JPH0673039B2 - Copying device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a copying apparatus capable of preventing an increase in temperature of a paper passage. BACKGROUND OF THE INVENTION Generally, in a copying machine, a latent image formed on a photoconductor drum by scanning an optical system is developed into a toner image by a developing device, transferred to recording paper supplied at a timing, and then fixed by a fixing device. It is designed to be ejected. This fixing device melts and fixes the toner image on the recording paper by heat and pressure, and is controlled at a necessary and sufficient temperature (about 200 ° C). Therefore, when performing continuous copying, the temperature of the paper passage from the fixing unit to the paper discharge unit becomes considerably high. In particular, when the paper discharge unit is equipped with a path switching mechanism for switching between the paper discharge path and the double-sided copy path, as in a copying machine equipped with a double-sided copy function, when the paper discharge unit becomes hot, a plurality of paper-passage paths are formed. Not only did the phenomenon of dew condensation occur under the influence of the temperature difference from the outside of the machine, which caused jams, but the recording sheets after one-sided copying stuck to each other via toner inside the stacker, Due to the high heat, the toner adhered to the guide members that made up the paper, and troubles such as obstructing paper feeding and transportation occurred. This problem is an important technical problem for middle-speed machines and higher models, and it has been dealt with by installing a dedicated fan or by increasing the temperature of the fuser during single-sided copying and lowering it during double-sided copying. ． However, in the case of, there is a cost disadvantage, and there is a problem that the space for that is occupied. Also,
Since only a dedicated fan was provided, the fan stopped at the same time as the copying was completed and the temperature increased after the stop due to a phenomenon called so-called overshoot, which was not sufficient for solving the above problem. In the case of, there was a problem that fixing failure was likely to occur in single-sided copying immediately after continuous copying. [Object of the Invention] In view of the above points, the present invention utilizes the exhausted air from an existing cooling fan to send the air toward the fixing portion of the sheet passing path including the guide member including the movable branch body by the fan,
It is an object of the present invention to provide a copying machine which is intended to improve the reliability by extending the same function even after completion of copying to prevent the temperature of the discharge portion from becoming high and eliminating the so-called overshoot phenomenon.

[Structure of Invention]

