JPH0288255A - Electrophotographic recorder - Google Patents

Abstract

PURPOSE:To make recording speed quick by a method wherein toner having applied to a charged electrode is made to fly by Coulomb's force caused by potential difference between a surface potential of a photosensitive layer varied by light from a first light source and a potential of a charged electrode, and the toner is stuck to a recording medium. CONSTITUTION:An electric potential Vs of a surface electrode 5 is kept at a second electric potential V2, and an electric potential Vb of a back surface electrode 3 is kept at a second electric potential V2. First light 8a is radiated from a first light source 8, and a surface electric potential Vfp becomes almost the first electric potential V1. When the surface electric potential Vtp exceeds a threshold voltage Vth a that time, a toner image 9a is formed on a recording medium 7. The electric potential Vb of the back surface electrode 3 is switched to the second electric potential V2 by a switching means 10. Since a photosensitive layer 4 has become low resistant, the surface electric potential Vfp is switched to the second electric potential V2 for a short time. Then, the electric potential Vb is switched again to the first electric potential V1 by the switching means 10. Since the surface electric potential Vfp has been preliminarily switched to the second eleciric potential V2, a recovery term is extremely short to shift instantly to a stationary term (a).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic recording device used in copying machines, printers, facsimile machines, and the like.

[Prior Art] Although electrophotographic recording devices using the so-called Carlson process have been widely put into practical use, the inventors of the present application have proposed an electrophotographic recording device using a non-Carlson process. (Japanese Patent Application No. Sho 63-161307) FIG. 8 is an explanatory diagram showing the recording principle of this electrophotographic recording apparatus using the non-Carlson process.

In the same figure, 1 is a first support having a light-transmitting property, 2 is a second support installed opposite to this first support,
3 is a transparent back electrode formed on the first support, 4 is a photosensitive layer formed on this back electrode 3, and 5 is a surface electrode partially formed on this photosensitive layer 4. , 6 is a charging electrode formed on the second support 2, 7 is a recording medium installed between the first support 1 and the second support 2, 8° is a light source, 9 is toner.

Note that the back electrode 3. , the surface electrode 5 and the charged electrode 6 are
They are held at a first potential v1, a second potential V2, and a third potential v3, respectively.

Figure (A) shows the state when no light is irradiated (hereinafter referred to as dark time). Considering the resistance of the portion of the photosensitive layer 4 where the surface electrode 5 is not formed (hereinafter referred to as the photosensitive layer surface), as shown in the figure, the resistance component of the resistance Rvd in the stacking direction of the photosensitive layer and the surface resistance Rsd Can be divided. If the resistivity, film thickness, and distance of the portion where the surface electrode 5 is not formed of the photosensitive layer 4 are appropriately selected to be Rvd)Rsd, the surface potential of the surface of the photosensitive layer is approximately equal to that of the surface electrode 5. It becomes equal to the potential v2. Therefore V2
By appropriately selecting the values of and v3, the potential v of the charging electrode 6 is
3 and the above surface potential (=V2) (2V3-V
21) is set below a predetermined electric field, and the toner 9
If the adhesion force between the toner and the charging electrode 6 is made greater, the toner 9 will not fly out.

Figure (B) shows when the light is irradiated (hereinafter referred to as open state).
This shows the state of

When light 8°a from a light source 8° is irradiated from the back side of the first support 1 to a portion of the photosensitive layer 4 where the surface electrode 5 is not formed, photocarriers are present in this portion of the photosensitive layer 4. As a result, the resistance value in the stacking direction decreases to RV9. - The value Rsp of the blade surface resistance hardly changes. That is, Rv
p (Rvd, RspzRsd. If the resistivity of the photosensitive layer 6 at the time of light irradiation is an appropriate value, R
vp (Rsp), and in this case, the surface potential of the surface of the photosensitive layer becomes approximately equal to the potential Vl of the back electrode 3. Therefore, by appropriately selecting the value of Vl, the potential v of the charged electrode 6
3 and the above surface potential (==Vl) (,1V8−
The electric field generated by Vl l) is set to be higher than a predetermined electric field, and the coulomb force acting on the toner 9 due to the above electric field is
If the adhesion force between the charging electrode 6 and the charging electrode 6 is made larger, the toner 9 leaves the charging electrode 6 and flies toward the recording medium 7, forming a toner image 9a on the recording medium 7.

That is, a toner image is formed on a recording medium by causing the toner to fly using a coroner.

