gold, titanium, chrome, palladium,
A metal such as silver, a metal oxide such as copper oxide, a composite of glass coated with copper powder, graphite, nickel, silver, or the like, or a conductive material such as graphite or carbon fiber can be used. It is desirable that the electrode portion formed of these materials be insulation-coated in order to prevent discharge, prevent rust, and impart strength.

The length of the electrode portion 82 in the circumferential direction of the developing sleeve 130 depends on the diameter of the developing sleeve 130 and the conveying speed, but is preferably 0.05 to 5 mm, particularly preferably 0.1 to 1 mm. If it is less than 0.05 mm, a sufficient toner cloud cannot be generated, and if it is more than 5 mm, the toner is charged by vibration and becomes excessively charged, so that the developability is reduced.

When the developer D is conveyed onto the developing sleeve 130, the control electrode plate 80 causes the developer D to be caught between the insulating member 83 and the developing sleeve 130 as shown in FIGS. 12 (a) and 12 (b). In order to enter, the insulating member 83 is slightly curved so as to face the developing sleeve 130 with a slight gap or almost no gap, that is, the insulating member 83 faces the developing sleeve 130 while being in contact with / close to the developing sleeve 130. Like

The electrode portion 82 of the control electrode plate 80 and the insulating member 8
3 (see FIG. 8) is the sum of the thicknesses of the photosensitive drum 10 and the developing sleeve 130.
_{Assuming 0} (mm), it is preferable that (1/10) g ₀ <t <(2/3) g ₀ .

At t> (2/3) g ₀ , the dielectric substance, which is a photoconductor, approaches the electrode portion 82, so that the electric field strength increases on the electrode portion 82 and a high bias voltage is applied to the electrode portion 82. At that time, the latent image may be disturbed, or the multicolor toner on the photoconductor drum 10, which is an image forming body, may be peeled off when the multicolor image is formed.

When t <(1/10) g ₀ , the electrode portion 82 is separated from the photosensitive drum 10, so that the electric field is weakened and a sufficient toner cloud is not formed. Further, the insulating member 83 becomes thinner, its rigidity becomes lower, and it becomes easier to crack.

The thickness of the control electrode plate 80 is measured by a micrometer (M320-25A, manufactured by Mitutoyo) in the rotating shaft direction of the developing sleeve 130 of the control electrode plate 80.
The average value of the values obtained by the point measurement was defined as the thickness t of the control electrode plate 80.

FIG. 10 is a diagram showing the relationship between the width of the electrode portion 82 and the width of the developing area. In FIG. 10, W ₃ is the width of the electrode portion 82 (the axial length of the developing sleeve 130), W ₄
Is the width of the developing area on the developing sleeve 130 in the axial direction (width of the developer layer), and W ₃ > W ₄ , and the terminal portion 82 a for applying a DC voltage to the electrode portion 82 also has the width of the developing area. It is provided on the outside of W ₄ to prevent unnecessary toner cloud.

Further, the surface roughness R of the developing sleeve 130
z ₁ (μm) and the roughness Rz ₂ (μm) of the surface of the insulating member 83 that faces the developing sleeve 130, when Rz ₂ ≧ Rz ₁ , the developer D conveyed onto the developing sleeve 130 has the insulating member 83. As a result, the amount of toner conveyed to the developing area is reduced and the image density is reduced. Rz ₁ is 0.2 μm
-20 μm, Rz ₂ is 0.02 μm-5.0 μm
Within the range, good transportability and no image disturbance,
It is preferable to obtain a high density image. The surface roughness R
z conforms to JIS B 0601 and is manufactured by Mitutoyo Surf
Using test-402, the measurement was performed at a reference length of 25 mm.

Next, the toner of the developer D will be described.

Generally, when the average particle size of the toner particles becomes small, the charge amount qualitatively decreases in proportion to the square of the particle size.
Adhesive force, such as van der Waals force, becomes relatively large, so that the particles are easily scattered and fog is easily generated. Then, when the average particle size is 10 μm or less, this problem becomes remarkable. In the developing device of this embodiment, this point is solved by developing under a double oscillating electric field.

As the volume average particle diameter D ₅₀ (μm) of the toner becomes large, as already mentioned, the roughness of the image becomes noticeable. If D ₅₀ is used the toner following micronized 10 [mu] m, the resolution is remarkably improved, so give a clear high-quality images shading difference also faithfully reproduced. When D ₅₀ is 20 μm or more, the image quality is deteriorated, and when D ₅₀ is 1 μm or less, poor charging and scattering are likely to occur.

