JP2856506B2 - Recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a recording apparatus based on an electrophotographic system,
More specifically, the present invention relates to a cleanerless recording apparatus that performs image recording without using a cleaning device that cleans transfer residual toner.

(Prior Art) In a recording apparatus based on an electrophotographic system, without using a cleaning device for cleaning transfer residual toner,
A recording device (hereinafter referred to as a cleanerless recording device) for collecting transfer residual toner into a developing device simultaneously with development by a developing device (means) is disclosed in, for example, JP-A-59-133573 and JP-A-59-157661. It is known from publications and the like. These publications disclose the basic idea of a cleanerless recording device, and the gist of the device is summarized as follows. That is, as shown in FIG.
In an electrophotographic printer represented by a laser printer, a well-known reversal developing method is often used. In the reversal developing method, the toner particles 2 charged to the same polarity as the electrostatic latent image holding member (photosensitive member) 1 are used, and a portion of the surface of the electrostatic latent image holding member 1 where no charge exists (or the charge amount). The toner particles 2 are adhered to the portion where there is little charge, and the toner particles 2 are not adhered to the portion where electric charge exists. In order to realize such selective toner adhesion, the potential V ₀ of the charged portion on the surface of the electrostatic latent image holding member 1 and the potential V ₀ of the non-charged portion are applied to the toner carrier 4 in the developing device (developing means) 3. Applying a voltage V _b (| V ₁ | <| V _b | <| V ₀ |) between the potentials V ₁ and suppressing toner adhesion to the electrostatic latent image holding member 1 by an electric field between the charged portions Then, the toner 2 adheres to the electrostatic latent image holding member 1 by an electric field between the uncharged portion and the uncharged portion. Here, the toner 2 attached to the electrostatic latent image holder 1 is transferred to the image support 6 by a well-known transfer device 5. In this transfer step, generally, not all of the toner is transferred, and the untransferred toner 2 'is distributed imagewise on the surface of the electrostatic latent image holding member 1 after the transfer.

In an ordinary electrophotographic apparatus, after the transfer residual toner 2 'is collected by the cleaner 7 shown by the broken line, the charge on the surface of the electrostatic latent image holding member 1 is removed by the discharging lamp 8,
The process again reaches an electrostatic latent image forming process (a uniform charging process using the charger 9 and an exposure process using the light beam 10). In contrast,
In the cleanerless recording apparatus, the transfer residual toner 2 'is brought to the developing step without using the cleaner 7, and the transfer residual toner 2' is collected in the developing device 3 at the same time as the development. Strictly speaking, of the latent image formed by exposure to the light beam 10, the transfer residual toner 2 ′ present in the charged portion (that is, the unexposed portion or the non-image portion) is the same as the latent image by the charger 9. Charged to polarity. For this reason,
The toner particles 2 are transferred to the toner carrier 4 by an electric field that suppresses the transfer of the toner particles 2 from the toner carrier 4 to the electrostatic latent image holder 1 (that is, an electric field due to the potential difference between V ₀ and _Vb ). At the same time, the non-charged part (ie, exposed part or image part)
The transfer residual toner 2 ′ existing on the surface of the electrostatic latent image carrier 1 receives a force from the toner carrier 4 toward the electrostatic latent image carrier 1. New toner particles 2 are transferred from the toner carrier 4 to the non-charged portion, and the cleaning is performed simultaneously with the development.

As described above, in the cleanerless recording apparatus, since the cleaner 7 and the waste toner box for storing the cleaned toner (that is, waste toner) are not required, the apparatus can be easily reduced in size and simplified. Further, since the transfer residual toner 2 ′ is collected and reused in the developing device 3, it is economical without waste toner, and it is possible to rub the electrostatic latent image holder 1 with a cleaning blade. Since there is no electrostatic latent image holding member 1, a number of advantages can be obtained, such as the service life of the electrostatic latent image holding member 1 can be extended.

However, in this cleanerless recording apparatus, a ghost image may appear for the following reasons.

First, in a high-humidity environment, paper as the image support 6 absorbs moisture and lowers resistance, so that transfer efficiency generally decreases, and a large amount of toner remains on the surface of the electrostatic latent image holder 1. Tend to. When the amount of the transfer residual toner 2 'becomes excessive, the developing device (developing means) 3 cannot completely clean the transfer residual toner 2', and the transfer residual toner 2 'remains in the non-image area. A positive ghost appears (hereinafter referred to as a positive ghost or a positive memory).