FIG. 9 shows the structure on the first support 1 of an example of an electrophotographic recording apparatus having the above recording principle.

This has a surface electrode 5 formed in the shape of a ladder and a floating electrode 21 formed on the photosensitive layer 4, so that a toner image with good resolution can be recorded.

[Problem to be Solvedffi] FIG. 10 shows potential changes on the surface of the photoreceptor during light irradiation and non-irradiation in the electrophotographic recording apparatus described above.

In the figure, Vs and vb are the potentials of the front and back electrodes, respectively, and Pl is the irradiation (on) of light from the light source.
and non-irradiated (off) waveforms.

Vfp and Vrd are the surface potentials of the light-irradiated part and the non-irradiated part of the surface of the photosensitive layer, respectively. Note that the above-mentioned surface potentials Vl'p and Vl'd indicate the potentials of the floating electrodes formed on the surface of the photosensitive layer. In addition, a in the same figure
Each period lb and d corresponds to each state of the surface potential accompanying light irradiation, and each period is a steady period (a
), irradiation period (b) and recovery period (d).

As shown in the figure, the surface potential V[p of the photosensitive layer changes rapidly when the light transitions from OFF to ON, but changes slowly when the light transitions from ON to OFF; takes time to recover. This is due to the difference in time constant; when transitioning from off to on, a large number of carriers are generated in the photosensitive layer due to light irradiation and the resistance of the photosensitive layer decreases, whereas when transitioning from on to off, This is because the resistance of the photosensitive layer increases due to the disappearance of carriers.

If the resistivity of the photosensitive layer is lowered to reduce the time constant when light is not irradiated (dark time), the sensitivity of the photosensitive layer may decrease, and the gap between the electrodes may decrease due to heat generation in the photosensitive layer or an increase in flakes in the photosensitive layer. The resistivity of the photosensitive layer cannot be lowered because short circuits may occur. Therefore, it is not possible to speed up the recovery time of the surface potential of the photosensitive layer when transitioning from on to off.

By the way, when using the above-mentioned electrophotographic recording device in a printer or facsimile, conventionally, as mentioned above, it takes time to recover the potential when switching from on to off, so this potential recovery time slows down the recording speed. However, it was not possible to obtain a recording device that operated at high speed.

The present invention has been made to solve the above-mentioned conventional problems,
The purpose of the present invention is to provide an electrophotographic recording device capable of high-speed operation.

[Means for Solving the Problems] The present invention includes: a first support having translucency; a second support disposed opposite to the first support; and the first support. a light-transmissive back electrode held at a first potential formed on the surface of the body facing the second support; a photosensitive layer formed at least on the back electrode; and a photosensitive layer formed on the photosensitive layer. a surface electrode partially formed on the surface and held at a second potential; and a charging electrode formed on the surface of the second support facing the first support and held at a third potential. , irradiating the recording medium placed between the first support and the second support and the photosensitive layer in the portion where the surface electrode is not formed from the back side of the first support; (a) a first light source that changes the surface potential of the photosensitive layer in a portion irradiated with light; A switching means for switching the potential to another potential, and/or (b) a second light source that irradiates light onto the surface of the photosensitive layer after a predetermined time elapses after irradiation with light from the first light source, and/or (C ) a conductive portion that comes into contact with the surface electrode after a predetermined time has elapsed since the light irradiation from the first light source as the recording medium moves; , causing the toner deposited on the charging electrode to fly due to a Coulomb force generated by a potential difference between the surface potential of the photosensitive layer changed by the light from the first light source and the charging electrode;
The above object is achieved by an electrophotographic recording apparatus characterized in that a toner image is formed by depositing the toner on the recording medium.

[Example code] Embodiments of the present invention will be described below based on the drawings.

Embodiment 1 FIG. 1 shows a first embodiment of the present invention.

In the same figure, 1 is a first support having a light-transmitting property, 2 is a second support installed opposite to this first support,
3 is a light-transmitting back electrode formed on the first support, 4 is a photosensitive layer formed on this back electrode 3 and the first support 1, and 5 is on this photosensitive layer 4. 6 is a charging electrode formed on the second support 2; 7 is a surface electrode formed on the first support 1 and the second support 2;
8 is a first light source; 8a is the first light irradiated from the first light source 8 to the photosensitive layer 4; 9 is toner; 9a is formed on the recording medium 7; The toner image 21 is a floating electrode.

