Protection apparatus, and image processing apparatus

Abstract

To provide a protection apparatus which can prevent an inrush current caused when a motor is activated while a motor driver is applied with a power source voltage with a simple arrangement and can provide satisfactory response while the motor is driven, and an image processing apparatus having the protection apparatus.SOLUTION: A protection circuit 18 has an output resistance R1 provided in a power source line L1 through which a power source circuit 32 supplies a power source voltage to a motor driver, and a switching unit 40 including a MOSFET 41 provided in parallel to the output resistance R1 on a power source line L2 bypassing the power source line L1. The switching unit 40 brings the MOSFET unit 41 to its on state if an operation signal is input, thereby conducting electricity to the power source line L2.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a protection device that suppresses inrush current that occurs when a motor is started, and to an image processing apparatus that includes the protection device. [Background technology]

[0002] Image processing devices such as copiers, printers, facsimiles, and image readers are equipped with motors that supply the driving force required for image processing operations. When the motor is started, a so-called inrush current flows through the motor. Conventionally, proposals have been disclosed to prevent this inrush current (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-095845 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology, the power supply voltage is supplied in sequence at regular time intervals, and the response to a motor drive command may be slow.

[0005] An object of the present invention is to provide a protection device that can prevent, with a simple configuration, the inrush current that occurs when a motor is started with a power supply voltage applied to the motor driver, and that has good response when the motor is driven, and an image processing device that is equipped with this protection device. [Means for solving the problem]

[0006] A protection device according to one aspect of the present invention is a protection device that suppresses inrush current that occurs when a motor is started, and includes: an output resistor provided in a power supply line through which a power supply voltage is supplied from a power source to a motor driver; a switching unit provided in parallel with the output resistor in a bypass power supply line that bypasses the power supply line, the switching unit maintaining an off state to make the bypass power supply line non-conductive when a predetermined operation signal is not input, and turning on when the operation signal is input, to make the bypass power supply line conductive; and an operation signal output unit that does not input the operation signal to the switching unit when the motor is started by the motor driver, and inputs the operation signal to the switching unit at a predetermined timing after the motor is started.

[0007] An image processing device according to another aspect of the present invention includes a power supply device having the protection device, and an image processing unit operated by the motor. [Effects of the Invention]

[0008] According to the present invention, it is possible to prevent, with a simple configuration, the inrush current that occurs when a motor is started with a power supply voltage applied to the motor driver, and it is also possible to realize a protection device that has good response when the motor is driven. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of a protection device according to an embodiment of the present invention. [Figure 3] FIG. 3 is a circuit diagram showing the configuration of a protection circuit according to an embodiment of the present invention. [Figure 4] FIG. 4 is a timing chart showing the currents, voltages, signals, motor operating states, switching element operating states, and the like used in the protection circuit of the present invention. [Figure 5] FIG. 5 is a diagram showing a first modified example of the configuration of the protection device according to the embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing a second modified example of the configuration of the protection device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example of the present invention, and does not limit the technical scope of the present invention.

[0011] [Image forming apparatus 10] The configuration of an image forming apparatus 10 according to one embodiment of the present invention will be described with reference to Figure 1. Note that in this embodiment, the image forming apparatus 10 will be described as an example of an image processing apparatus of the present invention, but the image processing apparatus of the present invention may also be an image processing apparatus such as a printer, a facsimile machine, a copier, a scanner, or a multifunction machine having the functions of each of these.

[0012] As shown in FIG. 1, image forming apparatus 10 includes image reading unit 11 (image processing unit), image forming unit 12 (image processing unit), operation and display unit 13, paper feed unit 14, communication unit 15, and main control unit 20 that controls these components. Each of these components is provided in a housing of image forming apparatus 10. Image forming apparatus 10 also includes multiple motors 16 as drive units for image reading unit 11 and image forming unit 12, motor drivers 17 that drive and control these motors 16, and a protection circuit 18. Image forming apparatus 10 also includes power supply unit 30 (an example of a power supply device of the present invention) that supplies power required for image reading unit 11, image forming unit 12, operation and display unit 13, paper feed unit 14, communication unit 15, main control unit 20, motor driver 17, etc. In FIG. 1, power lines are indicated by solid lines, and signal lines are indicated by dashed lines.

