JPH07134534A - Image forming device - Google Patents

Abstract

PURPOSE:To further miniaturize the image forming device while sufficiently keeping the heat exhausting effect by arranging a power source part in the adequate place. CONSTITUTION:This image forming device is constituted that the sheet containing part 12 for containing a recording paper is disposed so as to incline upward from the center part of the device frame body 11 toward the outside and the low-voltage power source 43 for generating the low-voltage power supplied to the control part is arranged in the dead space below the sheet containing part 12. The sheet containing part 12 is provided with the paper feeding baseplate 52 for placing the recording paper, and the paper feeding baseplate 52 is provided with the vent port 53 in the place never blocked by the recording paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a laser beam printer, and more particularly to an image forming apparatus in which a power source is arranged so that the image forming apparatus can be downsized.

[0002]

2. Description of the Related Art An image forming apparatus, such as a laser beam printer, which forms a toner image on a recording paper by an electrophotographic copying method, is supplied from an optical system device and a sheet accommodating portion inside a machine frame of the image forming apparatus. An image forming unit for reproducing an image on a recording paper sheet by an electrophotographic process, a control unit for controlling the operation timing of each member in the apparatus, electric devices, a large number of mechanical devices such as rollers are stored. There is. These devices are arranged in consideration of mutual functionality within the machine frame body, but in order for each device to fully exhibit its prescribed functions, a certain temperature is required to ensure reliability. It needs to be considered to be kept within range.

For example, the distance between the laser generator and the optical system must be set very accurately within the allowable depth of focus, but even if affected by heat, the thermal expansions of the respective parts cancel each other out. There is a device in which the distance between the laser generator and the optical system is kept within a predetermined range as a whole (see JP-A-55-43577).

However, the one disclosed in this publication is intended to eliminate the harmful effects after the thermal expansion.
Much less is considered about means of actively expelling heated air. That is, the power source unit that generates a relatively large amount of heat is merely arranged below the horizontally provided separation plate.

Therefore, in the conventional image forming apparatus,
In many cases, a fan that forcibly blows air is provided to enhance the cooling effect. In this case, on the rear part inside the machine frame where the fan is arranged, or on the side part relatively close to the fan,
The power supply is arranged. If you do this,
The effect of forced air cooling by the fan is great.

[0006]

By the way, in recent years, in particular, there is an increasing demand for further downsizing of the entire image forming apparatus. Therefore, as described above, when the power supply unit is arranged in the rear part or the side part of the machine frame main body in order to sufficiently obtain the effect of forced air cooling by the fan, it is necessary to expand the arrangement space by that amount. The size of the machine frame main body of the image forming apparatus in the front-rear direction or the left-right direction becomes large, which has been an obstacle to achieving further downsizing of the image forming apparatus.

The present invention has been made in view of the above-mentioned problems of the prior art, and by arranging the power source portion in a proper place, it is possible to further reduce the size of the image forming apparatus while maintaining a sufficient heat discharging effect. To achieve.

[0008]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides an image forming apparatus having a substantially rectangular parallelepiped machine frame main body, in which a sheet accommodating portion for holding recording paper is provided in the machine frame main body. The image forming apparatus is characterized in that it is provided so as to incline upward from the central portion toward the outside, and a power supply unit for supplying electric power to a predetermined portion inside the machine frame main body is arranged below the sheet storage unit. . Further, the sheet accommodating portion has a paper feed base plate on which the recording paper is placed, and the vent holes are provided at positions on the paper feed base plate that are not blocked by the recording paper.

[0009]

In the present invention having the above-described structure, the power source section is arranged in the dead space formed below the slanted sheet accommodating section, and it is not necessary to expand the arrangement space by that amount, and the image formation is performed. The size of the device can be further reduced.

Moreover, the seat accommodating portion is provided so as to incline upward from the central portion inside the machine frame main body, and the hot air generated by the power supply portion rises and contacts the seat accommodating portion. , Goes up along the inclined surface and is discharged to the outside. In this way, smooth convection is formed by the inclined sheet storage portion, and good natural air cooling is performed.

