JP2003228239A - Developing device and image forming apparatus provided with the same - Google Patents

Abstract

(57) Abstract: An object of the present invention is to prevent a disturbance in a state of transporting a developer due to a tilt of a developer supply member and to form a good image having a uniform image density. A width of a developer layer forming region on a developer supply member is set to L (mm), a pitch between electrodes of the developer transfer member is set to λ (mm), and a distance between the developer transfer member and the developer supply member is set. When the inclination angle of the contact region (developer supply region E) with respect to the longitudinal direction of the electrode is θ (°), [| sin θ | <1
0 × λ / L]. In addition, the pitch λ between the electrodes is 100 μm or more and 750 μm or less. Further, the traveling wave electric field forming time T (s) and the electrode pitch λ (m) are set so as to satisfy the relationship of [λ / T <2]. Further, the developing gap d (mm) and the electrode pitch λ (mm) are set so as to satisfy the relationship of [d> 20 × λ].

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 developing an electrostatic latent image formed on a latent image bearing member (image bearing member) with a developer or the like, and an image forming apparatus including the developing device.
In particular, the present invention relates to a developing device and an image forming apparatus that utilize a mechanism (electric field curtain) that conveys a developer using a traveling wave electric field.

Further, the electrostatic latent image is not limited to one in which optical information is written on an image carrier charged with a predetermined electric charge and charged directly on a dielectric like an ion flow system. An electrostatic latent image is formed in the space by applying an arbitrary voltage to the one forming a charge latent image or the electrode having a plurality of openings like the toner jet method, and the developer is caused to fly to the recording medium. It can also be applied to a device that directly forms an image.

[0003]

2. Description of the Related Art As a developing device applied to an image forming apparatus using an electrophotographic process such as a copying machine and a printer,
At present, a non-contact type developing device that develops without bringing the developer carrier into contact with the image carrier is drawing attention, and a method using the powder round method / jumping method or the electric field curtain (traveling wave electric field) is proposed. Has been done.

As an apparatus using an electric field curtain, for example, Japanese Patent Publication No. 5-31146 and Japanese Patent Publication No. 5-31147.
Japanese Patent Laid-Open Publication No. 2003-242242, etc., it is formed by applying an alternating voltage from the power source to a power source for generating a plurality of types of alternating voltages having mutually different phases and electrodes arranged in plural at a predetermined interval on a base material. A developing device has been proposed that includes a developer transport member that supplies the developer to an image carrier (photoconductor) by a traveling wave electric field.

Further, in Japanese Patent Laid-Open No. 3-21967,
There has been proposed an apparatus provided with a pre-charging means for pre-charging a developer carried by a developer carrying carrier and an electric field curtain generating means for acting an electric field curtain on the developer carrying carrier. In the apparatus described in this publication, a pre-charging roller made of, for example, urethane foam is used as the pre-charging means, and the pre-charging roller is provided so as to be in contact with the developer carrying carrier.
A blade is provided so that its tip is in contact with the preliminary charging roller. The pre-charging roller pre-charges the developer by rubbing the developer with the developer-carrying carrier, and also regulates the layer thickness of the developer.

According to Japanese Patent Laid-Open No. 3-21967, it is possible to uniformly charge the developer to an appropriate charge amount and to stably convey the developer to the image carrier by the above-mentioned structure. become able to. as a result,
It is described that it is possible to avoid scattering of the developer during transportation and fogging of the formed image.

[0007]

By the way, in the developing device of the type in which the developer is supplied to the developer conveying member by the developer supplying member (preliminary charging roller or the like), the following problems may occur. .

First, in a developing device that conveys a developer in a traveling wave electric field, a plurality of electrodes (traveling wave generating electrodes) of a developer conveying member are arranged in substantially parallel comb teeth for each phase. (See Figure 3). Therefore, when a predetermined alternating voltage is applied to these electrodes so as to form a traveling wave electric field, the electric field for moving the developer is formed in a substantially linear shape along the longitudinal direction of the electrodes with a constant period. .

