JPH02188770A - Image recorder - Google Patents

Abstract

PURPOSE:To eliminate the adverse effect of a toner cloud on image quality and to improve the image quality by impressing a voltage having the same polarity as toner on an auxiliary electrode provided around a back electrode. CONSTITUTION:The auxiliary electrode 21 is provided near the back electrode supporting part of a supporting body 6 and the bias voltage having the same polarity as the toner is impressed on it. That means, when recording operation is executed by impressing a positive voltage on the back electrode 7, repulsing and flying the toner (the developer) which is electrostatically charged negatively from a recording electrode array 4 where a negative voltage is impressed and attaching the toner to a material to be transferred, the bias voltage having the same polarity as the toner, that means, the negative bias voltage is impressed on the auxiliary electrode 21. Due to that, the auxiliary electrode 21 fills the function that it keeps the floating toner which gets off an original conveying path to the back electrode 7 side from a recording head, becomes the toner cloud and scatters outside back in the conveying path by coulomb force according to the line of electric force 22. Thus, the toner cloud is suppressed and the toner is attached to the material to be transferred by following the original conveying path.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention conveys a transfer material between a recording electrode array and a back electrode arranged opposite each other, and records an image by adhering a developer to the transfer material. It relates to a recording device.

As a conventional example of this type of image recording device, Japanese Patent Application Laid-Open No. 57-1
There are devices described in Japanese Patent Application Laid-open No. 14156 and Japanese Patent Application Laid-open No. 190964/1983, and their configurations are generally as shown in FIG. 4.

This image recording apparatus performs a recording operation by applying toner (developer) 17 from the recording electrode 4 side to a transfer material 5 such as recording paper that is conveyed between a recording electrode 4 and a back electrode 7 that are arranged facing each other. The basic configuration is to perform the following.

To be more specific, a magnet roller l that rotates clockwise as indicated by the arrow in the figure is rotatably provided inside the sleeve 2 that is fixedly arranged at a predetermined position in the main body of the device. As a result, the positively or negatively charged developer 17 is taken out from the casing 16.

The developer 17 taken out moves so as to cover the peripheral surface of the sleeve 2 in a thin layer, and is conveyed to the position of the recording head 3 provided on the left end peripheral surface of the sleeve 2.

The recording head 3 has a support block 3 that is long in the front and back direction of the paper surface.
0, and a recording electrode array 4 in which a large number of pin electrodes (not shown) are embedded in an array in the longitudinal direction. A back electrode 7 is provided on the left side of the recording head 3.
are placed opposite each other.

The back electrode 7 is supported by a holder 6 as shown in FIG. The holder 6 has a block shape long in the axial direction of the sleeve 2, and has a structure in which the back electrode 7 is supported under pressure at the center of the holder 6. The length of the back electrode 7 is set to be approximately the same as that of the recording electrode array 4. Holder 6
The tip end face is formed with an R (R) 60 to smoothly guide the movement (sliding movement) of the transfer material 5.

The recording electrode array 4 is connected to a recording electrode (pulse power source) 12 that selectively applies a voltage corresponding to a recording signal to each pin electrode, while the back electrode 7 is connected to a bias power source 8. Thus, when a voltage is applied to each pin electrode of the recording electrode array 4 and a potential difference is created between this and the back electrode 7, the electric field formed between them transports the recording head 3 to the position of the recording head 3. The toner 17 adheres to the transfer material 5, and a recording operation is performed.

As the developer, a one-component developer of a conductive magnetic toner or an insulating magnetic toner, or a two-component developer formed by stirring and mixing a magnetic toner and a magnetic carrier is used.

In order to improve the image quality in such an image recording device, it is necessary to pay attention to the following points.

■Ensure sufficient image density.

For this purpose, it is necessary to control the layer thickness of the developer that moves in a thin layer on the sleeve 2.

■To suppress fogging (a phenomenon in which noise components such as black dots are printed on the periphery of print, impairing image quality) and to improve contrast.

For this purpose, it is necessary to control the distance between the toner 17 and the transfer material 5.

■Have sufficient resolution.

For this purpose, it is necessary to manage the electric field strength (distribution) between the recording electrode array 4 and the back electrode 7.

■Select the type of developer appropriately.

In the image recording apparatus configured as described above, the layer thickness management of the toner 17 described in the above item (2) is performed by adjusting the separation distance between the sleeve 2 and the tip of the doctor blade 18.

