JPH01195468A - Digital copying machine - Google Patents

Abstract

PURPOSE:To detect the temperature of a color separation prism and to control a cooling fan without providing an independent temperature sensor by providing a detecting means for detecting the dark current of a photodetector in an original reading part and a driver which controls the blowing quantity of the cooling fan according to outputs from the detecting means. CONSTITUTION:The dark current detecting means 29 detects the temperature of the prism 22 by digitally converting the dark currents of an R-chCCD25 and a C-chCCD27 into voltage values in a signal processing part 28 and comparing the value with the data of temperature-current characteristic in a memory 31. And the detecting means 29 outputs the command of the blowing quantity in accordance with the temperature of the prism 22 to the driver 34 of the cooling fan 33 and outputs chrominance signals color-separated according to the colors of an original to a writing unit 35 provided in a printer part B. Thus, the temperature of the color separation prism 22 can be accurately detected without providing the independent temperature sensor and also the blowing quantity of the cooling fan 33 can be appropriately controlled according to the detected temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement of a digital copying machine that is equipped with a cooling fan in the printer section that commonly exhausts the document reading section and the printer section.

[Conventional technology]

Conventional digital copying machines include an original reading unit that scans an original placed on a platen glass by the movement of a moving optical system and extracts the original information as an electrical signal, and a laser beam that is modulated by the signal extracted by the original reading unit. , a rotating photosensitive drum is exposed to light to create a latent image, and after being developed in a developing device, it is transferred to a recording paper fed to a transfer section at the appropriate timing, and is fixed and ejected. The copying machine is equipped with a printer section, and a temperature sensor installed in the reading section controls the air flow rate of a cooling fan that commonly exhausts the document reading section and the printer section, thereby preventing each part of the copying machine from overheating.

[Problem that the invention seeks to solve]

Therefore, in conventional digital copying machines, the temperature detected by the temperature sensor depends on the location where it is installed, so the color separation prism (the adhesive may peel off if heated above 60 degrees), which is the least likely to be heated, is placed inside the reading unit. Temperature could not be detected accurately.

As a result, the cooling fan has to be operated at a large capacity for a long time, and problems such as noise and suction of dust tend to occur. In addition, providing the temperature sensor independently has problems such as an increase in the number of parts and assembly man-hours, and a tendency to increase costs.

This invention is intended to solve the above-mentioned problems, and is a digital copying machine that can accurately detect the temperature of the color separation prism and control the air volume of the cooling fan at the appropriate time without installing an independent temperature sensor. is intended to provide.

[Means for solving problems]

In order to achieve the above object, the present invention provides a detection means for detecting dark current of a light receiving element in the document reading section in a digital copying machine equipped with a cooling fan in the printer section that commonly exhausts the document reading section and the printer section. and a driver for controlling the amount of air blown by the cooling fan according to the output of the detection means, so that the temperature of the color separation prism can be detected and the cooling fan can be controlled without providing an independent temperature sensor. It is.

[Example] Next, the present invention will be described based on an example shown in the accompanying drawings.

Fig. 1 is an overall configuration diagram of the digital copying machine of the present invention;
This figure is a block diagram of the reading unit, FIG. 3 is a plan view showing the structure of the printer section and the principle of laser beam scanning, and FIG. 4 is a block diagram of the cooling fan drive system.

In FIG. 1, A is a document reading section, and B is a printer section. The document reading section A is equipped with a platen glass 1 provided on the top surface of the housing.
A halogen lamp 5 provided on a carriage 4 moving on a slide rail 3 illuminates the original 2 placed on the document 2.
The reflected light is taken out by the first mirror 7 through the slit 6, and guided to the lens reading unit 20 via the mirror 9.9' provided in the movable mirror unit 8.

The carriage 4 and movable mirror unit 8 are powered by a timing pulley 12 attached to a stepping motor 10 via a wire 11.
It is connected via a wire 14 to a pulley 13 coaxial with the tail pulley J15a, 15b. In this case, the movable mirror unit 8 moves on the slide rail 3 at 1/2 the speed of the carriage 4 in the same direction.

Reference numerals 16 and 17 denote standard white plates provided on the lower surface of both ends of the platen glass l, and the standard white plates 16 and 17 are used to obtain standard white signals before and after the start and end of document reading scanning.

The lens reading unit 20 has a lens 2 as shown in the second figure.
1. Prism 22, first reading board 24, red channel (hereinafter referred to as R-ch) CCD 25, second reading board 2
6. Cyan channel (hereinafter referred to as C-ch) CCD2
It consists of 7. The original optical image transmitted by the first mirror 7 and the mirror 9 is focused by the lens 21 and separated into an R-ch image and a C-ch image by a dichroic mirror 23 built into the prism 22.

R-ch CCD 25 provided on the first reading board 24,
An image is formed on each light receiving surface of the C-ch CCD 27 provided on the second reading board 26. This R-chCCD2
The image signals output from the C-ch CCD 27 and the C-ch CCD 27 are subjected to signal processing in the signal processing section 28.

