JPH06262798A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To stabilize recording characteristics of an image forming apparatus by exciting electric field control means and varying its exciting state. CONSTITUTION:An interval of 2mm is provided at an upper side of an aperture electrode 1 as electric field control means, and a back electrode roller 22 as a counter electrode is rotatably arranged on a chassis. An exciter 30, a vibration absorber 32 are provided as vibrating means at both ends of the electrode 1 to generate a traveling wave of an ultrasonic vibration on an insulation sheet 2. The exciter 30 can be excited by applying an AC voltage of a frequency suitable for a piezoelectric element from a control power source 31. A CPU controls the power source 31 based on an image signal externally input. Thus, recording with high resolution can be simply obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which can be used as a printing means mounted on a copying machine, a printer, a plotter, a facsimile or the like.

[0002]

2. Description of the Related Art Conventionally, an image recording apparatus for controlling the passage of toner particles through an aperture to obtain an image on a support by applying an image signal to an electrode having an aperture has been proposed in US Pat. No. 3,689,935. ing. In this proposal, a reference electrode that is continuous on one side across an insulator layer,
An aperture having a plurality of control electrodes insulated from each other on the other surface, and further having apertures formed through three layers for each insulated plurality of control electrodes and arranged in at least one row. An electrode body, a means for selectively applying a potential between the control electrode and the reference electrode, a means for projecting charged particles so that the flow of toner particles through the aperture is modulated by the applied potential, and a support And a means for relatively moving the aperture electrode body to position the support in the particle flow path.

However, according to this apparatus, in addition to the poor recording quality due to the clogging of the aperture due to the toner,
The recording speed could not be increased sufficiently.

The applicant of the present invention further studied,
As already filed in the application No. 254494, an image recording apparatus has been proposed in which the recording characteristics can be greatly improved by disposing the carrier holding the toner and the recording electrode in contact with each other. According to this apparatus, the image quality is remarkably improved, and the image recording apparatus can be downsized and the cost can be reduced.

[0005]

However, although the image forming apparatus of the present invention has excellent recording speed and resolution, there is some concern about recording stability. That is, in a normal printing state, it is less likely that toner will accumulate inside the aperture and clog. However, when recording is started when left for a long period of time or when printing is performed in a bad environment, a hole is clogged and it becomes impossible to record.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to propose an image forming apparatus capable of obtaining stable recording characteristics.

[0007]

To achieve this object, an image forming apparatus of the present invention controls a carrier which holds and supplies charged particles and a flow of charged particles supplied from the carrier by an electric field. An image forming apparatus comprising: an electric field control means for controlling the electric field control means; and an opposing electrode arranged with the image receptor interposed between the electric field control means, and at least an exciting means for exciting the electric field control means is provided and the excitation is performed. A control means for changing the excitation state of the means is provided.

Further, the control means may control the excitation means so as to strongly excite the electric field control means during non-image formation as compared with during image formation.

[0009]

According to the image forming apparatus of the present invention having the above construction, for example, strong vibration can be applied to the electric field control means before printing by the excitation means. The charged particles adhering to the electric field control means are removed and cleaned, and the good printing state is restored.

[0010]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an outline of an image forming apparatus of the present invention, in which an aperture electrode body 1 serving as an electric field control means has a 1 mm gap on the upper side thereof and serves as a cylindrical counter electrode. A back electrode roller 22 is rotatably arranged on a chassis (not shown), and is configured to be able to convey the support body 20 as an image receiving body inserted into the gap. In addition, below the aperture electrode body 1, along the longitudinal direction of the aperture electrode body 1, the toner supply device 10 is provided.
Further, a fixing device 26 is arranged at the destination of the conveyed support 20.

Next, the respective components will be described in detail. The toner supply device 10 includes a toner case 11 which also serves as a housing of the entire device, and a toner 16 which is stored in the toner case 11 as charged particles. A supply roller 12, a toner carrying roller 14 as a carrying member, and a toner layer regulating blade 18 are provided.

Here, the toner carrying roller 14
Carries toner 16 and conveys it toward the aperture electrode body 1. The supply roller 12 supplies the toner 16 to the toner carrying roller 14.
Then, the supply roller 12 and the toner carrying roller 14
Are rotatably supported by the toner case 11 in the direction of the arrow shown in the figure, and the two are arranged in parallel with a slight gap. Further, the toner layer regulating blade 18 is
The amount of toner 16 carried by the toner carrying roller 14 is adjusted so as to be uniform on the roller surface, and the toner carrying roller 14 is pressed against the toner carrying roller 14.

