Image forming apparatus
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- CANON KK
- Filing Date
- 2022-04-21
- Publication Date
- 2026-08-03
Smart Images
Figure 0007898917000001 
Figure 0007898917000002 
Figure 0007898917000003
Abstract
Description
Technical Field
[0001] The present invention relates to an image forming apparatus that forms an image on a recording material.
Background Art
[0002] Image forming apparatuses such as printers, copiers, and multifunction devices change the operation settings during image formation according to conditions such as the temperature and humidity of the environment in which the image forming apparatus is installed (hereinafter referred to as environmental conditions). Therefore, the image forming apparatus has a sensor for measuring environmental conditions.
[0003] Patent Document 1 describes an arrangement example of a temperature and humidity sensor disposed inside the housing of an image forming apparatus. According to this document, two ventilation holes are formed in an exterior cover that covers the frame of the image forming apparatus, and a temperature and humidity sensor is disposed in the gap between the exterior cover and the frame between the two ventilation holes, and an exhaust fan for discharging the air in the gap from one of the ventilation holes is disposed.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] However, in the arrangement of the temperature and humidity sensor described in the above document, not only the outside air flowing in from the intake-side ventilation hole but also the air flowing from the inside of the image forming apparatus toward the exhaust fan passes through the temperature and humidity sensor. Therefore, during the execution of the image forming operation, the temperature in the vicinity of the temperature and humidity sensor gradually rises due to the air heated inside the image forming apparatus, and the measurement accuracy of the temperature and humidity may decrease.
[0006] Therefore, an object of the present invention is to provide an image forming apparatus capable of improving the detection accuracy of environmental conditions during the execution of an image forming operation. [Means for solving the problem]
[0007] One aspect of the present invention is an image forming apparatus comprising: a housing for housing an image forming means for forming an image on a recording material; a fan disposed inside the housing for generating airflow; a duct member disposed inside the housing for forming a flow path for the airflow; electrical components disposed inside the duct member; and a sensor unit disposed inside the housing for detecting environmental conditions around the housing, wherein the housing has a cover member constituting at least a part of the exterior surface of the housing in a first direction; an air intake port provided in the cover member; and an exhaust port provided in a second direction along the cover member at a position downstream from the air intake port. The duct member has (i) an upstream opening defined by the upstream end of the duct member in the second direction and opening to the upstream side in the second direction, and (ii) a downstream opening defined by the downstream end of the duct member in the second direction and opening to the downstream side in the second direction. The fan takes in air from the upstream side in the second direction and blows it out to the downstream side in the second direction, The upstream opening, The downstream opening, The image forming apparatus is characterized in that it generates the airflow that flows through the exhaust port, and the sensor unit is located in the region between the intake port and the rotation axis of the fan in the first direction, and is located upstream of the fan in the second direction. [Effects of the Invention]
[0008] According to the present invention, the accuracy of detecting environmental conditions during the execution of image formation operations can be improved. [Brief explanation of the drawing]
[0009] [Figure 1] An external view of the image forming apparatus according to Example 1, as seen from the front. [Figure 2] External view (a, b) of the image forming apparatus according to Example 1, as seen from the rear side. [Figure 3] A schematic diagram showing the internal configuration of the image forming apparatus according to Example 1. [Figure 4] A diagram showing the image forming apparatus according to Example 1 with the rear cover removed. [Figure 5] Perspective view (a) and exploded view (b) of the low-voltage power supply unit according to Example 1. [Figure 6] A perspective view (a) and an axial side view (b) of the power supply fan unit according to Example 1. [Figure 7] Figures (a, b) show the front and back surfaces of the environmental sensor according to Example 1. [Figure 8] A diagram showing the configuration of the humidity sensor according to Example 1. [Figure 9] A graph showing the relationship between temperature, humidity, and impedance of the humidity sensor according to Example 1. [Figure 10] A cross-sectional view showing the airflow inside the image forming apparatus according to Example 1. [Figure 11] An enlarged view showing the airflow around the environmental sensor according to Example 1. [Figure 12] Graphs showing the temperature detection results of environmental sensors in Example 1 and the Comparative Example. [Figure 13] An external view of the image forming apparatus according to Example 2, as seen from the rear. [Figure 14] A cross-sectional view showing the airflow inside the image forming apparatus according to Example 2. [Figure 15] A cross-sectional view showing the airflow inside the image forming apparatus according to Example 3. [Modes for carrying out the invention]
[0010] The embodiments relating to this disclosure will be described below with reference to the drawings. [Examples]
[0011] (Housing of an image forming apparatus) Using FIGS. 1 and 2(a, b), the appearance of the image forming apparatus 1 according to one embodiment (Example 1) will be described. FIG. 1 is a view of the image forming apparatus 1 as viewed from the front side, and FIGS. 2(a, b) are views of the image forming apparatus 1 as viewed from the back side. Here, the "front" referred to herein means the side facing the user when the user stands in front of the image forming apparatus 1 to pick up the output, replenish the recording material, or replace the consumables. The front of the image forming apparatus 1 can be confirmed, for example, in the product manual. Also, the surface opposite to the front of the image forming apparatus 1 is called the "back".
[0012] In the following description, when the image forming apparatus 1 is installed on a horizontal plane, the upward direction (vertical direction) is defined as the Z direction, and the downward direction is defined as the -Z direction. Among the horizontal directions orthogonal to the Z direction, the direction along one surface of the housing of the image forming apparatus 1 is defined as the X direction, and the direction orthogonal to the X direction is defined as the Y direction. In this embodiment, the X direction is the direction from the left side to the right side as viewed from the front side of the image forming apparatus 1, and the opposite direction is referred to as the -X direction. Also, the Y direction is the direction from the front side to the back side of the image forming apparatus 1, and the opposite direction is referred to as the -Y direction. Also, for the units and components incorporated in the image forming apparatus 1, unless otherwise specified, the X, Y, and Z directions will be used for description based on the orientation in the incorporated state.
[0013] As shown in FIGS. 1 and 2(a, b), the image forming apparatus 1 has a substantially rectangular parallelepiped housing 1A (apparatus main body). The housing 1A includes a frame constituting the frame of the image forming apparatus 1, a front door 101, an upper surface cover 102, side surface covers 103a, and 103a, and a back cover 105 as an exterior covering the frame. Also, the front cover portion 104a of the cassette 104 that is detachably attached to the lower portion of the housing 1A is also a part of the exterior of the housing 1A.
[0014] The front door 101 forms the upper part of the front of the housing 1A. The front cover portion 104a of the cassette 104 forms the lower part of the front of the housing 1A. The front door 101 is rotatably supported (openable and closable) by the frame of the housing 1A. When the front door 101 and cassette 104 are closed, the outer surface of the front door 101 and the front cover portion 104a of the cassette 104 are planar (flat) surfaces that intersect approximately perpendicularly with the Y direction and extend in the X and Z directions.
