JP2007152646A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device having an interlocking mechanism in which wiring of power source line is eliminated, cost and assembling property is improved, further the insulation between patterns before and after interlocking the power source line when the power source line is relayed in the pattern in a multilayer circuit board is improved, and noise caused by the fluctuation of power source voltage is reduced. <P>SOLUTION: In the power source line from the low voltage power source circuit board 26 present in the bottom portion of the device to the load system, the pattern is wired using the inner layer or a surface layer of the multilayer circuit board 21 standing upright in the back portion of the device and connected to an interlock switch from the near position of the interlock switch of the upper portion of the device via a wire, further is returned to the near position from the interlock switch via the wire, and thereafter the pattern is wired in another layer of the multilayer circuit board 21 to supply power to each load. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus having an interlock mechanism.

  Recently, as an image forming apparatus, a digital multifunction machine called a multi-function printer (MFP) having functions of a copying machine, a printer, and a facsimile has become widespread.

  In such an image forming apparatus, for example, a user may open a part of the apparatus to expose the inside for cartridge replacement or jam processing. At this time, it is dangerous if the user contacts the exposed high-voltage contact or the gear of the main motor. For this reason, an interlock mechanism is provided to provide safety by shutting off the power supply (24 V) of the drive system and the high-voltage circuit during paper jam processing and cartridge replacement.

  The conventional configuration described above has the following problems.

  In the image forming apparatus having the interlock mechanism, as the function of the main body becomes higher and the size thereof is reduced, the routing of the bundled wires (wires) of the power source and the signal line becomes complicated. Along with this, the number of wires increases, the wire length becomes longer, the cost becomes expensive, and the assemblability becomes poor.

  For devices with an interlock mechanism, when the pattern before interlocking (24V power supply on the supply side) and the pattern after interlocking are formed in the multilayer circuit board, the amount of current is increased when the load is driven or when the load fluctuates. Change. Due to the influence, malfunctions of peripheral digital circuits in the substrate are caused, and radiation noise (broadband) is generated.

  The present invention has been made in such a background, and an object of the present invention is to eliminate the routing of a power supply line in an image forming apparatus having an interlock mechanism, and to improve cost and assemblability.

  Another object of the present invention is to achieve good insulation between the patterns before and after the interlocking of the power supply line when the power supply line is relayed by the pattern in the multilayer circuit board in the image forming apparatus having the interlock mechanism. The purpose is to reduce noise accompanying voltage fluctuation.

  An image forming apparatus according to the present invention includes a low-voltage power supply circuit, a load system to which a predetermined power supply voltage is supplied from the low-voltage power supply circuit, an interlock switch interposed in a power supply line of the power supply voltage supplied to the load system, A multilayer circuit board on which a predetermined circuit is mounted, and a power line from the low-voltage power circuit to the load system extends from a position in the vicinity of the interlock switch to the interlock switch via a wire from the interlock switch. A wire that returns to the vicinity position, a first path from the vicinity position of the interlock switch to the low-voltage power supply circuit, and a second path from the vicinity position of the interlock switch to each load, For at least one of the first and second paths, a pattern in any layer of the multilayer circuit board is used. And wherein the Rukoto.

  Thus, by using the wiring of the multilayer circuit board for the wiring accompanying the interlock switch, it is not necessary to route a long wire, and the cost and assemblability can be improved.

  When both the first and second paths use layers of the multilayer circuit board, one path uses an inner layer or a surface layer of the multilayer circuit board, and the other path is the other layer of the multilayer circuit board. Can be used. As a result, insulation between the pattern before the interlock and the pattern after the interlock is ensured between the layers, so that it is not necessary to increase the substrate size more than necessary.

  When the power supply circuit board on which the low-voltage power supply circuit is mounted is disposed at the bottom of the apparatus, the multilayer circuit board is provided if the multilayer circuit board is disposed substantially perpendicularly to the power supply circuit board at the back of the apparatus. It is convenient to use the pattern for relaying wires.

  The pattern routed in the layer of the multilayer circuit board with respect to the second path is connected to a load that consumes a relatively large current on the side close to the interlock switch, before the interlock of the multilayer circuit board. You may make it make the pattern thickness to the part connected to the said load at least of the pattern and the pattern after interlocking thicker than the remaining part of the pattern after interlocking. As a result, a sufficient current capacity can be ensured only in a necessary portion of the pattern.

