JPH04240864A - Electrophotographic recorder - Google Patents

Abstract

PURPOSE:To suppress the temperature rise inside the device without utilizing a cooling fan by containing an electrical power source unit containing electrical power source parts to a bottom part of an image transfer means and providing a ventilation opening in vicinity of a paper feeding means of the electrical power source until and in a fixing device side. CONSTITUTION:The air inflow opening 21 is provided in the vicinity of a paper feeding means and the air outflow opening 22 is provided in the vicinity of a fixing device on the opposite side in the composite electric circuit unit 16. However, the exterior of the other peripheral units are constituted to be sealed. Then, the parts are installed so that the heat generating quantity is gradually increased from the paper feeding means side to the fixing device side. Therefore, the air taken in from the paper feeding means side gradually flows from the heat generating parts of comparatively low temperature to the high temperature fixing device side by the chimney draft effect, and the exothermic element is effectively cooled.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus, and more particularly to a device configuration such as a printer that forms images using an electrophotographic process.

0002

[Prior Art] Conventional electrophotographic laser beam printers (LBPs) of this type that use laser beam scanning exposure and transfer methods
has a configuration as shown in FIG. 5, for example. In FIG. 5, 1 is the main body of the image forming apparatus (printer), 2
Reference numeral denotes a paper feed cassette that accommodates the transfer paper S, 3 a paper feed roller that takes out the transfer paper S one by one from the cassette 2, and 4 a registration roller that controls the conveyance timing of the transfer paper S.

A process cartridge 6 houses a photosensitive drum 7, a developing device and a charger (not shown), a cleaning device for the drum 7, and the like. 8 is a fixing device, 10a is a fixing roller made of aluminum pipe, 10
b is a pressure roller made of rubber, and the toner transferred onto the transfer paper S is melted and fixed by heat and pressure applied from the fixing roller 10a and the pressure roller 10b. And 11
1 is a paper conveyance unit, 12 is a paper ejection roller, 13 is a paper ejection tray, 1
4 is a scanning optical system that scans the laser; 15 is a folding mirror that guides the laser beam to the photosensitive drum 7; In addition, 16 is an electric circuit unit installed vertically on the side of the device body.
A power input section, a low voltage power supply circuit, a high voltage power supply circuit, etc. are arranged independently.

Next, the printing operation of the printer shown in FIG. 5 will be explained. When a print signal is input from a host computer (not shown), the transfer paper S is taken out from the paper feed cassette 2 by the paper feed roller 3. The transfer paper S is conveyed by the registration roller 4 in synchronization with the developed image on the photosensitive drum 7, and the developed image written on the drum 7 by the laser beam L is transferred to the transfer paper S by the transfer charger. . Then, the transfer paper S carrying the transferred image toner passes over the surface of the paper transport section 11, is fixed by the fixing device 8, is transported and discharged by the paper discharge roller 12, and is stacked on the paper discharge tray 13. .

[0005]

[Problems to be Solved by the Invention] However, the above conventional example has the following problems. conventionally,
They were working very hard to reduce the temperature rise inside the equipment. For example, if heat builds up inside the device, molded parts (exterior, etc.) may melt, heat-sensitive electrical circuit components may be destroyed, or a thermal shutdown may occur, stopping the electrical circuit from operating. A fan was installed to forcefully exhaust the hot air inside the device. In addition, forced air cooling fans were sometimes installed specifically for electrical and electrical components to prevent the temperature of electrical components from rising.

[0006] In such a configuration, since a space is required for installing the fan, not only is the space efficiency poor, but if the fan stops, the reliability of the device will be affected. . Furthermore, the increased number of parts also led to an increase in costs.

The present invention aims to solve the above problems. That is, the present invention can suppress the temperature rise inside the device without using a cooling fan, can effectively utilize the space inside the device, and requires almost no cooling components. It is an object of the present invention to provide an electrophotographic recording device that can reduce costs.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a paper feeding means for feeding recording paper into an apparatus according to a signal from a central control unit, and an electrophotographic process on the recording paper. In an electrophotographic recording apparatus having an image transfer means for forming an image using the image transfer means, and a fixing means for heating and fixing the recording paper after the transfer, a power supply unit containing main power supply components is housed below the image transfer means, Ventilation holes were provided in the vicinity of the paper feeding means of the power supply unit and on the side of the fixing unit to allow air to pass through the unit, and the other surrounding components were sealed.

