JPS59212073A - Image recording device - Google Patents

Abstract

PURPOSE:To prevent a short circuit between signal electrodes which is caused when the movement speed of toner is slow by applying an image signal voltage to recording electrodes only when the movement speed of the toner passing through the gap between recording electrodes and a recording medium is more than a specific value. CONSTITUTION:A rotating magnet 3 is driven by a driving source 16 coupled directly with a generator 17. The voltage generated by the generator 17 at this time is read by a detector 18, which applies the image signal voltage from a signal power source 9 to between recording electrodes 4 and a back electrode 6 only when the driving source 16 is at higher than the specific rotating speed. Thus, the detector 18 is provided to apply the image signal voltage to recording electrodes 4 only when the speed of the driving source is more than the specific rotating speed, i.e. when the movement speed of the toner exceeds a critical value, so the image signal voltage is raised without breaking any recording electrode 4 to perform recording of good image quality with high density.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image recording apparatus, particularly an image recording apparatus that records an image by depositing a one-component conductive magnetic developer (hereinafter abbreviated as toner) on a recording medium in direct response to an image wake-up signal. It relates to a recording device.

Conventionally, as this type of image recording device, the
There is one disclosed in the specification of No. 840. A very brief overview of this conventional device will be explained with reference to FIG.

In FIG. 1, reference numeral 1 denotes a toner conveying member consisting of a stationary non-magnetic cylinder immersed in conductive magnetic toner contained in a toner container 2, and 3 rotates in the direction of arrow A inside the toner conveying member 1. The magnet is arranged so that the magnetic poles of different polarities are alternately magnetized at substantially equal intervals on the circumference. Reference numeral 4 denotes a plurality of recording electrodes arranged in a play-like arrangement on the surface of the toner conveying member 1 in the axial direction of the member, each of which is independently and electrically insulated, and is made of conductive material such as permalloy, nickel, or iron. Made of magnetic material.

Reference numeral 5 denotes a recording medium that faces the recording electrode 4 and is transported in the direction of arrow B. In the illustrated example, it is made of a conductive substrate 5a with an insulating layer 5b formed on the surface, but other generally commercially available static media are used. It is also possible to use electronic recording paper. Reference numeral 6 denotes a conductive roller-shaped back electrode disposed opposite the recording electrode 4 so as to sandwich the recording medium 5 therebetween, and is in contact with the surface of the conductive substrate 5 of the recording medium 5. 7 is doctor grade, 8
9 is a recording position, and 9 is an image signal power source.

In the above configuration, the magnet 3 moves toward the recording medium 5 in the direction of the arrow.
are driven in the direction of arrow B by respective driving sources (not shown). The toner T in the container 2 is conveyed in a direction A' opposite to the rotating direction of the magnet 3 while being held on the Qi conveying member l by the magnetic field of the magnet 3.

The toner T being conveyed is regulated into a uniform thin layer by a doctor grade 7 provided at the outlet of the container 2, and then transferred to the recording electrode 4.
When the toner reaches the recording position 8 where the tip of the recording electrode 4 faces the back electrode 6, the toner stands in the form of a spike on the tip of the recording electrode 4, and the tip of the spike comes into contact with the surface of the recording medium 50. At this time, when a voltage according to the image is applied between both electrodes 4 and 6 from the signal power source 9, the charge injected into the toner at the tip through the toner ear and the back side of the insulating layer 5b of the recording medium 5 are The toner T adheres to the insulating layer 5b of the recording medium 5 due to the electrostatic force with the injected charges, forming an image.

The toner image on the insulating layer 5b is fixed by a fixing means (not shown) such as heating or pressure.

Figure 2 shows another conventional example of this type of image recording device published in Japanese Unexamined Patent Publication No. 5
5-127578. 1st
The same numbers as in the figures indicate parts that perform the same functions. The recording medium 5 is a cylindrical body formed by forming an insulating layer 5bi on a conductive substrate 5a, and rotates in the direction of the arrow. Reference numeral 10 denotes a stationary toner application roller made of a non-magnetic cylinder that is immersed in the toner T in the toner container 12, and has a rotating magnet 11 rotated by a drive system (not shown) inside.