In such a developing device, as shown in FIG.
As shown in FIG.
When the contact area with 1, that is, the developer supply area G is substantially parallel to the electrode, the developer is uniformly transported in the longitudinal direction of the electrode, and there is no problem. However, FIG.
As shown in (b), when the developer supply region G is not parallel to the electrodes and is inclined, an electric field for supplying and transporting the developer is formed in a certain region in the longitudinal direction of the electrodes, but another region is formed. In this region, this action is not performed. That is, unevenness in the supply and conveyance of the developer occurs in the longitudinal direction of the electrode.

The present invention has been made in order to solve such a problem, and prevents the developer carrying state from being disturbed due to the inclination of the developer supplying member, so that the developer carrying state is always stable and uniform. SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing device capable of obtaining the above, and an image forming device including the developing device having such characteristics and capable of performing excellent image formation.

[0011]

A developing device of the present invention is a developing device for developing an electrostatic latent image formed on an image carrier, and is substantially parallel to a base material at a predetermined interval. A developer having a plurality of long electrodes arranged and transporting the developer toward the image carrier by a traveling wave electric field formed by applying a multi-phase alternating voltage to the electrodes. In a developing device equipped with a transport member and a developer supply member that is in contact with the developer transport member and supplies the developer, the width of the developer layer forming region on the developer supply member is L (mm) If the electrode-to-electrode pitch of the agent transport member is λ (mm), and the inclination angle of the contact area between the developer transport member and the developer supply member with respect to the longitudinal direction of the electrode is θ (°), then [| si
It is characterized by satisfying the relationship of nθ | <10 × λ / L].

In the developing device of the present invention, the inter-electrode pitch λ of the developer conveying member is 100 μm or more and 750 μm.
The following is preferable.

In the developing device of the present invention, when the time for forming the traveling wave electric field is T (s) and the electrode pitch of the developer transport member is λ (m), the relationship of [λ / T <2] is satisfied. You may set the conditions that satisfy the conditions.

In the developing device of the present invention, when the developing gap between the image carrier and the developer carrying member is d (mm) and the electrode pitch of the developer carrying member is λ (mm), [d
Conditions may be set so as to satisfy the relationship of> 20 × λ].

The developing device of the present invention will be described in detail below.

First, as described above, in the developing device of the type in which the developer is conveyed toward the image carrier by the traveling wave electric field, the contact area (developer supply area) between the developer supplying member and the developer conveying member. Is inclined with respect to the electrode of the developer transport member, the developer transport state is disturbed and good image formation cannot be performed. The reason why such a problem occurs will be described in detail.

FIG. 6 shows the positional relationship between the developer supply member and the developer transport member when the developer supply region is inclined.

In the positional relationship of FIG. 6, the developer supply member 44
Are arranged with an angle of θ with respect to the electrodes of the developer transport member 41, and the developer supply region G is in a state of straddling a plurality of electrodes arranged in a comb tooth shape. Here, the contact point where the electrode and the developer supply area G are in contact is Y2, the contact point where the electrode and the developer supply area G are in contact is Y3, and the contact point where the electrode and the developer supply area G are in contact is Y1. Further, the area FA between the left end Y0 and the contact point Y1 of the developer layer forming area E on the developer supply member 44, the area FB between the contact points Y1 and Y2, and the contact point Y2 and the contact point Y3. A region FC between the contact point Y3 and the contact point Y3 and the right end Y4 of the developer layer forming region E is a region FD, and the transport of the developer in such a state is considered.

First, for comparison, as shown in FIG.
The developer moving state when the positional relationship between the developer transport member 41 and the developer supply member 44 is appropriate will be described with reference to FIG. 7. In FIG. 7, the symbols A to D surrounded by circles represent the developers supplied to the areas FA to FD, respectively.

When the positional relationship is appropriate as shown in FIG. 5 (a), it is not necessary to consider the area division in the electrode longitudinal direction as shown in FIG. Therefore, the concept of area division is intentionally described. Here, consider a case where the positive polarity developer is supplied from the developer supply member 44 onto the electrode of the developer transport member 41.

As shown in FIG. 7, it is assumed that the developers A to D in the areas FA to FD exist on the electrodes at time t11. Looking at the state of the electrode adjacent to the electrode and the electrode during the time t11 to t12, the electrode has a negative potential, and the developers A to D on the electrode move simultaneously toward the electrode.

