JPH0699607A - Image forming device - Google Patents

Abstract

PURPOSE:To constitute the title method so that generation of streaklike turbulence by synchronizing with sweep of frequency can be prevented easily to an image and clogging of aperture by a toner can be prevented effectively. CONSTITUTION:An exitation body 2 exiting an oscillation of an aperture electrode 1 is joined electrically to a driving circuit 3, this driving circuit 3 is constituted of an electric voltage control oscillator 31 generating an alternate current electric signal, a modulation control signal oscillator 32 performing modulation control of frequency of the electric signal to be put out through the electric voltage control oscillator 31 and an amplifier 33 amplifying the electric signal put out through the electric voltage control oscillator 31. Hereupon, the oscillation from which frequency is swept is exited upon the aperture electrode 1 and established so that sweep cycle of the oscillation becomes shorter than a time required for formation of dots.

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, and more particularly to an image forming apparatus for forming an image on a recording medium by directly controlling the modulation of toner by an aperture electrode. .

[0002]

2. Description of the Related Art Conventionally, the above image forming apparatus has been proposed in the specification and drawings of US Pat. No. 3,689,935. This image forming apparatus is composed of a toner crowder, an aperture electrode, and a counter electrode. The toner clouder is a means for generating a cloud of charged toner and supplying the toner cloud to the vicinity of the aperture electrode.

The aperture electrode is a control means for modulating and controlling the flow of toner from the toner cloud, and is provided on an insulating layer having a large number of apertures or openings and one surface of the insulating layer. A first electrode layer,
The second electrode layer is provided on the other surface of the insulating layer and is independently provided for each of the plurality of apertures. Further, the counter electrode attracts and holds a recording medium such as paper and is arranged so as to face the aperture electrode.

In the image forming apparatus constructed as described above, the toner flow supplied by the toner crowder is controlled by an electric signal applied to the aperture electrode and the counter electrode, so that the recording material such as paper is recorded. An image is formed.

When an image is formed by this image forming apparatus, there is a problem that the aperture portion of the aperture electrode is clogged with toner. That is, for example, in order to obtain a recording density of 240 DPI, the dot size is 100 μm at the maximum, so it is necessary to reduce the inner diameter of the aperture of the aperture electrode to about 50 μm at the maximum. When the inner diameter of the aperture is reduced in this way, toner particles are deposited on the aperture electrode due to image force and the like, and as a result, the aperture electrode is clogged with the toner particles, and it is difficult to always obtain a stable image output. There was a problem.

Therefore, the present applicant has filed Japanese Patent Application No. 2-29111.
As described in the specification and drawings attached to the application of No. 6, a method of exciting a traveling wave on the aperture electrode to prevent the accumulation of toner particles was proposed. In this method, a vibration acceleration generated by a traveling wave excited on the aperture electrode is applied to the toner particles, so that the toner particles to be deposited on the aperture electrode have a repulsive force larger than the image force or the like that causes the deposition. Is added to prevent the accumulation of toner particles. In such an image forming apparatus, when exciting the traveling wave, in order to make the amplitude distribution of the traveling wave in the traveling direction substantially constant, the energy of vibration input from the exciter is completely terminated. It needs to be consumed by the body. For that purpose, it is necessary to make a complicated device such as perfect impedance matching at the terminal end, and it is very difficult to completely eliminate the reflected wave. As a method for solving this problem, a method has been proposed in which the node pattern of the standing wave formed on the aperture electrode is moved by sweeping the frequency of vibration.

[0007]

However, when the frequency of the vibration excited on the aperture electrode is swept as described above, the sweep period becomes longer than the time required for the toner charged by the aperture electrode to form dots. , The image formed as a collection of these dots,
There has been a problem that a striped disturbance parallel to the propagation direction of vibrations synchronized with the sweep period occurs.

The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to easily prevent the occurrence of striped disturbances synchronized with the sweep cycle in an image,
Another object of the present invention is to provide an image forming apparatus provided with means capable of effectively preventing clogging of the aperture due to toner.

[0009]

In order to achieve this object, an image forming apparatus of the present invention comprises an aperture electrode for modulating and controlling charged toner to form dots on a recording medium.
A vibrating body attached to the aperture electrode for vibrating the aperture electrode and an exciter for exciting the vibrating body are provided, and the frequency of the vibration excited in the vibrating body is swept. A sweeping means is provided, and a sweeping cycle of the frequency of the vibration is set shorter than a time required to form the dots.

