JP2520502B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus using powder toner.

(Prior Art) For word processors, facsimile machines, computers and the like, an image forming method using an ink jet printer is known.

Ink jet printers are typical of so-called non-impact printers.
By applying pressure while applying ultrasonic vibration with a piezoelectric element or the like, the liquid ink is ejected from an ink nozzle into a predetermined electric field, and the ink particles are controlled by the electric field to adhere to the recording paper Are formed on the recording paper. Such an inkjet printer system has an advantage that noise is not generated when an image is formed and a clear image can be formed. On the other hand, in order to control the speed at which ink permeates the recording paper, it is necessary to use special paper that has undergone surface treatment, etc., and since ink is supplied from the nozzle, the nozzle has foreign matter inside the ink. There is a problem that it is easily clogged due to factors such as.

In order to solve the problem of such an ink jet printer, an image forming apparatus using powder toner as an image recording medium is disclosed in, for example, Japanese Patent Laid-Open No. 62-263962. This image forming apparatus is provided with toner control means for controlling powder toner particles to pass through a pinhole-shaped toner passage hole by electrostatic attraction generated in response to an image output signal. By the toner control means,
A predetermined recording image is formed on the recording paper by selectively feeding the toner particles onto the recording paper. In such an apparatus, plain paper that has not been surface-treated can be used as recording paper, and since fine particle powder toner is used, clogging of toner in each toner passage hole is suppressed. To be done.

The toner control means for controlling the powder toner is provided with an insulating substrate provided with a large number of pinhole-shaped toner passage holes, and the insulation substrate interposed so as to form an electric field in each toner passage hole. And a pair of electrodes provided. Each pair of electrodes is provided with a pinhole-shaped through-hole of the same size as each toner passage hole, and each through-hole is formed on one surface of the insulating substrate. Installed in aligned condition. Then, a predetermined voltage is applied between both electrodes to form an electric field in the toner passage hole in a predetermined direction, so that the toner particles pass through the toner passage hole. When the toner particles are not allowed to pass through the toner passage hole, a predetermined voltage is applied between the electrodes so that an electric field is formed in the toner passage hole in a direction opposite to the direction in which the toner passes. You.

The insulating substrate on which a large number of pinhole-shaped toner passage holes are formed is usually made of plastic, and each electrode is an aluminum plate with a large number of pinhole-shaped throughholes, and each throughhole has an insulating property. It is configured to be stacked so as to be aligned with the toner passage hole of the substrate.

(Problems to be Solved by the Invention) In recent years, image forming apparatuses have been required to form high-quality images, and for this reason, there has been a demand for reducing the diameter of toner passage holes. Since the toner passing through the toner passage hole forms dots on the recording paper, the dot diameter can be reduced by reducing the diameter of the toner passage hole. However, if the diameter of the toner passage hole is reduced, the toner may be clogged in the toner passage hole. In order to suppress the toner clogging, the thickness of the insulating substrate may be reduced and the axial direction of the toner passage hole may be shortened.

However, since an insulating substrate having a large number of toner passage holes is provided with a pair of electric fields that form a predetermined electric field in each toner passage hole, a predetermined dielectric breakdown strength is required, and mechanical insulation Strength is also required. Therefore, it is not easy to reduce the thickness of the insulating substrate.

The present invention solves the above-mentioned conventional problems, and an object thereof is to make it possible to thin the insulating substrate on which the toner passage holes are formed, and thus to form a small-diameter toner passage hole that does not clog the toner. Therefore, an object is to provide an image forming apparatus capable of forming a high quality image.

(Means for Solving the Problems) The image forming apparatus of the present invention is an insulating substrate made of polymide provided with a toner passage hole, and a toner provided so as to sandwich the insulating substrate and communicating with the toner passage hole. Toner control means having a pair of electrodes each having a passage hole, and ultrasonic vibration applied to the insulating substrate placed on the insulating substrate to pulverize the toner conveyed to one electrode. Then, an ultrasonic vibration generating means for dropping the toner into the toner passage hole formed in the electrode and an electric field at least in the toner passage direction are formed in each toner passage hole according to the image information. And image information generating means for setting a predetermined potential between electrodes forming a pair with the toner control means, whereby the above object is achieved.

(Operation) Toner is conveyed onto one of the electrodes located above the insulating substrate, for example, via a toner supply roller.
Here, since one of the electrodes and the outer peripheral surface of the toner supply roller are close to each other, the toner located between the two is pressed into a lump.

However, the ultrasonic vibration generating means is placed on the insulating substrate, and the insulating substrate and the pair of electrodes assembled to this are vibrated. For this reason, the lumped toner on one electrode is crushed by the vibration.

Here, a toner passage hole communicating with the toner passage hole formed through the insulating substrate is also formed in this electrode.
For this reason, the toner crushed on the electrode immediately falls into the toner passage hole. Therefore, the pulverized toner does not scatter around and is efficiently guided into each toner passage hole through the toner passage hole.

