Brake control circuit, electromagnetic brake control device, electromagnetic brake control system, electromagnetic brake, and electromagnetic brake control method

Abstract

To provide a brake control circuit that can eliminate a time lag from the start of power supply to the start of voltage application to a coil of a non-excitation actuated electromagnetic brake even though it is possible to reduce the power consumption when the electromagnetic brake is in the released state.SOLUTION: When power supply to a brake control circuit 4 is started, the brake control circuit 4 applies, to a coil 3, a first voltage which is a DC voltage that releases an electromagnetic brake and is an input voltage to the brake control circuit 4 for a predetermined time, and then applies, to the coil 3, a second voltage which is a DC voltage that maintains the released state of the electromagnetic brake, and starts the application of the first voltage to the coil 3 in synchronization with the start of power supply. Further, the brake control circuit 4 stops a first drive signal for generating the first voltage when a predetermined time elapses after the start of power supply, and starts to generate a second drive signal to generate the second voltage before the first drive signal is stopped.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a brake control circuit for controlling an electromagnetic brake of a non-excitation operation type and a control device for an electromagnetic brake. The present invention also relates to a control system for an electromagnetic brake including a control device for an electromagnetic brake. Further, the present invention relates to an electromagnetic brake including a coil to which a DC voltage is applied by a brake control circuit. The present invention also relates to a control method for an electromagnetic brake for controlling an electromagnetic brake of a non-excitation operation type.

Background Art

[0002] Conventionally, a motor with a brake having an electromagnetic brake of a non-excitation operation type is known (see, for example, Patent Document 1). The motor with a brake described in Patent Document 1 includes a DC voltage control circuit electrically connected to a brake coil of the electromagnetic brake. A DC voltage source is electrically connected to the input side of the DC voltage control circuit. When the relay is opened, power is supplied from the DC voltage source to the DC voltage control circuit. On the other hand, when the relay is cut off, the supply of power from the DC voltage source to the DC voltage control circuit stops.

[0003] The DC voltage control circuit includes a reference voltage generation circuit, a switching signal generator, a gate drive circuit, and a switching element. The reference voltage generation circuit generates a reference voltage for controlling the DC voltage actually applied to the brake coil. The switching signal generator generates a switching signal using the output of the reference voltage generation circuit. The switching element performs an on / off operation based on the switching signal input via the gate drive circuit.

[0004] In the motor with brake described in Patent Document 1, power is supplied to the DC voltage control circuit when the electromagnetic brake switches from a braking state in which the braking force of the electromagnetic brake is applied to a released state in which the braking force of the electromagnetic brake is not applied. When power is supplied to the DC voltage control circuit, the DC voltage control circuit applies a first effective voltage to the brake coil with a first voltage pattern at a fixed level during a first period starting from the start of power supply, thereby releasing the electromagnetic brake. Subsequently, during a second period following the first period, the DC voltage control circuit applies a second effective voltage to the brake coil with a second voltage pattern in which rectangular pulses are repeated, thereby maintaining the released state of the electromagnetic brake.

[0005] The reference voltage generation circuit generates a first reference voltage for generating a first voltage pattern during the first period, and generates a second reference voltage for generating a second voltage pattern during the second period. The second reference voltage is a voltage that can maintain the release state of the electromagnetic brake and is smaller than the first reference voltage. The switching signal generator generates a first switching signal that is fixed ON in accordance with the first reference voltage during the first period, and generates a second switching signal that repeatedly switches ON and OFF in accordance with the second reference voltage during the second period. The switching element maintains an ON state in the first period by driving the gate drive circuit in accordance with the first switching signal, and performs ON / OFF operation in the second period by driving the gate drive circuit in accordance with the second switching signal.

