JP2001356616A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quicken first printing time by shortening the warm-up time of a heat roller by shortening waiting time at the time of starting the printing of the small number of sheets such as one sheet to about a few sheets. SOLUTION: This electrophotographic device is provided with a means to judge whether the number of printing sheets inputted is small or not at the time of starting a device in which a transfer-fixing part is not heated, and in the case of judging that it is a small number, heating temperature at the transfer-fixing part is suppressed to be much lower than the heating temperature at a normal time and also fixing speed is made much lower than speed at the normal time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus, and more particularly, to an electrophotographic apparatus in which a warm-up time for heating in a transfer fixing unit is reduced.

[0002]

2. Description of the Related Art In an electrophotographic apparatus, a fusion transfer process for fixing to a print medium requires that the toner particles and the medium both have a temperature higher than the melting temperature of the toner particles when the toner particles come into contact with and transfer to the medium. In rare cases, the toner particles adhere to the medium by the backup pressure from the back surface of the medium, and transfer is performed by the adhesive force of the melted toner particles. This fusion transfer process requires a warm-up time during initial printing to heat the toner particles to a predetermined temperature.

[0003] The length of the warm-up time is determined to some extent by the printing speed of the printer device and the use thereof (applications corresponding to the personal, office and printing industries). In general, the power consumption of the heater of the transfer / fixing unit, the diameter of the fixing roller, the thickness, and the material are determined from the printing speed. As a result, the waiting time (warm-up time) at the time of initial printing immediately after startup of the apparatus is reduced. Tend to become longer as the size increases.

In particular, when used in an office, the ratio of printing a small number of copies of one to two or three sheets is not lower than that of continuous mass printing. In such a case, when the power of the printer is turned on or when the printer is restarted from the energy saving mode, the standby time of the fixing unit becomes the resultant “print time”, and the printing speed of the printer is canceled. ing.

For this reason, conventionally, improvement in thermal efficiency such as heat roller material, heat capacity and heat conduction, and adoption of a heater material capable of rapid heating called on-demand printing have been employed. However, many printer devices capable of high-speed printing still employ a heat roller having a large heat capacity, and the warm-up time actually takes about 5 to 10 minutes.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems and to reduce the waiting time at the start-up of printing one to a few copies of a fractional number of copies. It is an object of the present invention to provide an electrophotographic apparatus in which the warm-up time is shortened and the first print time is shortened.

[0007]

According to the present invention, there is provided an electrophotographic apparatus which supplies a developer in contact with an image support on which an electrostatic latent image is formed, and which is formed between the image support and the image support. A developing unit for forming a toner image by adhering toner particles of the developer to the image support according to an electric field, an intermediate transfer body for transferring the toner image on the image support, and an intermediate transfer A transfer / fixing unit that heats and fuses the toner image transferred to the body at a contact portion with the print medium and melt-transfers the toner image to the print medium. The apparatus further comprises means for judging whether or not the input number of printed sheets is a decimal part at the time of start-up of the apparatus in which the transfer and fixing unit is not heated. Is kept sufficiently lower than the normal heating temperature, and the fixing speed is made sufficiently lower than the normal speed. As a result, it is possible to reduce the waiting time at the time of startup when printing a small number of copies, and to shorten the warm-up time of the heat roller.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail according to embodiments. FIG. 1 is a diagram illustrating an electrophotographic apparatus embodying the present invention.

First, referring to FIG. 1, an outline of the whole of a liquid developing electrophotographic apparatus including a transfer fixing unit which is a feature of the present invention will be described. A developing unit is provided at the bottom of the apparatus, an intermediate transfer unit is provided thereon, and a transfer fixing unit is provided at the top of the apparatus. Since the illustrated apparatus is provided with the transfer fixing unit that generates a large amount of heat at the top of the apparatus, heat can be efficiently discharged from the apparatus. Further, since the developing section for handling the liquid toner is provided at the lowermost portion of the apparatus, even if the liquid toner leaks, the printing medium is hardly stained.