From the above reason, the volume average particle diameter D _{50 of the} toner is
Is 1 to 20 μm, preferably 4 μm <D ₅₀ <10 μm.

When D ₅₀ > 10 μm, the particle size is large and the resolving power is insufficient, and when D ₅₀ <4 μm, the cohesive force is large and frictional electrification is apt to occur.

Here, the volume average particle diameter D used for the average particle diameter is used.
₅₀ is Coulter Counter TA-II type (Aperture 1
00 μm, manufactured by Coulter Corporation).

In addition, since the toner particles follow the electric field, the absolute value of the charge amount of the toner particles is 1 to 30 μC / g, particularly 1 to 20 μC / g in the case of the one-component developer.
From the viewpoint of securing developability and preventing fogging and scattering, it is desirable to set g. In particular, when the particle size is small, a high charge amount is required.

Here, the average charge amount Q ₁ of the non-magnetic toner is
Is a conductive plate of 2 cm × 5 cm, which is opposed to the developing device (8a) having the developing blade 130 having the diameter of 20 mm and including the regulating blade 86A described above at the closest distance of 0.7 mm, and the developing sleeve 130 is charged. While supplying the one-component developer and rotating it at 200 rpm, the superimposed voltage of DC and AC (for example, DC; 1000
V, AC; 750V _OP , AC frequency 8kHz) is applied to develop the toner in the developer on the conductive plate, and the conductive plate on which the toner is developed is connected to a Faraday gauge to make the toner nitrogen. It is a value obtained by blowing off with a gas and measuring the charge amount and weight of the toner blown off at this time.

Examples of binder resins for such toners include styrene resins, vinyl resins, ethyl resins, rosin-modified resins, acrylic resins, polyamide resins, epoxy resins, polyester resins, and styrene-acryl resins. And the like, or a mixed resin or the like. Coloring components such as color pigments, and if necessary, a charge control agent, a release agent such as wax, and the like are added to these resins, and toners such as conventionally known pulverization granulation method, suspension polymerization method, emulsion polymerization method, etc. It can be manufactured by a method equivalent to the manufacturing method.

As the one-component developer D, a fluidizing agent such as colloidal silica may be added to the above toner in an amount of about 0.1 to 10 parts by weight based on the toner and used as the developer D as it is.

[Comparative Experiment of Example of the Present Invention and Comparative Example] In Example 1 and Comparative Examples 1 to 7, the developing device 13 shown in FIG.
2 using the color image forming apparatus shown in FIG. 2, each photoconductor drum 10 is an OPC photoconductor, and the potential lowering time T is 0.05 (sec) and the peripheral speed is 180 mm / se.
c. The maximum potential of the electrostatic latent image formed on the photosensitive drum 10 is −850V (non-image portion potential), and the minimum potential is −50V.
(Image portion potential), g ₀ = 0.3 mm, developing sleeve 13
0 surface roughness Rz = 1.7 μm, L ₁ = 15 mm, L ₂ =
With a width w ₁ = 1 (mm) of a 12 mm developing area, L ₁ > L ₂ > V
There is a relationship of T + w ₁ (15>12> 10). Other process conditions are as described in Table 1.

The structures and dimensions of the control electrode plates 80 of Examples 1 and 2 and Comparative Examples 1 to 7 are shown in FIG.
A glass epoxy plate having a thickness of 0.1 mm is used as No. 3, and as shown in FIG.
It was formed by a laminate etching method using a copper foil having a thickness of 5 mm and a thickness of 0.02 mm. Furthermore, the thickness is 0.1 mm
A support member 81 made of a stainless steel (SUS) plate is attached to the insulating member 83 with an adhesive, and the control electrode plate 80
Was fixed to the developing casing 138 of the developing device 13.
The surface roughness of the insulating member 83 on the developing sleeve 130 side is Rz.
= 0.8 μm.

In each of the examples and comparative examples, a regulating blade made of an elastic blade of urethane rubber was used as the regulating member for the developer D layer.

As the developer D, the following ones were used in Examples 1 and 2 and Comparative Examples 1 to 6.

100 parts by weight of styrene-acrylic resin, 10 parts by weight of color pigment, and 2 parts by weight of nigrosine were melted and kneaded, and then pulverized and classified to obtain yellow, magenta, cyan, and black particles having a volume average particle diameter of 5.5 μm. Each toner was obtained. Each of the toners to which 2 parts by weight of colloidal silica was added as a fluidizing agent was used as the developer D as it was.

The charge amount Q ₁ is Y; -3.3 μC / g,
M; -3.0 [mu] C / g, C; -2.9 [mu] C / g, K;-
It is 3.5 μC / g.