Further, the sheet accommodating portion has a paper feed base plate on which the recording paper is placed, and ventilation holes are provided at positions on the paper feed base plate that are not blocked by the recording paper. In addition to the natural air cooling by the convection, natural air cooling is performed in which hot air is discharged upward through the ventilation holes.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a sectional view schematically showing the entire structure of a laser beam printer according to an embodiment of the present invention, FIG. 2 is a view showing a natural air cooling effect by a sheet accommodating portion of the printer body shown in FIG. 1, and FIG. FIG. 4 is a view showing a natural air cooling effect by a ventilation hole formed in a sheet feeding base plate of a sheet accommodating portion of the printer body shown in FIG. 1, and FIG. 4 is a schematic perspective view showing the natural air cooling effect shown in FIG. FIG. 5 is a schematic plan view showing the sheet storage portion and the low voltage power supply shown in FIG.

As shown in FIG. 1, the laser beam printer of the present embodiment has a machine frame body 11 forming the outer shell of the apparatus main body, and the left side in FIG. Has become. A sheet accommodating portion 12 is provided so as to incline upward from the center of the machine frame 11 toward the outside. The sheet accommodating portion 12 has a paper feed base plate 52 on which the recording paper is placed, and the recording paper is stacked and held on the paper feed base plate 52. Sheet feed base plate 5 of the sheet storage unit 12
The front end of the sheet feeding device 2 can be projected to the outside of the machine frame 11, and when holding a long recording sheet of legal size or the like, the front end of the sheet feeding base plate 52 is projected. . Further, a paper guide 13 is provided in the sheet storage portion 12 in order to regulate the width direction of the recording paper. A front cover 14 is attached to the machine frame 11 so as to be openable and closable so that the recording paper can be easily loaded into the sheet storage portion 12.

As shown in FIG. 1, the dead space formed below the sheet accommodating portion 12 is positioned on the front side of the bottom of the machine frame 11 and supplied to the control portion 77 (see FIG. 9). A low voltage power supply 43 is arranged as a power supply unit that generates a low voltage. As a result, the size can be reduced without expanding the arrangement space. Here, the inclination angle of the sheet storage portion 12 is set to a predetermined angle at which the low voltage power source 43 can be stored. The low voltage power source 43 is, for example, 100V to 1
It is composed of a transformer that steps down to 2V or 5V, a diode and a capacitor that performs rectification, and generates a large amount of heat during the step-down operation as compared with other parts.

As shown in FIG. 2, a plurality of ventilation holes 51, 51 ... Are formed in the front wall 11a of the machine frame 11, and the hot air generated by the low voltage power source 43 rises. After coming into contact with the sheet feeding base plate 52 of the sheet accommodating portion 12 and proceeding to the upper left in the figure along the inclined surface thereof, the sheet is discharged from the upper ventilation hole 51 in the direction of the arrow D shown in the drawing. In this way, since the sheet storage portion 12 is inclined upward to the outside at a predetermined angle, hot air is less trapped and the effect of natural air cooling is high. Further, the ventilation hole 51 is also provided in the lower portion of the front wall 11a as shown in the drawing, and is replaced by the heat generated by the low voltage power source 43 and rising.
Cool air enters from the lower ventilation hole 51 in the direction of the arrow C in the figure, and a smooth convection is formed in combination with the effect of the inclined sheet accommodating portion 12. Further, a flow of air from the front to the rear in the machine frame 11 is also formed in the direction of arrow E in the figure, and as a result, the efficiency of forced air cooling by the fan 65 is also improved.

As shown in FIGS. 3 to 5, the sheet feeding base plate 52 of the sheet accommodating portion 12 is connected to a portion which is not blocked by the recording sheets stacked and placed thereon. Pores 53,
53 ... are provided. That is, as shown in FIG. 5, no matter what size recording paper P is placed, the ventilation holes 53, 53 ... Are not blocked. Therefore, as shown in FIGS. 3 and 4, the hot air generated by the low-voltage power source 43 passes through the ventilation holes 53, 53 ... And is discharged upward as it is. Is formed.

A laser beam scanning optical system unit 15 is provided at a substantially central portion of the machine frame 11. A lid member 17 is attached so as to be swingable around a hinge portion 16 provided at the rear end of the machine frame body 11. In this printer, the machine frame body is formed by the machine frame body 11 and the lid member 17. It has a clamshell type structure. And the machine frame 11
An image forming cartridge 18 is removably mounted inside the lid member 17 so as to be positioned below the lid member 17.

The recording paper placed on the paper feed base plate 52 of the sheet accommodating portion 12 is fed one by one by the paper feed roller 21 and the cam 22 and the pinch roller 23 that comes into contact therewith, and is guided by the guide member. Is conveyed while being guided by the lid member 17
The sheet is discharged toward the front of the image forming apparatus on the lid member 17 through the opening 24 formed in.