[0006] In the motor with brake described in Patent Document 1, the second effective voltage is lower than the first effective voltage, making it possible to reduce the power consumption of the electromagnetic brake when it is released. Also, in the motor with brake described in Patent Document 1, when the electromagnetic brake switches from the released state to the braking state, the power supply to the DC voltage control circuit is stopped. When the power supply to the DC voltage control circuit is stopped, the current flowing through the brake coil rapidly becomes zero, and the electromagnetic brake enters the braking state. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 5911639 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In the motor with brake described in Patent Document 1, as mentioned above, it is possible to reduce the power consumption of the electromagnetic brake when it is released. On the other hand, in the case of this motor with brake, since the reference voltage generation circuit is generally composed of a logic circuit, the inventors of this invention have found that there is a time lag between the start of power supply to the DC voltage control circuit and the start of voltage application to the brake coil. Specifically, after the start of power supply to the DC voltage control circuit, the reference voltage generation circuit is not reset until the input voltage of the DC voltage control circuit reaches a predetermined value and stabilizes, and the reference voltage generation circuit does not generate the first reference voltage Vf1 (that is, the reference voltage generation circuit starts generating the first reference voltage Vf1 when the input voltage of the DC voltage control circuit stabilizes), so the inventors of this invention have found that there is an unresponsive period after the start of power supply to the DC voltage control circuit during which the reference voltage generation circuit does not generate the first reference voltage Vf1 (see Figure 9).

[0009] Furthermore, the inventors' investigations revealed that during the unresponsive time, the reference voltage generation circuit does not generate the first reference voltage Vf1, and therefore the switching signal generator also does not generate the first switching signal (see Figure 9), and as a result, the switching elements do not operate. In addition, the inventors' investigations revealed that because the switching elements do not operate during the unresponsive time, a time lag equivalent to the unresponsive time occurs between the start of power supply to the DC voltage control circuit and the start of voltage application to the brake coil (see Figure 9).

[0010] If there is a time lag between the start of power supply to the DC voltage control circuit and the start of voltage application to the brake coil, the time it takes for the electromagnetic brake to release from the braking state after the start of power supply to the DC voltage control circuit will increase, making it impossible to control the braked motor accurately with high-speed response.

[0011] Therefore, the first object of the present invention is to provide a brake control circuit and an electromagnetic brake control method that can reduce the power consumption when an unexcited electromagnetic brake is released, while eliminating the time lag between the start of power supply to the brake control circuit that applies a DC voltage to the coil of the electromagnetic brake and the start of voltage application to the coil of the electromagnetic brake. Another object of the present invention is to provide an electromagnetic brake equipped with a coil to which a DC voltage is applied by this brake control circuit.

[0012] Furthermore, the braked motor described in Patent Document 1 may be used, for example, as a drive source to drive the arm of an industrial robot. In this case, the braked motor is connected to the arm via a reduction gear, for example. When an emergency such as a power outage occurs while the industrial robot is in operation, it is necessary to stop the braked motor and the industrial robot in order to ensure safety. To stop the braked motor described in Patent Document 1 in an emergency, the power supplied to the DC voltage control circuit should be immediately cut off to bring the braked motor to a sudden stop.

[0013] However, if the brake-equipped motor described in Patent Document 1 is connected to an arm via a reduction gear, for example, immediately cutting off the power supplied to the DC voltage control circuit to abruptly stop the brake-equipped motor may cause an excessive load to act on the reduction gear due to the inertia moment of the arm in operation, potentially damaging the reduction gear.

[0014] Therefore, a second object of the present invention is to provide an electromagnetic brake control device and an electromagnetic brake control method that can suppress excessive load acting on a reduction gear or the like connected to a motor, even when an electromagnetic brake is to be brought to an emergency stop. Another second object of the present invention is to provide a brake control system equipped with this electromagnetic brake control device. Furthermore, a second object of the present invention is to provide an electromagnetic brake equipped with a coil to which a DC voltage is applied by a brake control circuit of the brake control system. [Means for solving the problem]

