JPS5926760A - Developing device - Google Patents

Abstract

PURPOSE:To obtain a stable and sharp picture all the time, by providing a toner supplying part with a conductive mesh body so that to bring into contact with or passes through the toner, and applying a specific potential to this mesh body. CONSTITUTION:A developing device 2 arranged facing a grounded photosensitive drum 1 is provided with the conductive mesh body 5 almost horizontally at the internal lower part of the toner supplying part 3 which supplies single-component toner 4, which falls through the mesh body 5. The surface of a conductive developing roll 6 for conveying the toner 4 from the toner supplying part 3 is treated by applying sand blast and the surface rotates as shown by the arrow (b); the toner 4 is leveled uniformly by a specifying blade 7. A grid 8 provided between the photosensitive drum 1 and developing roll 6 applies voltages from power sources 12 and 13 to the photosensitive drum 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developing device for developing an electrostatic latent image formed on a photosensitive drum of, for example, an electronic copying machine.

[Technical background of the invention]

Recently, as this type of developing device, a grid made of a plurality of parallel wires is installed between the photosensitive drum as an image carrier and the developing roller as a toner holding member, and a direct current is applied to the grid 19 and the developing roller. By applying a bias voltage of either V1 or T, 1, the one-component toner conveyed by the developing roller is caused to fly W,
And the toner is transferred between the developing roller and the grid. Udaklau t-shaped kt! and feeling) Y-body l.

Developing electrostatic latent images on rams is being developed.

[Problems with background technology]

However, the current state of such a method is 1'! ! The U-U had the following problems. That is, in order to obtain stable image quality, t:ll, 1 holder and 1. The purpose of this is to form a sufficiently charged layer on the soil of the developing roller, but in the conventional surface mounting, only frictional electrification occurs with the toner regulation blade provided in the vicinity of the developing roller. No good,
Sufficient triboelectrification cannot be obtained. As a result, phenomena such as flying toner with a small charge n adhering to the non-latent image area of the photoreceptor drum occur, causing fog on the copied image and lines in the copied image becoming too thick. There was a problem that something like this would occur.

OBJECTS OF THE INVENTION] The present invention 1.1 has been made in view of the above circumstances, and has the following objects: To provide a developing device that can always provide stable and clear image quality.

[Existing requirements of the invention]

According to the present invention, an electrically conductive mesh member is provided in the toner supply section, and the toner passes through the mesh member by applying a predetermined potential depending on the polarity of the toner to the mesh member. The purpose of this is to sufficiently and uniformly apply an electric charge to the toner to be used.

[Example of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In Figure 1, the IF port! An image bearing member, such as a photosensitive drum, which is attached to the secondary copying machine, has an electrostatic latent image corresponding to the original image formed on its surface by an exposure means (not shown), and is indicated by the arrow shown in the drawing. & Rotate in direction. Note that this photosensitive drum 1t is electrically grounded. 7
A developing device 2 is disposed in close proximity to a portion facing the photosensitive drum 1. To explain this developing device 2, it is a toner supply section that supplies 3F, 1, - component toner 4, and a lower blade inside it has a tit, a guide 't1 (
A transparent mesh body 5 is stretched in a substantially horizontal state, and the L-ner 4 passes through this mesh body 5 and falls downward. 6 is a toner holder (for example, a conductive developing roller that conveys the toner 4 supplied from the toner supply section 3), whose surface is sandblasted so that it can convey the toner #-, t, and is shown in the figure. Rotate in the direction of the arrow. Seven regulation blades uniformly level the thickness of the toner conveyed by the developing roller 6. 8t'' grid, which is arranged between the photosensitive drum 1 and the developing roller 6. For example, as shown in FIG. 2, this grid 8 is made up of a plurality of conductive wires (9) arranged in parallel to each other, and each of these wires (9) has both ends thereof 1 supported by the wire support plates 10, 10, respectively, and the wires 9... They are arranged in an arc shape so as to be concentric with the photoreceptor drum 1. Here, each wire 9...t has an insulating # film formed on its surface, and has a diameter of 12
0 tlnt, and are arranged at 1 m intervals.

