JP4060133B2 - Pulse encoder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulse encoder used for a rotary encoder that detects the number of rotations and a rotation angle of a rotating body.
[0002]
[Prior art]
Conventionally, a rotary encoder that detects the number of rotations and the rotation angle of a rotary drive unit has been used in devices that control the position of a door by detecting the position of an electric open / close slide door of an automobile or adjust the angle of a door mirror. It has been. In such a rotary encoder, a non-contact type sensor such as an optical type or a magnetic type that generates a pulse at every predetermined rotation angle of a rotating body is used. This kind of non-contact type sensor usually needs to be supplied with a backup battery in order to maintain a standby state when the main power supply is turned off, but the current consumption (dark current) at that time is large. Therefore, various proposals have been made to reduce the current consumption of the backup battery and improve the battery life.
[0003]
For example, in Japanese Patent Laid-Open No. 5-79853, when the main power supply of the entire circuit is turned off, a light-emitting element with large power consumption is energized only when the rotating disk is near the origin position, and the power consumption is reduced. A technique for continuously energizing a battery power source is disclosed for an electric circuit for counting the number of revolutions including a small number of magnetoresistive detection elements and counter circuits. This extends the life of the backup battery without consuming a large amount of current consumption during the backup operation with the battery after the power is stopped.
[0004]
In Japanese Patent Laid-Open No. 7-35574, the power source of the A / B phase magnetoresistive effect element is a power source circuit using a diode that switches between two systems of an external power source and a battery, and the Z phase magnetoresistive effect A configuration is disclosed in which a power supply circuit that supplies power from only an external power supply is used. In this case, in the case of battery driving at the time of a power failure, power is supplied only to the A / B phase magnetoresistive effect element, so the current consumption of the backup battery is reduced.
[0005]
Further, in the rotary encoder disclosed in Japanese Patent Application Laid-Open No. 10-73458, when the main power is turned on, power is supplied from the main power to the entire circuit, the light emitter, the single rotation detection element, and the multiple rotation detection element. When the main power supply is turned off due to a power failure or the like, power is supplied from the backup battery to the multi-rotation detection element and the multi-rotation data detection circuit of the light emitter control circuit, the light emitter, and the light receiver. . This reduces the current consumption when the main power is off, and extends the life of the backup battery.
[0006]
[Problems to be solved by the invention]
However, in such a conventional example, the power source is supplied from the backup power source battery to only a specific circuit or element in the event of a power failure or the main power source is turned off to reduce current consumption, but the rotating body stops. Even when no detection pulse is generated (when the pulse is stopped), power is continuously supplied to a specific circuit or element. That is, in a pulse encoder using a non-contact type sensor, even if power is supplied only to a specific circuit or element from a backup battery, the current consumption is as large as several mA to several tens of mA, which is similar to an automobile. In the apparatus using a battery, there exists a problem that a battery runs out.
[0007]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a pulse encoder that can greatly reduce the dark current of a non-contact sensor when a rotating body is stopped. It is said. Furthermore, a second technical problem of the present invention is to provide a pulse encoder capable of simultaneously detecting a rough rotational state as well as an accurate rotational state of a rotating body.
[0008]
[Means for Solving the Problems]
A pulse encoder according to the present invention (Claim 1) includes a first rotating body and an annular magnet that rotates in synchronization with the first rotating body and is alternately magnetized with N and S poles. A second rotating body, a non-contact type sensor that generates a pulse every rotation of the first rotating body at a certain angle, and a detecting means for detecting a rotating state / stopped state of the second rotating body. , Interposed between the power source and the sensor, the power supply from the power source to the sensor is cut off when the detecting means detects the stop state of the second rotating body, and the power source is supplied when the rotating state is detected. A switching element that holds the output of the sensor when the rotating body is stopped, and the detecting means is provided adjacent to the second rotating body, Lee which turns on / off every rotation of a certain angle of the rotating body of 2 It is characterized in that it comprises a switch.
[0009]
It said latch means, to configure a latch circuit consisting of CMOS devices good preferable (claim 2).
[0011]
In such a pulse encoder, the non-contact type sensor is provided with a Hall element, which the first rotating body also serves as the second rotating member is preferably (claim 3).
[0012]
[Operation and effect of the invention]
In the pulse encoder of the present invention (Claim 1), while the rotating body is rotating, the detecting means detects the rotation, and the switch element is activated to supply power from the power source to the sensor. Therefore, power is supplied to the non-contact type sensor to start operation, and pulses are generated or output as the rotating body rotates. When the rotation of the rotating body is stopped, the detecting means detects the stop of the rotation, and the switch element cuts off the power supply to the sensor.