[0010]

The image forming apparatus of the present invention having the above structure is
By the sweeping means, the value of the vibration frequency of the incident wave and the reflected wave, or the difference between them and the phase difference between them change in a cycle shorter than the time required for dot formation, so the effect of the vibration frequency sweep on the formed image is Also, since the node pattern of the standing wave is constantly moved, the aperture is not clogged with the toner particles. As a result, it is possible to easily prevent the occurrence of striped disturbance in the image.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 5, the toner jet recording apparatus 1
Reference numeral 00 includes a recording unit 101 and a heat fixing unit 102. An insertion opening 117 for inserting a paper P to be recorded is provided on the side of the toner jet recording apparatus 100.
And a take-out port 11 for taking out the recorded paper P
And 8 are provided. In the recording unit 101,
The pair of feed rollers 11 are inserted from the insertion opening 117.
An image is recorded on the paper P conveyed by 6. Then, the image recorded on the paper P is fixed in the heat fixing unit 102. Further, the paper P is sent to the take-out port 118 via the guide 115.

The recording section 101 is provided with a brush for charging the toner T and is rotatable, a brush roller 103, an aperture electrode 1, and a counter electrode 112 provided to face the aperture electrode 1 at a predetermined interval. It consists of and. The counter electrode 112 is connected to the power source E2 (minus).

The heat fixing section 102 comprises a heat roller 113 having a heat source and a press roller 114. The heat roller 113 and the press roller 114 are arranged so that the paper P can pass between these rollers.

Around the brush roller 103, it is rotatable according to the rotation direction of the brush roller 103, and a supply roller 104 for supplying the toner T to the brush roller 103 and a toner T attached to the brush of the brush roller 103. A scraping member 110 for repelling the brush is provided in contact with the brush roller 103, respectively. Further, a supply blade 111 for supplying the toner T to the supply roller 104 in a uniform thickness is provided in contact with the supply roller 104. The toner T is stored on the supply blade 111. The supply roller 104 and the supply blade 111 are covered with a case K. The aperture electrode 1 is provided above the brush roller 103.

Next, the structure of the aperture electrode 1 will be described with reference to FIG.

As shown in FIG. 1, the aperture electrode 1 is
The insulating layer 106 and the reference electrode layer 107 are superposed on each other, and the vibrating body 21 is provided on the side of the reference electrode layer 107. On the insulating layer 106 side, a large number of control electrode layers 108 formed in rows are provided. The control electrode layer 108 includes the insulating layer 106, the reference electrode layer 107, and the vibrating body 21, respectively. Aperture 1 to penetrate
1 is provided. Further, the vibrating body 21 excites vibrations following the vibrations excited by the vibrating body 21 on the aperture electrode 1. The vibrating body 21 is composed of a rectangular flat metal plate. The vibrating body 21 is provided with an exciting body 2 for exciting the vibrating body 21 at one end, and a reflecting body 20 for reflecting the vibration incident from the exciting body 2 is provided at the other end. There is.

The excitation body 2 is formed of a laminated piezoelectric body, and the shape and size of the excitation body 2 are such that the resonance frequency of the lowest extensional vibration in the Y direction of the excitation body 2 is that of the vibration excited on the aperture electrode 1. It is adjusted to be sufficiently higher than the frequency.

The aperture electrode 1 is arranged so that the vibrating body 21 side faces the brush roller 103 side. The reference electrode layer 107 is connected to the ground, and the multiple control electrode layers 108 are connected to multiple signal sources (not shown).

Now, with reference to FIG. 2 to FIG. 4, a sweep method and a sweep cycle of the vibration frequency of the vibration excited on the aperture electrode 1 will be described.

Exciter 2 provided at one end of vibrator 21
Are electrically connected to the drive circuit 3, and the drive circuit 3 is, as shown in FIG. 2, a voltage controlled oscillator 31 that generates an AC electric signal and an electric signal output from the voltage controlled oscillator 31. It is composed of a modulation control signal oscillator 32 that modulates and controls the frequency of 1 and an amplifier 33 that amplifies the electric signal output from the voltage control oscillator 31.