The latent image formed on the photosensitive drum 25 of the image forming unit 18 is transferred to the conveyed recording paper in cooperation with the transfer roller 26 provided on the machine frame 11 and transferred. The image is the fixing roller 2 provided on the machine frame 11.
7, 28 is heat-sealed to the recording paper. In order to discharge the recording paper on which the image is formed onto the lid member 17 through the discharge port 24, a pair of paper discharge rollers 29 is provided inside the lid member 17.
Is installed.

The optical system unit 15 has a Bolgon mirror 31 which is irradiated with light from a light source composed of a semiconductor laser and a collimator lens (not shown), and further has known members such as a folding mirror 32. A shutter 33 is rotatably mounted in the optical unit 15, and when the image forming cartridge 18 is loaded at a predetermined position, the shutter 33 is separated from the mirror 32 as shown in FIG. When the lid member 17 is opened, the shutter 33 covers the mirror 32. Lid member 17
The opening / closing movement of the shutter 33 linked to the above is achieved by a member (not shown).

Photosensitive drum 25 of image forming cartridge 18
Is irradiated with a laser beam from the optical system unit 15, and a developing sleeve 34 is provided inside the image forming cartridge 18 adjacent to the photosensitive drum 25. Toner contained in the toner tank 35 is supplied to the developing sleeve 34 through a window formed in the partition wall 37 by the rotation of the blade member 36. The residual toner on the photosensitive drum 25 is removed by a cleaning blade (not shown), and a tank 38 for waste toner is formed in the upper portion of the cartridge 18 to accommodate the removed toner.
A charging brush 39 is in contact with the outer peripheral surface of the photosensitive drum 25, and is charged to a predetermined potential by the charging brush 39. The image forming cartridge 18 having such a structure is also called an image cartridge or a process cartridge, and is replaced with a new one when the life of the photosensitive drum 25 or the toner is used up.

FIG. 6 is a view showing the forced air cooling effect by the fan of the printer body shown in FIG. 1, FIG. 7 is a schematic perspective view showing the structure around the fan shown in FIG. 6, and FIG. 8 is FIG.
FIG. 4A is a diagram showing the forced air cooling effect shown in FIG. 4A, showing a case where the ventilation resistance from the image forming cartridge is high,
FIG. 6B is a diagram showing a case where the ventilation resistance from the image forming cartridge is low.

In this embodiment, as shown in FIG. 1, a ventilation switching section 61 is provided below the fixing rollers 27 and 28. Then, as shown in FIGS. 6 and 7, the ventilation switching section 61 is configured such that the inclination of the ventilation switching plate 55 causes the air flow A mainly from the image forming cartridge 18 to be generated by the operation of the fan 65 and the machine frame. The air volume ratio with the air flow B from the low-voltage power supply 43 provided on the front side of the bottom of the body 11 is switched. The ventilation switching plate 55 is pivotally supported by a main shaft 56 of a motor 57 and is rotatable at a predetermined inclination angle.

As shown in FIG. 8 (a), when the ventilation switching plate 55 is set up in a slightly inclined position (hereinafter referred to as angle 1).
That is, the air flow resistance of the air flow A from the image forming cartridge 18 becomes large, and the air flow rate of the air flow B from the low-voltage power supply 43, which has an alternative relationship with the air flow A, increases due to this effect. The low-voltage power supply 43 is positively forcedly cooled by the fan 65 as well as by natural air cooling. On the other hand, as shown in FIG. 8B, when the ventilation switching plate 55 is made substantially horizontal (hereinafter referred to as angle 2), the ventilation resistance of the air flow A from the image forming cartridge 18 becomes small, and therefore, The flow rate of the air flow A increases, which is effective for forcedly cooling the image forming cartridge 18 and the fixing section. In this case, the flow rate of the air flow B from the low voltage power source 43 is slightly reduced. A plurality of duct holes 72, 72 for forming the above-described air flow A from the image forming cartridge 18 to the fan 65 are formed in the guide plate 71 that guides the recording paper when the recording paper is conveyed. Is provided.

As shown in FIG. 7, the image forming cartridge 1
8. A temperature sensor 82 that quantitatively detects the temperature of the surroundings, and a temperature sensor 83 that quantitatively detects the temperature of the low-voltage power supply 43 and its surroundings.
Are provided in the vicinity of each, and as the temperature sensors, for example, a thermistor, a thermocouple, etc. are used. Based on the detection values of these temperature sensors 82 and 83, the ventilation switching plate 55 can be rotated at a predetermined angle to perform optimum forced air cooling by the fan 65.

