JP2016061641A - Position information output device and position information output method, and motor driving device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to use in common motors having a different number of motor pole pairs.SOLUTION: A position information output device acquires one signal in each of sections obtained by dividing one signal of three or more signals respectively output according to the rotation angles of motors from three or more Hall elements, at a timing at which the other two signals cross the one signal, from each of the three or more signals; compares the signal levels of the acquired signals with a plurality of threshold levels, and creates an encoding signals indicating the rotation position of the motors on the basis of a timing at which the signal levels sequentially cross over the plurality of threshold levels according to a result of the comparison; and selects, as the plurality of threshold levels, any one of the first number of threshold levels and the second number of threshold levels.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a position information output device, a position information output method, a motor drive device, and an image forming apparatus.

  Conventionally, there is a problem that it is desired to perform quantitative rotational driving while suppressing power consumption of a stepping motor. On the other hand, Patent Document 1 describes a motor driving device that realizes quantitative rotation driving of a roller with a DC motor with low power consumption.

  By the way, the motor drive device described in Patent Document 1 determines the drive stop timing of the DC motor based on the result of detecting the rotation amount of the roller by the optical encoder. As a result, there are issues with robustness to the environment, such as the occurrence of false detection due to dirt or dirt on the optical encoder code wheel, sensor dirt, etc., and the upper limit of the ambient ambient temperature being determined by the specifications of the encoder sensor. was there.

  Also, when using an optical encoder, the cost of the encoder sensor and code wheel and the assembly work cost account for a large proportion of the motor cost, and the size of the motor, particularly the length, is significant and hinders downsizing. It was a factor. For this reason, Patent Document 2 and Patent Document 3 propose a driving method in which an encoder signal is generated from an existing Hall element output and an optical encoder is not used.

  In these Patent Documents 2 and 3, a plurality of signals output from a plurality of Hall elements and having a phase different from each other are compared with a plurality of threshold levels to detect the phase, and the detected phase is determined based on the plurality of signals. Dividing into a plurality of phase sections based on the crossing points. Then, one signal is selected from a plurality of signals output from a plurality of Hall elements in a plurality of phase sections, and it is detected that the selected signal has reached a predetermined threshold level corresponding to a predetermined phase of the motor. The phase information signal is output.

  The resolution (number of pulses per rotation) in the generation of encoder pulses using the output signal of the Hall element is the number of motor magnet pole pairs (called the number of motor pole pairs) in the methods of Patent Document 2 and Patent Document 3 described above. ) And the number of slices (threshold level number). Therefore, if the number of motor pole pairs is different, the resolution is also different.

  Here, selection of the number of motor pole pairs is an important item in determining the motor specifications, and is comprehensively determined according to motor efficiency, cost, output, and the like. For motor integration, it is desirable to match the resolution, that is, the number of motor pole pairs, for a plurality of motors. However, the number of motor pole pairs differs depending on the motor manufacturer, for example, and there is a problem that motor integration is not easy.

  The present invention has been made in view of the above, and an object of the present invention is to make it possible to commonly use motors having different numbers of motor pole pairs.

  In order to solve the above-described problems and achieve the object, the present invention relates one signal among three or more signals output from three or more hall elements according to the rotation angle of the motor to the other two signals. An acquisition unit that acquires one signal in the section divided by the timing of crossing from each of three or more signals, a comparison unit that compares the signal level of the one signal acquired by the acquisition unit with a plurality of threshold levels, According to the comparison result of the comparison unit, a generation unit that generates an encode signal indicating the rotational position of the motor based on the timing at which the signal level sequentially crosses a plurality of threshold levels, and a first number of threshold levels as the plurality of threshold levels And a selection unit that selects any one of the second number of threshold levels.

  According to the present invention, there is an effect that motors having different numbers of motor pole pairs can be used in common.

FIG. 1 is a block diagram illustrating a configuration of an example of a motor drive device according to the first embodiment. FIG. 2 is a diagram illustrating an example of each signal according to the first embodiment. FIG. 3 is a diagram for explaining the phase detection process and the detection signal selection process according to the first embodiment. FIG. 4 is a diagram for explaining the phase detection processing according to the first embodiment. FIG. 5 is a diagram illustrating a configuration of an example of the motor driving unit according to the first embodiment. FIG. 6 is a block diagram illustrating a configuration of an example of a slice unit that switches the number of slices according to the first embodiment. FIG. 7 is a circuit diagram illustrating an example of a more detailed configuration of the slice unit according to the first embodiment. FIG. 8 is a diagram illustrating a configuration of an example of an MFP applicable to the second embodiment. FIG. 9 is a diagram illustrating a configuration of an example of an ADF that can be applied to the second embodiment.

  Exemplary embodiments of a position information output device, a position information output method, a motor drive device, and an image forming apparatus will be described below in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 shows an exemplary configuration of a motor drive device according to the first embodiment. In FIG. 1, a motor driving device 1 drives a DC brushless motor 100 (hereinafter, motor 100). The motor 100 is a motor having the number of motor pole pairs N, 2N poles (N = 1, 2,...), And according to the three-phase (U phase, V phase, and W phase) drive signals supplied from the motor drive unit 101. Driven by rotation.

The sensor unit 102 includes Hall elements 102U, 102V, and 102W attached to the motor 100 with an angle difference of 120 °. Hall elements 102U, 102V, and 102W output detection signals U ₁ , V _1, and W ₁ corresponding to the rotation angle of motor 100 with respect to each position, that is, the magnet pair (pole pair) of motor 100, respectively. The detection signals U ₁ , V ₁ and W ₁ are sinusoidal signals whose phases differ from each other by 120 °.

Each Hall element 102U, 102V, and 102W combines detection signals U ₁ , V _1, and W ₁ with two signals U + and U−, V + and V−, and W + and W− whose phases are mutually inverted. Output as. The detection signals U ₁ , V _1, and W ₁ output from the hall elements 102U, 102V, and 102W are amplified by the signal amplification unit 103 and supplied to the first phase detection unit 104 and the signal level adjustment unit 105, respectively. .