[0015] To solve the first problem described above, the brake control circuit of the present invention is a brake control circuit for controlling an unexcited electromagnetic brake in which a braking state occurs when the coil is unexcited and a release state occurs when the coil is excited, and no braking force is applied. The brake control circuit comprises a first drive signal stop circuit that generates and then stops a first drive signal, a second drive signal generation circuit that generates a second drive signal, and a semiconductor switch that turns on when at least one of the first drive signal and the second drive signal is output, thereby putting the coil into the excited state. The first drive signal stop circuit is configured to release the electromagnetic brake by starting to generate the first drive signal in synchronization with the start of power supply to the brake control circuit, and to stop the first drive signal after a predetermined time has elapsed since the start of power supply to the brake control circuit. The second drive signal generation circuit is configured to start generating the second drive signal before the first drive signal stops, and to continue generating the second drive signal after the first drive signal stops to maintain the electromagnetic brake in the released state. The first drive signal is an analog signal corresponding to the current flowing from the DC power supply to the capacitor of the first drive signal stop circuit. In the first configuration, the first drive signal is an analog signal corresponding to the current flowing from the DC power supply through the series connection of the resistor and capacitor in the first drive signal stop circuit. The predetermined time The aforementioned capacitor is charged handThe first drive signal stops. It is the time until It is characterized by the following: In the second configuration, The first drive signal is an analog signal corresponding to the current flowing from the DC power supply through the series connection of the resistor and capacitor in the first drive signal stop circuit. The second drive signal generation circuit includes an oscillator circuit, and the oscillator circuit is configured to generate and output the second drive signal when the input voltage of the brake control circuit reaches a predetermined value after power supply from the DC power supply to the brake control circuit is started and the oscillator circuit is reset.

[0016] Furthermore, in order to solve the first problem described above, the electromagnetic brake control method of the present invention is an electromagnetic brake control method for controlling an unexcited electromagnetic brake which is in a braking state in which a braking force is applied when the coil is in an unexcited state, and in a release state in which no braking force is applied when the coil is excited, and comprises the steps of (a) generating a first drive signal to turn on a semiconductor switch that puts the coil into the excited state in synchronization with the start of power supply to a brake control circuit that applies a DC voltage to the coil, thereby putting the electromagnetic brake into the release state, and stopping the first drive signal after a predetermined time has elapsed since the start of power supply to the brake control circuit, and (b) generating a second drive signal to turn on the semiconductor switch after the start of power supply to the brake control circuit, thereby putting the electromagnetic brake into the release state. The step (b) includes the step of starting to generate a second drive signal before the first drive signal stops, and the step of continuously generating the second drive signal after the first drive signal stops to maintain the electromagnetic brake in the released state, wherein the first drive signal is an analog signal corresponding to the current flowing from a DC power supply to a capacitor in a first drive signal stop circuit that is stopped after the first drive signal is generated. The first drive signal is an analog signal corresponding to the current flowing from a DC power supply to a series connection of a resistor and a capacitor in a first drive signal stop circuit that is stopped after the first drive signal is generated, The predetermined time The aforementioned capacitor is charged hand The first drive signal stops. It is the time until It is characterized by the following:

[0017] In this invention, when power is supplied to the brake control circuit, a first voltage, which is a DC voltage that releases the electromagnetic brake for a predetermined time, is applied to the coil, and then a second voltage, which is a DC voltage that maintains the released state of the electromagnetic brake, is applied to the coil. Therefore, in this invention, it is possible to reduce the power consumption when an unexcited electromagnetic brake is released. Furthermore, in this invention, since the application of the first voltage to the coil is started in synchronization with the start of power supply to the brake control circuit, it is possible to eliminate the time lag between the start of power supply to the brake control circuit and the start of voltage application to the electromagnetic brake coil. In other words, in this invention, even though it is possible to reduce the power consumption when an unexcited electromagnetic brake is released, it is possible to eliminate the time lag between the start of power supply to the brake control circuit and the start of voltage application to the electromagnetic brake coil.

