JP2017041995A - Motor lock detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor lock detection device capable of swiftly detecting a motor lock on the basis of a drastic change of a motor even when a motor current in normal operation is small.SOLUTION: The motor lock detection device comprises: a resistance 11 that functions as a motor current detection section for detecting a motor current flowing on a lift motor 7b; and a motor lock detection section 81 that functions as a variable lock threshold level setting section for setting a variable lock threshold level (reference voltage V2) based on a motor current in a normal operation and that detects a motor lock when the motor current exceeds a variable lock threshold level (reference voltage V2).SELECTED DRAWING: Figure 3

Description

  The present invention relates to a motor lock detection device that detects a lock of a motor.

  Image forming apparatuses such as copiers, scanners, and multifunction machines include various motors that are used to transport originals and recording paper. These motors may be locked in rotation due to catching of a document or recording paper. If the locked state continues, the motor will be damaged. Therefore, a technique has been proposed in which the motor current is compared with a reference value, motor lock is detected when the motor current exceeds the reference value, and the power supply to the motor is cut off (see, for example, Patent Document 1). .

JP-A-8-223786

  However, the prior art does not take into account changes in the motor current during steady state. In other words, when the motor current changes depending on the state of the document or recording paper, the reference value to be compared with the motor current assumes that the motor current in the steady state is the largest in order to prevent false detection caused by noise etc. Is set. Therefore, when the motor current at the steady state is small, it is not possible to cope with a sudden change of the motor, and it takes time until the motor current reaches the reference value and the motor lock is detected. There was a problem that it could lead to breakage.

  An object of the present invention is to solve the above-described problems and provide a motor lock detection device that can quickly detect a motor lock against a sudden change in the motor even when the motor current during steady state is small. .

The motor lock detection device of the present invention includes a motor current detection unit that detects a motor current flowing through a motor, a lock threshold value setting unit that sets a variable lock threshold value based on the motor current in a steady state, and the motor current is the variable lock. And a motor lock detecting unit that detects a motor lock when a threshold value is exceeded.
Further, in the motor lock detection device of the present invention, the motor current in a steady state may be the motor current detected at a time when a predetermined time elapses after the start of the motor and the influence of the inrush current disappears. .
Furthermore, in the motor lock detection device of the present invention, the lock threshold value setting unit may set the variable lock threshold value by adding a fluctuation width to the motor current in a steady state.
Further, in the motor lock detection device of the present invention, the lock threshold value setting unit adds the fluctuation width having a smaller value to the motor current in the steady state to increase the variable lock threshold value as the motor current in the steady state increases. May be set.
Further, in the motor lock detection device of the present invention, a fixed lock threshold is set in advance, and the motor lock detection unit locks the motor when the motor current exceeds either the variable lock threshold or the fixed lock threshold. It may be detected.

  According to the present invention, even when the steady-state motor current is small, it is possible to quickly detect a motor lock against a sudden change in the motor.

1 is a schematic cross-sectional view showing an internal configuration of an embodiment of an image forming apparatus including a motor lock detection device according to the present invention. It is a perspective view which shows the structure of the paper feed part shown in FIG. FIG. 2 is a block diagram illustrating a schematic configuration of an embodiment of the image forming apparatus illustrated in FIG. 1. It is a wave form diagram which shows the example of a setting of the variable lock threshold voltage by the motor lock detection part shown in FIG. It is a wave form diagram which shows the other example of a variable lock threshold voltage set by the motor lock detection part shown in FIG.

Next, embodiments of the present invention will be specifically described with reference to the drawings.
An image forming apparatus 1 according to the present embodiment is a copying machine. Referring to FIGS. 1 and 2, the image forming apparatus 1 includes a document reading unit 2, a document feeding unit 3, a main body unit 4, and an operation unit 5. Yes. The document reading unit 2 is disposed on the top of the main body unit 4, and the document feeding unit 3 is disposed on the top of the document reading unit 2. The operation unit 5 is disposed on the front side of the image forming apparatus 1. The document feeding unit 3 and the document reading unit 2 are connected by a hinge mechanism on the back side of the image forming apparatus 1, and the document reading unit 2 is opened by opening the document feeding unit 3 upward from the near side. The upper surface can be opened. Although the image forming apparatus 1 of the present embodiment has been described with reference to a copying machine, it is needless to say that a scanner, a multifunction machine, and the like are included.