(Setting Position of Control Electrode Plate 80) The control electrode plate 80 shown in FIG.
The setting positions for 0 are all g ₀ = 0.3 mm, Examples 1 and 2 are at the positions shown by Actual 1 and Actual 2 in FIG. 5, and Comparative Examples 1, 2, and 3 are the ratios 1 to 1 in FIG. The developing device at the position indicated by the ratio 3, the comparative examples 4 and 5 at the positions indicated by the ratios 4 and 5 in FIG. 6, and the comparative examples 6 and 7 at the positions indicated by the ratios 6 and 7 in FIG. Comparative experiments were conducted under the conditions shown in Table 1 according to No. 13.

At this time, an image roughness measuring method was performed as follows. After the recording of the full-color image of each of the examples and the comparative example (for every 500,000 copies, a halftone with a copy output density of 0.7 is output, and the density unevenness at that portion is detected by an image analyzer RT-2000C (Yaman Corporation). The measurement was performed with a window size of 30 μm × 30 μm, and the measurement length was 30 mm in the direction perpendicular to the developing direction.
When the standard deviation (σ) of the density unevenness was 0.15 or less, the image was judged to be a good image with no blemishes or roughness.

[0102]

[Table 1]

Using the above color image forming apparatus, 50,000 full-color images were recorded under the conditions shown in Table 1. In Examples 1 and 2, vertical stripes and image unevenness were observed from the beginning to the end. It was possible to stably obtain an image with high image density and high resolution.

In particular, in Examples 1 and 2, good images with very little image unevenness could be obtained.

On the other hand, in Comparative Examples 1 to 7, as shown in Table 1, vertical stripes and development unevenness due to stains, undulations, and warpage of the control electrode plate 80 occurred after several thousand copies. Stable image formation could not be performed.

[0106]

According to the present invention, the developing bias voltage having the oscillating electric field is applied to the control electrode plate position of the present invention, and the developing device using the non-magnetic one-component developer causes the problems of the conventional control electrode method. By solving the problems, it is possible to provide a developing device which can stably obtain an image having high image density and high resolution without vertical stripes and image unevenness.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a developing device of the present invention.

FIG. 2 is a schematic sectional view showing an example of a color image forming apparatus including the developing device of FIG.

FIG. 3 is a sectional view showing a photosensitive drum, a supporting member and a cartridge of FIG.

FIG. 4 is a graph showing a decrease in potential due to exposure of an image forming body.

FIG. 5 is a graph showing the relationship between the position d of the control electrode plate and the toner adhesion amount under proper conditions.

FIG. 6 is a graph showing the relationship between the position d of the control electrode plate and the toner adhesion amount when the bias is high.

FIG. 7 is a graph showing the relationship between the position d of the control electrode plate and the toner adhesion amount when the bias is low.

FIG. 8 is a sectional view showing the configuration of a control electrode plate.

FIG. 9 is a cross-sectional view showing another configuration of the control electrode plate.

FIG. 10 is a plan view showing a width relationship between a control electrode plate and a developer transport body.

FIG. 11 is a cross-sectional view showing specific dimensions of a control electrode plate.

FIG. 12 is a side view showing an installed state of a control electrode plate.

FIG. 13 is an explanatory diagram of a case where d is adjusted using a jig.

[Explanation of symbols]

10 Photoreceptor Drum (Image Forming Body) 11 Scorotron Charger 12 Exposure Optical System (Exposure Means) 13 Developing Device 130 Developing Sleeve (Developer Conveying Body) 138 Developing Casing 80 Control Electrode Plate 81 Supporting Member 82 Electrode Section 83 Insulating Member E ₁ , E ₃ DC power supply E ₂ AC power supply

Claims (2)

[Claims] 1. A developer transporting body provided opposite to an image forming body, and an electrode part supported by an insulating member in a gap between the developer transporting body and the image forming body and capable of applying a voltage. In a developing device in which a control electrode plate is arranged and development is performed using a non-magnetic one-component developer, the toner adhesion amount of the image forming body at the time of development without the control electrode plate is M ₀ (m
g / cm ² ), having the control electrode plate, and changing the position of the control electrode plate along the peripheral surface of the developer transport body, the maximum toner adhesion amount of the image forming body is M _max (mg / mg / cm ² ), a developing bias voltage having an oscillating electric field such that 0.1 ≦ (M ₀ / M _max ) ≦ 0.5 is set. 2. When the toner adhesion amount at an arbitrary setting position is M (mg / cm ² ) using the control electrode plate, 0.5 ≦ (M / M _max ) ≦ 0.9, and M The developing device according to claim 1, wherein the control electrode plate is set at a position where> M ₀ .