[0015] Side cover 103a constitutes the side of housing 1A in the -X direction, and side cover 103b constitutes the side of housing 1A in the X direction. Side covers 103a and 103b are planar (flat) in shape, extending in the Y and Z directions, respectively, intersecting the X direction approximately perpendicularly. An exhaust louver 107, which will be described later, is provided on side cover 103b.
[0016] The top cover 102 constitutes the top surface (Z-direction surface) of the housing 1A. The top cover 102 is planar (flat plate-shaped) and extends in the X and Y directions, intersecting approximately perpendicularly to the Z direction. The top cover 102 is provided with a loading section 102a on which recording material with an image formed on it is loaded as output.
[0017] The rear cover 105 constitutes the rear of the housing 1A. The rear cover 105 constitutes at least a part (all in this embodiment) of the exterior surface of the housing 1A in the Y direction, which is the first direction. The rear cover 105 is planar (flat) in shape, extending in the X and Z directions, intersecting the Y direction almost perpendicularly. The rear cover 105 is provided with an intake louver 106, which will be described later, and a cord hole 108, which is an opening for inserting a power cord 109.
[0018] (Inside the image forming apparatus) Figure 3 is a schematic diagram showing the internal structure of the image forming apparatus 1. The image forming apparatus 1 in this embodiment is an in-line color laser beam printer, and is configured to output color images by layering toners, which are four colors of developer: yellow (Y), magenta (M), cyan (C), and black (K).
[0019] As shown in Figure 3, an electrophotographic mechanism 1B, which serves as an image forming means, is mounted inside the housing 1A. The electrophotographic mechanism 1B includes process units PY, PM, PC, and PK, each having an image carrier, an intermediate transfer belt 17 which is an intermediate transfer body, a secondary transfer roller 19 which is a transfer member, and a fixing device 20 which is a fixing means. The electrophotographic mechanism 1B forms an image on the recording material P by an electrophotographic process.
[0020] Each process unit PY to PK includes a photosensitive drum 11 as an image carrier, a charging roller 12 as a charging means, a developing roller 13 as a developing means, and a laser scanner 15 as an exposure means. The photosensitive drum 11, the charging roller 12, and the developing roller 13 are arranged in a cartridge 14 of each process unit PY. Each cartridge 14 contains a developer containing toner of the color of the image formed by the process units PY to PK.
[0021] The intermediate transfer belt 17 is stretched over a plurality of rollers, including a drive roller 18 (secondary transfer inner roller). The outer surface of the intermediate transfer belt 17 faces the photosensitive drum 11 of each process unit PY to PK. On the inner circumference side of the intermediate transfer belt 17, primary transfer rollers 16 are positioned opposite each photosensitive drum 11, with the intermediate transfer belt 17 in between. A secondary transfer section is formed as a nip between the secondary transfer roller 19 and the intermediate transfer belt 17.
[0022] The fixing device 20 has a thermal fixing configuration comprising a pair of rotating bodies consisting of a belt (film) or rollers, and a heating means for heating the image (toner image) on the recording material. The heating means can be, for example, a halogen lamp that heats the rotating bodies by radiant heat, a heater substrate that generates heat when energized and heats the rotating bodies by resistive heat conduction, or an induction heating mechanism that heats the conductive layer of the rotating bodies by induction heating.
[0023] Furthermore, the image forming apparatus 1 has a feeding roller 2, a pair of transport rollers 3, a pair of registration rollers 4, and a pair of discharge rollers 21 as transport means for transporting the recording material P. The feeding roller 2 is a feeding unit that feeds the recording material P from the cassette 104 (storage compartment, mounting section). The pair of transport rollers 3 is a separation transport unit that feeds the recording material P one sheet at a time while separating them. The pair of discharge rollers 21 is a discharge unit that discharges the recording material P to the outside of the housing 1A. As the recording material P, a variety of sheet materials of different sizes and materials can be used, such as plain paper and cardboard, plastic film, cloth, sheet materials with surface treatments such as coated paper, and sheet materials of special shapes such as envelopes and index paper.
[0024] Figure 4 shows the image forming apparatus 1 as viewed from the rear after removing the rear cover 105. The image forming apparatus 1 includes a main drive unit 111, a fixing motor 112, a controller 113, and a low-voltage power supply unit 114. In this embodiment, these electrical components are located on the rear side inside the housing 1A. The image forming apparatus 1 also has a high-voltage power supply unit that applies high voltage to the process means (charging roller 12, developing roller 13, primary transfer roller 16, secondary transfer roller 19) of the electrophotographic mechanism 1B.
[0025] The main drive unit 111 includes main motors 111Y, 111M, 111C, and 111K that supply driving force to rotate the photosensitive drum 11, developing roller 13, etc., to each process unit PY to PK, as well as gears, etc., that distribute and transmit the driving force to the objects to be driven. The fuser motor 112 rotates the pair of rotating bodies of the fuser device 20. The controller 113 controls the operation of the image forming apparatus 1 and also performs communication with an external computer or network.
[0026] The low-voltage power supply unit 114 supplies power to operate actuators such as the main motors 111Y~111K and the fixing motor 112, the controller 113, the laser scanner 15, and the heating means of the fixing device 20. The low-voltage power supply unit 114 has a power inlet 116 to which a power cord 109 (Figure 2(a, b)) is connected to receive power from an external power source (e.g., commercial power).
[0027] The housing 1A has a rear plate 115 which is part of the frame. The rear plate 115 positions the main drive unit 111, the controller 113, and the low-voltage power supply unit 114, thereby fixing the position of each unit within the housing 1A.
[0028] (Image formation process) Next, the image forming operation of the image forming apparatus 1 will be explained using Figure 3. The image forming apparatus 1 starts its image forming operation when the controller 113 receives image data from an external computer or the like.
[0029] In the image formation operation, first, each photosensitive drum 11 and the intermediate transfer belt 17 are rotated by the driving force from the main drive unit 111, and the charging roller 12 uniformly charges the surface of each photosensitive drum 11. The laser scanner 15 flashes based on the image data received by the controller 113, forming an electrostatic latent image on the surface of the photosensitive drum 11. This electrostatic latent image is developed using a developer by the developing roller 13 and visualized as a monochrome toner image. The toner images formed on each photosensitive drum 11 are transferred onto the intermediate transfer belt 17 by the primary transfer roller 16. At this time, the toner images of each color overlap on the intermediate transfer belt 17 to form a color image (hereinafter simply referred to as "image").