In order to achieve the above-mentioned object, the present invention has a fan in a copying machine main body and a timer for extending the operating time of the fan after completion of copying, and is provided in a paper discharge section on the downstream side of a fixing section. A copying machine including a guide member such as a switching mechanism for forming a paper discharge path and a double-sided copy path, wherein an inlet for collecting air near the fan and a ventilation duct near the outside of the paper discharge section are provided. By providing the outlet of the duct for ventilation only near the fixing portion of the paper discharge portion, it is possible to blow the wind from the fan through the duct toward the fixing portion of the guide member without passing through the fixing portion. The member is configured to cool the fan by extending the operation time after the completion of copying by the air supplied from the fan outside the paper discharge section. [Embodiment] Next, the present invention will be described based on an embodiment shown in the accompanying drawings. FIG. 1 shows a sectional view of a double-sided copying machine to which the present invention is applied. In the figure, 1 is a copying apparatus main body, 2 is a paper feed section, 3 is an optical system unit for irradiating information from a document placed on a document table 4 onto the photoconductor drum 5, and 6 is on the photoconductor drum 5. Developing unit for developing the formed latent image into a toner image, 7
Is a transfer unit for transferring the toner image onto the papers sent out one by one from the cassette mounted in the paper supply unit 2, and 8 is a fixing unit for receiving the transferred papers via the conveyor belt 9 and fixing the copy surface. Is. On the downstream side of the fixing unit 8, there is provided a paper discharge unit 13 having a mechanism 13 'for switching between a paper discharge path 11 for discharging the paper to a paper discharge tray 10 outside the machine and a double-sided copy path 12. A paper reversing mechanism in which the double-sided copying path 12 communicates with each other via a conveying path 15, 16 is a stacker, 17 is a paper re-feeding mechanism for the paper stored in the stacker 16, and 18 is a paper fed from the re-feeding mechanism 17. It is a relay unit that relays to the paper feed path of the paper feed unit 2. Reference numeral 19 denotes an existing cooling fan for preventing heating of the optical system unit 3 in the copying machine main body 1. The fan 19 is provided with a duct 21 at an exhaust port 20 provided on the side wall of the main body 1 as shown in FIGS.
Reference numeral 22 denotes an exhaust duct that is externally locked to the partition frame of the exhaust port 20, and the exhaust duct 22 is exhausted to the outside of the machine through the exhaust port 20 from the cooling fan 19. This is to allow a part of the wind to be introduced into the paper discharge section 13 from the opening 24 provided on the upper surface of the cover body 23 into the paper passage including the switching mechanism from the fixing section 8 side. This exhaust air is an air flow in the optical system unit 3 and does not exceed 60 ° C experimentally. This temperature of 60 ° C is considered to be a sufficient temperature for cooling these parts, considering that the temperature of the guide member constituting the paper discharge section 13 and the paper passage around it is higher than about 120 ° C. I can say. Reference numeral 25 is a timer for extending the operating time of the cooling fan 19. The timer 25 operates via a microcomputer or the like in response to a copy completion signal, and only the drive motor 26 of the cooling fan 19 for a set time (about 5 to 10 seconds). It functions to extend energization. That is, generally, when the copying is completed and the cooling fan 19 is stopped at the same time, there is a temperature rise (overshoot phenomenon) after the stop as shown in FIG. 4, which is effective for preventing this, and the operation time of the cooling fan 19 is reduced. The extension prevents the overshoot phenomenon as shown in FIG.
And, the reliability of preventing the temperature rise of the paper passage around and around it can be greatly improved. [Effect of the Invention] As described above, the copying machine according to the present invention has the fan (19) in the copying machine body and the timer (25) for extending the operating time of the fan (19) after copying is completed. And a guide member such as a switching mechanism (13 ') for forming a paper discharge path (11) and a double-sided copy path (12) provided in a paper discharge section (13) downstream of the fixing section (8). In the copying machine, an inlet for collecting air near the fan (19) and a duct for ventilation (21) near the outside of the paper discharge unit (13) are provided, and an outlet for the duct for ventilation (21) is provided. By providing the discharge unit (13) near the fixing unit (8), the air from the fan (19) passes through the duct (21) and near the fixing unit (8) of the guide member. 8) The guide member can be blown without passing it through, and the guide member is supplied to the fan from the space outside the paper discharge unit (13). The feature is that the air is cooled by extending the fan operating time after completion of copying, so that part of the exhaust air is constantly introduced into the paper discharge section and the paper passage formed around it while the copying machine is operating. Therefore, the heat of the fixing device does not raise the temperature of the guide plate and the like, and the recording sheets after one-sided copying adhere to each other via the toner in the stacker, or the recording sheets after one-sided / double-sided copying pass through. It prevents the occurrence of troubles such as toner adhesion to the guide members that make up the path. Moreover, since the existing cooling fan is used, the cost does not increase, and there is no need for an installation space such as a dedicated fan. Moreover, even after the completion of copying, the air is blown for a certain period of time to cool it and prevent the guide member from becoming hot (overshoot) than during copying.
This will prevent jams and poor transport. Also, by blowing air from the guide member near the fixing, which is the entrance side of the paper after fixing, the heat entering side is cooled,
It can block the heat transfer from the fixing. Furthermore, it is not necessary to change the temperature of the fixing device between single-sided copying and double-sided copying, and there are various excellent effects such as no room for fixing failure.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a double-sided copying machine to which the present invention is applied, FIG. 2 is an enlarged sectional view of essential parts, FIG. 3 is an external perspective view of an exhaust duct, and FIG. 4 is a graph showing an overshoot phenomenon. , Fig. 5 is a graph that eliminates the overshoot phenomenon. 1 ... Copier body, 19 ... Cooling fan 20 ... Exhaust port, 21 ... Exhaust duct 25 ... Timer

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-56-117252 (JP, A) JP-A-59-33482 (JP, A) JP-A-57-101861 (JP, A) Actual development Sho-62- 41155 (JP, U) JP-B 4-23790 (JP, B2) JP-B 4-72228 (JP, B2) JP-B 4-68629 (JP, B2)

Claims (1)

[Claims] 1. A fan (19) inside the apparatus body, and a timer (2) for extending the operating time of the fan (19) after completion of copying.
5) and a discharge unit (1) downstream of the fixing unit (8).
A copying machine provided with a guide member such as a switching mechanism (13 ') for forming a paper discharge path (11) and a double-sided copy path (12) provided in 3), and blowing air near the fan (19). A ventilation duct (21) near the collecting entrance and the outside of the paper discharge section (13)
And the outlet of the ventilation duct (21) is provided near the fixing section (8) of the paper discharge section (13) so that the wind from the fan (19) passes through the duct (21). Of the guide member can be sprayed to the vicinity of the fixing unit (8) without passing through the fixing unit (8), and the fan operates after the completion of copying by the air outside the paper discharge unit (13) supplied from the fan. A copying machine characterized by extended cooling.