Second, if the amount of the transfer residual toner 2 'becomes excessive, the transfer residual toner 2' shields the light beam 10 in the exposure step using the light beam 10, so that the surface potential of the electrostatic latent image holding 1 is not attenuated. Sufficient, and a potential state intermediate between V ₀ and V ₁ (V ₁ ′
). In such a site,
The developing voltage becomes V _b −V ₁ ′, and the developing voltage V _b
−V _{1, the} amount of toner transferred from the toner carrier 4 to the electrostatic latent image carrier 1 is smaller than that of the surroundings. It will appear as a blank image (hereinafter referred to as a negative ghost or negative memory). This phenomenon is particularly noticeable in a halftone image composed of a set of halftone images and line images.

On the other hand, Japanese Unexamined Patent Publication No. Sho 62-203183 discloses that a ghost is applied by applying a voltage to a conductive brush 12 having a shape shown in section in FIG. Is disclosed. That is, a voltage having a polarity opposite to the charging polarity of the toner is applied to the conductive brush 12 by the DC power supply 13, and the transfer residual toner 2 'is once attracted to the brush 12 by Coulomb force. As a result, the amount of the transfer residual toner 2 'on the surface of the electrostatic latent image holding member 1 is greatly reduced, and the occurrence of the ghost is prevented.

(Problems to be solved by the invention) However, the following two problems occur in the above method.

Instead of removing the cleaner, it is necessary to separately provide the uniformizing means 12 such as the brush, so that a great effect cannot always be obtained in reducing the size and cost of the apparatus. In particular, the conductive brush 12 is not easy to adjust the electric resistance at the time of manufacturing, or the fiber is easily broken, so that not only the yield is inferior and it tends to be expensive, but also a voltage is applied to the conductive brush 12. The problem is that a new power supply must be prepared for the operation.

When a corona charger as shown in FIG. 5 is used as the charging means 9 for uniformly charging the electrostatic latent image holder 1, a large amount of ozone is generated as a corona discharge product.
This large amount of ozone is not only harmful to the human body, but also causes deterioration of components such as the electrostatic latent image holder 1.

Thus, in the conventional cleanerless recording apparatus,
It is difficult to reduce the size and cost of the device, or there are problems such as the generation of harmful discharge products, and it cannot be said that the device is sufficiently satisfactory in practical use.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an economical and highly safe recording apparatus that can be easily reduced in size and cost and does not generate harmful discharge products. And

[Configuration of the Invention] (Means for Solving the Problems) In the present invention, in a cleanerless recording apparatus having the above-described configuration and function, the configuration and arrangement of the charging unit are particularly selected to make the residual toner image uniform. The main point is to use the means.

That is, an electrostatic latent image holding member, charging means for uniformly charging the surface of the electrostatic latent image holding member, and a part of the surface charge of the electrostatic latent image holding member charged by the charging means are attenuated. Means for forming a latent image, developing means for forming a toner image by attaching toner to the electrostatic latent image, transfer means for transferring the formed toner image onto an image support,
A residual toner image uniforming means for disturbing the residual toner image remaining on the surface of the electrostatic latent image holding body after the transfer and making the distribution of the toner uniform, wherein the developing means sucks and collects the residual toner into the developing means In the recording apparatus which develops an electrostatic latent image when performing, the charging means is a conductive contact to which a DC voltage is applied to an AC voltage, and also serves as a residual toner image uniforming means.

(Operation) In the cleanerless recording apparatus according to the present invention, since the charging means also serves as the residual toner image uniformizing means, it is not necessary to install a cleaner or separately install the residual toner image uniforming means. Can be realized. That is, the charging unit has a configuration in which the charging unit is configured to be in contact with the surface of the electrostatic latent image holding member and has a configuration in which a voltage obtained by superimposing a DC voltage on an AC voltage is applied. When the electrostatic latent image holding member is uniformly charged by the charging means in accordance with the configuration like the photoreceptor, while the transfer residual toner remaining on the electrostatic latent image holding member after the transfer is slid, A voltage is applied. Thus, the distribution of the transfer residual toner is disturbed by the application of the voltage, and the distribution of the transfer residual toner is made uniform as a whole. Therefore, the transfer residual toner does not cause ghost in the next image. In addition, the electrostatic latent image holding member is not charged by so-called corona discharge, but by a well-known mechanism such as field emission or ion conduction. There is no adverse effect on the electrostatic latent image carrier and the like.

(Example) Hereinafter, an example of the present invention is described with reference to drawings.

Embodiment 1 FIG. 1 is a sectional view showing an essential part of an example of a recording apparatus according to the present invention. Components common to FIGS. 5 and 6 described above are denoted by the same reference numerals. And the description is omitted.