[0030] Meanwhile, the recording material P loaded onto the cassette 104 is fed one sheet at a time by the feed roller 2 and the transport roller pair 3. The registration roller pair 4 corrects the skew of the recording material P and then feeds the recording material P to the secondary transfer section in synchronization with the timing when the image formed on the intermediate transfer belt 17 reaches the secondary transfer section. Then, in the secondary transfer section, the image is transferred from the intermediate transfer belt 17 to the recording material P by the secondary transfer roller 19.
[0031] As the recording material P passes through the secondary transfer section and then the fixing device 20, the image is heated and pressurized, fixing the image to the recording material P. After that, the recording material P is discharged to the outside of the housing 1A by the discharge roller pair 21 and loaded onto the loading section 102a as the finished product.
[0032] When a job to continuously form images on multiple recording materials P (continuous image formation job) is submitted, the image forming apparatus 1 feeds the recording materials P one by one from the cassette 104 and forms an image on each recording material P using the electrophotographic mechanism 1B. In this way, the image forming apparatus 1 transports multiple recording materials P at predetermined intervals and at a constant throughput while forming an image on each recording material P.
[0033] (Low-voltage power supply unit) The details of the low-voltage power supply unit 114 will be explained using Figures 5(a, b). Figure 5(a) is a perspective view of the low-voltage power supply unit 114 as seen from the front (-Y side), and Figure 5(b) is an exploded view of the low-voltage power supply unit 114. The low-voltage power supply unit 114 is an elongated unit in the X direction. The low-voltage power supply unit 114 is located on the rear side (+Y side) and bottom side (-Z side) inside the housing 1A (Figure 4).
[0034] As shown in Figures 5(a, b), the low-voltage power supply unit 114 includes a power supply board 121, a stay 122, a duct cover 124, a fan unit 125, and a power inlet 116 (see also Figure 4).
[0035] The power supply board 121 is a circuit board having a substrate 121a and a plurality of electrical components that are components of a power supply circuit formed on the substrate 121a. The electrical components (electrical elements) include a capacitor 121b, a transformer 121c, and an FET 121d. The power supply circuit composed of these electrical components generates a DC current (DC voltage) and supplies it to the aforementioned motor, controller 113, and fixing device 20, etc. In addition, a connector 121e is mounted on the substrate 121a for electrically connecting the circuit on the substrate 121a to the devices to which power is supplied.
[0036] The stay 122 is a plate-shaped member that extends in the X and Z directions and is elongated in the X direction. The stay 122 is located on the Y direction side relative to the power supply board 121 and supports the power supply board 121. The power supply board 121 is fixed to the stay 122 with a plurality of screws 123.
[0037] The duct cover 124 is an elongated member extending in the X direction, and has a roughly U-shaped (rectangular with the Y side open) cross-section that opens approximately towards the Y direction in a cross-section perpendicular to the X direction. The duct cover 124 covers at least a portion of the power supply board 121 from the -Y direction side.
[0038] The stay 122 as the first member and the duct cover 124 as the second member are combined to form a roughly cylindrical duct 126 extending in the X direction. In other words, the stay 122 and the duct cover 124 are examples of duct members that form an air passage. At least a part of the power supply board 121 (in particular, the electrical components that constitute the power supply circuit) are arranged in the internal space of the duct 126.
[0039] The fan unit 125 is positioned at the -X side (upstream side in the airflow direction) end of the duct 126. The fan unit 125 is connected to the -X side end of the duct cover 124 (the upstream end 124a of the duct 126). The configuration of the fan unit 125 will be described later.
[0040] The power inlet 116 is electrically connected to the power supply board 121 by a bundle of wires 127. Power from the commercial power supply is supplied to the power supply board 121 via the power inlet 116 and the bundle of wires 127.
[0041] It is preferable to position the power inlet 116 adjacent to the power supply board 121. This minimizes the length of the wire bundle 127, which reduces the component cost of the wire bundle 127 and reduces electrical noise emitted from the wire bundle 127.
[0042] Furthermore, the flow path formed by the duct member does not need to be a completely closed shape (cylindrical) in a plane perpendicular to the flow direction, as long as it can guide air from the fan unit 125. Also, in this embodiment, the width of the duct cover 124 in the Z direction is narrower than the width of the power supply board 121 in the Z direction. Therefore, the internal space of the duct 126 is divided by the power supply board 121 into a space between the duct cover 124 and the power supply board 121, and a space between the power supply board 121 and the stay 122.
[0043] (Fan unit) The configuration of the fan unit 125 will be explained using Figure 6. The fan unit 125 includes an intake fan 131, an environmental sensor 132, and a holder 133 for fixing them.
[0044] The intake fan 131 is a propeller fan having a rotating shaft 131b, a plurality of blades 131a projecting radially from the rotating shaft 131b, and a drive unit (motor unit) that rotates the rotating shaft 131b. The intake fan 131 rotates around the rotation axis 131x. The intake fan 131 is an axial flow type fan in which the axial direction of the rotating shaft 131b (rotation axis direction) coincides with the direction in which the air is discharged. In this embodiment, the intake fan 131 is installed to discharge air in the X direction. Specifically, the intake fan 131 is positioned so that the rotation axis 131x is substantially parallel to the X direction. Note that, for example, a mixed flow fan can also be used as the intake fan 131.
[0045] The intake fan 131 rotates using power supplied from the power supply board 121, drawing in air from the -X direction and blowing it out in the X direction toward the duct 126.
[0046] The holder 133 is configured to surround the intake fan 131 when viewed in the X direction and holds the intake fan 131. The environmental sensor 132 is fixed in a predetermined position on the holder 133. The arrangement of the environmental sensor 132 will be described later.
[0047] The holder 133 has a canopy portion 133a that extends in the -X direction relative to the intake fan 131. The canopy portion 133a has an upper surface portion a1 that covers the environmental sensor 132 when viewed from above, and a side surface portion a2 on the -Y direction relative to the environmental sensor 132. The canopy portion 133a can guide the outside air taken in from the intake louver 106 toward the intake fan 131.
[0048] (Environmental sensor) The details of the environmental sensor 132 will be explained using Figures 7(a, b). Figure 7(a) is a view of the environmental sensor 132 from one side (mounting side 144a), and Figure 7(b) is a view of the environmental sensor 132 from the other side (non-mounting side 144b).
[0049] The environmental sensor 132 comprises a sensor substrate 144, a temperature sensor 141, a humidity sensor 142, and a connector 143. The environmental sensor 132 is an example of a sensor unit for detecting the environmental conditions of the environment in which the image forming apparatus is installed (the state of the air around the image forming apparatus). Here, the "environmental conditions" detected by the sensor unit may be either temperature or humidity (for example, relative humidity or absolute moisture content).
[0050] The sensor substrate 144 is a plate-shaped circuit board. The sensor substrate 144 has a mounting surface 144a (first surface) on which circuit patterns 144c and 144e are formed, and a non-mounting surface 144b on the opposite side of the mounting surface 144a (second surface) on which no circuit patterns are formed.