The first phase detector 104 detects the phases of the detection signals U ₁ , V ₁ and W ₁ . For example, the first phase detection unit 104 detects the first phase signals CMP_U, CMP_V, and CMP_W in which the high state (H) and the low state (L) are inverted at the phase 0 ° for each of the detection signals U ₁ , V _1, and W _1. Are output respectively. FIG. 2A shows an example of the first phase signals CMP_U, CMP_V, and CMP_W. The first phase signals CMP_U, CMP_V, and CMP_W are supplied to the arithmetic unit 120.

  The arithmetic unit 120 includes, for example, an MPU (Micro Processor Unit), operates in accordance with a clock signal CLK, and performs control such as rotation start and rotation stop of the motor 100 according to a signal COM supplied from the outside. Further, the calculation unit 120 is supplied with a signal POW indicating the power state of the device in which the motor driving device 1 is mounted.

The arithmetic unit 120 is supplied with a level signal AD ₁ indicating the levels of the detection signals U ₁ , V _1, and W ₁ by the Hall elements 102U, 102V, and 102W, which is output from the signal level detection unit 109 described later. Based on the level signal AD ₁ and the first phase signals CMP_U, CMP_V, and CMP_W supplied from the first phase detection unit 104, the calculation unit 120 indicates gains for the detection signals U ₁ , V _1, and W ₁ . Gain signals GA_U, GA_V and GA_W are output, respectively. The gain signals GA_U, GA_V, and GA_W are supplied to the signal level adjustment unit 105.

The signal level adjustment unit 105 adjusts the signal levels of the detection signals U ₁ , V _1, and W ₁ supplied from the signal amplification unit 103 in accordance with the gain signals GA_U, GA_V, and GA_W, and the level-adjusted detection signals Output as U ₂ , V ₂ and W ₂ . At this time, the signal level adjustment unit 105 outputs the detection signals U ₂ , V _2, and W ₂ as single-phase signals. The detection signals U ₂ , V _2, and W ₂ output from the signal level adjustment unit 105 are supplied to the signal selection unit 106, the detection signal selection unit 108, and the second phase detection unit 110, respectively.

In addition, the arithmetic unit 120 generates selection signals SEL ₁ and SEL ₂ based on the first phase signals CMP_U, CMP_V, and CMP_W supplied from the first phase detection unit 104. The selection signal SEL ₁ is a signal corresponding to the timing at which the H state and the L state of each of the first phase signals CMP_U, CMP_V, and CMP_W are switched, for example.

For example, the arithmetic unit 120 follows each first phase signal CMP_U shown in FIG. 2B according to the rising and falling edges of the first phase signals CMP_U, CMP_V, and CMP_W shown in FIG. A sensor phase signal is generated that divides one cycle of CMP_V and CMP_W into six-phase information. For example, the arithmetic unit 120 selects the detection signal U ₂ in the first and fourth phases from among the phase information of the six phases, selects the detection signal V ₂ in the second and fifth phases, and performs the third and sixth. The selection signal SEL ₁ is generated so that the detection signal W ₂ is selected in phase.

The detection signal selection unit 108 is supplied with the selection signal SEL ₁ from the calculation unit 120. The detection signal selection unit 108 selects _one of the supplied detection signals U ₂ , V _2, and W ₂ at the timing indicated by the selection signal SEL ₁ , for example, as indicated by a black circle in FIG. The signal level detection unit 109 is supplied. Note that FIG. 3 shows an example in which the phase differences of the first phase signals CMP_U, CMP_V, and CMP_W are different from those of FIG.

The signal level detection unit 109 detects the level of the supplied signal, and supplies the level signal AD ₁ indicating the detected signal level to the calculation unit 120. Here, as shown in FIG. 3, the signal supplied to the signal level detection unit 109 is a signal having an electrical angle of 60 ° or −60 ° of each detection signal U ₂ , V _2, and W ₂ . Therefore, the signal level detection unit 109 detects a value obtained by multiplying the level of the supplied signal by 1 / sin (60 °) ≈1.155 as the signal level of the supplied signal.

The second phase detector 110, as illustrated in FIGS. 4 (a) and 4 (b), based on the detection signal supplied U _2, V ₂ and W _2, respective detection signals U _2, V _Second phase signals UV, VW, and WU that switch between the H state and the L state at the timing when two signals of ₂ and W ₂ cross each other are generated. FIG. 4A shows the detection signals U ₂ , V ₂ and W ₂ . The detection signals U ₂ , V _2, and W ₂ are thus signals whose phases are shifted from each other by 120 °.

The second phase signals UV, VW and WU generated by the second phase detector 110 are, for example, from the H state at the timing when two of the detection signals U ₂ , V ₂ and W ₂ cross on the positive side. The state changes to the H state at the timing of crossing on the negative side. In the example of FIG. 4 (b), the second phase signal UV according to the detection signal U ₂ and V _2, at the timing when the detection signal U ₂ and V ₂ intersect at the positive side is switched from the H state to the L state, the negative side At the time of crossover at, the L state is switched to the H state. The same applies to the second phase signal VW related to the detection signals V ₂ and W ₂ and the second phase signal WU related to the detection signals W ₂ and U ₂ .

  The second phase signals UV, VW, and WU output from the second phase detection unit 110 are supplied to the synthesis unit 111 and the calculation unit 120, respectively.

The calculation unit 120 selects the signal selection unit 106 to select the detection signals U ₂ , V _2, and W ₂ based on the second phase signals UV, VW, and WU supplied from the second phase detection unit 110. A signal SEL ₂ is generated. For example, the calculation unit 120 detects a section in which two signals of the second phase signals UV, VW, and WU shown in FIG. 4B are in the H state and the L state, respectively. The computing unit 120 generates a selection signal SEL ₂ that selects any one of the detection signals U ₂ , V _2, and W ₂ in each section based on the detected H state and L state of each section.