The developing section includes yellow / magenta / cyan /
It is provided in association with black. Photosensitive drums (photosensitive members) 11 to 14 are provided, respectively, and a charger for charging the photosensitive drums 11 to 14 to about 700 V is provided (not shown). Exposure indicated by an arrow is performed by charging the charged photosensitive drums 11 to 14 based on image data, for example, 7 times.
This is performed using laser light having a wavelength of 80 nm. As a result, an electrostatic latent image is formed on the photosensitive drums 11 to 14 in which the potential of the exposed portion is about 100 V. Further, a static eliminator (not shown) is provided to eliminate residual potential on the photosensitive drums 11 to 14.

The developing roller is biased to a predetermined voltage such as about 400 V to 600 V, and
4, the positively charged toner is supplied to the photosensitive drums 11 to 14. As a result, toner is adhered to the exposed portions on the photosensitive drums 11 to 14 charged to about 100 V, and the electrostatic latent images on the photosensitive drums 11 to 14 are developed to form images. The toner supply roller includes one or a plurality of rollers for each color toner, and has a toner viscosity of 400 to 4000 mPa · S and a carrier viscosity of 20 to 500 cSt, preferably 100 cSt.
Is conveyed while being spread thinly from the toner pool to apply the liquid toner on the developing roller with a predetermined layer thickness (for example, 4 to 10 μm).

Intermediate transfer roller 1 as first intermediate transfer member
5 are biased to about -800 V, and each photosensitive drum 1
Photosensitive drums 11 to 14 according to an electric field between the photosensitive drums 11 to 14
The toner attached to is transferred. This intermediate transfer roller 1
5 firstly transfers, for example, yellow toner attached to the first photosensitive drum 11, subsequently transfers, for example, magenta toner attached to the second photosensitive drum 12, For example, cyan toner attached to the three photosensitive drums 13 is transferred, and finally, the fourth photosensitive drum 1 is transferred.
For example, the black toner attached to the toner image 4 is transferred. Thus, the first to fourth photosensitive drums 11 to 1
The four-color toner image developed on the intermediate transfer roller 1 is sequentially rotated by rotating the intermediate transfer roller 15 four times.
5 to form a color image. Alternatively, the image may be formed by a tandem method in which the four-color toner image is sequentially superimposed on the intermediate transfer roller 15 while the intermediate transfer roller 15 is rotated once. The cleaning blade comes in contact with the intermediate transfer roller at an appropriate timing to remove the toner and the pre-wet liquid remaining thereon.

Thereafter, the four-color image is electrostatically transferred onto the intermediate transfer belt 16 having a belt structure as a second intermediate transfer member, and is transferred after the carrier liquid is removed by the carrier removing section. The toner image is heated and melted at a contact portion with the print medium, and is melt-transferred to the print medium.
The image formed by the liquid toner on the intermediate transfer belt 16 contains a carrier liquid.
This carrier oil is removed.

FIG. 2 is a diagram showing in detail the transfer and fixing section of the electrophotographic apparatus shown in FIG. As shown, three carrier removing rollers are provided on the intermediate transfer belt 16 so as to contact the heat roller 18. These carrier removal rollers are in contact with the toner layer on the intermediate transfer belt heated at or near the melting temperature,
Remove excess oil from it. Further, a bias voltage is applied to the carrier removing roller. This bias is applied in the direction of pressing the toner particles against the intermediate transfer belt holding the image, for example, by + 2K with respect to the heat roller.
A voltage of V is applied. Note that a bias voltage of −2 KV is applied to the pressure roller 19 with respect to the heat roller for transfer and fixing. The carrier removing roller is a conductive roller having a resistance value equal to or lower than the electric resistance value of the molten toner, and its surface is mirror-finished, that is, smooth. Further, it has both heat resistance to withstand the heating temperature and electric withstand voltage to withstand the applied bias voltage. Further, a blade or the like for collecting the removed carrier is provided.

The toner image on the intermediate transfer belt 16 is heated and melted by a heat roller 18 and is transferred and fixed to a printing medium by a pressure roller 19 with a built-in heater cooperating with the heat roller 18.