[0051] The temperature sensor 141 uses an NTC thermistor, which is made by mixing and sintering oxides such as nickel, manganese, cobalt, and iron. In this case, the temperature can be detected by utilizing the fact that the resistance value (impedance) of the NTC thermistor decreases as the temperature rises. That is, the temperature sensor 141 outputs a signal (voltage value, etc.) corresponding to the ambient temperature. The controller 113 can detect the temperature as an environmental condition (also called the ambient temperature or ambient temperature of the image forming apparatus) based on the signal from the temperature sensor 141.
[0052] In this embodiment, the temperature sensor 141 is a surface-mount component. As shown in Figure 7(a), the temperature sensor 141 is mounted on a pair of circuit patterns 144c on the mounting surface 144a of the sensor substrate 144 by reflow soldering or the like, and is electrically connected to a pair of terminals 143a of the connector 143.
[0053] As shown in Figure 7(b), the humidity sensor 142 is placed on the non-mounted side 144b of the sensor substrate 144. The connection terminals 154a and 154b of the humidity sensor 142 pass through a pair of through-holes 144d drilled in the sensor substrate 144 and are soldered to the circuit pattern 144e on the mounting side 144a. This secures the humidity sensor 142 and provides an electrical connection with the terminals 143b of the connector 143.
[0054] The structure and principle of the humidity sensor 142 will be explained using Figure 8. The humidity sensor 142 in this embodiment is a resistance-type sensor. The humidity sensor 142 has a substrate 151 made of alumina or the like, a pair of comb-tooth electrodes 152a and 152b formed on the substrate 151, and a humidity-sensitive film 153 formed by coating a polymer material. The comb-tooth electrodes 152a and 152b are formed by printing a thick film conductor of a noble metal such as gold or ruthenium oxide into a comb shape and firing it. The comb-tooth electrodes 152a and 152b are electrically connected to a pair of connection terminals 154a and 154b.
[0055] When the humidity around the humidity sensor 142 increases and the number of water molecules in the air adsorbed onto the humidity-sensitive film 153 increases, the number of mobile ions on the humidity-sensitive film 153 increases, and the impedance between the comb-tooth electrodes 152a and 152b decreases. This can be used to detect humidity. In other words, the temperature sensor 141 outputs an alternating current as a signal corresponding to the ambient humidity, for example, when an alternating voltage is applied. The controller 113 can detect humidity as an environmental condition (ambient humidity of the image forming apparatus) based on the signal from the humidity sensor 142 (amplitude of the alternating current).
[0056] Connector 143 (Figure 7(b)) is electrically connected to controller 113 via wires not shown. Controller 113 detects temperature and humidity based on changes in the resistance and impedance of temperature sensor 141 and humidity sensor 142, and uses this information to control the image forming apparatus 1.
[0057] Thus, the environmental sensor 132 has a temperature sensor 141 positioned on the mounting surface 144a and a humidity sensor 142 positioned on the opposite, non-mounting surface 144b. This configuration has advantages such as making the environmental sensor 132 less likely to obstruct airflow and increasing the flexibility of its placement.
[0058] Figure 9 shows an example of measurement results illustrating the relationship between relative humidity, temperature, and impedance for the resistance-type humidity sensor 142 used in this embodiment. In Figure 9, the horizontal axis represents relative humidity, and the vertical axis represents impedance. Of the two curves, the dashed line represents the measurement results under low-temperature conditions, and the solid line represents the measurement results under high-temperature conditions.
[0059] As can be seen from the figure, the impedance of the humidity sensor 142 changes depending on both relative humidity and temperature. Therefore, in order to accurately detect relative humidity, it is necessary to accurately know the temperature of the humidity sensor 142 as well.
[0060] In this embodiment, the image forming apparatus 1 performs various controls using the temperature and humidity around the image forming apparatus 1 detected by the environmental sensor 132. For example, the target temperature of the fixing device 20 is changed to achieve the optimal fixing temperature depending on the ambient temperature. In addition, the absolute amount of moisture in the air is calculated from the ambient temperature and humidity, and process conditions (e.g., the applied voltage value) of the charging process, developing process, and transfer process are changed, or calibration is performed according to the ambient temperature or changes. Therefore, it is desirable that the temperature or humidity detected by the environmental sensor 132 accurately reflects the actual temperature or humidity around the image forming apparatus.
[0061] (Airflow inside the enclosure) Figure 10 illustrates the main airflow path generated by the intake fan 131. Figure 10 is a cross-sectional view of the image forming apparatus 1 cut along the horizontal plane (XY plane) at the height of the cutting line AA shown in Figure 2, and represents only a portion of the rear side (Y direction side) of the image forming apparatus 1.
[0062] As shown in Figure 10, the intake louver 106, which serves as an air intake, is provided at the -X-side end of the rear cover 105 (cover member) that constitutes the exterior surface on the Y-side of the housing 1A. The exhaust louver 107, which serves as an exhaust port, is provided at the Y-side end of the side cover 103b (another cover member) that constitutes the exterior surface on the X-side of the housing 1A. Therefore, the exhaust louver 107 is provided at a position downstream in the X-direction from the intake louver 106. Note that the intake port or exhaust port may have a large number of holes arranged in a mesh or grid pattern, for example.
[0063] The low-voltage power supply unit 114 is positioned between the upstream end 106a of the intake louver 106 and the exhaust louver 107 in the X direction, and extends in an elongated shape in the X direction. The duct 126 of the low-voltage power supply unit 114 extends in the X direction approximately parallel to the rear cover 105. In other words, the duct 126 extends in the X direction from the intake louver 106 toward the exhaust louver 107. The fan unit 125 is positioned at the upstream end of the low-voltage power supply unit 114 (the upstream end of the duct 126) in the X direction.
[0064] The low-voltage power supply unit 114 is positioned such that the fan unit 125, which is connected to the upstream end 124a of the duct 126, is located near the intake louver 106, and the other end (downstream end 124b) of the duct 126 is located near the exhaust louver 107. In this embodiment, the intake fan 131 is positioned so as to at least partially overlap the intake louver 106 when viewed from the Y-direction side (the opening side of the intake louver 106). Also, the opening of the downstream end 124b of the duct 126 is positioned so as to at least partially overlap the exhaust louver 107 when viewed from the X-direction side (the opening side of the exhaust louver 107).
[0065] The airflow around the low-voltage power supply unit 114 will now be described. Electrical components (electrical elements) on the power supply board 121 generate heat when they operate and consume power. In this embodiment, the power supply board 121 has electrical components that constitute a power supply circuit that generates DC current, so the amount of heat generated tends to be large. When the temperature of the electrical components rises, power consumption may increase due to thermal resistance, or malfunctions or failures may occur due to overheating. Therefore, in this embodiment, the power supply board 121 is actively cooled by the airflow generated by the intake fan 131.