[0013]
When the rotating body starts rotating from the stopped state, the detecting means detects the rotation, the switch element starts supplying power from the power source to the sensor, and the sensor starts to generate pulses again. As described above, in the pulse encoder of the present invention, the power supply to the sensor is performed only when necessary, that is, when the rotating body is rotating, so that the dark current of the sensor is almost unnecessary. Therefore, power consumption can be greatly reduced.
[0014]
Further, when the rotating body stops, it further includes a latch means for holding the output of the sensor at that time, so even if the power to the sensor is interrupted when the rotating body is stopped, Holds the sensor output at the moment. Therefore, a normal output signal of the sensor can be maintained, and erroneous pulse generation due to an unstable operation of the sensor can be prevented.
Further, the non-contact sensor accurately generates a pulse as the first rotating body rotates. As a result, the rotation of the rotating body and the generation of pulses correspond accurately, and the rotating state of the rotating body, that is, the rotation speed and the rotation angle can be accurately detected. On the other hand, when the second rotating body rotates, the reed switch is turned on / off every time the magnetic pole of the magnet facing the reed switch changes. Therefore, it is possible to detect the rough rotation state of the second rotating body, for example, whether it is rotating or stopped, with the ON / OFF contact signal. Also, the rotation direction can be detected together with the non-contact sensor. Furthermore, since the reed switch does not require dark current to operate, power can be saved.
[0015]
When the latch means is constituted by a latch circuit made of a CMOS device (claim 2 ), the consumption current of the latch means for holding the sensor output can be greatly reduced. Therefore, the current consumption can be further reduced in combination with the configuration in which the power is supplied to the sensor only when necessary.
[0017]
When the non-contact sensor includes a Hall element, the first rotating body can also serve as the second rotating body (Claim 3 ). The magnets of the rotating body that are alternately magnetized act on both the operation of the Hall element and the operation of the reed switch. As a result, the number of parts can be reduced, and the cooperation between the two operations is reliable.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall circuit diagram showing an embodiment of a pulse encoder of the present invention, FIGS. 2a and 2b are diagrams for explaining the operation of the pulse encoder of FIG. 1, and FIG. 3 is an embodiment of an activation circuit according to the present invention. FIG. 4 is a circuit diagram showing an embodiment of a latch circuit according to the present invention.
[0019]
The pulse encoder 10 shown in FIG. 1 detects the number of rotations and rotation angle of a rotating body (drum itself, gear, etc.) interlocked with, for example, a drive cable drum of an electric sliding door of an automobile, and based on the output. It is used to detect the position of the door and control the rotational speed, on / off, etc. of a motor (not shown). Further, when the sliding door is opened and closed by manual operation, it is also used for detecting the movement and automatically switching to automatic opening and closing. However, it can be used for all systems to which the pulse encoder can be applied, such as control of door mirror opening / closing motors, control of window regulator motors for window regulators, control of sunroof window opening / closing motors.
[0020]
Power to the entire circuit of the pulse encoder 10 is supplied from, for example, a battery 11 of an automobile, and a magnet 13 is connected to the rotating body 12 so as to rotate in synchronization. The magnet 13 is obtained by alternately magnetizing N poles and S poles in the circumferential direction. In this embodiment, two N poles and two S poles are alternately provided for simplicity. A Hall element (Hall IC) 14 that constitutes a non-contact sensor together with the magnet 13 is provided. Thereby, the magnet 13 is also rotated by the rotation of the rotating body 12, and a pulse is output from the output terminal of the Hall element 14 every ¼ rotation of the magnet 13.
[0021]
The power to the Hall element 14 is supplied through a control transistor Tr that is turned on / off by a shutdown signal from the start circuit 15. Adjacent to the magnet 13, a reed switch 16 is provided which is turned on when the boundary of the SN pole comes to the contact point and turned off otherwise. Then, the contact signal of the reed switch 16 is supplied to the starting circuit, and the starting signal is generated in the starting circuit by a pulse signal when the boundary of the SN pole comes to the contact and turns on. Note that a transfer type reed switch may be used, and in that case, it may be connected to a normally open lead that is always on and is turned off when the boundary of the SN pole reaches the contact.