[0018] Furthermore, the brake control circuit of the present invention includes a first drive signal stop circuit that stops the first drive signal for generating a first voltage after a predetermined time has elapsed since the start of power supply to the brake control circuit, and a second drive signal generation circuit that generates a second drive signal for generating a second voltage, wherein the second drive signal generation circuit starts generating the second drive signal even before the first drive signal stops. In addition, in the electromagnetic brake control method of the present invention, after a predetermined time has elapsed since the start of power supply to the brake control circuit, the first drive signal for generating a first voltage is stopped, and the second drive signal for generating a second voltage is started to be generated even before the first drive signal stops. Therefore, in the present invention, it is possible to prevent situations in which no voltage is applied to the coil immediately after the first voltage has been applied to the coil, and as a result, it is possible to prevent malfunction of the electromagnetic brake.

[0019] In the present invention, for example, the brake control circuit includes a semiconductor switch that performs on / off operation based on a first drive signal. When the semiconductor switch is in the ON state, a voltage is applied to the coil, and the first drive signal is generated directly from the input voltage to the brake control circuit.

[0020] In the present invention, it is preferable that the semiconductor switch performs an on / off operation based on a first drive signal and a second drive signal. With such a configuration, compared to a case where a semiconductor switch that applies a voltage to the coil when in the on state and a semiconductor switch that performs an on / off operation based on the first drive signal and a semiconductor switch that performs an on / off operation based on the second drive signal are provided separately, the configuration of the brake control circuit can be simplified and the cost of the brake control circuit can be reduced.

[0021] In the present invention, the semiconductor switch is a transistor, and it is preferable that a resistor and a capacitor are connected in parallel to the base of the transistor. With such a configuration, even if the second drive signal is a PWM (Pulse Width Modulation) signal, it is possible to improve the responsiveness of the transistor.

[0022] Also, in order to solve the above second problem, the control device for the electromagnetic brake of the present invention is for controlling a non-excitation operation type electromagnetic brake that becomes a braking state in which a braking force acts when the coil is in a non-excited state and becomes a released state in which the braking force does not act when the coil is in an excited state. Brake control circuit In the control device, a power supply for supplying power for applying a DC voltage to the coil is The aforementioned brake control circuit provided, and when at least suddenly stopping the motor to which the electromagnetic brake is attached, the power supply from the power supply is such that the braking state and the released state of the electromagnetic brake are alternately repeated, and the power supply from the power supply is To the aforementioned brake control circuit power supply and the power supply stop for temporarily stopping the power supply from the power supply are alternately repeated, and then the power supply from the power supply is To the aforementioned brake control circuit stopped. This is characterized by To the aforementioned brake control circuit stopping the power supply.

[0023] Furthermore, in order to solve the second problem described above, the electromagnetic brake control method of the present invention is for controlling an electromagnetic brake of the de-excitation type, in which a braking state occurs when the coil is de-excitation and a release state occurs when the coil is excited and no braking force is applied, and in order to stop the motor to which the electromagnetic brake is attached at least in an emergency stop, the braking state and the release state of the electromagnetic brake are alternately repeated from the power supply that provides power to apply a DC voltage to the coil. To the brake control circuit Power supply and from the power source To the aforementioned brake control circuit After repeatedly alternating between temporarily suspending the power supply and completely shutting it off, the power supply will then... To the aforementioned brake control circuit It is characterized by stopping the power supply.

[0024] In this invention, when an electromagnetic brake is attached to a motor and it is brought to an emergency stop, the braking state and the release state of the electromagnetic brake are alternately repeated, by alternately supplying power from a power source and then temporarily stopping the power supply, before the power supply from the power source is stopped. Therefore, in this invention, even when the motor is brought to an emergency stop, it is possible to stop the motor while gradually reducing the rotational speed of the motor, and as a result, it is possible to prevent the motor from coming to a sudden stop. Consequently, in this invention, even when the motor is brought to an emergency stop, it is possible to suppress the acting of excessive load on the reduction gear and the like connected to the motor.

[0025] In the present invention, it is preferable that the power supply time, which is the time during which power is supplied from the power source when the motor is at least brought to an emergency stop, and the power supply interruption time, which is the time during which power supply from the power source is temporarily suspended when the motor is at least brought to an emergency stop, can be arbitrarily set. With this configuration, it becomes possible to set the power supply time and the power supply interruption time according to the application and operating environment of the motor to which the electromagnetic brake is attached. Furthermore, for example, when the motor is used as a drive source for the arm of an industrial robot, it becomes possible to adjust the power supply time and the power supply interruption time while the arm is in operation.