  On the front side of the image forming apparatus 1, an operation unit 5 for setting and operating instructions of the image forming apparatus 1 is disposed. The operation unit 5 is provided with a liquid crystal display unit 51 and operation buttons 52. The user operates the operation unit 5 to input an instruction, thereby performing various settings of the image forming apparatus 1 and executing various functions such as image formation. The liquid crystal display unit 51 displays the state of the image forming apparatus 1, displays the image forming status and the number of copies, and can be used as a touch panel to perform various settings such as functions such as double-sided printing and black-and-white reversal, magnification setting, and density setting. It has become. The operation button 52 includes a start button for instructing the user to start image formation, a stop / clear button for use when stopping image formation, and various settings of the image forming apparatus 1 that are used for default settings. A reset button, a numeric keypad and the like are provided.

  The document reading unit 2 includes a scanner 21, a platen glass 22, and a document reading slit 23. The scanner 21 includes a light source 24 using an LED (Light Emitting Diode) and a light receiving unit 25 including a CCD (Charge Coupled Device) line sensor, a CMOS (Complementary Metal Oxide Semiconductor) line sensor, and the like. The unit 3 is configured to be movable in the document conveyance direction.

  The document feeding unit 3 includes a document placement unit 31, a document discharge unit 32, and a document transport mechanism 33. The originals placed on the original placement unit 31 are sequentially fed out one by one by the original conveyance mechanism 33, conveyed to a position facing the original reading slit 23, and then discharged to the original discharge unit 32.

  The document feeding unit 3 functions as a platen cover that opens and closes the upper surface of the platen glass 22. By opening the document feeding unit 3 upward, the upper surface of the platen glass 22 is opened and a document can be set on the platen glass 22. Become. In addition, the surface facing the platen glass 22 in the document feeding unit 3 is a white document pressing surface.

  When reading of a document is instructed by the operation button 52 of the operation unit 5 in a state where no document is placed on the document placement unit 31 or in an opened state where the document feeding unit 3 (platen cover) is opened, the platen A document placed on the glass 22 is read. When reading a document placed on the platen glass 22, the scanner 21 is moved to a position facing the platen glass 22, and the document placed on the platen glass 22 is moved in the sub-scanning direction orthogonal to the main scanning direction. Reading is performed while scanning to acquire image data, and the acquired image data is output to the main unit 4.

  When reading of a document is instructed by the operation button 52 of the operation unit 5 in a state where the document is placed on the document placing unit 31, the document conveyed by the document feeding unit 3 is read. When reading the document conveyed by the document feeding unit 3, the scanner 21 is moved to a position facing the document reading slit 23, and the document feeding operation by the document feeding unit 3 is performed via the document reading slit 23. The document is read synchronously to acquire image data, and the acquired image data is output to the main unit 4.

  The main body 4 includes a recording unit 6, and includes a paper feeding unit 7, a paper feeding roller 41, a paper conveyance path 42, a conveyance roller 43, and a discharge roller 44. The paper feed unit 7 is a paper feed cassette that stores a plurality of recording papers, and the paper feed roller 41 feeds the recording papers one by one from the paper feed unit 7 to the paper transport path 42. The recording paper fed to the paper transport path 42 by the paper feed roller 41 is transported to the recording unit 6 by the transport roller 43. The recording paper on which recording has been performed by the recording unit 6 is discharged by a discharge roller 44 into a discharge space 45 formed between the document reading unit 2 and the main body unit 4. Thus, the paper feed roller 41, the transport roller 43, and the discharge roller 44 function as a recording paper transport unit.

  Referring to FIG. 2, the paper feed unit 7 includes a paper feed cassette 7a on which recording paper is stacked, and a lift motor 7b provided in a cassette mounting unit on which the paper feed cassette 7a is detachably mounted. The The paper feed cassette 7a is provided on the bottom surface, and is supported by a lift plate 71 pivotally supported by the support portion X at the rear end in the paper feed direction, and by a drive shaft (not shown), with the drive shaft as the center. A push-up plate 72 that moves the tip of the lift plate 71 up and down with respect to the paper feed roller 41 by rotation is provided.

  The lift motor 7b is connected to the drive shaft of the push-up plate 72 through a connecting mechanism such as a worm gear when the paper feed cassette 7a is mounted on the cassette mounting portion. The push-up plate 72 is rotated by the rotational force of the lift motor 7b. However, the rotation of the push-up plate 72 is restricted when the lift motor 7b is not rotating. As the lift motor 7b, a DC motor capable of forward and reverse rotation according to the energization direction is used.

  FIG. 3 is a block diagram illustrating a schematic configuration of the image forming apparatus 1. The document reading unit 2, document feeding unit 3, transport unit (feed roller 41, transport roller 43, discharge roller 44), operation unit 5, recording unit 6, and paper feed unit 7 are connected to the control unit 8. The operation is controlled by the control unit 8. In addition, an image processing unit 9 and a storage unit 10 are connected to the control unit 8.

  The image processing unit 9 is means for performing predetermined image processing on the image data. For example, image improvement processing such as enlargement / reduction processing, gradation adjustment, and density adjustment is performed.