When the rotating magnet 11 rotates in the direction of the arrow C, the toner T moves from the toner container 12 in the direction of the arrow on the application roller 10 and is conveyed to the recording medium 5. In this case, since a voltage is applied between the power source 13 and the recording medium 5 and the toner application roller 10, the toner T is attached to the recording medium 5 by electrostatic force and is applied in a thin layer. The applied toner T reaches the recording electrode 4 as the recording medium 5 rotates.

The recording electrode 4 is a large number of recording electrodes arranged in an array made of a conductive magnetic material, and is sandwiched between opposing magnets 15. Here, the toner T forms a toner spike that comes into contact with the tip of the recording electrode 4, and the electric charge injected by the coating roller 10 escapes through the toner spike and the recording electrode 4, so that it adheres between the recording medium 5 and the toner 1. The power to do so becomes stronger. However, at this moment, when a signal voltage corresponding to the image is applied between the signal power source 9 and the recording medium 5 and the recording pole 4 of the recording medium 5, the toner T passes through the ears of the recording medium 5 as explained in FIG.
An electric charge is generated in the toner in contact with the recording medium 5, and a force that adheres to the recording medium 5 acts on the toner T due to this and the electric charge generated on the back side of the insulating layer 5b of the recording medium 5. Next, to the extent that this electric charge does not disturb the toner T obtained in the image pattern, the toner T that does not adhere to the recording medium is removed using a toner removing device 14, for example, a device 14 that uses magnetic attraction or air suction. A visual image appears above.

However, these image recording devices have the following problems when obtaining high resolution image quality. That is, when the toner T is not moving or the moving speed of the toner is slow, the toner T cross-links between adjacent signal electrodes 4, and when the signal voltage from the signal power supply 9 is applied to the signal electrode 4, the signal electrode A short circuit occurs between 4 and the signal (5) electrode is burnt. Therefore, the voltage supplied from the signal power source 9 cannot be increased, and the image density cannot be increased.

An object of the present invention is to prevent all the inconveniences that occur when the toner is not moving or when the moving speed is slow, as described above.

A feature of the present invention is that in the above-mentioned type of image recording device,
The purpose is to allow application of the image signal voltage to the recording electrode only when the moving speed of toner passing through the gap between the recording electrode and the recording medium is equal to or higher than a predetermined value.

An embodiment of the present invention will be explained with reference to FIG. In the figure, the same parts as in FIG. 1 are indicated by the same numbers. 16 is a drive source for driving the rotating magnet 3, and 17 is a power generation +fi (tachonoenerator) directly connected to the drive source 15. Reference numeral 18 denotes a detection device for reading the voltage generated by the generator 17, which detects the image signal voltage from the signal power source 9 between the recording electrode 4 and the back electrode 6 only when the drive source 15 has a rotational speed higher than a certain level. It is a device that issues commands that allow the application of As a means for detecting the rotational speed of the rotating magnet 3 (6), a Hall element, a coil, or the like may be provided on the toner conveying member 1 in place of the power generation d16 to detect the rotational speed.

This will be explained below using specific numerical values.

The gap between the recording medium 5 and the recording electrode 4 is usually 10-5000
Although it can be set to approximately micromicrometers, it was set to 75 micrometers in this example. The gap between each recording electrode 4 varies depending on the image density, but in this example, it is 12 per millimeter, and the valley recording basket electrode 4 is made entirely of 40 micrometer nickel wire, and each recording electrode 4 is arranged in parallel and Cemedine (
It was fixed and insulated using Cemedine Super sold by Co., Ltd. As toner T, a conductive magnetic toner UQC-355 sold by 3M Company was used. As the recording medium, an electrostatic recording paper FOR-01 sold by Jujo Paper Co., Ltd. was used, and the recording medium was transported in the direction of arrow B at a speed of 180 mm per second. The toner conveying member 1 was a cylinder with a diameter of 50 mm, and the rotating magnet 3 inside had 48 poles and produced a magnetic field of 360 Gauss on the surface of the cylinder 10.

FIG. 4 is a partially enlarged view of the vicinity of the recording position 8 in FIG.
4c... When the rotating magnet is stopped or its rotational speed is slow, therefore, when the toner does not move or its moving speed is slow, the conductive magnetic toner T on each recording electrode is used as a signal electrode. Between 4a and 4b, 4b
, 4c, etc. are short-circuited. In this state, the signal power supply 9 applies voltage No. 4g to the multi-signal electrode group 4, and the potential difference between each signal electrode (for example, there is an input signal on electrode 4a, electrode 4b
(e.g., none) occurs, the toner T is completely passed through and
A short circuit current flows, causing undesirable situations such as burning the signal electrode 4 or sticking the toner T.