Note that the back electrode 3, the front electrode 5, and the charging electrode 6 are held at a first potential v1, a second potential v2, and a third potential v3, respectively.

In this example, the recording principle itself for forming a toner image on the support is the same as the above conventional example, and when the light irradiated onto the photosensitive layer changes from on to off, the surface potential of the photosensitive layer quickly returns to a steady state. A switching means 1° for switching the potential of the back electrode 3 is provided so that the potential of the back electrode 3 is changed from one to the other.

FIG. 2 shows potential changes on the surface of the photosensitive layer for each step in FIG. 1.

In the figure, Vs and vb are the potentials of the front electrode 5 and the back electrode 3, respectively, and Pl is the potential of the first light source 8.
These are the irradiation (on) and non-irradiation (off) waveforms of the light 8a. vrp and Vfd are the surface potentials of the photosensitive layer 4 at the light irradiated part and the non-irradiated part, respectively. The above surface potentials Vf'p and Vfd indicate the potentials of the floating electrode 21 formed on the surface of the photosensitive layer 4. Note that a and b in the same figure.

Each period C and d corresponds to each state of the surface potential accompanying light irradiation, and these periods correspond to each step (
Corresponding to a), (b), (c) and (d), the steady period (a), the irradiation period (b), and the switching period (c
) and recovery period (d).

The operation of this example will be explained below according to a to d of FIGS. 1 and 2.

(a) The potential Vs of the front electrode 5 is held at the second potential v2, the potential vb of the back electrode 3 is held at the first potential Vl, and no light is emitted from the first light source 8 (Pl is off). ). Therefore, the surface potential Vrp is maintained at the second potential v2.

(b) The potential Vs of the front electrode 5 remains at the second potential v2, the potential vb of the back electrode 3 remains at the first potential vl, and the first light 8a is emitted from the first light source 8. be done (P
I is on). Therefore, the surface potential Vrp becomes approximately the first potential Vl after a predetermined period of time has elapsed. At this time, the surface potential v
When rp exceeds the threshold voltage Vth, the toner flies and a toner image 9a is formed on the recording medium 7.

(c) By the switching means 10, the potential vb of the back electrode 3
is switched to the second potential (2) connected to the surface electrode 5. Since the photosensitive layer 4 has a low resistance due to the irradiation with the first light 8a, the surface potential Vrp is switched to the second potential v2 connected to the back iIj electrode 3 in a short time. Note that the back electrode 3 switched by the switching means 10
The potential vb does not necessarily have to be the second potential V2, but may be another potential.

(d) The switching means 10 causes the potential vb of the back electrode 3 to
is switched back to the first potential Vt.

The surface potential vfp is changed to the second potential V2 in the step (c) above.
Since the period has already been switched to , the recovery period d may be an extremely short period, and the period immediately shifts to the steady period a. Note that the timing at which the first light 8a is turned off may be other than the period when the potential vb of the back electrode 3 is switched to another potential, but as in this example, when the potential vb of the back electrode 3 is switched to the first In order to shorten the recovery period d, it is preferable to turn it off immediately before switching to the potential Vl again.

Note that the floating electrode 21 does not necessarily need to be provided.

In this example, after the toner image is formed, the switching means 10 switches the potential vb of the back electrode 3 to another potential.
The surface potential Vrp is switched to another potential connected to the back electrode 3 in a short time, and the recovery period of the surface potential V"p can be extremely shortened.

Therefore, shortening this potential recovery time increases the recording speed,
An electrophotographic recording device that operates at high speed can be obtained.

Embodiment 2 FIG. 3 shows a second embodiment of the present invention.

Like the first embodiment, the recording principle itself for forming a toner image on the support is the same as in the conventional example, and when the light irradiated to the photosensitive layer changes from on to off, the photosensitive layer The second light source 11 is provided so that the surface potential of the surface quickly shifts to a steady state. Therefore, the numbers assigned to FIG. 3 are the same as the numbers assigned to FIG. 1.

FIG. 4 shows potential changes on the surface of the photosensitive layer for each step in FIG. 1.

P2 is the irradiation (on) and non-irradiation (off) waveforms of the second light 11a from the second light source 11, and the other symbols are the first
Indicates the same symbol as the one in the figure.