  The storage unit 10 is a storage unit such as a semiconductor memory or an HDD (Hard Disk Drive). The storage unit 10 stores image data acquired by reading a document by the document reading unit 2, and stores various management information. Yes.

  The control unit 8 is an information processing unit such as a microcomputer including a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The ROM stores a control program for controlling the operation of the image forming apparatus 1. The control unit 8 reads the control program stored in the ROM and develops the control program in the RAM, thereby controlling the entire apparatus according to predetermined instruction information input from the operation unit 5. The control unit 8 functions as a motor lock detection unit 81 that detects the lock of the lift motor 7b.

  The lift motor driving unit 7c that drives the lift motor 7b includes a motor current detection terminal ISEN that detects a motor current flowing through the lift motor 7b. Between the motor current detection terminal ISEN and the ground terminal, a resistor 11 that functions as a motor current detection unit that detects a motor current output from the motor current detection terminal ISEN as a motor voltage value is connected. The motor current output from the motor current detection terminal ISEN is converted into a voltage by the resistor 11 connected to the motor current detection terminal ISEN, and input to the non-inverting input terminal of the comparator 12 as a motor voltage value. A reference voltage V 1 is connected to the inverting input terminal of the comparator 12. As a result, the comparator 12 compares the motor voltage value with the reference voltage V 1, and the comparison result is input to the control unit 8. The motor voltage value converted into a voltage by the resistor 11 is converted into a digital value by an A / D converter (ADC) 13 and input to the control unit 8.

  The reference voltage V1 is a fixed lock threshold voltage set in advance to detect motor lock. The motor lock detection unit 81 detects motor lock when the motor voltage value exceeds the fixed lock threshold voltage (reference voltage V1) and the output of the comparator 12 becomes Hi level.

  In addition, referring to FIG. 4, the motor lock detection unit 81 reads the motor voltage value at the time t <b> 1 when the predetermined time TA has elapsed after the start of the lift motor 7 b as the initial motor voltage value. The motor lock detection unit 81 functions as a variable lock threshold setting unit, and a reference voltage V2 that is a value obtained by adding a preset amplitude ΔV to the initial motor voltage value is a variable lock for detecting motor lock. Set as threshold voltage. As shown in FIG. 4, the motor voltage value, that is, the motor current flowing through the lift motor 7 b rises due to an inrush current (temporary large current) that flows after starting, and then decreases and settles. The predetermined time TA until the initial motor voltage value is read after the lift motor 7b is started is set to be longer than the time when the motor voltage value settles without the influence of the inrush current. As a result, the motor voltage value at the steady state can be read as the initial motor voltage value.

  The motor lock detector 81 compares the input motor voltage value with the variable lock threshold voltage (reference voltage V2), and detects the motor lock when the motor voltage value exceeds the variable lock threshold voltage (reference voltage V2). To do.

  As the remaining amount of recording paper loaded on the lift plate 71 increases, the load (torque) increases, so the initial motor voltage value increases. Therefore, the variable lock threshold voltage (reference voltage V2) set by adding the fluctuation width ΔV to the initial motor voltage value also increases as the remaining amount of recording paper increases. 4A shows a change in motor voltage value when the remaining amount of recording paper is relatively small, and FIG. 4B shows a change in motor voltage value when the remaining amount of recording paper is relatively large. It is shown.

  As shown in FIG. 4A, when the remaining amount of recording paper is relatively small, the variable lock threshold voltage (reference voltage V2) is set lower than the fixed lock threshold voltage (reference voltage V1). Therefore, when the lift motor 7b is locked and the motor voltage value rises, the motor voltage value is variable-locked by the motor lock detection unit 81 earlier than the time t3 when the motor voltage value exceeds the fixed lock threshold voltage (reference voltage V1). Motor lock is detected at time t2 when the voltage exceeds the threshold voltage (reference voltage V2). That is, since the fixed lock threshold voltage (reference voltage V1) is a fixed value regardless of the remaining amount of recording paper, it takes time until the motor lock is detected when the initial motor voltage value is low. On the other hand, the variable lock threshold voltage (reference voltage V2) is a value that is set according to the initial motor voltage value that varies depending on the remaining amount of recording paper, and the motor lock is performed with a swing width ΔV from the initial motor voltage value. Since it can be detected, even when the initial motor voltage value is low, an abnormality can be detected promptly with respect to a sudden change in the lift motor 7b.

  As shown in FIG. 4B, when the remaining amount of recording paper is relatively large, the variable lock threshold voltage (reference voltage V2) is set higher than the fixed lock threshold voltage (reference voltage V1). Therefore, when the lift motor 7b is locked and the motor voltage value is increased, the motor voltage value is increased by the motor lock detection unit 81 before the motor voltage value exceeds the variable lock threshold voltage (reference voltage V2). A motor lock is detected at time t4 above the reference voltage V1). Thus, the motor lock probability can be reduced by detecting the motor lock twice with the fixed lock threshold voltage (reference voltage V1) and the variable lock threshold voltage (reference voltage V2).