Next, looking at time t12 to t13,
The developer moves from the electrode to the electrode. Thereafter, the developer moves in the order of electrode → electrode → electrode → ..., and the developer is transported. At this time,
The developers A to D in the areas FA to FD all move in the same phase, so that the developer can be transported smoothly and the developer can be transported in a stable and uniform state. As a result, good image formation can be performed.

Next, a case where the developer supply member 44 is inclined with respect to the electrode of the developer transport member 41 as shown in FIG. 5B will be described with reference to FIG. In FIG. 8, the symbols A to D surrounded by circles represent the developers supplied to the areas FA to FD, respectively.

First, when the developer is supplied to the developer conveying member 41 at time t11, the developer A in the area FA is supplied in the vicinity of the electrode, and the developer B in the area FB is supplied in the vicinity of the electrode. Further, the developer C in the area FC is supplied near the electrodes, and the developer D in the area FD is supplied near the electrodes.

Considering the movement of the developer at times t11 to t12, the developer B near the electrode moves to the electrode.
On the other hand, the developer D and the developer A existing in the vicinity of the electrodes and the electrodes are accumulated in that place because an electric field that can move between the adjacent electrodes is not formed. Further, with respect to the developer C existing in the vicinity of the electrode, an electric field toward the electrode is formed, and the developer C moves in the opposite direction to the developer B.

Next, from time t12 to t13, the developers A and B existing near the electrodes move to the electrodes. At this time, the developers C and D existing in the vicinity of the electrodes remain in the vicinity of the electrodes without moving because there is no moving electric field between the adjacent electrodes.

Next, at times t13 to t14, the developers A to D existing in the vicinity of the electrodes move to the electrodes. After this, the developer is moved and conveyed in the order of electrode → → →.

Immediately after the developer is supplied from the developer supply member 44, that is, from time t11 to t12, t1.
Consider transfer of developer up to 3.

When the developer B existing in the area FB moves from the electrode to the electrode, it may collide with the developer A on the electrode existing near the boundary between the area FB and the area FA. Due to this collision, the developer operates differently from the above-mentioned operation, and the developer conveyance state is disturbed. Similarly, in the vicinity of the boundary between the region FC and the region FD, the developer C existing in the vicinity of the electrode in the region FC reversely moves and collides with the developer D existing in the vicinity of the electrode in the region FD. Disturbance occurs in the developer transport state. Due to such disturbance of the developer conveyance state, a developer that moves differently from the original movement mode is generated, which causes another disturbance of the developer conveyance state and gives an uneven developer conveyance state. . Such a disturbance in the developer transport state
The greater the deviation in the parallelism between the developer supply member 44 and the electrodes, the more the deviation occurs, and the more unstable the developer conveyance state becomes.

Therefore, in the developing device of the present invention, the inclination of the developer supplying member with respect to the developer conveying member is regulated to prevent the above-mentioned disturbance of the developer conveying state. Specifically, the condition [| sin θ | <1
By setting the conditions within a range that satisfies 0 × λ / L], it is possible to obtain a stable and uniform developer transport state, thereby realizing good image formation.

In the developing device of the present invention, in order to suppress the disturbance of the developer carrying state, it is also effective to set the condition that the inter-electrode pitch λ of the developer carrying member is 100 μm or more and 750 μm or less. Is.

That is, when the pitch between the electrodes is narrow, the setting accuracy is severely limited and the stability is deteriorated. When the pitch between the electrodes is large, the potential difference between the adjacent electrodes becomes large, and when a collision between the developers during the movement between the electrodes occurs,
The collision energy increases and the developer is likely to scatter. Further, due to the collision, the developer is repelled from the electrode position which should originally exist, and the developer transport state is apt to be disturbed, but the above condition, that is, the interelectrode pitch λ is 100 μm or more and 750 μm or less is satisfied. By solving the above problem, such a problem is solved, a more stable developer transport state is obtained, and good image formation is possible (see the results of Table 2 described later).

Here, the disturbance of the developer transport state as described above raises the frequency of the traveling wave electric field for moving the developer, that is, shortens the time for forming the traveling wave electric field,
This can be alleviated by setting a condition in which this is repeated many times, and the uniformity of the developer transport state tends to improve. However, if the frequency of the traveling-wave electric field is set too high, the electric field conditions are switched within the time required for the developer to move between the electrodes, so that a sufficient amount of the developer to be conveyed cannot be obtained.