[0009]

[Operation] According to the present invention, a power supply unit that generates heat is housed below the image transfer means in the paper conveyance path in the main body of the image recording apparatus, and ventilation holes are provided near the paper feed means and on the fixing device side of the power supply unit. Since the unit is configured to allow air to pass through, and the other surrounding components are sealed, there are few heat-generating parts near the ventilation port on the paper feeding means side, and there are no heat-generating components near the ventilation port on the fuser side. Considering that there is a large amount of air present on the fuser side, the air on the fuser side expands greatly, and, as is known as the chimney effect, the ventilation opening on the paper feeding means side becomes an air inlet, and the air on the fuser side naturally expands. Since the ventilation port becomes an air outlet, that is, the air flows from the air inlet to the air outlet, temperature rise within the device can be suppressed without providing a cooling fan.

0010

1 is a sectional view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of FIG. 1, and FIG. 3 is a plan view showing the inside of FIG. In FIGS. 1 to 3,
Reference numerals 1 to 4, 6 to 8, 10a, 10b, and 11 to 16 are the same as those explained in FIG.

Reference numeral 9 in FIG. 1 is a transfer roller that transfers the developed image on the photosensitive drum 7 onto the recording paper S. Also 1
6 is an electric circuit unit, and in this embodiment, an AC
This is a composite electric circuit unit that integrates a power input section, a low-voltage power supply circuit, a high-voltage power supply circuit, a main motor driver, a fixing device control circuit, and a DC controller circuit that controls image recording of the main body of the image recording apparatus. Also, 1 in Figures 1 and 2
7 is a separation claw provided so that the paper is fed one by one;
Reference numeral 18 in FIGS. 2 and 3 is an arrow indicating an air flow path in the main body of the apparatus, and reference numerals 21 and 22 in FIG. 2 are slit ventilation holes.

As shown in FIG. 2, in the composite electric circuit unit 16, an air inlet is provided near the paper feeding means.
An air outlet was provided on the opposite side (near the fuser), and the other surrounding unit exteriors were sealed. Then, the parts are arranged while balancing the heat generation so that the amount of heat generation gradually increases from the paper feeding means side to the fixing device. therefore,
Air is drawn from the paper feeding means side of the heat generating component in this unit, and the air on the air outlet side of the heat generating component expands and becomes hot, and flows toward the higher temperature fixing unit as shown by arrow 18. This phenomenon is called the chimney effect.

That is, by flowing air into the composite electric circuit unit 16, it is possible to air-cool the ambient temperature within the unit 16 and the heating element, thereby easily lowering the junction temperature of the heating element.

In the apparatus configuration of this embodiment, the heat generation temperature of the fixing device 8 rises to about 180.degree. C., and the heat generation temperature of the heat generating element in the composite electric circuit unit 16 reaches about 85.degree. The total opening area of the ventilation ports 22, which serve as air outflow ports, provided near the top of the fixing device 8 on the exterior of the apparatus, and the total opening area of the ventilation ports 21, which serve as air inflow ports, provided near the paper feeding means, are as follows:
A large opening area was secured relative to the amount of heat generated by this device, and the air outlet was configured to be approximately 10% larger than the air inlet.

Also, like the composite electric circuit unit 16, the exterior structure of the device in this embodiment is a sealed structure. The air around the device is drawn into the vicinity of the paper feeding means inside the machine, the air near the paper feeding means is warmed, and then drawn into the power supply unit. Furthermore, the air warmed by the heat-generating parts in this unit is drawn into the fuser to promote the same effect as described above, and the air is warmed by the fuser, expands, and becomes lighter, causing the air to rise above the fuser. The air is naturally exhausted from the ventilation port 22 to the outside of the device. The upper cover of the unit 16 also serves as the paper conveying section 11, and is made of metal and used as a frame ground to prevent artificial electrostatic noise during jam processing at the door opening of the main body.

Furthermore, by constructing the upper cover of this unit 16 from a material with good thermal conductivity (metal such as aluminum), it also serves as a heat dissipation plate for the power supply and control circuit components, and the lower exterior (lower cover) The case is made of a heat insulating material (molded) to prevent heat from rising from the bottom surface of the composite electric circuit unit 16.