A characteristic point of this embodiment is that the recording apparatus having the configuration shown in FIG. 6 does not include the residual toner image equalizing means 12 and that the corona charger 9 is replaced with a conductive member to which a voltage is applied. Of using the conductive brush roller 21
Is a point. The conductive brush roller 21 has a volume resistance of 10 ²
A conductive fiber (brush) 22 of ¹⁰ to 10 ¹⁰ Ω · cm, preferably 10 ³ to 10 ⁸ Ω · cm. Such rigid conductors and elastic conductors such as conductive rubber or conductive foam are used. The thickness of the fiber forming the brush 22 is 0.
Is preferably 5 deniers to 10 deniers range, flocking density is good in the range of 5000 / cm ² to 100,000 / cm ^2, and the length of the fibers is preferably in the range of from 0.5 mm 5.0 mm . These values are mainly based on requirements from a charging function described later.

A superimposed AC and DC voltage is applied to a conductive base 23 of the brush roller 21 by a power supply 24.

Thus, when the electrostatic latent image holding member 1 is uniformly negatively charged, a negative voltage or a negatively biased AC voltage is applied to the brush roller 21. In this case, the direction of rotation of the brush roller 21 may be either the same direction or the opposite direction to the rotation direction of the electrostatic latent image holder 1, but the peripheral speed is different from the surface speed of the electrostatic latent image holder 1. Is preferred. That is, it is desirable that the peripheral speed of the brush roller 21 is higher than or slightly lower than the peripheral speed of the electrostatic latent image holder 1. In particular, the speed is more preferably 1.2 to 5.0 times the speed of the electrostatic latent image holder 1. It is desirable that the contact width between the brush roller 21 and the electrostatic latent image holder 1 is 0.5 mm or more.

For example, the peripheral speed of the electrostatic latent image holder 1 is 40 mm / sec, the outer diameter of the brush roller 21 is 25 mm, and the resistance value of the fiber forming the brush 22 is 10 mm.
The peripheral speed of the brush roller 21 composed of ⁵ Ω · cm, fiber length 2.5 mm, fiber thickness 3 denier, flocking density 40,000 / cm ² , 60 mm / sec, peak value difference as applied voltage A brush roller with a DC voltage of -500 V superimposed on an AC voltage of 800 V
The results in the case where the contact width between 21 and the electrostatic latent image holding member 1 was set to 3 mm are shown below.

First, under the above conditions, an organic photoreceptor (electrostatic latent image holder)
The surface of No. 1 was uniformly charged at -450 V to -500 V. The charged surface is exposed to a laser and developed by a well-known two-component developing method or a one-component non-magnetic developing method described in Japanese Patent Application No. 1-81921 (Japanese Patent Application Laid-Open No. 2-259784). The toner image was transferred to the transfer paper 6 by the charger 5. After the transfer, the untransferred toner 2 ′ remains imagewise on the organic photoreceptor (electrostatic latent image holder) 1. The surface of the organic photoreceptor 1 to which the residual toner 2 'has adhered is discharged by the discharge lamp 8, and then reaches below the charging brush roller 21 again.

The transfer residual toner 2 ′ is made uniform by the rubbing force of the brush roller 21 and, at the same time, is oscillated by an AC electric field, so that the uniformity is further improved. At the same time, a negative charge is given to the surface of the organic photoreceptor 1 by the conductive fibers 22 of the brush roller 21 which comes into contact with the surface of the organic photoreceptor 1, so that the organic photoreceptor 1 is uniformly charged.

Of course, when only a DC voltage of about -500 V to -800 V is applied to the brush roller 21, the same uniformity and charging effect can be obtained, but a more remarkable effect can be obtained by superimposing AC. AC voltage: peak value difference 300V
To 1200 V, and the frequency is preferably in the range of 200 Hz to 5 KHz. Also, the absolute value of the DC voltage to be superimposed is a desired potential of the electrostatic latent image carrier 1 or a value larger than this (in particular, 200
(Approximately 500 V). The fiber 22 for the brush roller 21 is made of a material such as rayon, polyamide, acryl, or tetrafluoropolyethylene which has been subjected to a conductive treatment.

In this way, the uniformity of the residual toner and the charging of the photoconductor can be simultaneously achieved by the brush roller 21.

Embodiment 2 In the case of Embodiment 1, instead of the brush roller 21,
The fixed type brush 31 shown in FIG. 2 may be used. In this case, the same operation and effect were obtained electrically under the same conditions as in the first embodiment. In the present embodiment, the brush 31, that is, a mechanism that also serves as a means for equalizing charged and residual toner images and the electrostatic latent image holder 1
The contact width with the electrode is preferably 3 mm or more.