[0013] The image reading unit 11, the image forming unit 12, the operation display unit 13, and the paper feeding unit 14 each have a drive unit that consumes power to operate, and are loads on the image forming apparatus 10. An example of the drive unit is a motor 16 provided in the image forming apparatus 10.

[0014] Image forming apparatus 10 is provided with a plurality of motors 16 for various purposes. Examples of motors 16 include a motor that drives a reading unit (described below) in image reading unit 11, a motor that rotates a photosensitive drum in image forming unit 12, a motor that rotates a developing roller in a developing device, a motor that rotates a fixing roller or pressure roller in a fixing device, a motor that rotates a polygon mirror in a laser scanner unit, and a motor that rotates a transport roller in a paper transport device. In this embodiment, motor 16 is, for example, a ⅛-C brushless motor or a stepping motor.

[0015] The image reading unit 11 is a so-called scanner equipped with a contact glass, a reading unit, a mirror, an optical lens, a CCD, and the like. The image reading unit 11 executes an image reading process to read image data from a document set at a predetermined position. Specifically, the document is placed on the contact glass, and then an image reading command is input from the operation display unit 13. The reading unit is then moved in the sub-scanning direction by a built-in drive motor 16. During this movement, a light source of the reading unit successively irradiates the document with light for one line at a time. The reflected light from the document is then guided to the CCD via the mirror and the optical lens, and light intensity data corresponding to the amount of light received by the CCD is output to the main control unit 20. The main control unit 20 generates image data of the document based on the optical data.

[0016] Image forming unit 12 performs an image formation process (printing process) based on electrophotography. Specifically, image forming unit 12 performs the image formation process based on image data read by image reading unit 11 or print data (print job) input via communication unit 15 from an external information processing device such as a personal computer. Image forming unit 12 includes a photosensitive drum, a charging device, a developing device, a transfer device, a fixing device, a laser scanner unit, a paper conveying device, and the like. When the print data is input, the charging device uniformly charges the photosensitive drum to a predetermined potential. Next, the laser scanner unit irradiates the surface of the photosensitive drum with light based on the image data included in the print job. This forms an electrostatic latent image on the surface of the photosensitive drum. The electrostatic latent image on the photosensitive drum is then developed into a toner image by the developing device. The toner image formed on the photosensitive drum is then transferred to a print sheet (sheet member) by the transfer device and then fixed to the print sheet by the fixing device. In this embodiment, an electrophotographic image forming unit 12 will be described as an example, but the image forming unit 12 is not limited to an electrophotographic image forming unit, and may be an inkjet recording unit, or may be any other recording or printing unit.

[0017] The operation and display unit 13 includes an operation unit such as a push button switch and a display unit such as a liquid crystal panel. The operation and display unit 13 is equipped with a panel control unit including a liquid crystal driver. The panel control unit recognizes signals input from the operation unit. The panel control unit also executes display processing of various data on the display unit.

[0018] The paper feed unit 14 stores printing paper on which an image is formed in the image forming unit 12. The paper feed unit 14 also includes a feeding mechanism (not shown), which feeds the printing paper stored in the paper feed unit 14 toward the image forming unit 12. The feeding mechanism is made up of a pickup roller that picks up printing paper from the paper storage unit, a feeding roller that sends the printing paper toward the image forming unit 12, and the like. The pickup roller and the feeding roller are driven to rotate by a drive motor 16. When the motor 16 is driven to rotate, the feeding roller feeds the printing paper.

[0019] The communication unit 15 is a communication interface that connects the image forming apparatus to a predetermined communication network and accepts input of print data and the like transmitted from the outside via the communication network. Specifically, the communication unit 15 is a communication interface card or the like that complies with the standard IEEE802.3. The print data sent to the image forming apparatus 10 from the outside is input via the communication unit 15.