More specifically, when the detected section is in the H state, the calculation unit 120 selects and detects a detection signal whose level increases in the section from the detection signals U ₂ , V _2, and W _2. When the selected section is in the L state, the selection signal SEL ₂ is selected so as to select the detection signal whose level decreases in the section. That is, as indicated by a thick line in FIG. 4C, the calculation unit 120 selects the detection signal W ₂ whose level decreases in the section in which the second phase signals VW and WU are in the L state, In the section in which the second phase signals UV and VW are in the H state, the detection signal V ₂ whose level increases in the section is selected, and in the next section in which the second phase signals UV and WU are in the L state, A selection signal SEL ₂ for selecting the detection signal U ₂ whose level decreases in the section is generated.

In other words, the selection signal SEL ₂ is one detection signal in a section in which one detection signal of the detection signals U ₂ , V _2, and W ₂ is divided at a timing at which the other two detection signals intersect. Is selected from each of the detection signals U ₂ , V ₂ and W ₂ . For example, the selection signal SEL ₂ is divided by the timing of crossing the detection signal U ₂ with the detection signal V ₂ and the timing of crossing the detection signal W ₂ , and the crossing point of the detection signal U ₂ and the detection signal V ₂ , It is generated so as to select the detection signal U ₂ in the section between the intersection point of the detection signal U ₂ and the detection signal W _2.

The signal selection unit 106 selects signals in the respective sections of the detection signals U ₂ , V _2, and W ₂ according to the selection signal SEL ₂ supplied from the calculation unit 120, and the signals in the selected sections are continuous. Signal X (see FIG. 4C). In this way, the signal selection unit 106 selects a signal in a substantially linear region in each of the sinusoidal detection signals U ₂ , V _2, and W ₂ to generate the signal X. The signal X is supplied to the slice unit 107.

  The slice unit 107 compares the level of the signal X supplied from the signal selection unit 106 with a plurality of threshold levels specified by the switching signal, as indicated by the horizontal arrow in FIG. Based on the comparison result, the slicing unit 107 generates a signal indicating the timing at which the level of the signal X crosses the threshold level as the phase information ph. The phase information ph is supplied to the combining unit 111. The operation in which the slice unit 107 compares the level of the signal X with a plurality of threshold levels is called a slice, and the number of levels divided by the plurality of threshold levels is called a slice number.

  The synthesizer 111 synthesizes the second phase signals UV, VW, and WU output from the second phase detector 110 and the phase information ph supplied from the slicer 107 to generate synthesized phase information. FIG. 4D shows an example of the combined phase signal generated by the combining unit 111. As shown in FIG. 4D, the composite phase signal is generated as a binary signal in which the H state and the L state are switched at the timing when the level of the signal X crosses the threshold level. The synthesized phase signal output from the synthesis unit 111 is shaped into a PWM (Pulse Width Modulation) signal by the motor controller 112 and supplied to the calculation unit 120 as an encode signal indicating the rotation position of the motor 100.

  Based on the PWM signal supplied from the motor control controller 112 and the first phase signals CMP_U, CMP_V, and CPM_W supplied from the first phase detection unit 104, the calculation unit 120 drives the motor 100 by the motor driving unit 101. Drive control signals UH, UL, VH, VL, WH and WL are generated.

  For example, the arithmetic unit 120 distributes the PWM signal supplied from the motor controller 112 to the three-phase drive control signals UH, VH, and WH based on the sensor phase signal shown in FIG. Further, the drive control signals UH, VH, and WH are shifted by ½ phase in the combined phase information, that is, ½ wave of the PWM signal, and further, the drive control signal forming the H state section (Low-ON). Generate UL, VL, and WL. FIG. 2C shows the drive control signals UH, UL, VH, VL, WH and WL generated in this way.

  The drive control signals UH, UL, VH, VL, WH and WL generated by the calculation unit 120 are supplied to the motor drive unit 101. The motor drive unit 101 generates U-phase, V-phase, and W-phase drive signals for driving the motor 100 based on the supplied drive control signals UH, UL, VH, VL, WH, and WL. Then, the motor 100 is driven to rotate.

  FIG. 5 shows an exemplary configuration of the motor drive unit 101. The motor drive unit 101 includes a pre-driver 1010 and a driver 1011 as shown in FIG. The pre-driver 1010 integrates the supplied drive control signals UH, UL, VH, VL, WH and WL, and outputs them to the driver 1011.

  Driver 1011 includes switches 1013UH, 1013UL, 1013VH, 1013VL, 1013WH and 1013WL whose open / close states are controlled by drive control signals UH, UL, VH, VL, WH and WL, respectively. In the example of FIG. 5, a driving power source 1012 for driving the motor is supplied to one end of each switch 1013UH, 1013VH, and 1013WH, and the other end of each switch 1013UH, 1013VH, and 1013WH is connected to one end of the switches 1013UL, 1013VL, and 1013WL. Is done. The other end of each switch 1013UL, 1013VL, and 1013WL is, for example, a ground voltage.

  A U-phase drive signal is output from the connection point of the switches 1013UH and 1013UL. Similarly, a V-phase drive signal is output from the connection point of the switches 1013VH and 1013VL, and a W-phase drive signal is output from the connection point of the switches 1013WH and 1013WL.

  Among the above-described configurations, for example, the first phase detection unit 104, the signal level adjustment unit 105, the signal selection unit 106, the slice unit 107, the detection signal selection unit 108, the signal level detection unit 109, The second phase detection unit 110, the synthesis unit 111, the motor control controller 112, and the calculation unit 120 can be configured on one integrated circuit.