[0066] The intake fan 131 of the fan unit 125 generates airflow by taking in air from the upstream side (-X direction side) in the X direction and sending it to the downstream side in the X direction. As a result, the intake fan 131 sends outside air (arrow 161) taken in from outside the housing 1A via the intake louver 106 downstream in the X direction and into the inside of the duct 126 (arrow 162).
[0067] This airflow (arrow 162) cools the electrical components (121b~121d) on the power supply board 121 located inside the duct 126. The airflow (arrow 163) released from the downstream end 124b of the duct 126 is exhausted to the outside of the housing 1A through the exhaust louver 107.
[0068] (Placement of environmental sensors) Next, the arrangement of the environmental sensor 132 will be described in detail. As mentioned above, the intake fan 131 draws in outside air from the housing 1A via the intake louver 106, but also draws in some air from inside the housing 1A, as shown by the dashed arrow 164 in Figure 10.
[0069] The air inside this housing is heated by the heat generated by heat sources such as the main drive unit 111, controller 113, and fixing device 20 during the image forming process, so its temperature gradually increases during the execution of a continuous image forming job. In addition, the humidity inside the image forming apparatus 1 may deviate from that of the outside air due to water vapor evaporated from the recording material. Therefore, if the proportion of air inside the image forming apparatus 1 mixed with the air taken in from outside the housing 1A by the intake fan 131 (outside air) increases near the environmental sensor 132, the accuracy of temperature or humidity detection by the environmental sensor 132 may decrease.
[0070] Therefore, in this embodiment, the placement of the environmental sensor 132 is defined in relation to the elements that determine the direction of the airflow generated by the intake fan 131 (for example, the intake fan 131 and the intake louver 106), thereby reducing the decrease in detection accuracy of the environmental sensor 132. In other words, the environmental sensor 132 is placed in the main airflow path (arrow 161) from the intake louver 106 to the intake fan 131, as far away as possible from the path (arrow 164) through which the air inside the housing is drawn into the intake fan 131.
[0071] The specific arrangement of the environmental sensor 132 will be explained below using Figures 11 and 6(b). Figure 11 is an enlarged view of a portion of Figure 10.
[0072] As shown in Figure 11, in the Y direction, the environmental sensor 132 is located in the region Ay from the position y0 of the intake louver 106 on the rear cover 105 to the position y1 of the rotation axis 131b of the intake fan 131 (position of the rotation axis 131x). In the X direction, the environmental sensor 132 is positioned upstream of the intake fan 131 (towards the -X direction). In other words, the sensor unit of this embodiment is located in the region (Ay) between the intake port and the rotation axis of the fan in the first direction (Y direction), and is positioned upstream of the fan in the second direction (X direction).
[0073] This arrangement ensures that at least a portion of the environmental sensor 132 is located within the main airflow path (arrow 161) when viewed in the Z direction. On the other hand, by positioning the environmental sensor 132 to avoid the area on the Y direction side of the rotation axis 131b, the possibility of reduced detection accuracy of the environmental sensor 132 due to air from inside the housing (arrow 164) can be reduced.
[0074] Incidentally, it is also conceivable to isolate the environmental sensor 132 from heat sources other than the low-voltage power supply unit 114 inside the housing by connecting the intake louver 106 and the intake fan 131 with a cylindrical member (duct) and placing the environmental sensor 132 inside it. This could potentially reduce the influence of air heated by other heat sources on the detection accuracy of the environmental sensor 132. However, this configuration would increase the number of parts and assembly man-hours due to the cylindrical member and its mounting structure, leading to a larger and more complex image forming apparatus. According to this embodiment, the influence of air heated by other heat sources on the detection accuracy of the environmental sensor 132 can be reduced with a simple configuration. Furthermore, in this embodiment, since there is an open space between the intake louver 106 and the intake fan 131, some of the heat emitted by other heat sources can be discharged outside the housing through the duct 126 and exhaust louver 201. However, the above description does not prevent the addition of fans or ventilation openings other than the intake fan 131, intake louver 106, and exhaust louver 107 of this embodiment.
[0075] If the intake louver 106 is separated from the side cover 103a in the X direction, the environmental sensor 132 may be positioned in the region Ax in the X direction from the upstream end position x0 of the intake louver 106 to the upstream surface position x1 of the intake fan 131.
[0076] As shown in Figure 11, when viewed in the Z direction, it is desirable to position the environmental sensor 132 such that at least a portion (preferably all) of the environmental sensor 132 is located on the same side as the downstream end 106b of the intake louver 106 with respect to the imaginary line L1 connecting points P1 and P2. Point P1 (the first point) is the position (y1) of the rotation axis of the intake fan 131 in the Y direction and the position (x1) of the upstream surface of the intake fan 131 in the X direction. Point P2 (the second point) is the position (x0, y0) of the upstream end of the intake louver 106 in the X direction.
[0077] This arrangement allows the intake fan 131 to be more likely to be hit by outside air taken in through the intake louvers 106, and less likely to be hit by air from inside the enclosure, thus further reducing the possibility of a decrease in the detection accuracy of the environmental sensor 132.
[0078] Furthermore, as shown in Figure 6(b), it is preferable that at least a portion of the environmental sensor 132 is located in the region Az from the lower end position z0 to the upper end position z1 of the intake fan 131 in the Z direction (vertical direction). It is also preferable that the environmental sensor 132 is positioned such that at least a portion of it overlaps with the intake fan 131 when viewed in the direction of the rotation axis 132b of the intake fan 131 (X direction). This arrangement makes it easier for the intake fan 131 to be hit by outside air taken in through the intake louvers 106 and less likely to be hit by air from inside the housing, thus further reducing the possibility of a decrease in the detection accuracy of the environmental sensor 132.
[0079] Furthermore, as shown in Figures 2(b) and 6(b), it is preferable that the environmental sensor 132 be located within the range where the intake louver 106, which serves as an air intake, is provided, when viewed in the Y direction (first direction). The range where the intake louver 106 is provided is defined by the range Ax2 from one end position to the other end position of the intake louver 106 in the X direction and the range Az2 from one end position to the other end position of the intake louver 106 in the Z direction. This arrangement makes it easier for the intake fan 131 to be exposed to outside air taken in through the intake louver 106.
[0080] In the arrangement of the environmental sensor 132 described above, when a part of the environmental sensor 132 is placed in a predetermined area or position, it is preferable that the position of the sensor element is located in that area or position. A sensor element is an element whose electrical characteristics (resistance, impedance, etc.) change according to temperature or humidity in order to convert a physical quantity to be detected into an electrical signal. In this embodiment, the NTC thermistor and the humidity-sensitive film 153 correspond to the sensor elements.