Note that the periods a, b, c, and d in the same figure correspond to each state of the surface potential associated with light irradiation, and these periods correspond to the respective steps (a), (b), and (C) in Fig. 3. ) and (d)
corresponding to the steady period (a) and the irradiation period (b), respectively.
, a switching period (c) and a recovery period (d).

The operation of this example will be explained below according to a to d of FIGS. 1 and 2.

(a) No light is emitted from the first light source 8 (PL
is off). Therefore, the surface potential Vrp is approximately the second potential V
2.

(b) The potential vb of the back electrode 3 remains at the first potential ■1, and the first light 8a is irradiated from the first light source 8 (PI is on). Therefore, the surface potential Vfp becomes approximately the first potential (1) after a predetermined period of time has elapsed. At this time,
When the surface potential vfp exceeds the threshold voltage Vth, the toner flies, and a toner image 9a is formed on the recording medium 7.

(c, d) The second light 11a from the first light source 11 is irradiated mainly onto the surface of the photosensitive layer 4. Therefore, the surface resistance of the photosensitive layer 4 decreases, and the surface potential Vrp is switched to the second potential 2 connected to the surface electrode 5 in a short time. In order to lower only the surface resistance of the photosensitive layer 4, the second light 11a
is the photosensitive layer 4 between the back electrode 3 and the floating electrode 21
It is preferable to irradiate only the surface of the photosensitive layer 4 so as not to transmit the light. Note that the on-periods of the first light 8a and the second light 11a may or may not overlap with each other.

In FIG. 5, a mag roller 2a is used as the second support, and the second light 11a is emitted from the photosensitive layer 4 as shown in the figure.
It is preferable to irradiate substantially parallel to the

Note that in this example as well, the floating electrode 21 is not necessarily required, as in the first example.

In this example, after the toner image is formed, the second light emitted from the second light source 11 is
The light 11a is irradiated mainly on the surface of the photosensitive layer 4 to lower the surface resistance of the photosensitive layer 4, and as a result, the surface potential Vfp is switched to the second potential V2 connected to the surface electrode 5 in a short time. The recovery period of the surface potential Vl'p can be extremely shortened.

Therefore, shortening this potential recovery time increases the recording speed,
An electrophotographic recording device that operates at high speed can be obtained.

Embodiment 3 FIG. 6 shows a third embodiment of the present invention.

Similar to the first and second embodiments, the recording principle itself for forming a toner image on a support is the same as in the conventional example, and when the light irradiated to the photosensitive layer changes from on to off. A conductive portion 12 is provided on the recording medium 7 so that the surface potential of the photosensitive layer quickly shifts to a steady state. Therefore, the numbers assigned to FIG. 6 are the same as the numbers assigned to FIG. 1. Note that in this figure, the second support, light source, etc. are omitted to make the drawing easier to see.
Actually, these items are installed in the same way as in the first and second embodiments. Further, the back electrode 3, the front electrode 5, and the charging electrode (not shown) are held at a first potential Vl, a second potential 2, and a third potential v3, respectively.

First, the photosensitive layer 4 is irradiated with light to form a toner image on a portion of the recording medium 7 using a film or the like where the conductive portion 12 is not formed. Floating electric t at this time! ii!
The potential of 21 is the first potential Vt connected to the back electrode 3.
approximately equal to. Next, the recording medium 7 is moved in the direction of the arrow so that the conductive portion 12 comes into contact with the bridge portion of the ladder-shaped surface electrode 5 and the floating electrode 21 . At this time, the surface electrode 5 and the floating electrode 2
1 is electrically conductive through the conductive part 12, the potential of the floating electrode 21, that is, the surface potential of the photosensitive layer 4 is
The second potential °V2 connected to the surface electrode 5 is reached and the system returns to steady state within a very short time.

Note that the bridge portion of the surface electrode 5 and the floating electrode 2
1 is not necessarily necessary, and it is sufficient as long as the recording medium 7 is moved after the toner image is formed, and the surface electrode 5 and the surface of the photosensitive layer 4 come into contact with each other via the conductive portion 12. For example, as shown in FIG. 7, if a conductive part 12 is formed on the recording medium 7, the surface electrode 5 and the surface of the photosensitive layer 4 can be in contact with each other via the conductive part 12.

In this example, after the toner image is formed, the surface potential of the photosensitive layer 4 is switched to the second potential v2 connected to the surface electrode 5 in a short time by the conductive portion 12 formed on the recording medium.
The recovery period of the surface potential can be extremely shortened. Therefore, the shortening of the potential recovery time increases the recording speed, making it possible to obtain an electrophotographic recording device that operates at high speed.