Here, as the number of slices by the slicing unit 107 increases, the combined phase information included per unit time increases, and the resolution of the encoded signal increases. On the other hand, the detection signals U ₁ , V _1, and W ₁ of the hall elements 102U, 102V, and 102W have a shorter cycle as the number of motor pole pairs of the motor 100 increases. Therefore, by changing the number of slices according to the number of motor pole pairs of the motor 100 to be used, it is possible to match the resolution of the encode signal between the motors 100 having different numbers of motor pole pairs.

When one cycle (360 °) of each detection signal U ₁ , V ₁ and W ₁ is divided by the number of slices n every 30 °, the resolution P of the encoded signal, that is, the number of pulses in one cycle, is expressed by the following equation (1). Is represented by In Equation (1), the value N indicates the number of pole pairs of the motor 100.
P = (360/30) × n × N (1)

  According to Expression (1), when the number of motor pole pairs of the motor 100 is 6 and the number of slices of the slice unit 107 is 5, resolution P = 360 (pulses). On the other hand, when the number of motor pole pairs of the motor 100 is 5, by setting the number of slices of the slice unit 107 to 6, the resolution P of the encoder signal is P = 360. In this way, by switching the number of slices in the slicing unit 107 in accordance with the number of motor pole pairs of the motor 100, the final output pulse number of the encode signal can be made the same.

  As described above, the slice unit 107 according to the first embodiment can switch a plurality of threshold levels to be compared with the signal X using the switching signal. For example, the slicing unit 107 switches whether to perform slicing for the signal level of the signal X according to the first slice number or the second slice number according to the switching signal. As a result, the resolution of the encode signal can be made common to a plurality of motor pole pairs, and the motor 100 can be replaced without changing the drive system.

  FIG. 6 shows an example of the configuration of the slice unit 107 that can switch the number of slices according to the first embodiment. In FIG. 6, the slice unit 107 includes a first slice unit 107 a that slices with the first number of slices, a second slice unit 107 b that slices with the second number of slices, and the first slice units 107 a and 107 b. And a switch 1070 for selecting and switching according to a switching signal from the outside. The switching signal may be input from an external control device or the like, or may be input by a method in which two or more pins on the integrated circuit on which the slice unit 107 is mounted are short-circuited by a jumper line or the like. Good.

FIG. 7A shows an exemplary configuration of the first slice unit 107a having six slices. In FIG. 7 (a), first slice unit 107a, a potential difference between the voltage VL ₂ and VL ₁ which is predetermined, each divided by the resistors R ₆₁ to R ₆₇ is a predetermined resistance value, the resistance R ₆₁ retrieve the sixth threshold level from a connection point to R _67. The six threshold levels are input to the reference input terminals (−) of the comparators 200 ₆₁ to 2006 ₆₆ , respectively. The signal X is input in common to the comparison input terminals (+) of the comparators 200 ₆₁ to 2006 ₆₆ .

Each of the comparators 200 ₆₁ to 200 ₆₆ uses the signal level of the signal X input to the comparison input terminal (+) as the threshold level input to the reference input terminal (−) of each of the comparators 200 ₆₁ to 2006 _66. In comparison, the comparison results are output as phase information ph (1) to ph (6), respectively. For example, the phase information ph (1) to ph (6) falls from the H state to the L state when the signal X crosses each threshold level while decreasing, and crosses each threshold level while the signal X increases. In this case, the L state rises to the H state.

FIG. 7B shows an example of the configuration of the second slice unit 107b having five slices. The configuration and operation of the second slice unit 107b are substantially the same as the configuration and operation of the first slice unit 107a described above. In FIG. 7 (b), the second slice section 107b, as in the first slice portion 107a described above, a potential difference between the voltage VL ₂ and the voltage VL _1, resistor R ₅₁ each is a predetermined resistance value ~R divided by _56, takes out the threshold level of 5 from the connecting point of the resistors R ₅₁ to R _56. The five threshold levels are respectively input to the reference input terminals (−) of the comparators 200 ₅₁ to 200 ₅₅ and compared with the signal level of the signal X input in common to each comparison input terminal (+). The comparison results by the comparators 200 ₅₁ to 200 ₅₅ are output as phase information ph (1) to ph (5), respectively.

  In the above description, the slice unit 107 has been described as having two slice units having different numbers of slices, but this is not limited to this example. For example, the slice unit 107 may include three or more slice units having different numbers of slices.

(Second Embodiment)
Next, a second embodiment will be described. The second embodiment is an example in which the motor drive device 1 according to the first embodiment described above is applied to an MFP (Multi Function Printer). The MFP is a multi-function machine that can realize a plurality of functions such as a printer function, a scanner function, and a copy function in a single casing.

  The MFP has, for example, an image forming mechanism that forms an image on a sheet according to image data, and a scanner mechanism that reads an image from a document. The image forming mechanism and the scanner mechanism are used in combination or independently. As a result, the printer function, the scanner function, and the copy function described above are realized in a single casing. The MFP can further include a communication unit that performs data communication, and can further realize a FAX function by combining the printer function, the scanner function, and the copy function described above with the communication function of the communication unit.

  FIG. 8 shows an exemplary configuration of an MFP applicable to the second embodiment. In FIG. 8, an MFP 500 is configured as a copier that can use a printer function, a scanner function, and a copy function.

  In FIG. 8, the MFP 500 includes an image forming unit 30 as an image forming apparatus, a transfer paper supply device 40, and an image reading unit 50. The image reading unit 50 as an image reading apparatus has a scanner 150 fixed on the image forming unit 30 and an automatic document feeder (hereinafter referred to as ADF) 51 as a sheet conveying device supported by the scanner 150. ing.