As shown in FIG. 2, the aperture electrode body 1 includes a 25 μm thick insulating sheet 2 made of polyimide and having a diameter of 1 μm.
A plurality of apertures 6 having a size of 00 μm are formed in one row, and a control electrode 4 having a thickness of 1 μm is formed at the peripheral edge of the opening of each aperture 6 on the upper surface of the insulating sheet 2. As shown in FIG. 1, the aperture electrode body 1 is arranged so that the control electrode 4 faces the support body 20 side and the insulating sheet 2 contacts the toner on the toner carrying roller 14 at the aperture position. .

At both ends of the aperture electrode body 1, an exciting body 30 as an exciting means and a vibration absorbing body 32 are provided so that a traveling wave of ultrasonic vibration is generated on the insulating sheet 2. The exciter 30 and the vibration absorber 32
For example, a Langevan oscillator having a structure in which a piezoelectric element is directly adhered to the insulating sheet 2 or the piezoelectric element is sandwiched is used. The exciter 30 is constructed so that it can be excited by applying an AC voltage of an appropriate frequency to the piezoelectric body by a control power supply 31. Further, a termination circuit 33 is connected to the piezoelectric element of the vibration absorber 32,
It is configured so that electromotive force due to vibration distortion can be consumed. The output voltage of the control power supply 31 is changed by the control device based on the flowchart described later.

A control voltage application circuit section 8 is connected between the control electrode 4 and the toner carrying roller 14. The control voltage application circuit unit 8 is configured to apply a voltage of 0 V or +50 V to the control electrode 4 based on the image signal.

Further, a back electrode 22 is arranged behind the support.

Further, a DC power supply 24 is connected between the back electrode roller 22 and the toner carrying roller 14, and this DC power supply can apply a voltage of +1 kV to the back electrode roller 22. It is like this.

Next, the electrical construction of the image forming apparatus will be described with reference to FIG.

The control device as the control means of the image forming apparatus of this embodiment is composed of a well-known microprocessor (hereinafter simply referred to as CPU) 35, and is connected to a ROM 36 and a RAM 37 which store a control program. There is. The CPU 35 can control the control voltage applying circuit unit 8 based on an image signal input from the outside,
Further, the output voltage can be varied by controlling the control power supply 31.

Next, the operation of the image forming apparatus configured as described above will be described with reference to the flowchart shown in FIG.

First, when the user turns on the power, the device starts up. Then, in S1, the CPU 35 controls the output voltage of the control power supply 31 to generate a strong excitation voltage, for example, 1
00 volt is applied to the exciter 30. Then the exciter 30
Vibrates greatly, and a progressive wave of ultrasonic vibration is generated on the aperture electrode body 1. At this time, the vibration amplitude of the insulating sheet 2 is about 0.5 μm. The traveling wave travels through the aperture 6 of the insulating sheet 2 in the direction of the vibration absorber 32, and is consumed and absorbed by the resistance component in the termination circuit 33. As a result, dust, dust, abnormal toner, or the like that has accumulated in the aperture 6 when the apparatus is stopped is removed by strong vibration, and printing is not hindered.

Without inputting a print start command (S
2: N) When a predetermined time has elapsed (S3: Y), in S4, the CPU 35 controls the output voltage of the control power supply 31 to once set the output voltage to zero volt, and the aperture electrode body 1
Stop the excitation of.

Next, in S1, strong excitation or S4 is performed.
When the print start command is input while the excitation is stopped in (S2: Y or S5: Y), C
The PU 35 controls the output voltage of the control power supply 31 to apply the weak excitation voltage to the exciter 30 (S6). A voltage which is lower than the strong excitation voltage and which does not adversely affect printing is selected as the weak excitation voltage, for example, about 30 volts. As a result, very small vibrations are excited near the aperture 6, and it is possible to prevent clogging of holes without affecting printing.

In this state, the printing described below is executed (S7).