In order to solve such a problem, the time T for forming the traveling wave electric field and the pitch λ between the electrodes of the developer transport member are set.
It is necessary to consider the relationship of the developer transport amount with respect to, and in the developing device of the present invention, by defining the traveling wave electric field formation time T and the interelectrode pitch λ, while preventing the disturbance of the developer transport state, Secure the developer conveyance amount. Specifically, based on the graph of FIG. 9, the condition [λ / T <
By setting [2], it is possible to obtain a necessary developer transport amount while ensuring a stable and uniform developer transport state.

Further, the disturbance of the developer carrying state as described above tends to be more easily affected by the narrower the distance between the developer carrying member and the image carrier in the developing step, that is, the developing gap. To make it less susceptible to the disturbance of the developer transport state, the development gap may be increased, but if the development gap is increased, the required developer amount, that is, the image density cannot be obtained. In order to solve this, in the developing device of the present invention, the developing gap d and the interelectrode pitch λ are set so as to satisfy the relationship of [d> 20 × λ]. By setting such conditions, it is possible to improve the uniformity and stability of the developer transport and to secure a sufficient developer transport amount (see the results of Table 3 described later).

In the present invention, the image forming apparatus may be configured using the developing device having the above characteristics. In this case, since the uniformity and stability of the developer conveyance are improved, it is possible to provide an image forming apparatus capable of forming an excellent image having a uniform image density.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of an image forming apparatus equipped with the developing device of the present invention.

Inside the image forming apparatus X, a cylindrical photosensitive drum 1 as an image bearing member is provided. Around the photosensitive drum 1, a charging member 2, an exposure member 3, a developing device 4, a transfer member 5, a cleaning member 6, and a charge removing member 7 are arranged in this order around the photosensitive drum 1.

Further, between the photosensitive drum 1 and the transfer member 5, there is arranged a paper transport path for transporting a paper (PPC paper or the like) P as a recording medium. A fixing device 8 including a pair of upper and lower fixing members 81, 81 is arranged on the downstream side of the photosensitive drum 1 when viewed from the conveyance direction of the sheet conveyance path.

In the electrophotographic process, an original image or an electrostatic latent image corresponding to data from a host computer (not shown) is formed on the photosensitive drum 1, and the electrostatic latent image is developed by the developing device 4 ( It is visualized) and transferred onto the sheet P to form an image.

The photoconductor drum 1 has a photoconductive layer 12 formed on a conductive substrate 11, and is rotatable from the charging member 2 in the order of arrangement of the members 3 to 7. First, the surface (photoconductive layer 12) of the photosensitive drum 1 is charged by the charging member 2 until it reaches a predetermined potential. The surface of the photoconductor drum 1 charged to a predetermined potential reaches the position of the exposure member 3 by the rotation of the photoconductor drum 1. The exposure member 3 is a writing unit, and writes an image on the surface of the photosensitive drum 1 which is charged by light such as laser light based on image information. by this,
An electrostatic latent image is formed on the photosensitive drum 1. The surface of the photoconductor drum 1 on which the electrostatic latent image is formed reaches the position of the developing device 4 by the rotation of the photoconductor drum 1.

In the developing device 4, the electrostatic latent image on the surface of the photosensitive drum 1 is developed as a developer image by the developer (toner) S conveyed on the developer conveying member 41. The surface of the photoconductor drum 1 carrying the developer S reaches the position of the transfer member 5 by the rotation of the photoconductor drum 1.

The transfer member 5 transfers the developer S on the surface of the photosensitive drum 1 onto the paper P. The developer image transferred from the photosensitive drum 1 onto the paper P is fixed on the paper P by the fixing device 8.

Photoreceptor drum 1 after the developer image is transferred
The surface of the photosensitive drum 1 reaches the position of the cleaning member 6 by the rotation of the photosensitive drum 1. Cleaning member 6
Removes the developer S, paper dust, etc. remaining on the surface of the photosensitive drum 1. The surface of the photoconductor drum 1 cleaned by the cleaning member 6 reaches the position of the charge removing member 7 by the rotation of the photoconductor drum 1.

The charge removing member 7 removes the potential remaining on the surface of the photosensitive drum 1. One image formation is completed by the series of operations described above.