[0081] Furthermore, as shown in Figure 11, it is preferable that the environmental sensor 132 be positioned such that the sensor substrate 144 is oriented substantially perpendicular to the rear cover 105 (perpendicular to the XZ plane). In other words, it is preferable that the sensor substrate 144 is substantially perpendicular to the rear cover 105 having the intake louvers 106. This configuration makes it possible to reduce the projected area of the sensor substrate 144 in the direction of the airflow taken in from the intake louvers 106 into the housing (-Y direction), thereby reducing the resistance (energy loss) when outside air is taken in by the intake fan 131.
[0082] In addition, this configuration allows outside air to be applied almost equally to both the temperature sensor 141 and the humidity sensor 142, which are mounted separately on the mounting surface 144a and the non-mounting surface 144b of the sensor substrate 144, as shown by arrows 161a and 161b in Figure 11. This makes it possible to maintain an almost uniform temperature on both sides of the sensor substrate 144, thereby improving the accuracy of temperature detection and the accuracy of humidity detection, which depends on the accuracy of temperature detection.
[0083] (Verification results of detection accuracy) Figure 12 is a graph showing the change in temperature detected by the environmental sensor 132 during the execution of a continuous image forming job. The horizontal axis represents the elapsed time from the start of the job, and the vertical axis represents the difference between the ambient temperature of the image forming apparatus 1 and the detected temperature obtained from the measured value (impedance) of the temperature sensor 141.
[0084] In Figure 12, the solid line represents the results when the environmental sensor 132 is placed at the position shown in this embodiment (Figure 11), while the dashed line represents the results when the environmental sensor 132 is placed at point Pc in Figure 11 as a comparative example. In other words, in this comparative example, the environmental sensor 132 is placed on the side of the intake louver 106 that is further away from the rotation axis 132b of the intake fan 131 (closer to the inside of the housing) in the Y direction. The ambient temperature remained constant during the experiment.
[0085] As can be seen from Figure 12, in the comparative example, during the execution of the continuous image formation job, the temperature detection result gradually deviates from the actual ambient temperature due to the influence of the air heated inside the enclosure. Furthermore, this deviation in the temperature detection result also causes the humidity detection result to deviate from the actual ambient humidity. On the other hand, by placing the environmental sensor 132 in the position of this embodiment, it was possible to reduce the fluctuation of the signal of the environmental sensor 132 due to the influence of the air heated inside the enclosure during the execution of the continuous image formation job. [Examples]
[0086] The image forming apparatus 1 according to Embodiment 2 will be described with reference to Figures 13 and 14. This embodiment differs from Embodiment 1 in the arrangement of the exhaust ports. Hereafter, elements with the same reference numerals as in Embodiment 1 will have substantially the same configuration and function as those described in Embodiment 1, and the parts that differ from Embodiment 1 will be mainly described.
[0087] Figure 13 is a perspective view of the image forming apparatus 1 from the rear side. Figure 14 is a cross-sectional view of the image forming apparatus 1 cut along the horizontal plane (XY plane) at the height of the cutting line AA shown in Figure 13, and shows only a portion of the rear side (Y direction side) of the image forming apparatus 1.
[0088] As shown in Figure 13, the exhaust louver 201 in this embodiment is provided on the rear cover 105. That is, the rear cover 105, as a cover member, has an intake louver 106 as an intake port and an exhaust louver 201 as an exhaust port. The exhaust louver 201 is provided at a position downstream in the X direction from the intake louver 106.
[0089] In this embodiment, an intake louver 106 is positioned at the upstream end in the X direction at the lower part of the rear cover 105, and an exhaust louver 201 is positioned at the downstream end in the X direction at the lower part of the rear cover 105. The rear cover 105 is also provided with a cord hole 108 for inserting a power cord 109 between the intake louver 106 and the exhaust louver 201 in the X direction.
[0090] As shown in Figure 14, the intake fan 131 of the fan unit 125 generates airflow by taking in air from the upstream side (-X direction side) in the X direction and sending it to the downstream side in the X direction. As a result, the intake fan 131 sends outside air (arrow 161) taken in from outside the housing 1A via the intake louver 106 into the inside of the duct 126 (arrow 162).
[0091] This airflow cools the electrical components (121b~121d) on the power supply board 121. The airflow (arrow 163) exiting the duct 126 from the downstream end 124b passes through the exhaust louver 107 and is exhausted to the outside of the housing 1A.
[0092] In this embodiment, the arrangement of the environmental sensor 132 relative to the intake fan 131 and intake louvers 106 is the same as in Embodiment 1. Therefore, the possibility of a decrease in the detection accuracy of the environmental sensor 132 due to air from inside the housing (arrow 164) can be reduced.
[0093] In addition, in this embodiment, since intake louvers 106 (intake port) and exhaust louvers 201 (exhaust port) are arranged on the rear cover 105, noise propagating to the front side of the image forming apparatus 1 can be reduced compared to Embodiment 1.
[0094] The intake fan 131 generates noise such as vibration and wind noise during operation. This noise leaks to the outside of the housing 1A through the intake louvers 106 and exhaust louvers 107 and 201, which are located near the intake fan 131. In addition, the intake fan 131 is controlled not only during image formation operations, but also for a predetermined period after the completion of a continuous image formation job, for example, to cool the power supply board 121 that was heated during the job. In such cases, since the electrophotographic mechanism 1B and the motors for transporting recording material are not operating, the noise originating from the intake fan 131 tends to be more noticeable.
[0095] According to this embodiment, since both the intake louver 106 and the exhaust louver 201 are provided on the rear side of the housing 1A, the volume of noise transmitted to users who often stand in front of the image forming apparatus 1 can be reduced. [Examples]
[0096] Using Figure 15, the image forming apparatus 1 according to Example 3 will be described. This example adds a windbreak to the configuration of Example 2. Hereafter, elements with the same reference numerals as in Example 1 have substantially the same configuration and function as those described in Example 1, and the differences from Example 1 will be mainly described.
[0097] Figure 15 is a cross-sectional view of the image forming apparatus 1 cut along the horizontal plane (XY plane) at the height of the cutting line AA shown in Figure 13, and shows only a portion of the back side (Y direction side) of the image forming apparatus 1.
[0098] As shown in Figure 15, the image forming apparatus 1 of this embodiment is provided with a windbreak wall 211 that closes the gap 212 between the inner surface of the rear cover 105 and the stay 122 of the low-voltage power supply unit 114 (outer surface of the duct 126). The windbreak wall 211 is formed to project from at least one of the inner surfaces of the rear cover 105 or the outer surface of the duct 126 toward the other in the Y direction or -Y direction. The windbreak wall 211 also extends in the Z direction. In the illustrated example, the windbreak wall 211 is formed integrally with the rear cover 105 so as to project from the inner surface of the rear cover 105 in the -Y direction.