[0022]
For the purpose of detecting both on and off, as shown by reference numerals 21 and 22 in FIG. 3, two 74 series CMOS devices, for example, 74HC123, each having an inverted polarity, may be mounted.
[0023]
Furthermore, in this embodiment, a function of an off timer is provided that turns off the transistor Tr when the reed switch is not switched on / off within a certain time and no pulse is input to the starter circuit 15. That is, referring to FIG. 3, the off-timer is increased when a predetermined time elapses without a pulse being input to start circuit 15. Then, the Q bar output becomes H, and the transistor Tr is turned off. This will cause a shutdown. When a pulse due to ON / OFF of the reed switch is generated during shutdown and input to the start circuit 15, the timer is reset and the Q bar output becomes L, the transistor Tr in FIG. Supplied. After that, if there are pulse inputs one after another within a certain time (during timer operation), the power continues to be supplied, but if there is no pulse input within a certain time, it is shut down.
[0024]
The output pulse from the Hall element 14 is input to the D input terminal of a latch circuit 17 that latches the output pulse. An inversion signal from the start circuit 15 through the inverter gate G is input to the enable terminal EN. When the enable terminal EN is at the H level, when a pulse is input from the D input terminal of the latch circuit 17, the output terminal A pulse signal is output from Q. A pulse signal from the output terminal Q of the latch circuit 17 is input as a detection signal of the rotating body 12 to an up / down counter or the like such as a control circuit (not shown), and the number of rotations and the rotation angle of the rotating body 12 are calculated to slide Used to detect the position of a door or the like.
[0025]
In FIG. 1, R1 is a pull-down resistor when the power is off, and R2 is a pull-up resistor. The circuit that is input from the starter circuit 15 to the enable terminal EN is constituted by two 74 series CMOS devices (for example, 74HC123) having the polarities inverted, as indicated by reference numerals 24 and 25 in FIG. be able to.
[0026]
Next, the control operation of the non-contact sensor 10 will be described with reference to FIGS. 1, 2a, and 2b. The uppermost part of FIG. 2a shows the rotating state and the stopped state of the rotating body. When the rotating body 12 is rotating, the magnet 13 is also rotating. Therefore, as shown in the reed switch line (second stage) in FIG. Pulses are sent one after another within the set time T of the off-timer circuit. Thereby, the start-up circuit 15 is kept on (see the start-up circuit line in the third stage). When the starter circuit 15 is turned on, the output of the starter circuit 15 becomes L level (see the starter circuit output line), and the PNP transistor Tr is turned on to continue supplying power to the hall element 14 ( Through the inverter gate G, the enable terminal EN of the latch circuit 17 is maintained at the H level via the control transistor and Hall element power supply line. As a result, the signal from the Hall element 14 is directly output as a pulse signal from the output terminal Q via the D input terminal of the latch circuit 17 (see the line of the D latch output).
[0027]
Next, when the rotation of the rotating body is stopped, the rotation of the magnet 13 is also stopped, and the reed switch 4 becomes constant when turned on or off, and no pulse is generated (see the reed switch line). When the next pulse is not input within the set time T of the off timer, a shutdown signal is output by the off timer function of the starting circuit (see the starting circuit line), and the transistor Tr is turned off. Thereby, the supply of power to the Hall element 14 is cut off. Therefore, electricity consumption is greatly reduced. Note that the shutdown signal from the activation circuit 15 is output after a certain time T from the last pulse of the reed switch. In addition, power is always supplied to the starter circuit 15 and the latch circuit 17, but since the amount of electricity consumed is much smaller than the amount of electricity consumed by the Hall element 14, the overall amount of electricity consumed is greatly reduced.
[0028]
Further, when the transistor Tr is turned off, the enable terminal EN of the latch circuit 17 is at the H level. Therefore, the Hall element 14 in the signal state when the pulse encoder input to the D input terminal of the latch circuit 17 is stopped. Are output as they are (see the D latch output line).
[0029]
Thus, even if the power supply to the Hall element 14 is stopped, the latch circuit 17 latches the signal from the Hall element 14, and continues to output an L level signal from the output terminal Q of the latch circuit 17, for example. ing. That is, if the transistor Tr is turned off simultaneously with the stop of the rotation of the rotating body 12 (or pulse encoder) to stop the power supply to the Hall element 14, the output of the Hall element 14 becomes indefinite and the output signal is normally held. Can not be. Therefore, the sensor output (Hall element 14 output) may change even though the rotating body (pulse encoder) is not operating. Therefore, in this non-contact sensor 10, a latch circuit 17 is provided after the output of the Hall element 14, and the previous output state is maintained and stabilized even when the Hall element 14 is powered off.