As the photosensitive drum 1, for example, amorphous silicon (a-Si), selenium (Se), organic optical semiconductor (OPC) or the like is formed on the outer peripheral surface of a conductive substrate (metal drum) 11 made of aluminum or the like. Photoconductive layer 12
Although a structure in which is formed into a thin film is mentioned, it is not particularly limited.

Examples of the charging member 2 include a conductive wire such as a tungsten wire, a metallic shield plate, a corona charger including a grid plate, a charging roller, a charging brush, and the like, but are not particularly limited thereto. Absent.

The exposure member 3 may be, for example, a semiconductor laser or a light emitting diode, but is not particularly limited.

Examples of the transfer member 5 include, but are not limited to, a corona transfer device, a transfer roller, a transfer brush and the like.

The cleaning member 6 may be a cleaning blade or the like, but is not particularly limited.

The charge removing member 7 may be a charge removing lamp or the like, but is not particularly limited.

Next, the developing device 4 will be described.

As shown in FIG. 2, the developing device 4 includes a casing 40, a developer conveying member 41, a mixing paddle 4
2, a supporting member 43, a developer supplying member 44, and a developer collecting member 45, and a multi-phase AC power supply 46 is connected to the developer conveying member 41.

The casing 40 accommodates the developer S therein, and also supports members constituting the developing device 4 if necessary.

The mixing paddle 42 is a casing 40.
It is for mixing the developer S contained therein.

The developer transport member 41 has a belt shape so as to face the developing area of the photosensitive drum 1 and form a substantially flat surface. In this embodiment, the developer transporting member 41 has a substantially flat shape, but the shape of the developer transporting member 41 is not limited to this, and for example, a gentle curved surface may be formed. It may have any shape.

The developer carrying member 41 is arranged so as to be slightly inclined with respect to the vertical direction of the developing device 4 and to be substantially parallel to the tangent line of the developing area on the surface of the photosensitive drum 1. In addition, the belt-shaped developer transport member 4
A support member 43 that holds the developer transport member 41 is provided on the surface opposite to the surface that transports the developer S so that 1 can hold the above arrangement.

At the lower end of the developer carrying member 41, a developer supplying member 44 for supplying the developer S carried on the surface of the developer carrying member 41 is provided. A developer collecting member 45 for collecting the developer S on the surface of the developer carrying member 41 into the casing 40 is provided at the upper end of the developer carrying member 41. In the present embodiment, the developer recovery member 45 is in contact with the surface of the developer transport member 41 so as to be rotatable, but the present invention is not limited to this. It may be in a non-form.

The developer supplying member 44 is for supplying the developer S contained in the casing 40 to the developer conveying member 41, and its material is not particularly limited, but for example, Silicone, urethane, EP
Solid rubber such as DM (ethylene-propylene-methylene copolymer), foamed rubber and the like can be mentioned. Further, conductivity may be imparted by adding carbon black or an ion conductive agent (voltage application is also possible).

The contact pressure between the developer supply member 44 and the developer transport member 41 may be a predetermined contact pressure provided by a spring or the like. In addition, the developer supply member 4
4 and the developer transport member 41 may be adjusted in elastic modulus to control the positional relationship between the two. Further, the voltage applied to the developer supply member 44 may be set to an appropriate value to add the function of charging the developer S to the developer supply member 44. Alternatively, for example, a thin plate-shaped blade (the same material as the developer supply member 44 can be used) may be provided in front of the developer supply member 44 to charge the developer S.

The developer collecting member 45 is for collecting the developer S which does not contribute to the development of the electrostatic latent image on the photosensitive drum 1 and returning it to the casing 40, and its material is not particularly limited. Although not provided, for example, the same material as the developer supply member 44 can be used.

The supporting member 43 is for holding the belt-shaped developer conveying member 41 in a state of facing the developing area of the photosensitive drum 1, and its structure is not particularly limited. For example, ABS (Acrylonitrile-Butadiene-
Styrene: acrylonitrile butadiene styrene) resin and the like.

The developer conveying member 41 conveys the developer S by the electric field curtain action, and as shown in FIGS. 3 (a) and 3 (b), the developer 41 is formed on the base material 41a made of an insulating layer.
A plurality of long traveling wave generation electrodes 41b for generating the electric field curtain action are sequentially arranged, with four as one set. The surface side of the developer transport member 41 is covered with a surface protective layer 41c.