  The transfer paper supply device 40 includes two transfer paper feed cassettes 42 arranged in multiple stages in the paper bank 41, a transfer paper feed roller 43 that feeds transfer paper from the transfer paper feed cassette 42, and a print medium that has been sent out. A transfer paper separating roller 45 that separates the transfer paper and supplies it to the transfer paper feed path 44. In addition, a plurality of conveyance rollers 46 that convey transfer paper (paper) are provided in a main body side transfer paper feed path 37 as a conveyance path of the image forming unit 30. The transfer paper supply device 40 feeds the transfer paper in the transfer paper feed cassette 42 into the main body side transfer paper feed path 37 in the image forming unit 30.

  The image forming unit 30 includes the optical writing device 2, four process units 3K, 3Y, 3M that form toner images of black (K), yellow (Y), magenta (M), and cyan (C). 3C, a transfer unit 24, a paper transport unit 28, a registration roller pair 33, a fixing device 34, a switchback device 36, and a main body side transfer paper feed path 37. The image forming unit 30 drives a light source such as a laser diode (not shown) disposed in the optical writing device 2 to irradiate the four drum-shaped photoconductors 4K, 4Y, 4M, and 4C with laser light. To do. By this laser light irradiation, electrostatic latent images are formed on the surfaces of the photoreceptors 4K, 4Y, 4M, and 4C, and the latent images are developed into toner images via a predetermined development process.

  A transfer unit 24 is disposed below the four process units 3K, 3Y, 3M, and 3C. The transfer unit 24 moves the intermediate transfer belt 25 stretched by a plurality of rollers endlessly in the clockwise direction in the drawing while contacting the photoreceptors 4K, 4Y, 4M, and 4C. As a result, primary transfer nips for the respective colors K, Y, M, and C are formed in which the photoreceptors 4K, 4Y, 4M, and 4C contact the intermediate transfer belt 25.

  In the vicinity of the primary transfer nips for the colors K, Y, M, and C, the intermediate transfer belt 25 is pressed toward the photoreceptors 4K, 4Y, 4M, and 4C by the primary transfer rollers that are arranged inside the belt loop. doing. A primary transfer bias is applied to each primary transfer roller by a power source (not shown). As a result, a primary transfer electric field for electrostatically moving the toner images on the photoconductors 4K, 4Y, 4M, and 4C toward the intermediate transfer belt 25 is formed in the primary transfer nips for the colors K, Y, M, and C. The With the endless movement in the clockwise direction in the figure, toner images are sequentially formed at the primary transfer nips on the front side of the intermediate transfer belt 25 that sequentially passes through the primary transfer nips for K, Y, M, and C colors. Overlaid and primary transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as a four-color toner image) is formed on the front side surface of the intermediate transfer belt 25.

  Below the transfer unit 24 in the figure, there is provided a paper transport unit 28 that moves an endless paper transport belt between the driving roller and the secondary transfer roller so as to move endlessly. Then, the intermediate transfer belt 25 and the paper transport belt are sandwiched between the secondary transfer roller of itself and the lower stretching roller of the transfer unit 24. As a result, a secondary transfer nip is formed in which the front side surface of the intermediate transfer belt 25 and the front side surface of the paper transport belt come into contact with each other. A secondary transfer bias is applied to the secondary transfer roller by a power source. On the other hand, the lower stretching roller of the transfer unit 24 is grounded. Thereby, a secondary transfer electric field is formed in the secondary transfer nip.

  A registration roller pair 33 is disposed on the right side of the secondary transfer nip in the drawing. A registration roller sensor (not shown) is disposed near the entrance of the registration nip of the registration roller pair 33. The transfer paper transported from the transfer paper supply device 40 toward the registration roller pair 33 is temporarily stopped after a predetermined time when the leading edge of the transfer paper is detected by the registration roller sensor, and the leading edge is placed in the registration nip of the registration roller pair 33. Strike. As a result, the posture of the transfer paper is corrected, and preparations for synchronization with image formation are completed.

  When the leading edge of the transfer paper hits the registration nip, the registration roller pair 33 resumes roller rotation at a timing at which the transfer paper can be synchronized with the four-color toner image on the intermediate transfer belt 25, and the transfer paper is subjected to secondary transfer. Send to nip. In the secondary transfer nip, the four-color toner images on the intermediate transfer belt 25 are collectively transferred to the transfer paper under the influence of the secondary transfer electric field and the nip pressure, and become a full-color image combined with the white color of the transfer paper. The transfer paper that has passed through the secondary transfer nip is separated from the intermediate transfer belt 25 and conveyed to the fixing device 34 along with its endless movement while being held on the front side of the paper conveyance belt.

  The transfer residual toner that has not been transferred to the transfer paper at the secondary transfer nip is attached to the front side surface of the intermediate transfer belt 25 that has passed through the secondary transfer nip. This transfer residual toner is scraped off and removed by a belt cleaning device in which the cleaning member contacts the intermediate transfer belt 25.

  The transfer paper conveyed to the fixing device 34 is fed with a full-color image by pressurization and heating in the fixing device 34, and then sent from the fixing device 34 to a pair of paper discharge rollers 35. It is discharged to 501.

  Below the paper transport unit 28 and the fixing device 34, a switchback device 36 which is a transfer paper reversing device is disposed. As a result, when performing double-sided printing, the transfer path of the transfer paper that has undergone image fixing processing on one side is switched to the switchback device 36 side by the switching claw, is reversed there, and enters the secondary transfer nip again. . Then, after the secondary transfer process and the fixing process of the image are performed on the other side, the sheet is discharged onto the discharge tray 501.

  The image reading unit 50 including the scanner 150 fixed on the image forming unit 30 and the ADF 51 fixed on the image forming unit 30 includes a fixed reading unit and a moving reading unit 152. The movable reading unit 152 is disposed immediately below the second contact glass 155 fixed to the upper wall of the casing of the scanner 150 so as to come into contact with the document MS, and an optical system including a light source, a reflection mirror, and the like is illustrated. It can be moved in the left-right direction. Then, in the process of moving the optical system from the left side to the right side in the figure, after the light emitted from the light source is reflected by the lower surface of the document MS (not shown) placed on the second contact glass 155, a plurality of reflections are made. Light is received by the image reading sensor 153 fixed to the scanner 150 via the mirror.