Incidentally, according to the results of experiments conducted by the present inventors using a developer made by stirring and mixing a non-magnetic toner made of styrene-acrylic resin and a magnetic carrier made of insulating ferrite, it was found that a uniform layer thickness could be obtained. In order to obtain a beam, it was necessary to satisfy the condition of ≧0.2 cranes. It should be noted that if D is made infinitely large, the magnetic force between the toner 17 and the sleeve 2 will weaken, causing smoke to be generated and causing fog.
An upper limit value will naturally be determined.

In addition, the separation distance between the toner 17 and the transfer material 5, as described in (2) above, is controlled by the separation distance between the recording electrode array 4 and the back electrode 7, more specifically, the front end surface of the holder 6 that supports it. This is done by adjusting D3.

That is, if D3 is made infinitely small, the transferred material 5 will eventually come into contact with the toner layer, causing capri, and the toner layer will partially swell on the circumferential surface of the sleeve 2, resulting in a pooling phenomenon. As a result, the lower limit of D is naturally limited. However, if OS is made infinitely large, the lines of electric force generated between the pin electrode and the back electrode 7 will be diffused, resulting in thin wires. etc. cannot be recorded with high precision, so the upper limit value is naturally limited. Incidentally, according to the experimental results of the present invention, etc., it has been confirmed that the appropriate values are within the range of ≦D, ≦[), +Q, 3 mm.

In addition, regarding the electric field strength mentioned in item (2) above, it is sufficient to set the potential difference between the recording electrode array 4 and the back electrode 7 to be large when recording is ON (during recording operation) and small when recording is OFF (during non-recording operation). For this purpose, it is conceivable to increase the voltage applied to the recording electrode array 4 (hereinafter referred to as recording voltage v1).

However, this recording voltage v, , is limited by the following reasons. In other words, a resolution of 5 dots/w to 20 dots/ms is required for practical use, but in order to achieve this, even if the pin electrodes are selected to be as thin as possible, the distance between adjacent pin electrodes must be is several tens of μ
m.

Therefore, in the recording electrode array 4 having such dimensions, 1
If, in order to record pixels for a dot line, one of the adjacent pin electrodes is grounded and a voltage of -400 to -500 V is applied to the other, there is a problem that leakage occurs between the pin electrodes. Therefore, the recording voltage vr has an upper limit, and is practically limited to several hundred volts.

Furthermore, if the pin electrode is grounded and the back electrode 7 is grounded when recording is OFF, the toner 17 will adhere to the transfer material 5 and generate capri, so in this case, It is necessary to apply a bias voltage V of about -100 V to the back electrode 7.

From the above viewpoint, it can be inferred that the preferable values of the various dimensions and voltage values in actual use are within the ranges shown below.

D, 20.2m Ds+0.3 Weight ≧ D, ≧ 0, 2
100V J≦400V 1■11≧100V However, when the recording operation was actually performed under these conditions, capri occurred over the entire area of the transfer material 5, resulting in a problem that the contrast of the recorded image decreased. .

For this reason, after further experiments and research, we found that a toner cloud (a phenomenon in which floating toner that does not contribute to the recording operation diffuses in the form of a plume) occurs at the position of the recording head 3.
It was discovered that this was the cause of the above problem.

In order to eliminate the adverse effects of such toner cloud as much as possible, for example, a holder 6 supporting the back electrode 7 is provided.
We tried taking measures such as setting the radius of curvature of R60 smaller and correspondingly reducing the area of the transfer material 5 facing the recording head 3, but although we were able to achieve some improvement, the negative effects of the toner cloud At present, it has not been possible to completely eliminate it.

The present invention has been made in view of the current situation, and an object of the present invention is to provide an image recording apparatus that can perform high-quality recording over a long period of time.

In the present invention, a recording electrode array in which a large number of pin electrodes are arranged in a straight line is provided with a support supporting a back electrode, which supports the movement of a transfer material passed between them. In an image recording apparatus that performs recording by adhering toner to a transfer material from the recording electrode array side while being guided by the front end surface of the body, an auxiliary electrode is provided near the back electrode support portion of the support; A feature is that a bias voltage of the same polarity as the toner is applied.

As shown in Figure 2, a positive voltage is applied to the back electrode 7, and the negatively charged toner 17 (developer) is caused to repel and fly from the recording electrode array 4 to which a negative voltage has been applied. Assuming that a recording operation is performed while adhering to a transfer material (not shown), in this case, a bias voltage of the same polarity as the toner 17, that is, a negative bias voltage, is applied to the auxiliary electrode 21.