First, the supply roller 1 is rotated by rotating the toner carrying roller 14 and the supply roller 12 in the direction of the arrow shown in FIG.
The toner 16 sent from 2 is the toner carrying roller 1
4 is rubbed against the toner carrier 4, is negatively charged, and is carried on the toner carrying roller 14. Toner 16 carried
After being thinned and negatively charged by the layer regulation blade 18, the toner is conveyed toward the aperture electrode body 1 by the rotation of the toner carrying roller 14. Then, the toner on the toner carrying roller 14 is supplied to the bottom of the aperture 6 while being rubbed by the insulating sheet 2 of the aperture electrode body 1.

Here, the CPU 35 applies a control voltage to the control electrode 4 of the aperture electrode body 1 via the control voltage application circuit section 8 in accordance with the image signal. That is, a voltage of +50 V is applied from the control voltage application circuit unit 8 to the control electrode 4 corresponding to the image portion. As a result, near the aperture 6 corresponding to the image portion, an electric force line from the control electrode 4 toward the toner carrying roller 14 is formed due to the potential difference between the control electrode 4 and the toner carrying roller 14. As a result, the negatively charged toner receives an electrostatic force in the direction of higher electric potential, passes through the aperture 6 from the toner carrying roller 14, and is drawn out to the control electrode 4 side. The extracted toner 16 further flies toward the support body 20 due to the electric field formed between the support body 20 and the aperture electrode body 1 by the voltage applied to the back electrode 22, and on the support body 20. To form pixels.

Further, a voltage of 0V is applied from the control voltage application circuit section 8 to the control electrode 4 corresponding to the non-image portion. As a result, since no electric field is formed between the toner carrying roller 14 and the control electrode 4, the toner 16 on the toner carrying roller 14 does not receive the electrostatic force and therefore does not pass through the aperture 6.

Further, the support 20 is fed by one pixel in the direction perpendicular to the aperture row while the toner 16 forms one row of pixels on the surface thereof. Then, the toner image is formed on the entire surface of the support 20 by repeating the above process. Then, the formed toner image is fixed on the support 20 by the fixing device 26.

When recording on one support 20 is completed in this way (S8: Y), the CPU 35 performs strong excitation again in S1 to remove the toner and the like remaining on the aperture electrode body 1, and next time. Prevent failure.

In the case of continuous printing, the next page is printed while the weak excitation is performed again in S6 by the next print start command, and the strong excitation is performed again after the final output. Stop.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention.

For example, in the above embodiment, the control voltage of the aperture corresponding to the non-image portion is set to 0V, but this may be a negative voltage. In this case, an image with less fogging can be obtained. Further, in the above embodiment, the aperture electrode body is used as the toner flow control means, but it is also possible to use, for example, a stitched electrode body as described in JP-A-1-503221.

Further, in the present embodiment, the weakly excited state is formed as the weakly excited state, but it may be a non-excited state as long as there is no clogging of holes during printing.

Further, in this embodiment, the mechanism is constructed in a state where the aperture electrode and the carrying roller are always in contact with each other. However, a mechanism that can separate the aperture electrode and the carrier roller is provided,
A contact may be made in the printing state, and the toner may be separated at the time of strong excitation to enhance the toner removing property, or the output voltage of the control power supply may be FM-modulated so that the frequency periodically changes.

[0036]

As is apparent from the above description, the image forming apparatus of the present invention makes it possible to easily obtain high resolution recording. The cost of the device is low, and a device having excellent recording characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment embodying the configuration of an image forming apparatus of the present invention.

FIG. 2 is a perspective view showing a configuration of an aperture electrode body used in the image forming apparatus of the present invention.

FIG. 3 is a block diagram showing an electrical configuration of the image forming apparatus of the present invention.

FIG. 4 is a flowchart of an operation related to excitation control.

[Explanation of symbols]

 1 Aperture electrode body 2 Insulating sheet 4 Control electrode 6 Aperture 8 Control voltage application circuit section 14 Toner carrier roller 22 Back electrode 23 Holding member 24 DC power supply 30 Exciter 31 Control power supply 35 CPU

Claims (2)

[Claims] 1. A carrier for holding and supplying charged particles, an electric field control unit for controlling a flow of charged particles supplied from the carrier by an electric field, and an image receptor arranged with respect to the electric field control unit. In the image forming apparatus including the opposed electrodes, at least an exciting means for exciting the electric field controlling means is provided, and a controlling means for changing an exciting state of the exciting means is provided. 2. The image forming apparatus according to claim 1, wherein the control unit controls the excitation unit so as to strongly excite the electric field control unit during non-image formation as compared with during image formation.