The voltage control oscillator 31 is an oscillator in which the frequency of the output AC signal is modulated and controlled by the voltage of the control signal applied from the modulation control signal oscillator 32. Therefore, when the control signal applied from the modulation control signal oscillator 32 to the voltage controlled oscillator 31 is a sinusoidal signal as shown in FIG. 3, the drive signal applied from the drive circuit 3 to the exciter 2 is shown in FIG. As shown in, the frequency changes with time, so-called frequency swept signal. The excitation body 2 has a resonance frequency of the lowest order stretching vibration in the Y direction sufficiently higher than the frequency of the vibration excited on the aperture electrode 1 so as to expand and contract following the electric signal applied from the drive circuit 3. Since the shape and size of the aperture electrode 1 are adjusted so that when a signal whose vibration frequency is swept at a period t1 as shown in FIG.
Since the frequency difference and the phase difference between the incident wave and the reflected wave that are excited by are constantly changing, the node pattern of the standing wave formed on the aperture electrode 1 always moves.

Here, the above-mentioned vibration frequency sweep period t1
Is determined as follows. Printing speed is v [mm /
s] and the resolution is n [dot / mm], the time t2 required to form one dot on the paper P is t2 = 1 / (v · n). Therefore, if the vibration frequency sweep period t1 is set such that t1 <t2, the image formed on the paper P will have stripe-shaped disturbances in parallel with the vibration propagation direction in synchronization with the sweep period t1. There is no such thing. For example, set the printing speed to 1
When 0 [ppm] and the resolution is 300 [dpi], v≈50 [mm / s] n≈11.8 [dot / mm], so t2≈1.7 [ms]. Therefore, the oscillation frequency sweep period t1 is about 1 [m
s] or less. Further, when the matrix-like structure as disclosed in Japanese Patent Publication No. 59-43317 is adopted as the structure of the aperture electrode, the sweep cycle t1
Needs to be even shorter.

Next, the operation of the toner jet recording apparatus 100 will be described with reference to FIG.

When a well-known image forming signal and image data are input from an external device (not shown), the paper P inserted from the insertion opening 117 is fed by the feed roller 116 to the recording unit 101.
Be transported to. In the recording unit 101, the toner T is pressed against the supply roller 104 by the supply blade 111 and carried on the surface of the supply roller 104. The toner T is transferred to the brush roller 1 by the rotation of the supply roller 104.
03. At this time, the toner T is supplied to the supply roller 1
While being in contact with 04 and the brush roller 103, they are charged positively (+) by friction with the brush. The positively charged toner T is carried on the brush roller 103.

In the vicinity of the aperture electrode 1, the scraping member 110 scrapes the brush of the brush roller 103 as the brush roller 103 rotates. Then, when the brush returns to its original position due to elasticity, the toner T carried by the brush in an appropriate amount jumps up and is supplied to the aperture electrode 1 in the form of a cloud. At this time, each control electrode layer 1 of the aperture electrode 1 is changed from the signal source S in accordance with the input image signal.
The voltage applied to 08 is controlled to modulate the flow of toner T.

At this time, if a signal whose vibration frequency is swept at the sweep period t1 is applied to the exciter 2, as described above, the position of the node of the standing wave formed on the aperture electrode 1 forms a dot. Always move in a cycle shorter than time. Therefore, even if the charged toner T tries to adhere to the same position in the vicinity of the apertures 11 forming the aperture array 12 due to the image force or the like, the position of the aperture array 12 is affected by the vibration excited by the exciter 2. Since a large vibration acceleration is generated, the toner T does not adhere to the aperture 1
No clogging of 1. Further, the sweep of the vibration frequency for one cycle is completed in a time t1 shorter than the time t2 in which one dot is formed. As a result, the toner T supplied to the aperture electrode 1 is constantly and stably modulated by the voltage applied to each control electrode layer 108 from the signal source, and adheres onto the paper P.

That is, the modulated and positively (+) charged toner T is attracted by the negative (-) power source E2 connected to the counter electrode and flies toward the counter electrode. And
The toner T is attracted to the paper P guided by the guide 115 and the feed roller 116.

After that, the paper P on which the toner T is attached is conveyed to the heat fixing section 102. The image formed by the toner T adhering to the paper P is the heat roller 113.
The toner T is pressed against the press roller 114 to fix the toner T. Since this fixing method is a general method, detailed description is omitted. Then, the fixed sheet P is conveyed to the take-out port 118 via the guide 115 and is ejected.