Then, this auxiliary electrode 21
2, as shown by the arrow, the floating toner that deviates from the transport path that originally goes from the recording pad 3 to the back electrode 7 side and becomes a toner cloud and tries to diffuse outward is held down within the transport path by Coulomb force. It will function like this. As a result, the toner cloud is suppressed, and the toner 17 follows the original conveyance path and adheres to the transfer material.

In other words, due to the function of the auxiliary electrode 21, the lines of electric force 22
Among the components, the component that would normally take a large detour toward the outside is electrically pushed back between the opposing surfaces of the recording head 3 and the back electrode 7, so that the density of the lines of electric force between the opposing surfaces,
In other words, the electric flux density can be improved.

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the present invention will be described in detail based on the drawings. FIG. 1 is a perspective view showing a back electrode used in an image recording apparatus according to the present invention.

The general configuration of the image recording apparatus according to the present invention is the same as that shown in FIG. 4 except that the back electrode 7 is different.
Only the back electrode 7 will be explained with reference to the drawings.

This back electrode 7 has a flat plate shape and is supported by pinching at the center of the inside of the holder 6. That is, the holder 6 is made up of two plates 6a, 6a facing each other, and the plates 6
A, 63 are integrated with the back electrode 7 sandwiched between them. A radius 60 is formed on the tip end surface of the holder 6 in the same manner as in the conventional example described above, so that the transfer material 5 can be smoothly guided in movement. The holder 6 is made of an insulating material such as acrylic resin, ABS resin, or epoxy resin. The base end of the back electrode 7 corresponding to the lower end in the figure is pulled out from the holder 6 and serves as a power cord 7a for connecting the back electrode 7 and the bias power source 8 (see FIG. 4).

Furthermore, an auxiliary electrode 21 is provided around this back electrode 7. The auxiliary electrode 21 is formed by pasting a film-like electrode material onto the surface of the holder 6 using an adhesive or the like. Specifically, the line-shaped portions 21a, 21a corresponding to the left and right sides of the back electrode 7 on the tip surface of the holder 6, and the center portion of these line-shaped portions 21a, 21a to the holder 6
Perpendicular parts 2 connected to the upper terminals on both the left and right sides of
1b.

The linear portions 21a, 21a and the back electrode 7 are insulated by slits 23.23. The base end of the vertical portion 21b is connected to the power cord 21 connected to the bias power source 8.
It has become c. Note that in the drawing, only the vertical portion 21b on the right side of the drawing, that is, on the front side, is visible.

Thus, as shown in FIG. 2, a negative voltage is applied to the recording electrode array 4 from the recording power supply 12, a positive voltage is applied to the back electrode 7 from the bias power supply 8, and
If a negative voltage is applied from the bias power source 8 to record the negatively charged toner 17 on the transfer material 5, a recording operation with excellent image quality can be achieved for the reasons stated in the above-mentioned operation section. It turns out.

In this embodiment, the entire holder 6 is made of a conductive material, and is partially insulated from the back electrode 7, and a bias voltage of opposite polarity to the toner 17 is applied to the holder 6. -6 itself may have a role as the auxiliary electrode 21. In this case, there is an advantage that the structure of the back electrode 7 can be simplified.

Further, in the above embodiment, the back electrode 7 is formed by the slit 23.
The line-shaped portion 21a of the auxiliary electrode 21 is insulated from the line-shaped portion 21a of the auxiliary electrode 21, but it is also possible to provide a step between the two and provide insulation using this step.In such a case, the slit 23 This has the advantage that it is possible to eliminate more adverse effects on electric field formation than in the case of conventional methods, thereby contributing to an improvement in image quality.

Figure 3 shows a modification of the back electrode to which the present invention is applied.
This modification takes a configuration in which a back electrode array 70 similar to the recording electrode array 4 forms the back electrode. That is, the third
As shown in the figure, in the center of the interior of the holder 6, a large number of rear pin electrodes 71 are arranged and supported under pressure. In this case, the number of back pin electrodes 71... is selected to be the same as the number of the pin electrodes, and each back pin electrode 71...
are opposite to each pin electrode.

The tip of each back pin electrode 71 is slightly recessed from the tip surface of the holder 6. Here, the reason why the tips of the back pin electrodes 71 are recessed is to substantially increase the distance between adjacent back pin electrodes 71 compared to the flush state, and to that extent,
This is to improve insulation, prevent leakage caused by creeping discharge, etc. as much as possible, and improve image quality.