  It is preferable that the pattern of the power supply line arranged in the inner layer of the multilayer circuit board is formed so as to be sandwiched between GND patterns provided in other layers above and below it. Thereby, the influence of noise generated from the power supply line can be reduced.

  When a VIA is formed on the power supply line of the multilayer circuit board, the insulation distance is secured by taking into account the insulation distance in each layer in order to secure the insulation distance between the pattern before and after the interlock. It is preferable to do. Thereby, good insulation can be obtained even in a multilayer structure.

  In the multilayer circuit board, at least a portion where the pattern before interlocking and the pattern after interlocking are formed are surrounded by a ground guard, and the solder surface from the surface layer to the back surface of the substrate is connected by a plurality of GNDVIAs. Good. Thereby, the noise accompanying the power supply voltage fluctuation can be reduced.

  When the multilayer circuit board has a digital circuit area in the vicinity of the pattern of the power supply line, a ground guard may be provided between the pattern and the digital circuit and separated by a plurality of GNDVIAs. This prevents malfunction of the digital circuit due to the noise or the like.

  According to the present invention, in an image forming apparatus having an interlock mechanism, it is not necessary to route the wire of the power supply line to the load system from the low-voltage power source to the interlock switch, and further to each load with the wire. Can be improved. In addition, by arranging the power line pattern before and after the interlock on different layers of the multilayer circuit board, when the power line is relayed with the pattern in the multilayer circuit board, between the pattern before and after the interlock Good insulation can be achieved.

  In addition, at least the pattern where the pattern before interlock and the pattern after interlock are formed are surrounded by a ground guard, and the solder surface from the surface layer to the back surface of the substrate is connected by a plurality of GND VIAs. Noise can be reduced. For example, it is possible to prevent malfunctions of peripheral digital circuits, and to reduce radiation noise that occurs during load driving or load fluctuations.

  When a VIA is formed on the power supply line of the multilayer circuit board, the insulation distance is secured by taking into account the insulation distance in each layer in order to secure the insulation distance between the pattern before and after the interlock. By doing so, the insulation distance can be secured without increasing the outer shape of the substrate, so that the substrate can be designed compactly. This is also effective when a mechanical restriction is imposed on the outer shape of the substrate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an external view of an image forming apparatus to which the present invention is applied. This apparatus is a so-called multi-function printer (MFP) in which functions of a copying machine, a printer, and a facsimile are also integrated. This figure comprises an ADF (automatic document feeder) unit 10 that also serves as a cover for the platen glass 4 and a main body 11 that supports the ADF unit 10 so that it can be opened with its rear side as a pivot point. In the figure, the ADF unit 10 is shown open. A white sheet 3 as a pressure plate for pressing a document placed on the document table glass 4 is attached to the bottom surface of the ADF unit 10.

  A reader unit (reading device) 2 having an original table glass 4 is arranged on the upper portion of the main body 11. The reader unit 2 is slid in the direction of the arrow by the operation of the reader unit slide lever 1 by the user at the time of cartridge replacement or jam processing, and the user can access the inside by opening the inside. In addition, a paper cassette 6 for storing a bundle of paper is disposed at the lower part of the main body, and a paper discharge tray 7 for discharging recorded paper is provided on the side of the main body.

  Copying by this apparatus has the following two operation modes. One is a pressure plate copy on which an original is placed on the platen glass 4 and read, and the other is an ADF copy in which the original is read using an ADF unit. In pressure plate copying, reading is performed while the contact sensor in the reader unit 2 is moved from the edge of the document to a position corresponding to the document size by a stepping motor. In the case of ADF copying, the contact sensor is moved and fixed to a predetermined position (the right end in FIG. 1), and the document is read by flow reading.