[0099] The windbreak wall 211 functions as a windbreak that prevents a portion of the airflow (arrows 202, 211) released from the downstream end 124b of the duct 126 from flowing back in the -X direction through the gap 212 between the duct 126 and the rear cover 105. The presence of the windbreak wall 211 prevents air (arrow 213) that has been heated during the cooling of the power supply board 121 from entering the gap 212 and reaching the environmental sensor 132 and the intake fan 131. This reduces the possibility of a decrease in the detection accuracy of the environmental sensor 132. Furthermore, it improves the cooling efficiency of the power supply board 121.
[0100] In Figure 15, an example is shown in which an exhaust louver 201 is provided on the rear cover 105, as in Example 2. However, in a configuration where an exhaust louver 107 is provided on the side cover 103b, as in Example 1, a windbreak wall 211 may also be provided.
[0101] Furthermore, the windbreak wall 211 does not need to be integrated with the rear cover 105 or the duct 126; it may be a separate part, for example, it may be made of a sponge-like material.
[0102] Furthermore, the windbreak wall 211 is not limited to completely sealing the gap between the rear cover 105 and the duct 126. Verification results showed that if the gap between the windbreak wall 211 and the rear cover 105 is 2 mm or less, the impact on the environmental sensor 132 can be sufficiently reduced.
[0103] (Other embodiments) In the embodiments described above, the application of this technology to a color image forming apparatus equipped with an intermediate transfer type image forming means was explained. The image forming apparatus is not limited to this, and may also be equipped with a direct transfer type image forming means that transfers a toner image formed on an image carrier to a recording material without using an intermediate transfer body. Furthermore, this technology may also be applied to a monochrome image forming apparatus equipped with only one image carrier. Moreover, it is not limited to an electrophotographic method, but may also be equipped with an inkjet method or an offset printing method image forming means, for example.
[0104] Furthermore, the term "image forming apparatus" is not limited to a single-function printer that forms an image based on image data received from an external source; a copier that forms an image based on image data read from a document may also be a multifunction device equipped with multiple functions.
[0105] (Summary of the embodiments) This disclosure includes the following components: [Configuration 1] A housing for an image forming means that forms an image on a recording material, A fan is positioned inside the aforementioned enclosure to generate airflow, A duct member is disposed inside the housing and forms the airflow path, Electrical components arranged inside the duct member, A sensor unit is disposed inside the housing for detecting the environmental conditions surrounding the housing, An image forming apparatus comprising, The housing comprises a cover member that constitutes at least a portion of the exterior surface of the housing in a first direction, an air intake port provided in the cover member, and an exhaust port provided at a position downstream from the air intake port in a second direction along the cover member. The fan takes in air from the upstream side in the second direction and blows it out to the downstream side in the second direction, thereby generating the airflow that flows through the intake port, the fan, the duct member, and the exhaust port. The sensor unit is located in the region between the air intake and the rotation axis of the fan in the first direction, and is positioned upstream of the fan in the second direction. An image forming apparatus characterized by the following features. [Configuration 2] The sensor unit is positioned downstream of the upstream end position of the intake port in the second direction. The image forming apparatus according to configuration 1, characterized in that it is a picture forming apparatus. [Configuration 3] When viewed in a direction perpendicular to the first and second directions, at least a portion of the sensor unit is located on the same side as the downstream end position of the air intake port with respect to a virtual line connecting the first point and the second point. The first point is a point on the rotation axis of the fan in the first direction and on the upstream surface of the fan in the second direction. The second point is the point at the upstream end of the intake port in the second direction. An image forming apparatus according to configuration 1 or 2, characterized by the above. [Structure 4] When viewed in the first direction, at least a portion of the sensor unit is located within the range in which the air intake port is provided. An image forming apparatus according to any one of configurations 1 to 3, characterized by the above. [Composition 5] When viewed from the upstream side in the second direction, at least a portion of the sensor unit overlaps with the fan. An image forming apparatus according to any one of configurations 1 to 4, characterized by the above. [Composition 6] At least a portion of the sensor unit is located in the region between the lower end position and the upper end position of the fan in the vertical direction. An image forming apparatus according to any one of configurations 1 to 5, characterized by the above. [Composition 7] The sensor unit includes a temperature sensor that outputs a detection signal according to the ambient temperature and a humidity sensor that outputs a detection signal according to the ambient humidity. An image forming apparatus according to any one of configurations 1 to 6 characterized by the above. [Structure 8] The aforementioned sensor unit further comprises a circuit board, The temperature sensor is arranged on the first surface of the substrate. The humidity sensor is located on the second surface of the substrate opposite to the first surface. The image forming apparatus according to configuration 7, characterized by the features described above. [Composition 9] The sensor unit is arranged such that the substrate is perpendicular to the cover member. The image forming apparatus according to configuration 8, characterized by the above. [Configuration 10] The system further includes a controller for controlling the image forming means, The image forming means is an electrophotographic mechanism that forms an image on a recording material by an electrophotographic process, The controller changes at least one of the values of the applied voltages in the charging step, developing step, or transfer step of the electrophotographic process, or the fixing temperature in the fixing step of the electrophotographic process, according to the temperature and humidity detected based on the detection signal from the sensor unit. An image forming apparatus according to any one of configurations 7 to 9, characterized by the features described herein. [Composition 11] The aforementioned electrical component is a component of a power supply circuit that supplies direct current to the device inside the enclosure. An image forming apparatus according to any one of configurations 1 to 10, characterized by the above. [Composition 12] The power supply circuit supplies power to at least one of the following: a motor that supplies driving force for transporting the recording material or for image formation by the image forming means; a fixing device that heats the image formed by the image forming means and fixes it to the recording material; and a controller that controls the operation of the image forming device. The image forming apparatus according to configuration 11, characterized by the features described above. [Composition 13] The power supply circuit is formed on a circuit board that extends in a direction intersecting the first direction, The duct member comprises a plate-shaped first member that extends parallel to the circuit board and is positioned between the circuit board and the cover member in the first direction, and a second member that covers the electrical components mounted on the circuit board from the opposite side of the first member in the first direction. The second member is configured such that at least a portion of the airflow generated by the fan passes through the space between the second member and the circuit board. The image forming apparatus according to configuration 11 or 12, characterized by the above. [Composition 14] The duct member further has a windbreak portion that protrudes from at least one of the outer surface of the duct member or the inner surface of the cover member toward the other, between the intake port and the exhaust port in the second direction, and obstructs the flow of air toward the upstream side in the second direction through the gap between the outer surface and the inner surface. An image forming apparatus according to any one of configurations 1 to 13, characterized by the above. [Composition 15] The housing further comprises other cover members that constitute at least a portion of the outer surface on the downstream side in the second direction of the housing, The exhaust port is provided in the other cover member. An image forming apparatus according to any one