Also in this modification, the auxiliary electrode 21 is provided at a position corresponding to that of the above embodiment.

Thus, when a voltage corresponding to the recording signal is selectively applied to the corresponding pin electrodes of the recording head 3 and the back pin electrode 71, an electric field is formed between them, and the electric field transports the recording head 3 to the position of the recording head 3. The incoming toner 17 is repulsed and flies, forms a toner chain, and adheres to the transfer material 5, so that a recording operation is performed.

In this way, when the back electrode is constituted by the back electrode array 70 formed by arranging a large number of back pin electrodes 71, it is possible to record images with better image accuracy than when using the integrated back electrode 7 as in the above embodiment. It has the advantage of being actionable.

Note that this back electrode array 70 is manufactured as follows. That is, a large number of back pin electrodes 71 made of enamelled wires are held in alignment, and in this state, the plate material 6 is inserted from both sides.
a, 6a facing each other, and insulating resin (not shown) such as epoxy resin is poured into the gap formed at this time, and this is solidified to form the back pin electrodes 71...
and holder 6 are integrated. Thus, in the solidified state of the resin, the back pin electrodes 71 are insulated from each other and integrated with the holder 6 in an insulated state.

However, in this manufacturing state, the tip surfaces of the back pin electrodes 71... and the surface of the holder 6 are formed flush with each other, and in the post-process described below, the tip surfaces of the back pin electrodes 71... are depressed. I will let you do so.

That is, the tip side of the back electrode array 70, in which the tip surfaces of the back pin electrodes 71 and the surface of the holder 6 are flush with each other, is immersed in an aqueous solution of iron chloride (+hydrochloric acid), and the concentration, temperature, The depression is formed by dissolving (etching) the back pin electrodes 71 by a predetermined length by controlling the dipping time and the like.

The method for manufacturing such a back electrode array 70 and the back pin electrode 7
The materials etc. of 1... are not limited to those mentioned above, and the back pin electrodes 71... which are separately insulated are used.
It is sufficient if the structure supports the holder 6 with the holder 6 insulated from the holder 6.

Although the illustrated embodiment is as described above, the present invention can be modified in various ways. That is, in the above embodiment, an image is recorded on a transfer material 5 such as a recording paper, but the image is first recorded on an intermediate transfer material such as a transfer belt, and then this recorded image is transferred to a paper such as plain paper. It is also possible to take the form of re-transferring the image.

In the case of 111 and 4 or more according to the present invention, an auxiliary electrode is provided around the back electrode, and a voltage of the same polarity as that of the toner is applied to this.

Since the configuration is such that the toner cloud is applied, the adverse effect of the toner cloud on image quality can be eliminated by the function of the auxiliary electrode described above. Therefore, image quality can be significantly improved compared to the conventional example.

Similarly, the function of the auxiliary electrode makes it possible to improve the electric flux density between the facing surfaces of the recording electrode array and the back electrode, which has the advantage that the resolution of the recorded image can be improved accordingly.

In particular, in the case of the image recording apparatus according to claim 2, since the back electrode is constituted by a back electrode array formed by aligning a large number of back pin electrodes, it is said that the image quality can be further improved. There are advantages.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a back electrode used in an image recording apparatus according to the present invention, and FIG. 2 is a diagram illustrating the principle of the present invention in detail. FIG. 3 is a perspective view showing a modification of the back electrode used in the present invention. FIG. 4 is a front sectional view showing a schematic configuration of a conventional example, and FIG. 5 is a perspective view showing a conventional back electrode. 3... Recording head, 4... Recording electrode array, 5...
・Transfer material, 6... Holder, 7... Back electrode, 8
...Bias power supply, 17.. Toner, 21.. Auxiliary electrode, 7o.. Back electrode array. Patent applicant: Minolta Camera Co., Ltd. Figure 4

Claims (2)

[Claims] (1) A recording electrode array in which a large number of pin electrodes are arranged in a straight line is arranged opposite to a support supporting a back electrode, and the movement of the transfer material passed between these is guided by the tip surface of the support. In addition, in an image recording apparatus that performs recording by applying toner to a transfer material from the recording electrode array side, an auxiliary electrode is provided near the back electrode support portion of the support, and a bias having the same polarity as that of the toner is applied to the auxiliary electrode. An image recording device characterized by applying a voltage. (2) The image recording device according to claim 1, wherein the back electrode is a back electrode array in which a large number of back pin electrodes are arranged in an array.