FIG. 2 is a block diagram showing a schematic flow of image data. In this figure, a CPU 54, a contact sensor (CS) 41, an analog processor board 23, an image processing unit 51, a ROM 55, and a DRAM 53 for image memory are shown.
The CPU 54 retrieves a preset value in the ROM 55, and performs register setting of the analog processor, supply of a clock signal to the analog processor, and setting of the image processing unit 51 via the image controller 50. The image processing unit 51 includes a clock generation unit 52 that generates a clock signal to be supplied to the analog processor substrate 23 and the drive unit 42 in the CS 41. The inside of the contact sensor 41 is divided into an A area and a B area. From the A area, pixel-unit signals a1, a2, a3,... Read as analog signals vb are sequentially output serially. Similarly, the signals B1, b2, b3,... Are output serially from the B region as analog signals vb in the order of pixels b1, b2, b3,. The timing at which the signals a1 and b1 are output is the same.

  The analog signal obtained by reading the contact sensor (CS) 41 is converted into a digital signal by the analog processor board 23. This digital signal is subjected to image processing by the image controller 50 and sent as a video signal to the laser unit (laser scanner driver 29) of the engine controller 60. The engine controller 60 controls the laser unit, heater control, high voltage circuit and load system (main motor, solenoid, fan, etc. for controlling the paper feed mechanism, paper discharge roller, etc.). In FIG. 1, the laser scanner driver 29 is illustrated as belonging to the engine controller 60. Based on the video signal from the image processing unit 51, the engine controller 60 irradiates the photosensitive drum with a laser to form a latent image, and develops the latent image with toner. Further, this toner image is transferred to a sheet and fixed. The low-voltage power source is a unit including a heater drive circuit of the fixing device.

  3, 4 and 5 are layout diagrams of various substrate units inside the main body of the image forming apparatus shown in FIG. 3 is a perspective view seen from the back side of the apparatus, unlike FIG. FIG. 4 is a perspective view of the apparatus as viewed from the right front side. FIG. 5 is a view as seen from the left side of the apparatus (in the direction of arrow 39 in FIG. 3). In these drawings, some of the substrates are omitted for convenience.

  Arrangement of the various board units inevitably takes into consideration the paper conveyance path, and the DC controller circuit board 22 constituting a part of the engine controller 60 and the board relating to the low voltage power supply (power supply circuit board 26) are arranged at the bottom of the main body. It is reasonable to place it. Further, since it is advantageous that the substrate related to the image controller 50 is closer to the reader unit 2, it is attached to the back surface. Since a load system exists in the paper transport unit, signals and power lines are normally connected to the load from the DC controller circuit board 22 and the power circuit board 26 that control the load, and driving is performed.

  The printer controller circuit board 32 is a circuit portion for adding a printer function, and provides an interface for receiving an image signal to be printed from an external device.

  The network control unit (NCU) circuit board 27 and the modular jack circuit board 28 are circuit parts for adding a FAX function and perform connection and communication control with a telephone line.

  The operation unit circuit board 24 is disposed in the vicinity of the operation unit (operation panel) in the upper front portion of the apparatus. The sensor circuit board 25 is a sensor circuit for pressure plate open / close detection, contact sensor home position detection, and the like.

  In the image forming apparatus according to the present embodiment, toner is replenished by cartridge replacement. Therefore, the reader unit slide lever 1 shown in FIG. 1 is released, the reader unit 2 is slid in the direction of the arrow, the inside of the apparatus main body is opened, and the cartridge is replaced.

  The cartridge incorporates a photosensitive drum, has a high voltage contact (for primary charging, development, etc.), and a leaf spring is provided on the main body side so that it can be connected to the high voltage contact of the cartridge. The purpose of loading and unloading the cartridge is the above-described cartridge replacement and paper jam processing. At this time, the high-voltage contact is exposed and can be touched by the user, and the main motor gear may be touched. Therefore, as described above, an interlock mechanism is provided to provide safety by shutting off the power supply (24 V) of the drive system and the high-voltage circuit during paper jam processing and cartridge replacement.

  In this embodiment, when the reader unit 2 is slid, the interlock works and 24V is cut off. For this purpose, an interlock switch 32 is provided in the vicinity (upper part) of the main motor (driver) 31 as shown in FIG. The interlock is realized by interposing the interlock switch 32 in the 24V power line. That is, the 24V power supply line supplies 24V power to each load system (high voltage circuit and drive system) via the interlock switch 32 from the normal low voltage power supply (power supply circuit board 26). Therefore, the routing of the wire is complicated, and the insulation distance (in this case, basic insulation) must be taken into account, and depending on the location, there are some locations that need to be cared for with a Mylar member.