of configurations 1 to 14, characterized by the above. [Composition 16] The exhaust port is provided in the cover member. An image forming apparatus according to any one of configurations 1 to 14, characterized by the above. [Composition 17] The cover member is provided with an opening between the intake port and the exhaust port in the second direction through which a power cord for connecting the circuit including the electrical components to an external power source is inserted. The image forming apparatus according to configuration 16, characterized in that... [Composition 18] The cover member is positioned on the back of the housing. An image forming apparatus according to any one of configurations 1 to 17, characterized by the above. [Composition 19] The system further comprises a holder that holds the fan and is fixed to the housing, The aforementioned sensor unit is supported by the holder, An image forming apparatus according to any one of configurations 1 to 18, characterized by the above. [Configuration 20] The aforementioned fan is an axial flow fan. An image forming apparatus according to any one of configurations 1 to 19, characterized by the features described herein. [Composition 21] The image forming means has a plurality of image carriers, and a color image is formed on the recording material by superimposing images of different colors formed on the plurality of image carriers. An image forming apparatus according to any one of configurations 1 to 20, characterized by the above. [Explanation of symbols]
[0106] 1A…Housing / 1B…Image forming means (electrophotographic mechanism) / 105…Cover member (rear cover) / 106…Intake port (intake louver) / 107,201…Exhaust port (exhaust louver) / 121b,121c,121d…Electrical components / 122,124…Duct members (stays, duct covers) / 131…Fan (intake fan) / 132…Sensor unit (environmental sensor) / X…Second direction / Y…First direction
Claims
1. A housing for an image forming means that forms an image on a recording material, A fan is positioned inside the aforementioned enclosure to generate airflow, A duct member is disposed inside the housing and forms the airflow path, Electrical components arranged inside the duct member, A sensor unit is disposed inside the housing for detecting the environmental conditions surrounding the housing, An image forming apparatus comprising, The housing comprises a cover member that constitutes at least a part of the exterior surface of the housing in a first direction, an air intake port provided in the cover member, and an exhaust port provided at a position downstream from the air intake port in a second direction along the cover member. The duct member has (i) an upstream opening defined by the upstream end of the duct member in the second direction and opening to the upstream side in the second direction, and (ii) a downstream opening defined by the downstream end of the duct member in the second direction and opening to the downstream side in the second direction. The fan draws in air from the upstream side in the second direction and blows it out to the downstream side in the second direction, thereby generating the airflow that flows through the intake port, the upstream opening, the downstream opening, and the exhaust port. The sensor unit is located in the region between the intake port and the rotation axis of the fan in the first direction, and is positioned upstream of the fan in the second direction. An image forming apparatus characterized by the following features.
2. The sensor unit is positioned downstream of the upstream end position of the intake port in the second direction. The image forming apparatus according to feature 1.
3. When viewed in a direction perpendicular to the first and second directions, at least a portion of the sensor unit is located on the same side as the downstream end position of the air intake port with respect to the imaginary line connecting the first point and the second point. The first point is the intersection of the rotation axis of the fan and the upstream end of the fan in the second direction. The second point is the point at the upstream end of the intake port in the second direction. The image forming apparatus according to feature 1.
4. When viewed in the first direction, at least a portion of the sensor unit is located within the range in which the air intake port is provided. The image forming apparatus according to feature 1.
5. When viewed from the upstream side in the second direction, at least a portion of the sensor unit overlaps with the fan. The image forming apparatus according to feature 1.
6. At least a portion of the sensor unit is located in the region between the lower end position and the upper end position of the fan in the vertical direction. The image forming apparatus according to feature 1.
7. The sensor unit includes a temperature sensor that outputs a detection signal according to the ambient temperature and a humidity sensor that outputs a detection signal according to the ambient humidity. The image forming apparatus according to any one of claims 1 to 6.
8. The aforementioned sensor unit further comprises a circuit board, The temperature sensor is arranged on the first surface of the substrate. The humidity sensor is located on the second surface of the substrate opposite to the first surface. The image forming apparatus according to feature 7.
9. The sensor unit is arranged such that the substrate is perpendicular to the cover member. The image forming apparatus according to feature 8.
10. The system further includes a controller for controlling the image forming means, The image forming means is an electrophotographic mechanism that forms an image on a recording material by an electrophotographic process, The controller changes at least one of the values of the applied voltages in the charging step, developing step, or transfer step of the electrophotographic process, or the fixing temperature in the fixing step of the electrophotographic process, according to the temperature and humidity detected based on the detection signal from the sensor unit. The image forming apparatus according to feature 7.
11. The aforementioned electrical component is a component of a power supply circuit that supplies direct current to the device inside the enclosure. The image forming apparatus according to any one of claims 1 to 6.
12. The power supply circuit supplies power to at least one of the following: a motor that supplies driving force for transporting the recording material or for image formation by the image forming means; a fixing device that heats the image formed by the image forming means and fixes it to the recording material; and a controller that controls the operation of the image forming device. The image forming apparatus according to feature 11.
13. The power supply circuit is formed on a circuit board that extends in a direction intersecting the first direction, The duct member comprises a first plate-shaped member that extends parallel to the circuit board and is positioned between the circuit board and the cover member in the first direction, and a second member that covers the electrical components mounted on the circuit board from the opposite side of the first member in the first direction. The second member is configured such that at least a portion of the airflow generated by the fan passes through the space between the second member and the circuit board. The image forming apparatus according to feature 11.
14. The duct member further has a windbreak portion that protrudes from at least one of the outer surface of the duct member or the inner surface of the cover member toward the other, between the intake port and the exhaust port in the second direction, and obstructs the flow of air toward the upstream side in the second direction through the gap between the outer surface and the inner surface. The image forming apparatus according to any one of claims 1 to 6.
15. The housing further comprises other cover members that constitute at least a portion of the outer surface on the downstream side in the second direction of the housing, The exhaust port is provided in the other cover member. The image forming apparatus according to any one of claims 1 to 6.
16. The exhaust port is provided in the cover member. The image forming apparatus according to any one of claims 1 to 6.
17. The cover member is provided with an opening between the intake port and the exhaust port in the second direction through which a power cord for connecting the circuit including the electrical components to an external power source is inserted. The image forming apparatus according to feature 16.
18. The cover member is positioned on the back of the housing. The image forming apparatus according to any one of claims 1 to 6.
19. The system further comprises a holder that holds the fan and is fixed to the housing, The aforementioned sensor unit is supported by the holder, The image forming apparatus according to any one of claims 1 to 6.
20. The aforementioned fan is an axial flow fan. The image forming apparatus according to any one of claims 1 to 6.
21. The image forming means has a plurality of image carriers, and a color image is formed on the recording material by superimposing images of different colors formed on the plurality of image carriers. The image forming apparatus according to any one of claims 1 to 6.