Then, these traveling wave generating electrodes 41b ...
By applying a multi-phase alternating voltage from the multi-phase AC power source 46 to 41b, an electric field curtain is generated in a direction parallel to the surface of the developer conveying member 41, and thereby the developer reaches the developing region by the electric field curtain action. S is conveyed.

To give a specific example of the developer transport member 41,
For example, the base material 41a: polyimide (thickness: 25 μm), the traveling wave generating electrode 41b: copper (thickness: 18 μm), and the surface protection layer 41c: polyimide (thickness: 25 μm) can be mentioned.

The traveling wave generating electrode 41b is approximately 50 dpi.
(Dot per inch) ~ 300dpi, ie about 500μ
The electrodes are arranged in parallel with each other with a pitch of m to 85 μm, and are minute electrodes having a width of about 40 μm to 250 μm.

In the present embodiment, four traveling wave generating electrodes 41b are set as one set, and the traveling wave generating electrodes 4 of each set are formed.
For example, a four-phase alternating voltage having a voltage waveform as shown in FIG. 4 is applied to 1b to form a traveling-wave electric field on the traveling-wave generating electrodes 41b ... 41b, but the invention is not limited thereto. Instead, three traveling wave generating electrodes 41b are used as a set and
Alternate voltage of the phases may be applied.

The voltage waveform may be a sine wave or a trapezoidal wave, and the voltage value range is preferably about 100 V to 3 kV. The frequency range is 100 Hz to 5 kHz.
z is preferred. However, these voltage values and frequencies are not particularly limited as long as appropriate values may be set depending on the shape of the traveling wave generating electrode 41b, the transport speed of the developer S, the material used for the developer S, and the like.

The characteristic parts of the embodiment of the present invention will be described below.

<Embodiment 1> In the present invention, as shown in FIG. 6, a developer layer forming region E on the developer supplying member 44 is formed.
Is L (mm), the electrode pitch of the electrodes (traveling wave generating electrodes 41b) of the developer transport member 41 is λ (mm), and the contact region between the developer transport member 41 and the developer supply member 44 (developer) The inclination angle of the supply region G) with respect to the longitudinal direction of the electrode is θ
(°), by setting conditions so as to satisfy the relationship of | sin θ | <10 × λ / L, it is possible to form a good image without disturbing the developer transport state. The reason will be described below.

First, the developer transport state was examined when the inclination angle θ, the interelectrode pitch λ and the width L of the developer layer forming region E were changed, and the results shown in Table 1 below were obtained.

[0073]

[Table 1] As is clear from the results of Table 1, the above condition J
1: By setting the conditions so as to satisfy [| sin θ | <10 × λ / L], the influence of non-uniformity of developer conveyance does not appear and a stable and uniform developer conveyance state can be obtained. Therefore, good image formation becomes possible.

<Embodiment 2> In the present invention, it is preferable to set a condition that the interelectrode pitch λ is 100 μm or more and 750 μm or less. The reason will be described below.

First, in Table 1 above, when the inter-electrode pitch λ is 130 μm, in order to prevent uneven conveyance, the inclination angle θ is controlled to about 0.1 ° to 0.2 °. I have to. Therefore, the developer supply member 4
4, it becomes difficult to set the positions of the developer transport member 41 and the developer transport member 41, and a slight change in the relative position may adversely affect the maintenance of the uniformity of the developer transport state. Further, when the interelectrode pitch λ is large, the potential difference between the adjacent electrodes in the traveling wave generating electrode 41b is large, and when the developers collide with each other during the movement between the electrodes, the collision energy becomes large and the developer scatters. Is likely to occur. Further, due to the collision, the electrode position where it should originally exist is repelled, an irregular operation occurs, and the developer transport state is easily disturbed.

In order to eliminate such a point, the relationship between the interelectrode pitch λ, the inclination angle θ, the potential difference between adjacent electrodes, and the developer transport amount may be considered.

When the developer transport state was examined when the interelectrode pitch λ, the inclination angle θ, and the potential difference between adjacent electrodes were examined, the results shown in Table 2 below were obtained.