[0020] The main control unit 20 comprehensively controls the image forming apparatus 10. The main control unit 20 is configured as a control board on which a microcomputer is mounted, the main components of which include a CPU 21, a storage unit such as a ROM, a RAM, and a flash memory, and electronic devices such as an oscillator.

[0021] 1, the main control unit 20 is connected to each load unit such as the image reading unit 11 and the image forming unit 12 via an internal bus 26 so that they can communicate with each other. The main control unit 20 performs overall control of the image forming apparatus 10 by having the CPU 21 execute the program stored in the ROM.

[0022] The power supply unit 30 supplies power to each component, such as the image reading unit 11, the image forming unit 12, the operation display unit 13, the paper feed unit 14, the communication unit 15, the main control unit 20, and the motor driver 17. The power supply unit 30 is connected to each component by a power line.

[0023] The power supply unit 30 includes a power supply control unit 31 and a power supply circuit 32 .

[0024] The power supply circuit 32 is equipped with an AC / DC converter, a DC / DC converter, etc., and, for example, rectifies AC 100V, which is a commercial power supply, and converts it into DC 24V, which is then switched and controlled to convert it into an appropriate voltage for each of the components, such as the image reading unit 11, the image forming unit 12, the operation display unit 13, the paper feeding unit 14, the communication unit 15, the main control unit 20, and the motor driver 17, before supplying it to each component.

[0025] The power supply control unit 31 controls the supply of power output from the power supply circuit 32 to each component. The power supply control unit 31 is configured as a control board on which a microcomputer including a CPU, ROM, RAM, etc. as its main components is mounted. The power supply control unit 31 is specifically a power supply IC known as a Power Management IC (PMIC).

[0026] The motor driver 17 controls the driving of the various motors 16. A plurality of motor drivers 17 are provided corresponding to the respective motors 16. A power supply voltage is applied to the motor drivers 17 from a power supply circuit 32. When the motor driver 17 receives a drive control signal from the CPU 21 of the main control unit 20, it converts the power supply voltage from the power supply circuit 32 into a voltage appropriate for the motor 16 and outputs it to the motor 16 to drive it. Note that the motor driver 17 may be incorporated into the motor 16.

[0027] If, as in this embodiment, power supply voltage is applied from power supply circuit 32 to motor driver 17 while waiting before motor 16 is driven, an inrush current will inevitably occur when motor 16 is started by motor driver 17. This inrush current is a current that greatly exceeds the steady-state current value when motor 16 is driven steadily, and if this inrush current is supplied to motor driver 17, it could damage motor driver 17 or cause malfunction of motor 16. For this reason, in this embodiment, protection circuit 18 is provided between power supply circuit 32 and motor driver 17.

[0028] 2, the protection circuit 18 is provided on the power line L1 supplied from the power supply circuit 32 to the motor driver 17. The protection circuit 18 is an inrush current prevention circuit for suppressing the inrush current that occurs at the beginning of startup when the motor 16 is started by the motor driver 17.

[0029] As an example of an inrush current prevention circuit, a conventional circuit that suppresses the occurrence of inrush current by sequentially supplying power supply voltage at fixed time intervals is known. However, because the conventional circuit supplies power supply voltage at fixed time intervals, the drive response of the motor 16 to the drive control signal may be slow.

[0030] In contrast, the protection circuit 18 of this embodiment is configured as described below, and therefore can prevent the inrush current that occurs when the motor 16 is started with a simple configuration even when a power supply voltage is applied to the motor driver 17, and also provides good response to the drive control signal of the motor 16.

[0031] [Protection circuit 18] The configuration of the protection circuit 18 will be described below with reference to Fig. 3. Fig. 3 is a circuit diagram showing the configuration of the protection circuit 18.