Example 3 In the case of Example 1, instead of the brush roller 21,
A conductive roller 41 configured so that its main part is shown in cross section in FIG. 3 may be used. In this embodiment, when the electrostatic latent image holder 1 is made of a rigid body, it is desirable that the conductive roller 41 be made of an elastic body. FIG. 3 illustrates an example in which a conductive rubber layer 43 is provided on the outer periphery of a metal shaft 42 and a surface layer 44 made of a conductive resin or elastomer is provided on the surface thereof. Of course, a single layer type without the surface layer 44 may be used.

In the configuration of the recording apparatus, using a conductive roller 41 having a surface roughness of 0.3 μm Rz, 1.2 μm Rz or 15 μm Rz as the conductive roller 41, and conducting experiments respectively, in each case, a good charging and uniform function was achieved. Expression was observed. Incidentally, the constituent material of the conductive roller 41, except for the conductive shaft 42, the conductive rubber layer 43 and the surface layer 44 to 10 ^{3 to} 10 ¹⁰
Ω · cm is appropriate, and the electrical and mechanical conditions may be almost the same as in the first embodiment.

Embodiment 4 In the case of Embodiment 1, instead of the brush roller 21,
A well-known magnetic brush 51 configured so that its main part is shown in cross section in FIG. 4 may be used. The structure of the magnetic brush 51 is such that a fixed or rotating sleeve 53 made of a non-magnetic material is provided around a fixed or rotating magnet roller 54.
And well-known magnetic particles are adhered around it. As magnetic particles, the volume resistance is 10 ² to 10 ¹⁰ Ω
m, iron powder or ferrite having an average particle size of 10 μm to 200 μm is used. Also in this case, electrically the first embodiment
Under substantially the same conditions as in the above case, similar operations and effects were obtained. Other electrical and mechanical conditions
It may be almost the same as the case of the first embodiment.

[Effects of the Invention] As described above, according to the recording apparatus of the present invention, the charging of the electrostatic latent image holding member and the uniformity of the transfer residual toner are simultaneously and reliably performed by the charging and residual toner image uniforming means. I can do it. In addition, a cleaner-less recording apparatus that can easily output a good image free from ghosts without any contamination by discharge products, which can be easily reduced in size and cost, can be obtained.

[Brief description of the drawings]

1 to 4 are cross-sectional views showing an example of a configuration of a main part of a recording apparatus according to the present invention, and FIGS. 5 and 6 are cross-sectional views showing main parts of a conventional recording apparatus. DESCRIPTION OF SYMBOLS 1 ... Latent image holding body (photoreceptor) 2 ... Toner 3 ... Developing device 5 ... Transfer device 9 ... Charger 21, 31, 41, 51 ... Charging means 24 ... Applied power

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsutoshi Saito 1 Toshiba Research Institute, Komukai, Kawasaki-shi, Kanagawa Prefecture (72) Inventor Yoshimitsu Otaka 6-78 Minamicho, Mishima-shi, Shizuoka Tokyo Inside the Technical Research Institute of Electric Corporation (72) Inventor Kouji Endo 6-78 Minamimachi, Mishima-shi, Shizuoka Tokyo, Japan Technical Research Laboratory (56) Reference JP-A-61-42669 (JP, A) JP-A-1-191880 (JP, a) JP flat 2-64668 (JP, a) JP Akira 60-220587 (JP, a) JP Akira 62-245277 (JP, a) (58 ) investigated the field (Int.Cl. ⁶ G03G 15/02 101 G03G 15/08 507 G03G 15/24 G03G 15/02 102

Claims (1)

(57) [Claims] An electrostatic latent image holder, a charging unit for uniformly charging the surface of the electrostatic latent image holder, and a part of a surface charge of the electrostatic latent image holder charged by the charging unit; Means for forming an electrostatic latent image at least, developing means for forming a toner image by attaching toner to the electrostatic latent image, transfer means for transferring the formed toner image onto an image support,
A residual toner image uniforming means for disturbing the residual toner image remaining on the surface of the electrostatic latent image holding body after the transfer and making the distribution of the toner uniform, wherein the developing means sucks and collects the residual toner into the developing means A recording device that develops an electrostatic latent image when the recording is performed, wherein the charging unit is a conductive contact to which a DC voltage is applied to an AC voltage, and also serves as a residual toner image uniforming unit.