In this embodiment, as shown in the figure, the motor 57
A disk 58 is attached to the tip of the main shaft 56 of
Notch 58a or 58b formed in the disk 58
By detecting the position of the photo sensor 59, the ventilation switching plate 55 can be set at a predetermined angle. That is, when holding the ventilation switching plate 55 at the position where the photo sensor 59 detects the cutout portion 58a, the ventilation switching plate 55 is set to the angle 1 shown in FIG. 8A. On the other hand, when holding the ventilation switching plate 55 at the position where the photo sensor 59 detects the cutout portion 58b, the ventilation switching plate 55 is set to the angle 2 shown in FIG. 8B.

FIG. 9 is a schematic plan view of the printer body shown in FIG. As shown in FIG. 9, a control unit 77 is arranged on a side portion inside the machine frame 11, and the control unit 7 is provided.
A circuit for controlling the operation timing of each component incorporated in the image forming device and a microprocessor for analyzing image data, character code, etc. received from an external input device and converting them into dot data for printing are shown in FIG. The circuit including it is mounted.

Further, while forming an image on the recording paper fed from the sheet accommodating portion 12, the recording paper is made a U-turn and is discharged to the upper side of the lid member 17 below the conveyance path of the machine frame 11. A high-voltage power supply 78 is arranged at the bottom rear side. The high voltage power source 78 is used for the image forming cartridge 1
A high voltage necessary for the printing process such as the charging brush 39 and the developing sleeve 34 provided in the printer 8 is supplied.

The low-voltage power source 43 is connected to an AC inlet 75 for taking in external electric power, and as shown in FIG. 9, is arranged so as to extend in the left-right direction along the front surface portion of the machine frame 11. Therefore, the main switch 76 can be integrated with the low-voltage power supply 43, and can be provided on the front surface of the printer body with good operability.

FIG. 10 is a control block diagram of forced air cooling by the fan 65. The arithmetic means 81 is the control unit 77.
A temperature sensor 82 for detecting the temperature around the image forming cartridge 18, a temperature sensor 83 for detecting the temperature around the low-voltage power supply 43, and a photosensor 59 for detecting the angle of the ventilation switching plate 55 are provided inside. Signal is input. Then, based on these input signals, the calculation means 81 causes the fan 65 and the ventilation switching plate 55 via the driver.
A signal is output to the rotating motor 57 and the fan 65 performs optimum forced air cooling. In the present embodiment, the fan 65 can change the fan speed from level 0 to level n, and the number of levels n is appropriately set. The motor 5 for rotating the ventilation switching plate 55
7, when the step motor is used, the set inclination angle of the ventilation switching plate 55 is not limited to the two types described above, and it becomes possible to set an arbitrary angle with a certain minute angle as one unit. Moreover, it is possible to increase the number of set angles as necessary.

Next, the heat exhausting action of the printer body according to the present embodiment will be described with reference to the control flow chart of the forced air cooling by the fan 65 of FIG. According to this embodiment, when the main switch 76 of the printer body is turned on,
The fan speed of the fan 65 is set to 0 level (step S1). That is, the fan 65 does not operate at this stage. The ventilation switching plate 55 is initially set to the angle 1 (step S2, see FIG. 8A). Here, if the ventilation switching plate 55 is not in the angle 1, the calculating means 81 outputs a signal for driving the motor 57 to rotate the ventilation switching plate 55, and the photo sensor 59 causes the cutout portion 58a of the disk 58 to move. The ventilation switching plate 55 is set to the angle 1 by stopping at the detected position.

In step S3, it is determined whether the temperature around the low-voltage power supply 43 is below a preset specified value. Here, when the calculating means 81 determines that the temperature detected by the temperature sensor 83 for detecting the temperature around the low voltage power source 43 is equal to or lower than the specified value, the process proceeds to the next step S4 without operating the fan 65. . Therefore, the low voltage power source 43
When the surrounding temperature is relatively low, forced air cooling around the low-voltage power supply 43 is not performed, and only natural air cooling is performed.

In this case, as shown in FIG. 2, the low voltage power source 43 is formed under the sheet accommodating portion 12 that is inclined upward from the central portion of the machine frame 11 toward the outside. This low voltage power supply 43 is located in the space.
The hot air generated by the above rises and comes into contact with the sheet feeding base plate 52, moves upward along the inclined surface thereof, and is discharged to the outside from the ventilation hole 51 in the upper portion. In this way, smooth convection is formed by the slanted sheet accommodating portion 12, and good natural air cooling is performed. In addition to the natural air cooling due to this convection, as shown in FIG. 3 and FIG.
Natural air cooling is also performed in which hot air is discharged upward through the ventilation holes 53, 53 ...