The transfer / fixing section includes the above-described pressure roller 19, a plurality of transport rollers, an electrostatic belt wound around the roller, and the above-described intermediate transfer belt 16.
The electrostatic belt adsorbs and transports the print medium by electrostatic force. The heating by the heat roller 18 improves the carrier removal efficiency and cooperates with the pressure roller 19 with a built-in heater to melt the toner image on the intermediate transfer belt 16 and perform transfer and fixing to a print medium. It is. Thereafter, the intermediate transfer belt 16 thus heated needs to be cooled. This is, for example, the intermediate transfer belt 16
Can be performed by cooling a roller (cooling roller) around which is wound. The cooling is performed when the toner is transferred from the intermediate transfer roller 15 to the intermediate transfer belt 16, thereby preventing the occurrence of transfer failure due to the melting of the toner. This is to prevent heat from being transmitted to the photosensitive drum.

The operation of the electrophotographic apparatus in a normal state has been described above. Next, the operation in the case of printing one or a small number of a few copies using this electrophotographic apparatus will be described.

The fixing strength is correlated with the melt viscoelasticity of the toner particles, which viscoelasticity is a function of temperature. In general, toner particles that can be fixed at high speed (for example, 150 ° C.) can be sufficiently fixed at low speed (for example, 100 ° C.). Therefore, the present invention aims to shorten the warm-up time for heating the heat roller based on such knowledge. The present invention is directed to an electrophotographic apparatus in which when print data is sent to an electrophotographic apparatus, the number of copies is one or a few copies of about two or three, and the heat roller is not yet heated. The heat roller temperature, which is a setting condition of the apparatus, is normally set (for example, 150
１８０180 ° C.) lower than the temperature (for example, 100 to 11 ° C.).
(0 ° C.) and start printing. Instead, the fixing is performed by reducing the process speed of only the fixing portion to a speed several times lower than the normal speed at which the melt viscoelasticity can be fixed. The heat roller is provided with a means for detecting the surface temperature and a means for controlling the temperature. Since the printing of a small number of copies lowers the process speed, the printing time itself excluding the waiting time becomes longer. On the contrary,
When the number of copies is large, the normal printing has a shorter total printing time including the waiting time. Therefore, the decimal number here means the number of copies such that the printing time is shorter than the normal printing as a whole, for example, about one or a few sheets.

As a result, the first print time can be shortened, and energy saving in the printing of a small number of copies can be achieved. This method is particularly easy to adopt in a full-color electrophotographic apparatus capable of developing a toner image, electrostatic transfer to an intermediate transfer roller, and separating a process section of a toner transfer fixing section.

In the case of full-color printing, the intermediate transfer roller 1
Since a time is required to superimpose the toner images of a plurality of colors on 5, the speed of the intermediate transfer belt 16 during the melt transfer can be reduced by using this time. That is,
It is easy to independently control the speed of the intermediate transfer belt 16 by retreating from the intermediate transfer roller 15 after all the toner images of a plurality of colors to be printed are transferred from the intermediate transfer roller 15.

Further, as shown in FIG. 2, when the pressure roller has a heater and when it is determined that printing is performed for a small number of parts, the heat radiation from the paper medium is reduced. By raising the temperature of the pressure roller slightly higher than the glass transition point temperature of the toner, heat radiation to the pressure roller can be suppressed.

In addition to the heat roller, a means for detecting the surface temperature of the pressure roller and controlling the temperature is provided. After the transfer from the intermediate transfer roller on which all the full-color toner images are superimposed to the intermediate transfer belt, When it is determined that the printing is a decimal copy, the heating of the pressure roller is stopped,
Energy can be saved by supplying heat only from the heat roller. This is particularly effective when the heat roller is made of aluminum and the pressure roller is made of a rubber material which takes a long time to heat and has poor heat response.

[0023]

As described above, according to the present invention, when starting the apparatus in which the transfer and fixing unit is not heated, it is determined whether or not the input number of prints is a decimal part. The fixing temperature is set sufficiently lower than the normal heating temperature, and the fixing speed is set sufficiently lower than the normal speed, so that one to a few sheets of a small number of copies can be set up. There is an effect that it is possible to shorten the waiting time for raising, shorten the warm-up time of the heat roller, and shorten the first print time.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a liquid development type electrophotographic apparatus embodying the present invention.