[0078]

[Table 2] As is clear from the results in Table 2, when the interelectrode pitch λ is large (1.1 mm), a large potential difference between the adjacent electrodes causes a traveling wave electric field for transporting a desired amount of the developer. This is necessary, and the above-described action causes non-uniformity in developer transportability (unevenness in transport, scattering). Further, when the potential difference between the adjacent electrodes is reduced, the uniformity of developer transport is improved, but the transport electric field strength of the developer (electric field strength between adjacent electrodes) is insufficient, and a sufficient amount of developer cannot be transported.

From the results shown in Table 2, the above-mentioned condition, that is, the pitch λ between electrodes is 100 μm or more and 750 μm.
It is understood that by satisfying the condition J2 which is the following, it is possible to obtain a necessary developer transport amount while ensuring a stable and uniform developer transport state, and it becomes possible to form a good image. .

<Third Embodiment> In the present invention, the time for forming the traveling wave electric field for conveying the developer is T (s), and the inter-electrode pitch of the traveling wave generating electrodes 41b of the developer conveying member 41 is λ (m). Then, it is preferable to set the conditions so as to satisfy the relationship of [λ / T <2]. The reason will be described below.

First, the disturbance of the developer transport state is reduced by increasing the frequency of the traveling wave electric field for moving the developer, that is, shortening the time for forming the traveling wave electric field and setting the condition for repeating this a lot. Therefore, the uniformity of the developer conveyance state tends to be improved. However, if the frequency of the traveling-wave electric field is set too high, the electric field conditions are switched within the time required for the developer to move between the electrodes, so that a sufficient amount of the developer to be conveyed cannot be obtained.

In order to solve such a problem, the relationship between the time for forming the traveling wave electric field and the developer transport amount with respect to the electrode pitch of the developer transport member may be taken into consideration.

When the correlation between the traveling wave electric field formation time and the electrode pitch was changed and the developer transport state was investigated, the results shown in the graph of FIG. 9 were obtained.

As is clear from the graph of FIG. 9, when the electric field formation time T becomes shorter (frequency becomes higher), the developer carrying amount tends to decrease, and in particular, the interelectrode pitch λ.
The ratio [λ / T] between (m) and the electric field formation time T (s) is 2.
When it exceeds 0, the developer transport amount changes abruptly. Therefore, while ensuring a stable and uniform developer transport state,
To obtain the required developer transport amount, [λ /
It can be said that it is a preferable condition to set the electric field formation time T and the interelectrode pitch λ within the range where T <2] is satisfied.

<Embodiment 4> In the present invention, the development gap d (mm) and the interelectrode pitch λ (mm) are defined as [d>
It is preferable to set the conditions so as to satisfy the relationship of [20 × λ]. The reason will be described below.

First, the disturbance of the developer carrying state tends to be more affected by the narrower the developing gap between the developer carrying member and the image carrier. Further, in a general developing process, as shown in FIG.
In the vicinity of the surface of No. 1, the uneven distribution of the developer is large. Such uneven distribution of the developer is reduced as the distance from the developer transport member 41 increases. Therefore, by increasing the development gap d between the developer transport member 41 and the photosensitive drum 1 (image carrier). Therefore, it is possible to reduce the influence of the disturbance of the developer conveyance state. However, if the development gap d is large, the developer density in the region near the photosensitive drum 1 becomes low, and the required developer amount, that is, the image density cannot be obtained.

Therefore, conditions for reducing the influence of disturbance of the developer transport state and increasing the developer density were examined.
The examination results are shown in Table 3 below. Table 3 shows the results of examination of the developer transporting state when the electrode pitch λ, the potential difference between adjacent electrodes, the inclination angle θ, and the development gap d are changed.

[0088]

[Table 3] As is clear from the results of Table 3, the development gap d is reduced within the range where the condition J1 of the first embodiment and the condition J2 of the second embodiment are satisfied and the condition [d> 20 × λ] is satisfied. By making the settings as shown in FIG.
As shown in, the uneven distribution of the developer is reduced even in the area close to the surface of the developer transport member 41, and the developer density is increased in the area near the photoconductor drum 1 (image carrier). In addition, it is possible to perform development at a sufficient density.