The insulating thin film on the surface is necessary to prevent discharge from occurring between the developing roller 6 and the photosensitive drum I.

On the other hand, 11 is a direct line for applying a predetermined electric current ri7 to the mesh body 5. Ir, N, sources, 12 and 13 are bias power supplies to the developing roller 6, 12 is a DC power supply, 13 is an AC iW
There are four sources. In addition, 14 and 15 are bias power supplies to the grid 8, 14F is a DC power supply, I5 is connected to f,
It is a power source. At t-1~, the DC power supplies 11, 12, 1
41 (Y, switch 16, 17, 18 to change the polarity of the output voltage (positive or F, negative) according to the polarity of the toner used.
It is designed to be exchangeable depending on °CU.

At the bottom of such a tank, first, for example, use a non-magnetic negatively charged toner (average particle size lo, qo microns) with a specific resistance of 2.1 x 10'' as toner 4, and turn on a DC power supply. 1 output 11i, the river was closed at -6007 gelt, and the negative voltage was applied to the mesh body 5. 0.149.) was used, and for this tight toner band 11 conditions, the DC type,
Power source 12 output type, pressure -20011 volts, AC power source 1
3 output type, use 2000 volts (frequency
lz), the output voltage of the DC power supply 14 is +200 yl?
Ruto, AC city, source 15 output type, use 1000 volts (
Frequency t'', fly, ), intersection Mr, ? [T, source 1
As a result of conducting an A test with the output voltages of 3 and 15 set to the same phase, there was no fogging, the line was sharper, and it was more stable than the older brother, compared to when the mesh body 5 was not used.し／ζ
*A clear copy image was created. In other words, due to the frictional electrification of the toner due to regulation grade 7 and development 1)-ra 6, sufficient toner electrification required for development cannot be obtained, and the toner with a small amount of stagnation is To solve this problem, a conductive mesh body 5 was installed in the toner supply section 3, and several hundred) 1? By applying direct current pressure from the base, the toner 4 comes into contact with the string 1,
When passing, the toner 4 is injected with a charge, and the toner 4 is sufficiently and uniformly charged without producing reversely charged toner, and a stable and clear copy image is always produced. It is. Furthermore, by changing the voltage applied to the halftone dots 1 and 5, the amount of charge on the toner 4 can be arbitrarily controlled, thereby making it possible to adjust the image density.

Next, even if V is toner 4, -C specific resistance is 4.3X1
0100・Magnetic negatively charged toner (31' average particle size 1
1.2 microns), apply a voltage of -400 delt to the mesh body 5, and apply an actual F under the same conditions as above.
As with the 46 copies mentioned above, the results of performing A also showed that there was no fog, the lines were sharp, and the copies were always stable and clear.

In addition, the previous pQ real bT! In the example 1-1, we have explained that it is applied to the current QJ device of an electronic copying machine, but the same applies to developing devices such as electronic printers and facsimiles. It was carried out in 1 (I).

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide a developing device that can uniformly apply a sufficient charge to toner, thereby providing stable and clear image quality without fogging.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a block diagram showing the grid in detail in the same embodiment. DESCRIPTION OF SYMBOLS 1... Photosensitive drum (image carrier), 2... Developing device, 3... Toner supply section, 4... Toner, 5... Mesh body, 6... Developing roller (toner holding body), 8...
Grid, 9...Wire, 11, 12.14...DC power supply, 13.15...AC power supply. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (1)

[Claims] a toner supply section, this toner supply section and a static Y [disposed close to the image bearing member on which a latent image is formed] front i] 2 toner holder that conveys the toner supplied from the toner supply section; In the developing device, which develops the electrostatic latent image by applying a bias voltage to the toner holder to cause the toner conveyed by the toner holder to fly, the toner is supplied to the toner supply unit. The conductor'f that touches or passes through
I! 1. A developing device characterized in that it is provided with a transparent mesh body, and is formed so as to apply a predetermined potential to the mesh body.