[0032] As shown in FIG. 3, the protection circuit 18 has an output resistor R1 (an example of an output resistor of the present invention) provided on a power supply line L1 through which a power supply voltage is supplied from a power supply circuit 32 to a motor driver, and a switching unit 40 including a MOSFET 41 provided in parallel with the output resistor R1 on a power supply line L2 (an example of a bypass power supply line of the present invention) that bypasses the power supply line L1.

[0033] When a predetermined operation signal is not input to the protection circuit 18, the switching unit 40 maintains the MOSFET 41 in the off state, making the power supply line L2 non-conductive, and when the operation signal is input, the switching unit 40 turns the MOSFET 41 on, making the power supply line L2 conductive.

[0034] An example of the operation signal is the output signal Sig01 output from the motor driver 17. The output signal Sig01 is a signal that is output from the motor driver 17 when the rotation speed of the motor 16 reaches a predetermined steady rotation speed (an example of a set rotation speed). The output signal Sig01 is a voltage signal of a predetermined level (a high-level signal), and is input to an input terminal Sin (an example of a signal input section of the present invention) of the protection circuit 18. This output signal Sig01 is also output to the CPU 21 to notify the CPU 21 that the rotation speed of the motor 16 has reached the steady rotation speed.

[0035] In this embodiment, a speed sensor 16A is provided on the motor 16 to detect the rotation speed of the motor 16. The speed sensor 16A is an example of a rotation speed detection unit of the present invention, and detects when the rotation speed of the motor 16 has reached the steady rotation speed and sends the signal to the motor driver 17. Upon receiving a detection signal from the speed sensor 16A, the motor driver 17 generates the output signal Sig01 and outputs it to the protection circuit 18 and the CPU 21. The motor driver 17, which generates the output signal Sig01 and outputs it to the protection circuit 18, is an example of an operation signal output unit of the present invention. In this embodiment, the protection circuit 18 and the motor driver 17 constitute a protection device of the present invention.

[0036] The speed sensor 16A may detect the rotation speed of the motor 16 and send it to the motor driver 17. In this case, the motor driver 17 determines whether the rotation speed of the motor 16 has reached the steady rotation speed, and when the steady rotation speed has been reached, generates the output signal Sig01 and outputs it to both the protection circuit 18 and the CPU 21.

[0037] Specifically, the switching unit 40 has a MOSFET 41 provided on the power supply line L2, a first internal resistor R21, a second internal resistor R22, a PNP bipolar transistor 42 (hereinafter abbreviated as "transistor 42"), a third internal resistor R23, an NPN bipolar transistor 43 (hereinafter abbreviated as "transistor 43"), and a pull-up resistor R3.

[0038] The MOSFET 41 is a switching element that makes the power supply line L2 conductive or non-conductive, and is specifically a P-channel field-effect transistor. The source terminal of the MOSFET 41 is connected to the primary side (voltage input terminal Vin) of the power supply line L2, and the drain terminal is connected to the secondary side (voltage output terminal Vout) of the power supply line L2. When the voltage at the gate terminal (gate voltage) of the MOSFET 41 becomes lower than the voltage at the source terminal (source voltage), the source terminal and drain terminal become conductive, and the power supply voltage is supplied to the motor driver 17 via the power supply line L2. When the source terminal and drain terminal of the MOSFET 41 are non-conductive, the power supply voltage is supplied to the motor driver 17 via the power supply line L1, which is provided with an output resistor R1.

[0039] One end of the first internal resistor R21 is connected to the gate terminal of the MOSFET 41, and the other end is connected to the emitter terminal of the transistor 42. In other words, the first internal resistor R21 is provided between the gate terminal of the MOSFET 41 and the emitter terminal of the transistor 42.

[0040] The second internal resistor R22 is provided between the gate terminal and the source terminal of the MOSFET 41.