  In order to set the variable lock threshold voltage (reference voltage V2), the amplitude ΔV added to the initial motor voltage value may be changed according to the initial motor voltage value. FIG. 5 shows an example in which ½ of the difference between the preset reference voltage V0 and the initial motor voltage value is set as the fluctuation width ΔV. In this case, the greater the initial motor voltage value, the smaller the swing width ΔV. Therefore, as the initial motor voltage value is larger, the motor lock is detected with a smaller fluctuation width ΔV.

As described above, the present embodiment sets the resistor 11 that functions as a motor current detection unit that detects the motor current flowing through the lift motor 7b, and the variable lock threshold (reference voltage V2) based on the motor current in a steady state. And a motor lock detector 81 that detects motor lock when the motor current exceeds the variable lock threshold (reference voltage V2).
With this configuration, the variable lock threshold (reference voltage V2) is set in accordance with the magnitude of the steady-state motor current. Therefore, even when the steady-state motor current is small, the rapid change of the lift motor 7b is promptly achieved. Motor lock can be detected.

Further, in the present embodiment, the steady-state motor current is the motor current detected at time t1 when the predetermined time TA has elapsed after the lift motor 7b is started and the influence of the inrush current disappears.
With this configuration, it is possible to accurately measure the steady-state motor current without being affected by the inrush current.

Further, in the present embodiment, the motor lock detection unit 81 sets the variable lock threshold (reference voltage V2) by adding the fluctuation width ΔV to the motor current in the steady state.
With this configuration, the variable lock threshold (reference voltage V2) can be set by a simple calculation.

Further, in the present embodiment, the motor lock detection unit 81 sets the variable lock threshold (reference voltage V2) by adding the smaller value of the amplitude ΔV to the steady-state motor current as the steady-state motor current increases. To do.
With this configuration, the motor lock can be detected more quickly as the motor current in the steady state increases.

Further, in the present embodiment, a fixed lock threshold value (reference voltage V1) is set in advance, and the motor lock detector 81 has a motor current exceeding either the variable lock threshold value or the fixed lock threshold value (reference voltage V1). And detect motor lock.
With this configuration, it is possible to reduce the motor breakage probability by detecting the motor lock twice with the fixed lock threshold voltage (reference voltage V1) and the variable lock threshold voltage (reference voltage V2).

  Note that the present invention is not limited to the above-described embodiments, and it is obvious that the embodiments can be appropriately changed within the scope of the technical idea of the present invention. In addition, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to a number, position, shape, and the like that are suitable for implementing the present invention. In each figure, the same numerals are given to the same component.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Original reading part 3 Original feeding part 4 Main body part 5 Operation part 6 Recording part 7 Paper feed part 7a Paper feed cassette 7b Lift motor 7c Lift motor drive part 8 Control part 9 Image processing part 10 Storage part 11 Resistance 21 Scanner 22 Platen Glass 23 Document Reading Slit 24 Light Source 25 Light Receiving Section 31 Document Placement Section 32 Document Discharge Section 33 Document Conveying Mechanism 41 Paper Feed Roller 42 Paper Conveyance Path 43 Conveyance Roller 44 Discharge Roller 45 Discharge Space 51 Liquid Crystal Display Section 52 Operation Button 61 Photosensitive drum 62 Charging unit 63 Exposure unit 64 Image forming unit 65 Transfer unit 66 Fixing unit 67 Cleaning unit 71 Lift plate 72 Push-up plate 81 Motor lock detection unit

Claims (5)

A motor current detector for detecting the motor current flowing through the motor;
A lock threshold value setting unit for setting a variable lock threshold value based on the motor current at a constant time;
A motor lock detection device comprising: a motor lock detection unit that detects motor lock when the motor current exceeds the variable lock threshold value.   2. The motor lock detecting device according to claim 1, wherein the motor current at a constant time is the motor current detected at a time when the influence of the inrush current disappears after a predetermined time elapses after the motor is started. .   3. The motor lock detection device according to claim 1, wherein the lock threshold value setting unit sets the variable lock threshold value by adding a fluctuation width to the motor current in a steady state. 4.   4. The lock threshold value setting unit sets the variable lock threshold value by adding a smaller value of the fluctuation width to the motor current in a steady state as the motor current in a steady state is larger. Motor lock detection device. A fixed lock threshold is preset,
5. The motor lock detection according to claim 1, wherein the motor lock detection unit detects a motor lock when the motor current exceeds either the variable lock threshold value or the fixed lock threshold value. 6. apparatus.

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