  On the other hand, the image reading unit 50 includes, as fixed reading units, a first fixed reading unit 151 disposed in the scanner 150 and a second fixed reading unit described later disposed in the ADF 51. The first fixed reading unit 151 includes a light source, a reflection mirror, and an image reading sensor using a CCD (Charge Coupled Device), and is fixed to the upper wall of the casing of the scanner 150 so as to contact the document MS. It is disposed immediately below the contact glass 154. The first fixed reading unit 151 includes a plurality of reflecting mirrors while sequentially reflecting light emitted from the light source on the first surface of the document MS when the document MS conveyed by the ADF 51 passes over the first contact glass 154. Is received by the image reading sensor 153. Thus, the first surface of the document MS is scanned without moving the optical system including the light source and the reflection mirror. The second fixed reading unit scans the second surface of the document MS after passing through the first fixed reading unit 151.

  The ADF 51 disposed on the scanner 150 includes, on the main body cover 52, a document placing table 53 for placing the document MS before reading, a document transporting unit 54 for transporting the document MS, and a post-reading document. A document stacking base 55 for stacking the documents MS is held. The main body cover 52 is supported by a hinge fixed to the scanner 150 so as to be opened and closed in the vertical direction. The main body cover 52 exposes the first contact glass 154 and the second contact glass 155 on the upper surface of the scanner 150 in an opened state.

  When a document is a single-bound document in which one corner of a bundle of documents is bound, such as a book that has been bound, the documents cannot be separated one by one and cannot be conveyed by the ADF 51. Therefore, in the case of a single-sided original, after the ADF 51 is opened, the single-sided original on which the page to be read is opened is placed face down on the second contact glass 155, and then the ADF 51 is closed. Then, the moving reading unit 152 of the scanner 150 reads the image of the page.

  On the other hand, in the case of a bundle of documents obtained by simply stacking a plurality of documents MS independent of each other, the documents MS are separated and conveyed one by one by the ADF 51, while the first fixed reading unit 151 in the scanner 150 or the second fixed document in the ADF 51. The fixed reading unit can sequentially read. In this case, after the document bundle is set on the document placement table 53, the ADF 51 separates the document MS of the document bundle placed on the document placement table 53 in order from the top in response to an operation start operation by the user. The originals MS are fed one by one into the original conveying section 54 and conveyed toward the original stacking stage 55 while being reversed. In the course of this conveyance, the document MS is passed immediately above the first fixed reading unit 151 of the scanner 150 immediately after being inverted. At this time, the image on the first surface of the document MS is read by the first fixed reading unit 151 of the scanner 150.

  In the above description, the print medium on which the image forming unit 30 forms an image is a paper medium. However, this is not limited to this example. That is, the print medium on which the image forming unit 30 forms an image is not limited to a paper medium, and may be another medium such as a film.

  FIG. 9 shows an exemplary configuration of an ADF 51 applicable to the second embodiment in more detail along with the upper part of the scanner 150. The ADF 51 includes a document setting unit A, a separation conveyance unit B, a registration unit C, a turn unit D, a first reading conveyance unit E, a second reading conveyance unit F, a paper discharge unit G, and a stack unit H. With.

  The document setting section A has a document placement table 53 on which a bundle of documents MS is set so that the first surface is upward. The separation conveyance unit B separates and feeds the originals MS one by one from the set of originals MS set.

  The registration unit C temporarily abuts on the fed document MS and aligns the document MS to send it out. The turn portion D has a curved conveyance portion that is curved in a C-shape, and the document MS is turned upside down in the curved conveyance portion, and the first surface of the original MS is directed downward. The first reading / conveying unit E conveys the document MS on the first contact glass 154 while the document MS is transferred from the lower side of the first contact glass 154 to the first fixed reading unit 151 disposed in the scanner 150. Read the first side.

  The second reading conveyance unit F causes the second fixed reading unit 95 to read the second surface of the document MS while conveying the document MS by the second reading roller 96 disposed below the second fixed reading unit 95. Further, the paper discharge unit G discharges the original MS from which both-side images are read toward the stack unit H. The stack unit H stacks the document MS on the document stacking table 55.

  A document MS to be read includes a movable document table 53b that supports the document leading end portion and can swing in the directions of arrows a and b in the drawing according to the thickness of the bundle of documents MS, and a fixed document table that supports the document rear end side. 53a is set on the document placing table 53 composed of 53a with the first surface facing upward. At this time, positioning in the width direction is performed by abutting side guides (not shown) on the document placing table 53 against both ends in the width direction, that is, in the direction orthogonal to the conveyance direction of the document MS.

  The document MS set on the document table 53 in this manner pushes up the set filler 62 that is a lever member that is swingably disposed above the movable document table 53b. Accordingly, the document set sensor 63 detects the setting of the document MS, and a detection signal is transmitted to a controller (not shown) and is transmitted from the controller to a main body control unit (not shown).

  The fixed document table 53a includes a plurality of document length sensors 57, 58a, and 58b, each of which includes a reflective photosensor that detects the length of the document MS in the conveyance direction or an actuator type sensor that can detect even one document. Is arranged. By these document length sensors, an outline of the length of the document MS in the conveyance direction is determined.

  A pickup roller 80 is disposed above the movable document table 53b. The movable document table 53b is swung in the directions of arrows a and b in the figure by a cam mechanism to be driven by driving a bottom plate raising motor (not shown). When the set filler 62 or the document set sensor 63 detects that the document MS is set on the document table 53, the controller rotates the bottom plate raising motor in a normal direction so that the top surface of the bundled document MS contacts the pickup roller 80. Then, the movable document table 53b is raised.