In the above embodiment, an example of an apparatus for forming an electrostatic latent image by writing optical information on a photosensitive drum (image carrier) charged by applying a predetermined charge has been shown. In addition to this, for example, an electrostatic charge latent image is directly formed on a dielectric such as an ion flow system, or a space is formed by applying an arbitrary voltage to an electrode having a plurality of openings like a toner jet system. It is also applicable to a device in which an electrostatic latent image is formed on a recording medium and a developer is ejected onto a recording medium to directly form an image.

[0090]

As described above, according to the developing device of the present invention, the width of the developer layer forming region on the developer supplying member is L (mm) and the inter-electrode pitch of the developer conveying member is λ ( m
m), when the inclination angle of the contact area between the developer transport member and the developer supply member with respect to the electrode is θ (°), [| s
Since the conditions are set so as to satisfy the relationship of in θ | <10 × λ / L], it is possible to prevent the developer conveyance state from being disturbed due to the inclination of the developer supply member, so that the developer is always stable and uniform. It is possible to obtain a proper developer transport state.

Since the image forming apparatus of the present invention is equipped with the developing device having the characteristics as described above, it is possible to form an excellent image having a uniform image density.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a diagram schematically showing a configuration of an embodiment of a developing device of the present invention.

FIG. 3 is a diagram schematically showing a configuration of a developer transport member.

FIG. 4 is a diagram showing a traveling wave voltage waveform applied to a developer transport member in the embodiment of the present invention.

FIG. 5 shows a state (a) when the positional relationship between the developer transport member and the developer supply member is appropriate, and a state (b) when the developer supply member is inclined with respect to the electrodes of the developer transport member. It is a figure which shows typically.

FIG. 6 is a diagram schematically showing a positional relationship between a developer supply member and a developer transport member when the developer supply region is inclined.

FIG. 7 is a diagram schematically showing a developer moving state when the positional relationship between the developer transport member and the developer supply member is appropriate.

FIG. 8 is a diagram schematically illustrating a developer moving state when the developer supply member is inclined with respect to the electrode of the developer transport member.

FIG. 9 is a graph showing the correlation between electrode pitch / electric field formation time and developer transport amount.

FIG. 10 is an operation explanatory view of the developing device of the present invention.

FIG. 11 is a diagram illustrating a problem in a conventional general developing process.

[Explanation of symbols]

X image forming device 1 Photoconductor drum (image carrier) 11 Conductive substrate 12 Photoconductive layer 2 charging member 3 Exposure member 4 Developing device 40 casing 41 developer transport member 41a base material 41b Traveling wave generating electrode (electrode) 41c Surface protection layer 42 mixing paddle 43 Support member 44 developer supply member 45 Developer Collection Member 46 Multi-phase AC power supply 5 Transfer member 6 Cleaning member 7 Static elimination member 8 fixing device E Developer Layer Forming Area on Developer Supply Member G developer supply area (contact area) P paper S developer (toner)

Claims (5)

[Claims] 1. A developing device for developing an electrostatic latent image formed on an image carrier, comprising a plurality of long electrodes arranged substantially parallel to each other on a base material at predetermined intervals. A developer transport member for transporting the developer toward the image carrier by a traveling wave electric field formed by applying a multi-phase alternating voltage to the electrodes, and a developer transport member corresponding to the developer transport member. In a developing device including a developer supply member that is in contact with and supplies the developer, the width of the developer layer forming region on the developer supply member is L (m
m), the inter-electrode pitch of the developer transport member is λ (m
m), the inclination angle of the contact area between the developer transport member and the developer supply member with respect to the longitudinal direction of the electrode is θ.
The developing device is characterized in that the relationship of | sin θ | <10 × λ / L is satisfied, where (°). 2. The developing device according to claim 1, wherein the inter-electrode pitch λ of the developer transport member is 100 μm or more and 750 μm or less. 3. The time for forming the traveling wave electric field is T
(S), the pitch between the electrodes of the developer transport member is λ (m)
Then, the developing device according to claim 1 or 2, wherein the relationship of λ / T <2 is satisfied. 4. When the developing gap between the image carrier and the developer carrying member is d (mm) and the electrode pitch of the developer carrying member is λ (mm), d> 20 × λ The developing device according to claim 1, wherein the relationship is satisfied. 5. An image forming apparatus comprising the developing device according to any one of claims 1 to 4.