  Therefore, in the present embodiment, the 24V power supply line is not directly connected from the low-voltage power supply to the interlock switch 32 by the wire, but the intermediate wire is eliminated using the substrate.

  An image processor circuit board (image controller board) once receives a drive power supply (24 V) from a low-voltage power supply on the power supply circuit board 26, a laser control signal from the engine controller 50, and a drive signal of a load system (main motor, fan, solenoid, etc.). ) Send to 21. This is because the image processor circuit board 21 is attached to the back surface of the apparatus, and thus becomes the board closest to the load system of the paper transport path. Therefore, it is more advantageous to connect to the load via the image processor circuit board 21. If the connector is arranged as close to the load as possible on the image processor circuit board 21, the wire from there to the load can be shortened. The 24V power line is also connected from the low-voltage power source to the interlock switch 32 via the image processor circuit board 21 and is then returned to the image processor circuit board 21 before being sent to each load system.

  It is necessary to pay attention here to secure an insulation distance between the power supply line and the periphery of the power supply line in the substrate in order to pass the 24V power supply line through the image processor circuit board.

  6 and 7 show the inner layers of the image processor circuit board 21. FIG. In this example, the case of four layers is shown. 6A and 6B show the first layer and the second layer, respectively, and FIGS. 7A and 7B show the third layer and the fourth layer, respectively. In this example, the first layer is a component surface, the second layer is an inner layer ground (GND) surface, the third layer is an inner layer Vcc surface, and the fourth layer on the back surface of the substrate is a solder surface. Note that the number of layers is not necessarily four, but a plurality of layers is desirable.

  A drive signal of a load system (laser, main motor, fan, solenoid, etc.) output from the DC controller circuit board 22 is supplied to each load via the FFC connector J7. The 24V wire sent from the low voltage power source of the power circuit board 26 enters the first layer (component side) connector J1. This power line serves as the first path (component side) cassette. A wide wiring pattern (also referred to simply as a pattern) extends in the vicinity of the connector of the solenoid, and runs around the periphery of the board in a wide pattern as shown in FIG. 7A on the third layer surface in parallel with this, leading to the first pin of the connector J2. This 1st pin is connected to one end of the interlock switch 32 by a wire, and the other end through the interlock switch 32, that is, the return 24V power line is connected to the 3rd pin of the connector J2. The 24V power line from the third pin is connected to the first layer (component side) in parallel with the third layer power line shown in FIG. It runs as a wide pattern, and power is supplied to each load of the connectors J3 to J5 in each part of the pattern because the pattern width from the connectors J1 to J5 needs to be thick because all these loads are relatively large. This is because a large current (for example, a little less than 2A at the maximum) flows when each of the motors including a motor that is a load that consumes current is driven, and a pattern width that can withstand that is required. The second pin is not used, thereby ensuring an insulation distance between the first and third pins of the connector J2.

  Subsequent 24V power is supplied only to the multi-solenoid, cassette solenoid, and engine controller high-voltage circuit. The 24V power supply of the multi-solenoid and cassette solenoid and the 24V pattern sent to the high-voltage circuit of the engine controller are connected by running the first layer surface (component surface) in a thin pattern. In this case, the current sent to the high-voltage circuit of the multi-solenoid, cassette solenoid, and engine controller is so weak that it is not necessary to use a wide pattern. The space other than the 24V power supply line on the first layer surface (component surface) is used in the digital circuit. The second layer is normally GND. In this case, two GNDs, a power GND 61 and a digital GND 62, are prepared. Since the power GND 61 has a 24V power supply pattern in the first layer and the third layer, it is formed so as to overlap with the pattern. The other part becomes the digital GND 62. The two are insulated.

  For the fourth layer (solder surface) shown in FIG. 7B, the portion overlapping the 24V power supply pattern in the first layer and the third layer is solid GND. As a result, the shield on the fourth layer side is intended for the 24V power supply line.

  Further, the pattern of the third layer before interlock, that is, J1 to J2 (1st pin) and the pattern of the first layer after interlock, that is, J2 (3rd pin) to J6, are insulated between the layers. . If dielectric breakdown occurs in the pattern before and after the interlock, when the interlock switch 32 is cut off, the 24V power supply is turned on at the location where the dielectric breakdown occurs, and this does not make sense for the interlock. In this embodiment, the insulation distance is secured so as not to cause dielectric breakdown.