[0041] The transistor 42 is a switching element that makes the line from the first internal resistor R21 to the ground potential conductive or non-conductive. The transistor 42 has an emitter terminal connected to the other end of the first internal resistor R21 and a collector terminal connected to the ground potential. When the voltage of the base terminal (base voltage) of the transistor 42 becomes low, the emitter terminal and collector terminal become conductive, and the gate voltage of the MOSFET 41 drops to the ground potential. In this case, the gate voltage of the MOSFET 41 becomes lower than the source voltage. Note that when the base voltage of the transistor 42 is high, the emitter terminal and collector terminal become non-conductive, and in this case, the gate voltage of the MOSFET 41 is maintained at a voltage higher than the source voltage.

[0042] The third internal resistor R23 has one end connected to the base terminal of the transistor 42 and the other end connected to the collector terminal of the transistor 43. In other words, the third internal resistor R23 is provided between the base terminal of the transistor 42 and the collector terminal of the transistor 43.

[0043] The transistor 43 is a switching element that turns on or off the line from the third internal resistor R23 to the ground potential. The collector terminal of the transistor 43 is connected to the other end of the third internal resistor R23, and the emitter terminal is connected to the ground potential. The base terminal of the transistor 43 is connected to the input terminal Sin of the protection circuit 18.

[0044] The pull-up resistor R3 is provided between the collector terminal of the transistor 43 and a DC voltage source 44 that supplies a predetermined DC voltage. The voltage supplied from the DC voltage source 44 is a low voltage of, for example, DC 3.3 V or DC 5.0 V.

[0045] In the protection circuit 18 configured as described above, when the operation signal is not input to the input terminal Sin (see FIG. 4E), the transistor 43 does not operate and remains in the off state. At this time, the voltage of the DC voltage source 44 is applied to the base terminal of the transistor 42, so the base voltage of the transistor 42 remains at a high level (see FIG. 4F), and the transistor 42 does not operate and remains in the off state (see FIG. 4G). In this case, there is no conduction between the emitter terminal and the collector terminal, so the gate voltage of the MOSFET 41 remains higher than the source voltage, and the MOSFET 41 also remains in the off state (see FIG. 4H). Therefore, when the operation signal is not input to the input terminal Sin, the power supply voltage is supplied to the motor driver 17 via the power supply line L1 provided with the output resistor R1.

[0046] In this state, for example, at time T1 in Figure 4, when the drive control signal is output from the CPU 21 to the motor driver 17 (see Figure 4(A)), a load current flows to the motor driver 17 through the power supply line L1 provided with the output resistor R1 (see Figure 4(B)). In this case, an inrush current occurs in the power supply line L1, but the output resistor R1 suppresses a sudden increase in the current.

[0047] If a load current always flows through the power supply line L1, the current will always be consumed unnecessarily by the output resistor R1. Therefore, in this embodiment, when it is detected that the rotation speed of the motor 16 has reached the steady-state rotation speed, the motor driver 17 outputs the output signal Sig01 to the protection circuit 18 as the operation signal.

[0048] Time T2 in FIG. 4 is a timing determined after time T11 when the inrush current converges. At time T2, the output signal Sig01 is input to the input terminal Sin. This activates the transistor 43, causing it to change from an off state to an on state (see FIG. 4E). At this time, the voltage of the DC voltage source 44 drops to ground potential, causing the base voltage of the transistor 42 to change from high to low (see FIG. 4F). This activates the transistor 42, causing it to change from an off state to an on state (see FIG. 4G). In this case, conduction occurs between the emitter terminal and the collector terminal, so the gate voltage of the MOSFET 41 drops to ground potential and changes to a voltage lower than the source voltage. This also causes the MOSFET 41 to change from an off state to an on state (see FIG. 4H). Therefore, when the output signal Sig01 is input to the input terminal Sin, the power supply voltage is supplied to the motor driver 17 via the power supply line L2, not via the power supply line L1. As a result, after the inrush current is suppressed, the supply line of the power supply voltage is switched from the power supply line L1 to the power supply line L2, thereby preventing current from being wasted by the output resistor R1.