29 is a dark current detection means, and this detection means 29 is an R-chC
After detecting the dark current of the CD 25 and the C-ch CCD 27 and digitally converting the output current into a voltage value in the conversion unit 30,
The temperature of the prism 22 can be detected by comparing it with the temperature-current characteristic data in the memory 31. 32 is a processing circuit board, and this board 32 is a signal processing unit 2.
8, a detection means 29, a conversion section 30, and a memory 31 are mounted, and is provided at the lower part of the document reading section A. Signal processing section 2
The device instructs the driver 34 of the cooling fan 33 to output an air flow rate according to the temperature of the prism 22, and outputs color signals separated according to the toner color to the writing unit 35 provided in the printer section B. . For example, when the prism 22 is at a certain temperature or higher, the driver 34 performs large-capacity air blowing operation.
When the temperature is below a certain temperature, the cooling fan 33 is switched and controlled so as to operate at a small capacity.

The writing unit 35 includes a semiconductor laser 3 as shown in the third diagram.
7, a polygon mirror 38 that is rotated by a drive motor 36 to rotate and scan the laser beam generated by the semiconductor laser 37, an fθ lens 39, and a cylindrical lens 40. The laser beam generated by the semiconductor laser 37 is rotated and scanned by the polygon mirror 38, and is projected onto the surface of the photosensitive drum 41 via the fθ lens 39 and the cylindrical lens 40, thereby forming a bright line.

Reference numeral 42 denotes an index sensor that detects the start of beam scanning, and detects the start of scanning by a laser beam via a reflecting mirror 43.

When the index sensor 42 detects the start of scanning, modulation of the beam by the first color signal is started. The modulated beam scans the photosensitive drum 41, which has been uniformly charged in advance by a charger 47. A latent image corresponding to the first color is formed on the drum surface by the main scanning by this beam and the sub-scanning by the rotation of the drum 41, and this latent image is developed by a developing device 49 loaded with, for example, red toner. After this red toner image is formed, the drum surface is charged again by the charger 47 in the next copy cycle. In this case, the cleaning device 52 cleans the photosensitive drum 4.
1 to prevent the red toner image from being scraped off.

Next, the second color signal output from the signal processing section 28 is input to the writing unit 35, and the second color signal is inputted to the photosensitive drum 41.
Similarly to the above, a latent image corresponding to the second color is formed on the surface. The latent image is then developed by a developing device 50 loaded with, for example, blue toner. That is, the blue toner image is formed on top of the already formed red toner image.

Next, based on the control signal generated by the signal processing section 28, a black toner image is formed on the surface of the photosensitive drum 41 by the developing device 51 loaded with black toner in the same manner as described above.

AC and DC biases are applied to the sleeves of these developing units 49, 50, and 51, so that a jumping phenomenon is performed by the two-component toner, and development is performed without contacting the grounded photoreceptor drum 41. It has become.

The three-color toner image developed in this way is transferred to the transfer pole 56.
The image is transferred onto the recording paper 67 fed by the paper feed belt 68 and paper feed roller 69 of the paper feed section. After that,
The recording paper 67 is separated from the photosensitive drum 41 by the separation pole 57, and further conveyed to the fixing device 58 by the paper discharge belt 59 and fixed thereon, thereby obtaining a color hard copy.

After the transfer is completed, unnecessary toner remaining on the photosensitive drum 41 is scraped off by contact with the blade 53 of the cleaning device 52. A roller 55 provided on the downstream side of the cleaning device 52 rotates the blade 53 after cleaning is completed.
This is to completely remove a small amount of toner left between the drum surface and the blade when the blade is separated from the drum 41 for the next exposure and development, and rotates in the opposite direction to the drum.

〔Effect of the invention〕

As described above, the present invention provides a digital copying machine equipped with a cooling fan in the printer section that commonly exhausts the document reading section and the printer section, including a detection means for detecting dark current of a light-receiving element in the document reading section, and the detection means. The present invention is characterized in that it is equipped with a driver that controls the air flow rate of the cooling fan according to the output of the color separation prism. The amount of air blown by the cooling fan can be controlled appropriately. Therefore, it is possible to reliably prevent heating of the color separation prism, which particularly dislikes high temperatures, and it is possible to significantly shorten the operating time when using large-volume air blowing accompanied by noise. Furthermore, by reducing the number of parts and assembly man-hours, it has outstanding effects such as reducing costs and improving maintainability at the same time.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of the digital copying machine of the present invention;
This figure is a block diagram of the reading unit, FIG. 3 is a plan view showing the structure of the printer section and the principle of laser beam scanning, and FIG. 4 is a block diagram of the cooling fan drive system. A - Original reading section B - Printer section 1 - Platen glass 2 - Original 3 - Slide rail 4 - Carriage 5 - Fluorescent light 7 - First mirror 8 - Movable mirror Unit 9.9' - V mirror 20 - Lens reading unit 23 - Dichroic mirror 24.26 - First and second reading board 25.27 - CCD 28 - Signal processing unit 29 - Detection means 30--conversion unit 31...memory 32-board 34--driver 82 Contract Figure 3 + Figure procedure amendment (voluntary) April 14, 1999

Claims (1)

[Claims] In a digital copying machine equipped with a cooling fan in the printer section that commonly exhausts the document reading section and the printer section, there is provided a detection means for detecting a dark current of a light receiving element in the document reading section, and a cooling fan that detects the dark current of a light receiving element in the document reading section, and a cooling fan that detects the dark current of a light receiving element in the document reading section. A digital copying machine characterized by being equipped with a driver that controls the amount of air blown by a fan.