FIG. 2 is a diagram illustrating a transfer fixing unit of the electrophotographic apparatus illustrated in FIG. 1 in detail.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 1st photosensitive drum 12 2nd photosensitive drum 13 3rd photosensitive drum 14 4th photosensitive drum 15 Intermediate transfer roller 16 Intermediate transfer belt 18 Heat roller 19 Pressure roller

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/29 H04N 1/29 H (72) Inventor Shigeki Uesugi 98 Unoki Nunu, Unoki-cho, Kawakita-gun, Ishikawa Address No. 2 Inside PFU Co., Ltd. (72) Inventor Satoru Hongo 98, Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture Inventor Masaaki Takahata 98 Inventor Masanori Takahata Unoki-nu, Unoka-cho, Kawakita-gun Ishikawa No. 2 Inside PFU Co., Ltd. (72) Inventor Genji Ichida Unoki-cho, Unoki-cho, Kawakita-gun, Ishikawa 98-2 Inventor P72 Co., Ltd. (72) Inventor Shigeharu Okano Unoki-nu, Unokicho, Kawakita-gun, Ishikawa 98-2 PFU Co., Ltd. (72) Inventor Yasukazu Takeda 98 shares of Unoki-nu, Unoki-cho, Unoki-cho, Hebei-gun, Ishikawa 2 shares (72) Inventor Tadashi Nishikawa 98 Unouki-nu, Unoki-cho, Hebei-gun, Ishikawa Prefecture PFU Co., Ltd. (72) Inventor Satoshi Miyamoto 98 shares of Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa, Japan (72) Inventor Kazushi Terashima 98 Uno-nu, Unoki-cho, Hebei-gun, Ishikawa Prefecture 2 Pfu Corporation (72) Inventor Satoshi Sakai 98 shares, Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa (72) Inventor Hironaga Honkawa 98 Unouki-nu, Unoki-cho, Hebei-gun, Ishikawa Prefecture 2 PFU Inc. (72) Masanobu Motoe 98 Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa FP2 F-term in FU Corporation (reference) 2H030 AB02 AD04 AD16 AD18 BB42 BB46 BB53 2H032 AA14 BA05 BA08 BA09 BA21 2H033 AA30 BA11 BA12 BA25 BA30 BA32 BE09 CA03 CA07 CA19 CA30 CA36 CA48 2H078 AA40 BB01 BB12 DD06 DD DD FF04 5C074 AA12 DD 09 DD13 DD24 EE03 EE08 FF15 GG09 GG12 GG13 GG14

Claims (4)

[Claims] An image forming apparatus according to claim 1, wherein the developer is supplied in contact with an image support on which an electrostatic latent image is to be formed, and toner particles of the developer are supplied in response to an electric field generated between the image support and the image support. And a developing unit for forming a toner image by attaching the toner image to the image support, an intermediate transfer member for transferring the toner image on the image support, and a toner image transferred to the intermediate transfer member. An electrophotographic apparatus comprising: a transfer fixing unit that heats and melts at a contact portion of the transfer fixing unit that melts and transfers to a print medium. When it is determined that the number is a decimal part, the heating temperature in the transfer and fixing unit is stopped at a temperature sufficiently lower than the normal heating temperature, and the fixing speed is sufficiently lower than the normal speed. Slow down, consisting of Child-photographic apparatus. 2. An intermediate transfer member comprising: an intermediate transfer roller for superposing toner images of a plurality of colors; an intermediate transfer belt for transferring the toner image superimposed on the intermediate transfer roller; The electrophotographic apparatus according to claim 1, further comprising a heat roller around which the transfer roller is wound. And a heater provided on a pressure roller which is in contact with said heat roller via an intermediate transfer belt. When it is determined that printing is performed for a small number of parts, the temperature of said pressure roller is set to a glass transition point of toner. 3. The electrophotographic apparatus according to claim 2, wherein the temperature is raised slightly higher than the temperature. 4. A printing apparatus comprising: means for controlling the temperature by detecting the surface temperatures of the heat roller and the pressure roller. 4. The electrophotographic apparatus according to claim 3, wherein heating of the pressure roller is stopped after the transfer to the belt.