Next, with reference to FIG. 1, the operation of the aperture electrode 1 configured as described above will be described. When the sine wave signal shown in FIG. 3 is applied from the modulation control signal oscillator 32 to the voltage controlled oscillator 31, the AC electrical signal whose frequency is swept as shown in FIG. 4 from the voltage controlled oscillator 31 as described above. Is output. When the frequency-swept electric signal is applied to the exciter 2, the exciter 2 excites the aperture electrode 1 on which the vibration frequency is swept as shown in FIG. Here, the sweep cycle t1 of the vibration frequency is determined to be shorter than the time t2 required for dot formation, as described above in detail, so the exciter 2
Since the position of the node of the standing wave formed by the incident wave that is made incident from and the reflected wave that is reflected by the reflector 20 constantly moves in a cycle shorter than the dot formation time t2, the image formed on the paper P Is not affected by the vibration frequency sweep. Also, the aperture is not clogged with toner particles. As a result, an image as a set of dots is always clearly formed on the paper P.

Here, the excitation body 2 and the reflector 20 are
By arranging the vibrations entering the vibrating body 21 from the exciter body 2 and the vibrations reflected by the reflector body 20 so that the propagation directions thereof are substantially orthogonal to the feeding direction of the sheet P, the effect of preventing clogging of the aperture is obtained. Is high.

Further, the sweep range of the vibration frequency is set in Japanese Patent Application No.
As described in the specification and drawings attached to the application No. 120512, when the range including at least two types of resonance modes of the vibrating body 21 is set, the effect of preventing clogging of the aperture is high.

Further, the effect of preventing the clogging increases as the vibration acceleration increases. Therefore, in order to effectively prevent the clogging, the amplitude and frequency of the vibration excited on the aperture electrode 1 may be increased. Generally, when trying to excite a high frequency, its amplitude becomes small. Therefore, it is necessary to appropriately determine the excitation frequency according to the material of the aperture electrode 1 and the like.

In the embodiment of the present invention, the voltage controlled oscillator 31 is exemplified as the vibration frequency modulating means of the exciter, but the method is not limited to this method, and other methods may be used. Any method that can modulate the vibration frequency of the body 2 does not impair the effects of this method.

Although the resonator 2 made of a laminated piezoelectric material has been taken as an example of the excitation body 2, any method that can excite vibrations in the aperture electrode 1, for example, a method using magnetic force, etc. Even with this method, the same effect as that of the present invention can be obtained.

Other various modifications are possible without departing from the spirit of the present invention.

[0037]

As is apparent from the above description, the image forming apparatus of the present invention is provided with an aperture electrode for modulating and controlling charged toner to form dots on a recording medium, and an aperture electrode attached to the aperture electrode. And a vibrating body for vibrating the vibrating body, and an exciting body for exciting the vibrating body, further comprising a sweeping means for sweeping the frequency of the vibration excited by the vibrating body, and the sweeping period of the dot, By making it shorter than the time required for forming, the position of the node of the standing wave excited on the aperture electrode moves in a cycle shorter than the dot formation time, so it is synchronized with the vibration frequency sweep of the vibrating body in the image. The striped disturbance does not occur, and as a result, a clear image can be easily obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an aperture electrode used in an image forming apparatus of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of an exciter and a drive circuit connected thereto.

FIG. 3 is an explanatory diagram of a control signal input from a modulation control signal oscillator to a voltage control oscillator.

FIG. 4 is an explanatory diagram of a frequency-modulated electric signal applied from a drive circuit to an exciter.

5 is a diagram showing a configuration of an image forming apparatus using the aperture electrode shown in FIG.

[Explanation of symbols]

 1 Aperture Electrode 2 Exciter 21 Vibrator 31 Voltage Controlled Oscillator 32 Modulation Control Signal Oscillator P Paper

Claims (1)

[Claims] 1. An aperture electrode for modulating and controlling charged toner to form dots on a recording medium, and a vibrating body attached to the aperture electrode for vibrating the aperture electrode.
In an image recording apparatus including an exciting body that excites the vibrating body, a sweeping unit that sweeps a frequency of vibration excited in the vibrating body is provided, and a sweep cycle of the sweeping unit is required to form the dots. An image forming apparatus that is shorter than the time.