As described above, in the present invention, the lump of toner conveyed to one of the electrodes is crushed on the electrode, so that only the crushed small-diameter toner drops into the toner passage hole. Moreover, in the present invention, the insulating substrate is made of polymide. Here, the polymide has a dielectric breakdown voltage and a tensile strength even if it is thin. Therefore, the thickness of the insulating substrate should be 1m.
Since the diameter can be set to m or less, even if the diameter of the toner passage hole is reduced to reduce the dot diameter to improve the image quality, the small-diameter toner is not clogged.

(Example) Hereinafter, the Example of this invention is described.

As shown in FIG. 1, the image forming apparatus of the present invention has a toner container 10 containing powder toner. Above the toner storage container 10, it communicates with a toner storage section such as a toner hopper, and the toner is sequentially supplied to the toner storage container 10. An opening 11 is provided in the lower portion of the space in which the toner is stored in the toner storage container 10, and an upper portion of a toner supply roller 20 as a toner supply unit is fitted in the opening 11. There is. The toner contained in the toner container 10 is sequentially supplied downward by the rotation of the toner supply roller 20.

Below the toner supply roller 20, a toner control means 30 is provided in a state close to the toner supply roller 20. An image signal is supplied from the image information generating unit 50 to the toner control unit 30. The image information generating means 50 operates in response to a signal from a device body such as a word processor, a facsimile, a computer, etc., and generates an electric signal corresponding to the image information. According to this electric signal, the toner supply roller
The powder toner fed from the printer 20 is controlled by the toner controller 30, and a predetermined toner image is formed on the recording paper 70. The toner control means 30 may be in pressure contact with the toner supply roller 20.

The toner control means 30 is provided with an ultrasonic vibration generating means 40 for applying ultrasonic vibration, and below the toner control means 30, a base electrode 60 is provided facing the toner control means 30. ing.

On the base electrode 60, a recording paper 70 on which a toner image is formed is placed. The base electrode 60 may be moved in the direction of arrow A together with the recording paper to be placed, or
The base paper 60 is fixed, and the recording paper is conveyed by the recording paper conveying means.
Only 70 may be moved. Toner control means
When a predetermined toner image is formed on the recording paper 70 by 30, the recording paper 70 is conveyed to a predetermined fixing device (not shown), and the fixing device fixes the toner image on the recording paper 70. You.

As shown in FIG. 2, the toner control means 30 has a horizontal insulating substrate 31. The edge substrate 31 is made of polyimide. The insulating substrate 31 is provided with a large number of pinhole-shaped toner passage holes 31a penetrating in the vertical direction. Further, the ultrasonic vibration generating means 40 is disposed on the insulating substrate 31, and the ultrasonic vibration generating means 40 is provided.
Thereby, ultrasonic vibration is applied to the insulating substrate 31.

On the upper surface of the insulating substrate 31, a common electrode 35 is provided corresponding to each of the pinhole-shaped toner passage holes 31a.
The common electrode 35 is provided with a large number of pinhole-shaped through holes 35a penetrating vertically in the same size as the toner passing holes 31a.
Each through hole 35a is aligned with 31a, and the common electrode
35 is attached to the insulating substrate 31. Further, on the lower side of the insulating substrate 31, in correspondence with each toner passage hole 31a,
Signal electrodes 33 are provided respectively. Each signal electrode 33
Is also provided with a through hole 33a having the same size as each through hole 31a of the insulating substrate 31, the through hole 33a, the insulating substrate
Each signal electrode 33 is attached to the insulating substrate 31 so as to be aligned with each toner passage hole 31a of 31.

The common electrode 35 on the insulating substrate 31 is grounded. An image information generating means 50 is connected to each signal electrode 33 provided on the insulating substrate 31, and an electric signal is input from the image information generating means 50 to each signal electrode 33. Predetermined positive and negative potentials are applied to the respective signal electrodes 33 according to the image information. For example, in the case of information for which an image is to be formed, + 100V, for non-image information that does not require image formation, In this case, it is controlled so that a voltage of -100V is applied.

The insulating substrate 31 made of polymide in which a large number of toner passage holes are formed has a thickness of 1 mm or less. Since polymide has a breakdown voltage of 50 KV / mm or more and a tensile strength of 1 Kg / mm ² or more, even if its thickness is 1 mm or less, the voltage applied by each electrode 33 and 35 is There is no risk of damage, and there are many toner passage holes 31.
Even if an electrode is formed in each toner passage hole 31a by forming a, there is no risk of damage.

A process of forming a toner image by the image forming apparatus having such a configuration will be described.