On the other hand, in step S3, the calculation means 81
However, if it is determined that the temperature detected by the temperature sensor 83 for detecting the temperature around the low-voltage power supply 43 exceeds the specified value, the process proceeds to step S8, and the fan speed of the fan 65 is increased by one level. That is, the fan 65 is operated, and forced air cooling is started in addition to the above natural air cooling.
Here, since the ventilation switching plate 55 is set to the angle 1, as shown in FIG.
The airflow resistance of the air flow A from 8 increases, the flow rate of the air flow B from the low voltage power supply 43 increases reflexively, and the low voltage power supply 43 is positively forcedly cooled by the fan 65. .

When the fan 65 is operated for a predetermined time, the process proceeds to the next step S9, and again it is determined whether or not the temperature around the low-voltage power supply 43 is equal to or lower than a preset specified value. Here, if it is determined that it has not reached the specified value or less, the process returns to step S8, and the fan speed of the fan 65 is further increased by one level. And the low voltage power source 43
When it is determined that the ambient temperature has reached the specified value or less, the process proceeds to the next step S4.

In step S4, the image forming cartridge 18
It is determined whether the ambient temperature is equal to or lower than a preset specified value. Here, the calculation means 81 causes the image forming cartridge 18
When it is determined that the temperature detected by the temperature sensor 82 for detecting the surrounding temperature exceeds the specified value, step S
Go to 10. In this step S10, the ventilation switching plate 55
It is judged whether or not the angle is in the state of the angle 2 as shown in FIG. 8B, and if it is not the angle 2,
It proceeds to the next step S11. In step S11, the calculation means 81 outputs a signal for driving the motor 57 to rotate the ventilation switching plate 55, and the photo sensor 59 causes the disk 58 to rotate.
The cutout portion 58b is stopped at the detected position, and the ventilation switching plate 55 is set to the angle 2. Here, ventilation switching plate 5
When the angle 5 is set to the angle 2, as shown in FIG. 8B, the air flow A from the image forming cartridge 18 has a reduced airflow resistance and an increased flow rate, so that the image forming cartridge 18 and the fixing unit 18 are fixed. It is effective for forced air cooling of the section. In addition,
When the ventilation switching plate 55 is already set to the angle 2, the fan speed of the fan 65 is increased by one level to enhance the air cooling effect (step S12).

On the other hand, in step S4, the calculating means 81
However, if it is determined that the temperature detected by the temperature sensor 82 for detecting the temperature around the image forming cartridge 18 is equal to or lower than the specified value, the process proceeds to the next step S5 as it is. In step S5, it is determined whether or not the angle of the ventilation switching plate 55 is in the angle 1 state, and if it is in the angle 1 state, the fan speed of the fan 65 is decreased by one level, and the process returns to step S3. That is, step S
When the process proceeds to step 5, since the temperatures around the image forming cartridge 18 and the low-voltage power source 43 are also below the specified value, the fan speed is reduced to obtain the optimum air volume. The angle of the ventilation switching plate 55 is angle 1.
If not, the angle is switched to the same angle 1 as the initial setting in step S7.

As described above, according to this embodiment, the low voltage power source, which is conventionally arranged at the rear portion of the machine frame 11 in which the fan is installed or at the side portion relatively close to the fan, holds the recording paper. Since it is arranged in the dead space formed below the sheet accommodating portion 12 to be used, it is not necessary to increase the arrangement space by that amount, and it is possible to achieve further miniaturization of the image forming apparatus. .

Moreover, since the seat accommodating portion 12 is provided so as to be inclined upward from the central portion inside the machine frame body 11 to the outside, the hot air generated by the low voltage power source 43 rises and the seat rises. It contacts the sheet feeding base plate 52 of the accommodating portion 12, advances upward along the inclined surface thereof, and is discharged outward from the ventilation hole 51 in the upper portion. In this way, smooth convection is formed by the slanted sheet accommodating portion 12, and good natural air cooling can be performed.

Further, the sheet feeding base plate 5 of the sheet accommodating portion 12
Ventilation hole 5 should be placed in a place that is not blocked by the recording paper of 2.
.. are provided, the natural air cooling by the convection as well as the natural air cooling in which hot air is directly discharged upward through the ventilation holes 53, 53.