  FIG. 8 shows a cross-sectional view between the layers of the image processor circuit board 21. The image processor circuit board 21 in this embodiment has a four-layer board thickness of about 1.6 mm, and the board material is shown for reference. The pattern before interlock is the L3 layer (the third layer), and the pattern after interlock is the L1 layer. There is an L2 layer (the second layer) as a GND layer between them. For reference, the thickness of each layer and the distance between layers are illustrated. The L1 layer (the first layer) is obtained by applying a 0.02 mm thick plating layer to a 0.018 mm thick copper foil. A prepreg layer having a thickness of 0.3 mm is provided between the L1 layer and the L2 layer. Each of the L2 layer and the L3 layer is a copper foil having a thickness of 0.035 mm, and the thickness of the core material including both layers is 0.9 mm. Like the L1 layer, the L4 layer (the fourth layer) is obtained by applying a 0.02 mm thick plating layer to a 0.018 mm thick copper foil. A prepreg layer having a thickness of 0.3 mm is provided between the L3 layer and the L4 layer.

  The distance between the L3 layer and the L1 layer is 1.165 mm. As a result of conducting a withstand voltage test between the L1 layer and the L3 layer, dielectric breakdown did not occur even when a voltage of 3 kV was applied. Moreover, the result of having performed the same test about the L1-L2 interlayer and the L2-L3 interlayer was also the same. Actually, since the overvoltage detection is performed on the low-voltage power supply side, a voltage up to 3 kV cannot be output, and 3 kV cannot be output. Therefore, it can be said that this test result is sufficient.

  As described above, according to the present embodiment, the image processor circuit board 21 can be used as a relay board for supplying a 24V power supply line.

  Next, another embodiment of the present invention will be described. The basic configuration of this embodiment is the same as that of the above embodiment.

  FIG. 9 shows a portion of the first layer of the image processor circuit board 21 where the pattern after the 24V power supply interlock needs to be connected to the connector pins. In the example shown in the figure, there are mainly four locations (1), (2), (3), and (4). The unit of the numerical value attached to the dimension line in this figure and other figures is mm. In the vicinity of the connector J3 (location (1)) connected to the main motor and the laser unit, the 24V interlocked pattern and the resistor land are connected. A cross-sectional view of the VIA (via) configuration is shown in FIG. One end of the resistor is connected to the 24V power supply after the interlock, and the other end of the resistor is further connected to another resistor. The surface land and the interlocked pattern are connected. Since the resistor is a lead product, the lead penetrates to the solder surface of the L4 layer. Since the pattern before interlocking runs in the L3 layer, the insulation between the resistance hole and L3 must be secured by basic insulation (1.2 mm). Therefore, a distance of 1.2 mm is taken for the resistance hole. Eventually, the distance between the pattern before and after the interlock is 1.2 mm. When the substrate is viewed from the top, a 1.2 mm circular space is formed around the resistance hole in the L3 layer, and basic insulation is achieved.

  Next, the VIA of the multi-solenoid connector portion (2) will be described. The multi-solenoid connector has a 2-pin configuration. Pin 1 is connected to the 24V power supply after interlocking, and its land configuration is the same as the land configuration of the resistor described above. Pin 2 is connected to the drive signal of the multi-solenoid. A cross-sectional view of the land configuration is shown in FIG. The second pin itself is a signal line, but it is necessary to ensure basic insulation in order to pass the pattern before interlock and the pattern layer after interlock, and the insulation distance between the pattern before and after the interlock is 0. Basic insulation was secured as .5 + 1.165 + 1.2 = 2.865 mm.

  Next, FIG. 12 shows a cross-sectional view of a portion (3) of the connector land portion connected to the high voltage circuit of the connector J6. The connector J6 has a two-pin configuration, and the first and second pins are the same power supply 24V. In this case, care must be taken because the 24V pattern before interlock and the pattern after interlock exist on the surface layer. This is because, when a dielectric breakdown occurs between the 24V pattern before interlocking and the pattern after interlocking on the surface layer, even if the interlock is broken, conduction occurs at the place where the dielectric breakdown occurs. The layer of interest may be the surface L1 layer, and the insulation distance between the land and the pattern before interlocking was set to 4.3547 mm. The distance between the L3 layer pattern before the interlock and the center of the hole was a basic insulation of 1.2 mm.