Furthermore, when looking at the entire apparatus, the arrangement of the heat generating components of the entire apparatus is such that the main motor (approximately 90 mm In other words, the height of heat generation is balanced in the entire device, from the air inlet side to the outlet side, and from the lowest calorific value to the highest. This structure is capable of generating air flow from the vicinity of the paper means to the upper part of the fixing section due to a chimney effect.

Next, the printing operation will be explained. The operator first instructs the information to be printed from the host computer. Upon receiving the print command (signal), the printer performs a paper feeding operation, and the transfer paper S in the paper feed cassette 2 is conveyed to the transfer section. The developed image written on the photosensitive drum 7 by the laser beam L and developed by a developing device (not shown) in the process cartridge 6 is transferred to the transfer roller 9.
The image is transferred onto the transfer paper S, passes through the paper transport section 11, and is fixed by the fixing device 8. Then, the paper is stacked on the paper discharge tray 13.

[0019] By adopting such a configuration, it is possible not only to suppress the rise in temperature inside the device, but also to achieve natural cooling by natural convection utilizing the chimney effect within the device, without using a forced air cooling fan for exhaust. Became. Also, as shown in Figure 2,
Since the photosensitive drum 7 is located near the upper cover that also serves as a heat sink of the composite electric circuit unit 16, the photosensitive drum 7 is naturally preheated.
Since the recording paper S was heated on the paper transport surface (the upper cover), it was possible to cope with environmental changes, and it was also possible to reduce the power of the fixing device.

Furthermore, as shown in FIG. 4, a paper conveyance section 11 (composite electric circuit unit 1
The cover (exterior) of the unit 16 is composed of an upper cover (6) and a lower unit case made of a heat insulating material (mold), which also serves as a reinforcing material for the main body frame 19 of the apparatus. Note that 20 is a scanner unit. Therefore, as shown in FIG. 4, sufficient rigidity was obtained by assembling the composite electric circuit unit 16 to the flexible main body frame 19.

[0021]

[Effects of the Invention] As explained above, according to the present invention,
A power supply unit that generates heat is housed below an image transfer means in a paper conveyance path within the main body of the image recording apparatus, and ventilation holes are provided near the paper feed means and on the fixing side of the power supply unit to allow air to pass through the unit. Since the other surrounding components are sealed, there are few heat-generating parts near the ventilation port on the paper feeding means side, and there are many heat-generating parts near the ventilation port on the fuser side. The air on the fuser side expands greatly, and as is called the chimney effect, the ventilation opening on the paper feeding means side becomes an air inlet, and the ventilation opening on the fixing unit side becomes an air outlet, that is, Since the air is ventilated from the air inlet to the air outlet, temperature rise inside the device can be suppressed without providing a cooling fan. Therefore, the space within the device can be used effectively as is, and almost no cooling components are required, resulting in cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of FIG. 1;

FIG. 3 is a plan view showing the inside of FIG. 2;

FIG. 4 is a sectional view showing the main body frame reinforcement structure of FIG. 1;

FIG. 5 is a sectional view showing an example of a conventional technique.

[Explanation of symbols]

1: Image forming apparatus body 2: Paper cassette 6: Process cartridge
8: Fixing device 16: Composite electric circuit unit 1
8: Arrow indicating air flow path 21: Slit ventilation opening 22:
slit ventilation hole

Claims (3)

[Claims] 1. Paper feeding means for feeding recording paper into the apparatus in response to a signal from a central control unit; image transfer means for forming an image on the recording paper using an electrophotographic process; and the recording paper after transfer. In an electrophotographic recording apparatus having a fixing means for heating and fixing an image, a power supply unit containing main power supply components is housed below the image transfer means, and
A ventilation hole is provided in the vicinity of the paper feeding means of the power supply unit and on the side of the fixing device, and the structure is configured to allow air to pass through the unit, and other surrounding structures are sealed. An electrophotographic recording device. [Claim 2] The opening area of the ventilation port of the power supply unit is:
2. The electrophotographic recording apparatus according to claim 1, wherein the opening area near the paper feeding means is not larger than the opening area near the fixing device. 3. A ventilation hole on the exterior of the apparatus is provided near the paper feed means and at the top of the fuser, and the opening area of the ventilation hole is such that the opening area near the paper feed means is larger than the opening area at the top of the fuser. The electrophotographic recording device according to claim 1, wherein the electrophotographic recording device is not large.