Further, the ventilation switching section 61 is provided, and the inclination of the ventilation switching plate 55 is changed based on the detection values of the temperature sensors 82 and 83, so that the air mainly generated from the image forming cartridge 18 is generated by the operation of the fan 65. Flow A and air flow B from the low-voltage power supply 43 on the front side of the bottom of the machine casing 11
Since the air flow ratio is switched to and from, the optimum forced air cooling according to the situation becomes possible, and in combination with the natural air cooling described above, a sufficient cooling effect can be obtained.

Further, since the low-voltage power supply 43 is arranged so as to extend in the left-right direction along the front surface portion of the machine frame 11, the main switch 76 is integrated with the low-voltage power supply 43, so that the front surface of the printer main body is easy to operate. Can be provided.

In the above embodiment, the sheet accommodating portion 12 is inclined at a predetermined angle, the ventilation holes 53, 53 ... Are formed in the sheet feeding base plate 52 of the sheet accommodating portion 12, and the effect of forced air cooling is obtained. Although the ventilation switching unit 61 is provided in order to raise the temperature, the object of the present invention can be achieved by only any one of these cooling means or any combination thereof depending on the use conditions. The present invention is not limited to the above examples, and can be variously modified within the scope of the claims.

[0044]

As described above, according to the present invention,
Since the power supply unit is arranged in the dead space formed below the inclined sheet storage unit that holds the recording paper, it is not necessary to increase the arrangement space by that much, and the image forming apparatus can be made even smaller. It has become possible to achieve this.

Further, since the sheet accommodating portion is provided so as to be inclined upward from the central portion inside the machine frame main body, the hot air generated by the power source portion rises and contacts the sheet accommodating portion. Then, it goes upward along the inclined surface and is discharged to the outside. In this way, smooth convection is formed by the inclined sheet storage portion, and good natural air cooling can be performed.

Further, the sheet accommodating portion has a paper feed base plate on which the recording paper is placed, and the vent holes are provided at the portions of the paper feed base plate that are not blocked by the recording paper. So
In addition to the natural air cooling by the convection, natural air cooling in which hot air is discharged upward as it is through the ventilation holes is also performed.

Further, since the power supply unit is arranged on the side of the machine frame main body where the sheet storage unit is provided, the main switch is integrated with the power supply unit and provided on the sheet storage unit side of the printer main body with good operability. Became possible.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing the overall structure of a laser beam printer according to an embodiment of the present invention.

FIG. 2 is a diagram showing a natural air-cooling effect of a sheet storage portion of the printer body shown in FIG.

FIG. 3 is a diagram showing a natural air cooling effect by a ventilation hole formed in a sheet feeding base plate of a sheet accommodating portion of the printer body shown in FIG.

FIG. 4 is a schematic perspective view showing a natural air cooling effect shown in FIG.

5 is a schematic plan view showing the sheet storage portion and the low voltage power supply shown in FIG.

FIG. 6 is a diagram showing a forced air cooling effect by a fan of the printer body shown in FIG.

7 is a schematic perspective view showing the structure around the fan shown in FIG.

8A and 8B are diagrams showing the forced air cooling effect shown in FIG. 6, wherein FIG. 8A shows a case where the airflow resistance from the image forming cartridge is high, and FIG. 8B shows a case where the airflow resistance from the image forming cartridge is low. FIG.

FIG. 9 is a schematic plan view of the printer body shown in FIG.

FIG. 10 is a control block diagram of forced air cooling by a fan.

FIG. 11 is a control flowchart of forced air cooling by a fan.

[Explanation of symbols]

11 ... Machine frame, 12 ... Sheet accommodating part, 15 ... Optical system unit, 17 ... Lid member, 18 ... Image forming cartridge, 43 ... Low voltage power supply (power supply part), 52 ... Paper feed base plate, 53 ... Vent hole, 77 ... Control unit, 78 ... High-voltage power supply, P
…Recording paper.

Claims (2)

[Claims] 1. An image forming apparatus having a substantially rectangular parallelepiped machine frame main body, wherein a sheet accommodating portion for holding a recording sheet is provided so as to be inclined upward from a central portion in the machine frame main body to the outside. An image forming apparatus characterized in that a power supply unit for supplying electric power to a predetermined portion in the machine frame main body is arranged below the sheet storage unit. 2. The sheet accommodating portion has a paper feed base plate on which recording paper is placed, and ventilation holes are provided at portions of the paper feed base plate that are not blocked by the recording paper. The image forming apparatus according to claim 1.