  Next, the land configuration of the cassette solenoid connector (4) will be described. The connector of the cassette solenoid has a two-pin configuration. The first pin is connected to the 24V power supply after the interlock, and the second pin is connected to the drive signal of the cassette solenoid. First, a land sectional view of the first pin is shown in FIG. As in the connector J6, this also secured 4.385 mm as the insulation distance between the land and the pattern before interlocking. In addition, an insulation distance of 2.8929 mm between the land hole of the first pin and the pattern (L3) before the interlock was secured. FIG. 14 shows the land of the second pin. As with the connector J6, the insulation distance between the land of the 2nd pin of the cassette solenoid connector and the pattern before interlocking was 4.385 mm. The insulation distance between the L3 layer and the L1 layer was 3.1229 mm.

  The pre-interlock pattern and the post-interlock pattern are assumed not to cause penetration failure, and the withstand voltage test was conducted with the connector land configuration near the 24V power supply pattern as described above. The voltage was applied between the L1 and L3 layers, and no dielectric breakdown occurred up to 3 kV. Actually, since the overvoltage detection is performed on the low-voltage power supply side, a voltage up to 3 kV cannot be output, and 3 kV cannot be output. Therefore, it can be said that this test result is sufficient.

  As described above, the 24V power supply pattern of the image processor circuit board 21 and the connector pin can be connected with good insulation between predetermined patterns.

  Next, another embodiment will be described.

  FIG. 15 and FIG. 16 show the GND guard (GNDVIA) configuration diagram around the 24V power supply pattern of the image processor circuit board 21 in this embodiment. The basic configuration is the same as that of the first embodiment. 15A and 15B show the first layer and the second layer, respectively, and FIGS. 16A and 16B show the third layer and the fourth layer, respectively. As shown in FIGS. 15 and 16, a ground guard pattern 65 is run on the outer periphery of each layer of the image processor circuit board 21. The first to fourth ground guard patterns are formed so as to overlap each other. Although not clearly shown in FIGS. 15 and 16, GNDVIAs are formed at equal intervals (for example, about several mm to 10 mm) along the ground guard. A cross-sectional view of the GNDVIA is shown in FIG. The VIA hole diameter is 0.4 mm and the land diameter is 0.8 mm. The distance between the L3 layer pattern before interlock and the VIA hole is set to 0.5 mm. Further, the distance between the L1 layer interlocked pattern and VIA is set to 0.6025 to 5.5994 mm. The distance between the pattern before and after the interlock is 0.6025 to 5.5994 + 1.165 + 0.5 = 2.2675 to 7.2644 mm. The lands and holes are filled with solder, and the ground guard layers of the layers are electrically connected to each other.

  The dielectric strength test was conducted with the above configuration. With respect to the withstand voltage, a voltage was applied to the L1-L2 layer. As a result, dielectric breakdown occurred at 2.5 kV. Where the dielectric breakdown occurred, the pattern before the interlock and the surface layer of GNDVIA occurred. In addition, since overvoltage detection and overcurrent detection means are provided in the specifications of the low-voltage power supply, if a short circuit occurs between the pattern before the interlock and GNDVIA, the overcurrent detection of the low-voltage power supply works and the power supply is shut off. It will be.

  Although not shown, when the power supply of the drive system is close to a digital circuit, it is more effective to create a similar ground guard between the drive system power supply and the digital circuit and separate them by GNDVIA.

  Although the preferred embodiments of the present invention have been described above, various modifications and changes can be made within the technical scope of the present invention. For example, although a multi-function device is shown, it is not always necessary to be a multi-function device. The illustrated numerical values are merely illustrative examples, and the present invention is not limited to these specific numerical values. Only the example in which the pattern before the interlock and the pattern after the interlock are insulated by another layer of the multilayer circuit board is shown. However, in the embodiment in which the ground guard is applied, if the insulation distance of both patterns is secured, the same layer is shown. May be arranged. Although the pattern in the layer of the multilayer circuit board is employed for both the first and second paths, the present invention does not exclude the case where the pattern is employed for only one of the paths.