According to experiments in this embodiment, although it depends on the surrounding atmosphere and the amount of toner, when the rotation speed of the magnet 3 is slow and the voltage between the signal electrodes 4a, b... becomes approximately 30V or more, the signal electrode 4 Although damage was observed, it was confirmed that when the rotational speed of the magnet 3 exceeded about 360 Orpm, the separation voltage increased to about 40 to 50V. The reason for this is unknown, but perhaps when the toner movement speed is high, the distance between the signal electrodes 4m and 4b
4b.

This is thought to be due to the fact that the bond between the toners becomes smaller at a time of 40 or so. Therefore, as mentioned above, the rotation speed of the magnet 30 is detected,
If the image signal voltage is applied from the image signal voltage source 9 when the voltage exceeds a predetermined value and the detection device 18 issues a command, it is possible to increase the signal voltage without damaging the signal electrode 4. It was confirmed that images can be recorded with high density and excellent speed.

The embodiment for the image recording device of the type shown in FIG. 1 has been described above. Next, the embodiment for the image recording device of the type shown in FIG. It was observed that when the rotational speed of the recording medium 5 was approximately 1801111/llee or more at the circumferential speed, the breakdown voltage of the recording electrode 4 became high as described above. Therefore, even in this case, if a device (9) for detecting the rotational speed of the recording medium 5 is provided and the image signal voltage is applied to the i-recording electrode 4 only when the rotational speed is equal to or higher than a predetermined rotational speed, recording can be performed. Electrode 4
It is possible to increase the image signal voltage and record high-density, high-quality images without damaging the image.

The critical value of the above-mentioned rotational speed and thus of the toner movement speed that should permit the application of the image signal voltage to the recording electrodes depends on the gap between each recording electrode, the gap between the recording electrode and the recording medium, the magnitude of the image signal voltage, and Since it varies depending on the application time, the resistance value of the toner, etc., it is not appropriate to define it unambiguously, and it is preferable to determine it through experiments or the like in a specific implementation.

In addition, in the above explanation, it is assumed that no voltage is applied to the signal electrode 4 when the rotational speed of the magnet 3 (FIGS. 1 and 3) or the recording medium 5 (FIG. 2) is below a predetermined rotation speed. A similar effect can be obtained even if substantially the same voltage is applied to all of the signal electrodes 4 when the rotational speed is lower than the rotational speed, and in this case, the effect of cleaning the vicinity of the recording electrodes can also be obtained. Furthermore, when using roll recording paper or the like as a recording medium, by applying voltage to the signal electrode group for a short period of time, toner adheres to the recording medium in a straight line corresponding to the signal electrode (10) group. It is also possible to use this as a cutting symbol.

As explained above, according to the present invention, a high-voltage image signal can be applied to the signal electrode without causing damage to the signal electrode or deterioration of image quality, and high-speed image recording with high ruggedness is possible. .

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing different conventional examples of image recording devices related to the present invention, FIG. 3 is a cross-sectional view showing an embodiment of the present invention, and FIG. 4 is a recording electrode. and a partially enlarged view of its vicinity. l... Toner conveying member, 2... Toner container, 3
... Rotating magnet, 4... Recording electrode, 5...
- Recording medium, 6... Back electrode, 8... Recording position, 9... Image signal voltage source, 10...
・Toner application roller, 11... Rotating magnet, 12... Toner container,
13...Power supply, 14...Toner removal device. 15... Magnet, 16... Drive source, 17.
... Tacho generator, 18... Rotation speed detection device. (11) Figure 4-401=

Claims (1)

[Claims] A recording medium is moved in close opposition to an array of recording electrodes, each of which is independently and electrically insulated, and conductive magnetic toner is moved through a gap between the two, and a magnetic field crosses the gap. In an image recording apparatus of a type in which toner is attached to a recording medium by applying an image signal voltage between the back surface of the insulating layer of the recording medium and the recording electrode, the toner moves through the gap. An image recording apparatus characterized by comprising means for permitting application of the image signal voltage only when the speed is equal to or higher than a predetermined value.