When the toner supply roller 20 rotates, the toner container 10
The toner inside is supplied onto each common electrode 35 of the toner control means 30. The common electrode 35 is provided with ultrasonic vibration of a constant amplitude through the insulating substrate 31 by the ultrasonic vibration generating means 40 provided on the insulating substrate 31 made of polymide. The toner lumps of are crushed as appropriate, and the toner passage holes 3a of the insulating substrate 31 are passed through the through holes 35a of the common electrode 35.
Fall into 1a. Since the insulating substrate 31 is made of polymide, there is no risk of damage even if ultrasonic vibration is applied, and the ultrasonic waves propagated to the insulating substrate 31 cause the toner mass on each common electrode 35 to be lumped. Is reliably crushed.

The toner particles falling into the toner passage hole 31a of the insulating substrate 31 are controlled according to the image signal given to the signal electrode 33, and fall on the recording paper 70 or return to the common electrode 35.

For example, when a positive voltage is applied to the signal electrode 33 by the image information generating means 50, the signal electrode 3 is placed in the toner passage hole 31a.
An electric field is generated from 3 toward the counter electrode 35. Due to this electric field, the toner particles that have been negatively charged in advance
33, passes through the signal electrode 33, and passes through the base electrode 60.
It falls on the upper recording paper 70. Since a positive bias voltage is applied to the base electrode 60 with respect to the common electrode 35, the toner particles are promoted to drop from the toner passage hole 31a. The bias voltage applied to the base electrode 60 is sufficiently higher than the electric signal applied to the signal electrode 33, and in the case of negatively charged toner, it is 300 to 1000 V.
Range. If the bias voltage is less than 300V, the toner drop position may vary, and the image formed on the recording paper 70 may be disturbed. On the contrary, if the bias voltage is higher than 1000V, discharge may occur.

A non-image signal is given by the image information generating means 50,
When a negative voltage is applied to the signal electrode 33, the toner passage hole 31
In a, an electric field is formed from the upper common electrode 35 to the lower signal electrode 33, and the negatively charged toner is returned to the common electrode 35. As a result, a predetermined image is formed on the recording paper with the toner.

In the insulating substrate 31 made of polymide film, the ultrasonic vibration applied from the ultrasonic vibration generating means 40 is applied to the insulating substrate 31.
There is no risk of damage even when applied to 31, and it is not damaged even if holes are formed in each toner passage hole 31a and each electrode 33 and 35 is provided in each toner passage hole 31a. Further, the insulating substrate 31 is
Since the thickness is 1 mm or less, clogging of the toner particles in the toner passage hole 31a penetrating in the thickness direction is controlled. Insulating substrate 31 made of polymide
Has a high intensity, it is possible to increase the control frequency applied to the signal electrode 33. Moreover, in the insulating substrate 31 made of polymide, it is easy to form the signal electrode 33 and the common electrode 35 in the form of printed wiring.

(Effects of the Invention) In the image forming apparatus of the present invention, the ultrasonic vibration generating means is placed on the insulating substrate sandwiched by the pair of electrodes, and the ultrasonic vibration generating means vibrates the insulating substrate. Since the toner conveyed on one of the electrodes is crushed and dropped into the toner passage hole formed in this electrode, the toner crushed on the electrode is immediately crushed in the toner passage hole. Plunge into. Therefore, the pulverized toner is efficiently guided into the respective toner passage holes through the toner passage holes without being scattered around.

As described above, in the present invention, the lump of toner conveyed to one of the electrodes is crushed on the electrode, so only the crushed small-diameter toner falls into the toner passage hole.

In addition, in the present invention, the insulating substrate is made of polymide. Here, the polymide has a dielectric breakdown voltage and a tensile strength even if it is thin. For this reason, the thickness of the insulating substrate can be reduced to 1 mm or less.Thus, in order to reduce the dot diameter and improve the image quality, even if the diameter of the toner passage hole is reduced, the toner with a small diameter is It never clogs. As described above, according to the present invention, there is an effect that the clogging of the toner can be more reliably prevented by the synergistic effect of reliably crushing the toner and shortening the length of the toner passage hole. be able to. Further, there is an advantage that the image quality can be improved by reducing the diameter of the toner passage hole.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of the image forming apparatus of the present invention, and FIG. 2 is a block diagram showing the main part thereof. 10 toner container, 20 toner supply roller, 30
... Toner control means, 31 ... Polyimide insulating substrate, 31
a ... toner passage hole, 33 ... signal electrode, 35 ... common electrode, 40 ... ultrasonic vibration generating means.

Claims (1)

(57) [Claims] 1. A polymide insulating substrate provided with a toner passage hole, and a pair of electrodes provided with the insulating substrate sandwiched therebetween, each having a toner passage hole communicating with the toner passage hole. Toner control means and a toner passing hole formed on the electrode, which is placed on the insulating substrate, applies ultrasonic vibration to the insulating substrate, and crushes the toner conveyed to one electrode. Between the pair of electrodes of the toner control means so as to form an electric field in at least the toner passing direction in each toner passage hole according to the image information. An image forming apparatus comprising: an image information generating unit that sets a predetermined potential.