[0049] In the above embodiment, the output signal Sig01 is exemplified as the operation signal, but the operation signal is not limited to the output signal Sig01. For example, as shown in Fig. 5, another example of the operation signal may be the output signal Sig02 output from the state sensor 16B provided in the motor 16.

[0050] The status sensor 16B is provided on the motor 16. The status sensor 16B is, for example, a vibration sensor that detects vibrations generated when the motor 16 is driven. In this case, the status sensor 16B is an example of a vibration detection unit of the present invention, and detects that the vibrations generated when the motor 16 is driven have reached a predetermined set vibration value, and generates the output signal Sig02 and outputs it to the protection circuit 18. The set vibration value is, for example, set to a value equivalent to the vibration value generated when the motor 16 is rotating stably at a steady rotation speed. The status sensor 16B that generates the output signal Sig02 and outputs it to the protection circuit 18 is an example of an operation signal output unit of the present invention. In this embodiment, the protection circuit 18 and the status sensor 16B constitute a protection device of the present invention.

[0051] As another example of the operation signal, if the status sensor 16B is a sound sensor (an example of a sound detection unit of the present invention) that detects drive sound generated when the motor 16 is driven, the output signal Sig02 may be a signal output from the sound sensor. In this case, when the sound sensor detects that the drive sound has reached a predetermined threshold, it generates the output signal Sig02 and outputs it to the protection circuit 18. The threshold is set to a value equivalent to the drive sound generated when the motor 16 is rotating stably at a steady rotation speed, for example.

[0052] Furthermore, the status sensor 16B may send to the motor driver 17 a signal indicating the vibration during driving of the motor 16 or a signal indicating the driving sound during driving of the motor 16. In this case, the motor driver 17 determines whether the vibration during driving reaches the set vibration value based on the received signal, and if the vibration reaches the set vibration value, generates the output signal Sig02 and outputs it to the protection circuit 18. Alternatively, the motor driver 17 determines whether the driving sound reaches the set threshold value based on the received signal, and if the driving sound reaches the set threshold, generates the output signal Sig02 and outputs it to the protection circuit 18.

[0053] In the above-described embodiment, a configuration in which one operation signal is input to the input terminal Sin of the protection circuit 18 has been exemplified, but, for example, as shown in Fig. 6, a configuration in which both the output signal Sig01 and the output signal Sig02 are input to the input terminal Sin of the protection circuit 18 may be used. Also, a configuration in which both the output signal from the vibration sensor and the output signal from the sound sensor are input to the input terminal Sin of the protection circuit 18 may be used.

[0054] [Notes on the Invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0055] <Appendix 1> A protection device that suppresses inrush current that occurs when a motor starts, an output resistor provided on a power supply line through which a power supply voltage is supplied from a power supply to the motor driver; a switching unit that is provided in parallel with the output resistor on a bypass power supply line that bypasses the power supply line, the switching unit maintaining an off state to make the bypass power supply line non-conductive when a predetermined operation signal is not input, and turning on when the operation signal is input to make the bypass power supply line conductive; an operation signal output unit that does not input the operation signal to the switching unit when the motor is started by the motor driver, and that inputs the operation signal to the switching unit at a predetermined timing after the motor is started.

[0056] <Appendix 2> a protection circuit including the output resistor and the switching unit; The switching unit a P-channel MOSFET provided on the bypass power supply line; a first internal resistor having one end connected to the gate terminal of the MOSFET; a second internal resistor provided between the gate terminal and the source terminal of the MOSFET; a PNP bipolar transistor having an emitter terminal connected to the other end of the first internal resistor and a collector terminal connected to a ground potential; a third internal resistor having one end connected to the base terminal of the PNP bipolar transistor; an NPN bipolar transistor having a collector terminal connected to the other end of the third internal resistor, an emitter terminal connected to a ground potential, and a base terminal connected to a signal input portion for the operation signal; a pull-up resistor provided between the collector terminal of the NPN bipolar transistor and a predetermined DC voltage source; 2. The protection device according to claim 1, wherein the operation signal output unit outputs a high-level voltage signal as the operation signal to the signal input unit at a predetermined timing after start-up of the motor, thereby operating the MOSFET and the PNP bipolar transistor.