[0030]
The Hall element output and D latch output lines of FIG. 2a show the case where the rotating body is stopped while the Hall element output is L, and the D latch output while the Hall element power supply is shut off. Is maintained in the L state. On the other hand, FIG. 2b shows a state in which the rotation of the Hall element is stopped while the output of the Hall element is H. Even when the power supply is shut off and the output of the Hall element becomes L, the output of the latch circuit 17 remains in the H state. It has been shown.
[0031]
As a component of the latch circuit, a 74 series CMOS device (for example, 74HC74) can be used as shown by reference numerals 26 and 27 in FIG. 4, so that the pulse encoder is in a stopped state. The power supply to the Hall element 14 is turned off, and the current consumption of the latch circuit 17 can realize a power supply current level on the order of μA. The current consumption of the Hall element 14 is usually several mA to several tens mA. Therefore, when the rotation of the rotating body is stopped, the current consumption of the battery can be greatly reduced, and the life of the battery can be greatly improved.
[0032]
Next, when the rotating body 12 starts rotating, the reed switch 4 is switched on / off via the magnet 13 by the rotation, and a pulse is sent to the starting circuit 15. As a result, the starting circuit 15 is turned on. When the starter circuit 15 is turned on, the output of the starter circuit 15 becomes L level, the transistor Tr is turned on to start supplying power to the Hall element 14, and at the same time, the enable terminal of the latch circuit 17 is connected via the inverter gate G. EN is set to H level, and the pulse signal from the Hall element 14 input to the D input terminal is output as it is from the output terminal Q. That is, in the case of FIG. 2a, it outputs at L level, and in the case of FIG.
[0033]
In the above-described embodiment, the rotating body 12 and the magnet 13 are separated from each other. However, a plurality of magnets may be provided on the outer periphery of the rotating body 12 so that N poles and S poles are alternately arranged. Good. Also, a first rotating body with a magnet for the hall element and a second rotating body with a magnet for the reed switch are provided separately, and both are connected together by a shaft or connected via a gear. May be. In that case, the number of magnetic poles of the first rotating body may be different from the number of magnetic poles of the second rotating body.
[0034]
Furthermore, in the above-described embodiment, a magnetic detection type Hall element is adopted as the non-contact type sensor. However, an optical non-contact type sensor such as a phototransistor is used to transmit light to the rotating body (for example, You may make it provide alternately the part which does not let a through-hole or a transparent part pass. In this case as well, the first rotating body for the phototransistor and the second rotating body provided with the magnetic pole for the reed switch can be shared by one rotating body. In this case, the operation timing of the phototransistor and the reed switch can be shifted.
[Brief description of the drawings]
FIG. 1 is an overall circuit diagram showing an embodiment of a pulse encoder of the present invention.
FIGS. 2a and 2b are operation explanatory diagrams of the pulse encoder of FIG. 1, respectively.
FIG. 3 is a circuit diagram showing an embodiment of a startup circuit according to the present invention.
FIG. 4 is a circuit diagram showing an embodiment of a latch circuit according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Pulse encoder 11 Battery 12 Rotor 13 Magnet 14 Hall element 15 Starting circuit Tr Transistor 16 Reed switch 17 Latch circuit 21, 22, 24, 25, 26, 27 CMOS device

Claims (3)

A first rotating body;
A second rotating body that rotates in synchronization with the first rotating body and includes an annular magnet in which N and S poles are alternately magnetized;
A non-contact sensor that generates a pulse every rotation of the first rotating body at a constant angle;
Detecting means for detecting a rotation state / stop state of the second rotating body;
It is interposed between a power source and the sensor, and when the detection means detects the stop state of the second rotating body, the power supply from the power source to the sensor is cut off, and when the rotation state is detected, the power supply is supplied. A switch element to perform ,
Latching means for holding the output of the sensor at that time when the rotating body stops
And
A pulse encoder provided with a reed switch in which the detection means is provided adjacent to the second rotating body and is turned on / off every rotation of the second rotating body at a constant angle . 2. The pulse encoder according to claim 1 , wherein the latch means is constituted by a latch circuit made of a CMOS device. The pulse encoder according to claim 1 or 2, wherein the non-contact sensor includes a Hall element, and the first rotating body also serves as a second rotating body.

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