  The pickup roller 80 is movable in the directions of arrows c and d in the figure by a cam mechanism that is driven by a pickup lifting / lowering motor (not shown). Further, the pick-up roller 80 moves up in the direction of arrow c in the figure when the movable document table 53b is raised and pushed by the upper surface of the document MS on the movable document table 53b. By detecting this by the table lift sensor 59, the lift to the upper limit of the movable document table 53b is detected. As a result, the pickup raising / lowering motor stops and the bottom plate raising motor (not shown) stops.

  The pickup conveyance motor is driven in response to the operation start operation by the user, and the pickup roller 80 is rotationally driven to pick up one or several originals MS on the original placement table 53. The rotation direction of the pickup roller 80 is a direction in which the uppermost document MS is conveyed to the paper feed port 48.

  The document MS sent out by the pickup roller 80 enters the separation conveyance unit B and is sent to a contact position with the paper feed belt 84. The paper feed belt 84 is stretched around a drive roller 82 and a driven roller 83, and is endlessly moved in the clockwise direction in the drawing by the rotation of the drive roller 82 accompanying the forward rotation of the paper feed motor.

  A reverse roller 85 that is driven to rotate in the clockwise direction in the drawing by the forward rotation of the paper feed motor is in contact with the lower tension surface of the paper feed belt 84. At the contact portion of the reverse roller 85, the surface of the paper feed belt 84 moves in the paper feed direction. In contrast, the surface of the reverse roller 85 tends to move in the direction opposite to the paper feeding direction. On the other hand, a torque limiter (not shown) is provided in the drive transmission portion of the reverse roller 85, and the reverse roller 85 moves on the surface in the paper feed direction when the force in the paper feed direction is larger than the torque of the torque limiter. Rotate like so.

  The reverse roller 85 is in contact with the paper feeding belt 84 at a predetermined pressure, and when the reverse roller 85 is in direct contact with the paper feeding belt 84 or when only one document MS is sandwiched in the contact portion, Along with the paper feed belt 84 or the document MS. However, when a plurality of documents MS are sandwiched between the contact portions, the rotation force is set to be lower than the torque of the torque limiter. To rotate. As a result, a moving force in the direction opposite to the feeding direction is applied to the original document MS below the uppermost position by the reverse roller 85, and only the uppermost original document MS is separated from several originals. Thereby, double feeding is prevented.

  The original MS separated into one sheet by the action of the paper feed belt 84 and the reverse roller 85 enters the registration portion C. Then, the paper is further fed by the paper feed belt 84, and the front end is detected by the abutting sensor 72, and further abuts against the pull-out roller pair 86 that has stopped. Thereafter, the paper feed motor is driven for a predetermined time from the detection of the tip by the abutting sensor 72 and stopped. As a result, the document MS is fed by a predetermined distance from the position detected by the abutting sensor 72. As a result, the document MS is fed in a state where the document MS is pressed against the pull-out roller pair 86 with a predetermined amount of bending. The conveyance of the document MS by the belt 84 is stopped.

  When the leading edge of the document MS is detected by the abutting sensor 72, the pickup roller 80 is retracted from the upper surface of the document MS by rotating the pickup raising / lowering motor, and the document MS is sent only by the conveying force of the paper feed belt 84. As a result, the leading edge of the document MS enters the nip formed by the upper and lower rollers of the pull-out roller pair 86, and leading edge alignment (skew correction) is performed.

  The document MS sent out by the pull-out roller pair 86 passes directly under the document width sensor 73. The document width sensor 73 is a sensor in which a plurality of paper detection sensors such as reflective photosensors are arranged in the document width direction (direction orthogonal to the conveyance direction), and is based on which paper detection sensor detects the document MS. Thus, the size of the document MS in the width direction is detected. The length of the document MS in the conveyance direction is from when the leading edge of the document MS is detected by the abutting sensor 72 to when the document MS is not detected by the abutting sensor 72 (the trailing edge of the document MS passes). Detect from motor pulse based on timing.

  The document MS conveyed by the drive of the pull-out roller pair 86 and the intermediate roller pair 66 enters the turn part D conveyed by the intermediate roller pair 66 and the reading entrance roller pair 90. The intermediate roller pair 66 is configured such that the drive is transmitted from both the pull-out motor that is the drive source of the pull-out roller pair 86 and the reading inlet motor that is the driving source of the reading inlet roller pair 90. A mechanism is provided in which the rotational speed is determined by driving the motor on the side of the two motors whose rotational speed is faster.

  In the image reading unit 50, when the document MS is conveyed from the registration unit C to the turn unit D by the rotational driving of the pull-out roller pair 86 and the intermediate roller pair 66, the conveyance speed at the registration unit C is set to the first reading conveyance unit. The speed is set to be higher than the transport speed at E, and the processing time for feeding the original MS to the first reading transport section E is shortened. At this time, the intermediate roller pair 66 rotates using a pull-out motor as a drive source.

  When the leading edge of the document MS is detected by the reading entrance sensor 67, the transportation speed of the document MS is set to the first scanning transportation before the leading edge of the document MS enters the nip formed by the upper and lower rollers of the pair of scanning entrance rollers 90. In order to make it the same speed as the conveyance speed in the part E, the pull-out motor starts to be decelerated. At the same time, the reading inlet motor and the reading motor are driven forward. By driving the reading inlet motor in the forward direction, the reading inlet roller pair 90 is rotationally driven in the conveying direction, and by driving the reading motor in the forward direction, the reading outlet roller pair 92 and the second reading outlet roller pair 93 are respectively moved in the conveying direction. To drive.

  When the registration sensor 65 detects the leading edge of the document MS from the turn portion D toward the first reading and conveying portion E, the controller decelerates the driving of each motor over a predetermined time, thereby setting the conveyance speed of the document MS to a predetermined value. Decelerate over the transfer distance. Then, the controller controls the document MS to be temporarily stopped before the first reading position 400 by the first fixed reading unit 151, and transmits a registration stop signal to the main body control unit.