[0057] <Appendix 3> a rotation speed detection unit that detects whether the rotation speed of the motor has reached a predetermined set number of rotations; 3. The protection device according to claim 2, wherein the voltage signal is a detection signal output from the rotation speed detection unit.

[0058] <Appendix 4> a vibration detection unit that detects whether vibration generated when the motor is driven has reached a predetermined set vibration value; 4. The protection device according to claim 2, wherein the voltage signal is a detection signal output from the vibration detection unit.

[0059] <Appendix 5> a sound detection unit that detects whether a driving sound generated when the motor is driven reaches a predetermined threshold; 5. The protection device according to claim 2, wherein the voltage signal is a detection signal output from the sound detection unit.

[0060] Appendix 6 A power supply device having a protection device according to any one of appendices 1 to 5; an image processing unit operated by the motor. [Explanation of symbols]

[0061] 10: Image forming device 11: Image reading unit 12: Image forming unit 16: Motor 16A: Speed ​​sensor 16B: Status sensor 17: Motor driver 18:Protection circuit 20: Main control unit 21: CPU 30: Power supply unit 31: Power supply control unit 32: Power supply circuit 40: Switching section 41:MOSFET 42: PNP bipolar transistor 43: NPN bipolar transistor 44: DC voltage source L1: Power line L2: Power line R1: Output resistor R21: 1st internal resistance R22: 2nd internal resistance R23: 3rd internal resistance R3: Pull-up resistor Sig01: Output signal Sig02: Output signal Sin: Input terminal

Claims

1. A protection device that suppresses inrush current that occurs when a motor starts, an output resistor provided on a power supply line through which a power supply voltage is supplied from a power supply to the motor driver; a switching unit that is provided in parallel with the output resistor on a bypass power supply line that bypasses the power supply line, the switching unit maintaining an off state to make the bypass power supply line non-conductive when a predetermined operation signal is not input, and turning on when the operation signal is input to make the bypass power supply line conductive; an operation signal output unit that does not input the operation signal to the switching unit when the motor is started by the motor driver, and that inputs the operation signal to the switching unit at a predetermined timing after the motor is started.

2. a protection circuit including the output resistor and the switching unit; The switching unit a P-channel MOSFET provided on the bypass power supply line; a first internal resistor having one end connected to a gate terminal of the MOSFET; a second internal resistor provided between the gate terminal and the source terminal of the MOSFET; a PNP bipolar transistor having an emitter terminal connected to the other end of the first internal resistor and a collector terminal connected to a ground potential; a third internal resistor having one end connected to the base terminal of the PNP bipolar transistor; an NPN bipolar transistor having a collector terminal connected to the other end of the third internal resistor, an emitter terminal connected to a ground potential, and a base terminal connected to a signal input portion for the operation signal; a pull-up resistor provided between the collector terminal of the NPN bipolar transistor and a predetermined DC voltage source; 2. The protection device according to claim 1, wherein the operation signal output unit outputs a high-level voltage signal as the operation signal to the signal input unit at a predetermined timing after start-up of the motor, thereby operating the MOSFET and the PNP bipolar transistor.

3. a rotation speed detection unit that detects whether the rotation speed of the motor has reached a predetermined set number of rotations; The protection device according to claim 2 , wherein the voltage signal is a detection signal output from the rotational speed detection unit.

4. a vibration detection unit that detects whether vibration generated when the motor is driven has reached a predetermined set vibration value; The protection device according to claim 2 or 3, wherein the voltage signal is a detection signal output from the vibration detection unit.

5. a sound detection unit that detects whether a driving sound generated when the motor is driven reaches a predetermined threshold; The protection device according to claim 2 or 3, wherein the voltage signal is a detection signal output from the sound detection unit.

6. a power supply device having the protection device according to claim 1 or 2; an image processing unit operated by the motor.

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