1 is an external view of an image forming apparatus to which the present invention is applied. FIG. 2 is a block diagram illustrating a schematic flow of image data in the image forming apparatus of FIG. 1. FIG. 2 is a diagram illustrating an arrangement of various substrate units inside a main body of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a diagram illustrating an arrangement of various substrate units inside a main body of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a diagram illustrating an arrangement of various substrate units inside a main body of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a diagram showing an inner layer of an image processor circuit board 21 in the image forming apparatus of FIG. 1. FIG. 2 is a diagram showing an inner layer of an image processor circuit board 21 in the image forming apparatus of FIG. 1. FIG. 2 is a cross-sectional view between layers of an image processor circuit board 21 in the image forming apparatus of FIG. 1. It is a figure which shows the location which needs to connect the pattern after 24V power supply interlock of the image processor circuit board 21 to a connector pin. It is sectional drawing of the VIA structure of the location (1) shown in FIG. It is sectional drawing of the VIA structure of the location (2) shown in FIG. It is sectional drawing of the VIA structure of the location (3) shown in FIG. It is sectional drawing of the VIA structure of the 1st pin of the location (4) shown in FIG. It is sectional drawing of the VIA structure of the 2nd pin of the location (4) shown in FIG. It is a figure which shows the internal layer of the image processor circuit board 21 in other embodiment of this invention. It is a figure which shows the internal layer of the image processor circuit board 21 in other embodiment of this invention. It is sectional drawing of GNDVIA in other embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Reader unit slide lever, 2 ... Reader unit, 3 ... White sheet, 4 ... Original plate glass, 5 ... Operation panel, 6 ... Paper cassette, 7 ... Paper discharge tray, 10 ... ADF unit, 11 ... Main body

Claims (8)

A low voltage power circuit;
A load system to which a predetermined power supply voltage is supplied from the low-voltage power supply circuit;
An interlock switch interposed in a power supply line of a power supply voltage supplied to the load system;
A multilayer circuit board on which a predetermined circuit is mounted,
A power supply line from the low-voltage power supply circuit to the load system extends from a position near the interlock switch to the interlock switch, and returns from the interlock switch via the wire to the vicinity position. A first path from a proximity position to the low-voltage power supply circuit and a second path from a proximity position of the interlock switch to each load, and at least one of the first and second paths An image forming apparatus using a pattern in any one layer of the multilayer circuit board.   When both the first and second paths use layers of the multilayer circuit board, one path uses an inner layer or a surface layer of the multilayer circuit board, and the other path is the other layer of the multilayer circuit board. The image forming apparatus according to claim 1, wherein:   The power circuit board on which the low-voltage power circuit is mounted is disposed at the bottom of the apparatus, and the multilayer circuit board is disposed substantially perpendicular to the power circuit board at the back of the apparatus. Image forming apparatus.   The pattern routed in the layer of the multilayer circuit board with respect to the second path is connected to a load that consumes a relatively large current on the side close to the interlock switch, before the interlock of the multilayer circuit board. 2. The image forming apparatus according to claim 1, wherein a pattern thickness of at least a portion connected to the load of the pattern and the interlocked pattern is thicker than a remaining portion of the pattern after the interlock.   2. The image forming apparatus according to claim 1, wherein the pattern of the power supply line arranged on the inner layer of the multilayer circuit board is formed so as to be sandwiched between GND patterns provided on the upper and lower layers.   When a VIA is formed on the power supply line of the multilayer circuit board, the insulation distance is secured by taking into account the insulation distance in each layer in order to secure the insulation distance between the pattern before and after the interlock. The image forming apparatus according to claim 1.   In the multilayer circuit board, at least a portion where a pattern before interlocking and a pattern after interlocking are formed are surrounded by a ground guard, and a solder surface from the surface layer to the back surface of the substrate is connected by a plurality of GNDVIAs. The image forming apparatus according to claim 1.   8. The multilayer circuit board has a digital circuit area in the vicinity of the pattern of the power supply line, a ground guard is provided between the pattern and the digital circuit, and separated by a plurality of GND VIAs. The image forming apparatus described.

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