[Effect] According to the present invention, after toner image formation, the switching means, the second
By using the light source and the conductive portion, the recovery time of the surface potential of the photosensitive layer can be extremely shortened. Therefore, the shortening of this potential recovery time increases the recording speed, making it possible to obtain an electrophotographic recording device that operates at high speed.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a first embodiment of the present invention,
FIG. 2 is a time chart showing the operation of the first embodiment, FIGS. 3 and 5 are explanatory diagrams showing the second embodiment of the present invention, and FIG. 4 is a time chart showing the operation of the second embodiment. FIG. 6 is an explanatory diagram showing the third embodiment of the present invention, FIG. 7 is a plan view showing an example of the pattern of the conductive part in the third embodiment, and FIGS. The figure is an explanatory diagram showing a conventional example, and FIG. 10 is a time chart showing the operation of the conventional example. 1...First support 2...Second support 3...Back electrode 4...Photosensitive layer 5...Surface Electrode 6...Charging electrode 7...Recording medium 8...First light source 9...Toner 0...Switching means 1... ...Second light source 2...Conductive part and above Applicant Seikosha Co., Ltd.

Claims (3)

[Claims] (1) A first support having translucency, a second support installed opposite to the first support, and facing the second support of the first support. a light-transmissive back electrode formed on the surface of the substrate and held at a first potential; a photosensitive layer formed at least on the back electrode; and a photosensitive layer partially formed on the photosensitive layer and held at a second potential. a surface electrode held in the
a charging electrode formed on a surface of the second support opposite to the first support and held at a third potential;
A recording medium placed between a support and a second support, and a portion of the photosensitive layer where the surface electrode is not formed are irradiated with light from the back side of the first support. a first light source that changes the surface potential of the photosensitive layer at the irradiated portion; and a second light source that changes the potential of the back electrode that is maintained at the first potential after a predetermined time elapses after the light irradiation from the first light source. the toner deposited on the charging electrode by a Coulon force generated by the difference in potential between the surface potential of the photosensitive layer changed by the light irradiation from the first light source and the charging electrode; An electrophotographic recording apparatus characterized in that a toner image is formed by causing the toner to fly and adhere to the recording medium. (2) A first support having translucency, a second support installed opposite to the first support, and facing the second support of the first support. a light-transmissive back electrode formed on the surface of the substrate and held at a first potential; a photosensitive layer formed at least on the back electrode; and a photosensitive layer partially formed on the photosensitive layer and held at a first potential. a surface electrode held in the
a charging electrode formed on a surface of the second support facing the first support and held at a second potential;
A recording medium placed between a support and a second support, and a portion of the photosensitive layer where the surface electrode is not formed are irradiated with light from the back side of the first support. a first light source that changes the surface potential of the photosensitive layer at a portion irradiated with the light, and a second light source that irradiates the surface of the photosensitive layer with light after a predetermined time has elapsed after the light irradiation from the first photoelectric. The toner deposited on the charging electrode is caused to fly by the Coulomb force generated by the potential difference between the surface potential of the photosensitive layer changed by the light irradiation from the first light source and the charging electrode, and the toner is attached to the recording medium. An electrophotographic recording apparatus characterized in that a toner image is formed by attaching the toner to the surface of the electrophotographic recording apparatus. (3) A first support having translucency, a second support installed opposite to the first support, and facing the second support of the first support. a light-transmissive back electrode formed on the surface of the substrate and held at a first potential; a photosensitive layer formed at least on the back electrode; and a photosensitive layer partially formed on the photosensitive layer and held at a first potential. a surface electrode held in the
a charging electrode formed on a surface of the second support facing the first support and held at a second potential;
a first light source that irradiates light from the back side of the support to a portion of the photosensitive layer where the surface electrode is not formed to change the surface potential of the photosensitive layer in the irradiated portion;
A recording medium installed between a support and a second support, and a conductive member that comes into contact with the surface electrode after a predetermined period of time has elapsed after irradiation with light from the first light source as the recording medium moves. and a Coulomb force generated by a potential difference between the surface potential of the photosensitive layer changed by light irradiation from the first light source and the charged electrode, the toner deposited on the charged electrode is caused to fly, and the toner deposited on the charged electrode is caused to fly. An electrophotographic recording apparatus characterized in that a toner image is formed by depositing the toner on a recording medium.