  Subsequently, when the controller receives a reading start signal from the main body control unit, the conveying speed of the document MS is set to a predetermined conveying speed until the leading edge of the document MS that has been registered stops reaching the first reading position 400. The driving of the reading inlet motor and the reading motor is controlled so as to rise. As a result, the document MS is transported toward the first reading position 400 while the transport speed is increased. Then, at the timing when the leading edge of the document MS calculated based on the pulse count of the reading entrance motor reaches the first reading position 400, the controller controls the main body control unit in the sub-scanning direction of the first surface of the document MS. A gate signal indicating the image area is transmitted. This transmission is continued until the trailing edge of the document MS exits the first reading position 400, and the first surface of the document MS is read by the first fixed reading unit 151.

  The document MS that has passed through the first reading / conveying section E passes through the nip of the reading exit roller pair 92, and then the leading edge thereof is detected by the paper discharge sensor 61, and then passes through the second reading / conveying section F. It is conveyed to the paper discharge unit G.

  When reading only one side (first side) of the document MS, the second fixed reading unit 95 does not need to read the second side of the document MS. Therefore, when the leading edge of the document is detected by the paper discharge sensor 61, the forward drive of the paper discharge motor is started, and the upper paper discharge roller in the drawing roller pair 94 rotates counterclockwise in the drawing. Driven. The timing at which the trailing end of the document MS exits the nip of the sheet discharge roller pair 94 is calculated based on the pulse count of the sheet discharge motor after the leading edge of the document MS is detected by the sheet discharge sensor 61. Based on this calculation result, the drive speed of the discharge motor is decelerated at the timing immediately before the trailing edge of the document MS comes out of the nip of the discharge roller pair 94, and the document MS jumps out of the document stack table 55. Control is performed so that the paper is discharged at such a speed as not to occur.

  On the other hand, when both sides (first side and second side) of the document MS are read, the timing until the second fixed reading unit 95 is reached after the leading edge of the document MS is detected by the paper discharge sensor 61 is read. Calculation is performed based on the pulse count of the motor. At that timing, a gate signal indicating an effective image area in the sub-scanning direction on the second surface of the document MS is transmitted from the controller to the main body control unit. This transmission is continued until the rear end of the document MS exits the second reading position by the second fixed reading unit 95, and the second surface of the document MS is read by the second fixed reading unit 95.

  The second fixed reading unit 95 includes, for example, a close contact image sensor (CIS), and is provided on the reading surface for the purpose of preventing vertical reading streaks due to adhesive-like foreign matter adhering to the document MS adhering to the reading surface. A coating process is applied. Further, a second reading roller as a document supporting means for supporting the document MS from the non-reading surface side (first surface side) is located at a position facing the second fixed reading unit 95 across the conveyance path through which the document MS passes. 96 is arranged. The second reading roller 96 serves to suppress the floating of the document MS at the second reading position by the second fixed reading unit 95 and to function as a reference white portion for acquiring shading data in the second fixed reading unit 95. Is responsible.

  Here, the motor drive device 1 described in the first embodiment may be applied to drive any motor used in the MFP 500 and the ADF 51. For example, the motor drive device 1 can be applied to the motor for driving the drive roller 82 described above or the motor for driving the pull-out roller pair 86.

  Each of the above-described embodiments is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Motor drive device 100 DC brushless motor 101 Motor drive part 102 Sensor part 102U, 102V, 102W Hall element 103 Signal amplification part 104 First phase detection part 105 Signal level adjustment part 106 Signal selection part 107 Slice part 108 Detection signal selection part 109 Signal level detection unit 110 Second phase detection unit 111 Combining unit 112 Motor controller 120 Calculation unit

JP 2012-213308 A JP 2013-099022 A JP 2013-099023 A

Claims (6)

The one signal in a section obtained by dividing one signal out of three or more signals output from three or more Hall elements according to the rotation angle of the motor at a timing at which the other two signals cross each other is An acquisition unit that acquires from each of the above signals;
A comparison unit that compares the signal level of the one signal acquired by the acquisition unit with a plurality of threshold levels;
According to the comparison result of the comparison unit, a generation unit that generates an encode signal indicating a rotational position of the motor based on a timing at which the signal level crosses the plurality of threshold levels;
A position information output device comprising: a selection unit that selects one of a first number of threshold levels and a second number of threshold levels as the plurality of threshold levels. The acquisition unit, the comparison unit, the generation unit, and the selection unit are formed on the same integrated circuit,
The selection unit includes:
2. The method according to claim 1, wherein either one of the first number of threshold levels and the second number of threshold levels is selected in response to an input using at least two pins of the integrated circuit. The position information output device described. The first number and the second number are:
When the first number of threshold levels is selected for the third number of motor pole pairs, and the second number of motor pole pairs is the fourth number of motors. The position information output device according to claim 1 or 2, wherein the number of resolutions of the encoded signals is the same when the threshold level is selected. The one signal in a section obtained by dividing one signal out of three or more signals output from three or more Hall elements according to the rotation angle of the motor at a timing at which the other two signals cross each other is An acquisition step of acquiring from each of the above signals;
A comparison step of comparing the signal level of the one signal acquired by the acquisition step with a plurality of threshold levels;
In accordance with the comparison result in the comparison step, a generation step for generating an encode signal indicating a rotational position of the motor based on a timing at which the signal level crosses the plurality of threshold levels;
A position information output method comprising: a selection step of selecting any one of a first number of threshold levels and a second number of threshold levels as the plurality of threshold levels. The position information output device according to any one of claims 1 to 3,
A motor drive device comprising: a drive unit that drives the motor based on the encode signal. A motor driving device according to claim 5;
A transport unit that is driven by the motor to transport the print medium;
An image forming apparatus comprising: an image forming unit that forms an image on the print medium transported by the transport unit according to image data.

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