[0026] In the present invention, the control device for the electromagnetic brake includes, for example, a second semiconductor switch that turns the power supply from the power source on and off.

[0027] In the present invention, it is preferable that the power supply includes a battery that stores at least one of the regenerative power of the motor and the power supplied from the main power source to which the power supply is connected. With this configuration, for example, even if a power outage occurs and the motor is stopped in an emergency, it becomes possible to alternately supply and stop power supply using the power supplied from the battery so that the braking state and the release state of the electromagnetic brake alternately repeat.

[0028] The electromagnetic brake control device of the present invention can be used in an electromagnetic brake control system that includes a brake control circuit that receives power from a power source and applies a DC voltage to a coil. In this electromagnetic brake control system, it is preferable that the brake control circuit starts applying voltage to the coil in synchronization with the start of power supply from the power source to the brake control circuit. With this configuration, even if power supply and power supply interruption are repeated alternately when the motor is brought to an emergency stop, it is possible to eliminate the time lag between the start of power supply and the start of voltage application to the electromagnetic brake coil. Therefore, even if the time from the start of power supply to the stop of power supply is short when the motor is brought to an emergency stop, it is possible to release the electromagnetic brake, and as a result, it is possible to alternately repeat the braking state and the release state of the electromagnetic brake.

[0029] In the present invention, for example, the brake control circuit includes a semiconductor switch that performs on / off operation based on a first drive signal for generating a first voltage, which is a DC voltage that releases the electromagnetic brake and is the input voltage from the power supply to the brake control circuit. When the semiconductor switch is turned on, a voltage is applied to the coil, and the first drive signal is generated directly from the input voltage from the power supply to the brake control circuit.

[0030] An electromagnetic brake equipped with a coil to which a DC voltage is applied by the brake control circuit of the present invention includes, for example, a built-in control board on which the brake control circuit is mounted. In this case, it is possible to increase the added value of the electromagnetic brake compared to a case where a separate control board on which the brake control circuit is mounted is provided. [Effects of the Invention]

[0031] As described above, the present invention makes it possible to reduce the power consumption when the unexcited electromagnetic brake is released, while also eliminating the time lag between the start of power supply to the brake control circuit that applies a DC voltage to the electromagnetic brake coil and the start of voltage application to the electromagnetic brake coil. Furthermore, the present invention makes it possible to suppress excessive load on the reduction gear and other components connected to the motor, even when the motor to which the electromagnetic brake is attached is brought to an emergency stop. [Brief explanation of the drawing]

[0032] [Figure 1] This is a block diagram illustrating the schematic configuration of an electromagnetic brake control system according to an embodiment of the present invention. [Figure 2] Figure 1 is a cross-sectional view illustrating the configuration of an electromagnetic brake controlled by an electromagnetic brake control device and brake control circuit. [Figure 3] Figure 2 is a schematic diagram illustrating an example of the use of an electromagnetic brake. [Figure 4] Figure 1 is a circuit diagram of an example of a brake control circuit. [Figure 5] Figure 1 is a diagram illustrating the function of the brake control circuit. [Figure 6] (A) is a waveform diagram illustrating the operation of the brake control circuit during normal use of the motor shown in Figure 3, and (B) is a waveform diagram illustrating the operation of the electromagnetic brake control system during emergency stop of the motor shown in Figure 3. [Figure 7]This is a circuit diagram illustrating the configuration of an electromagnetic brake control device according to another embodiment of the present invention. [Figure 8] This waveform diagram illustrates the operation of the electromagnetic brake control system during an emergency stop of a motor when the power on / off circuit shown in Figure 7 is used. [Figure 9] This waveform diagram illustrates the problems with conventional technology. [Modes for carrying out the invention]

[0033] Embodiments of the present invention will be described below with reference to the drawings.

[0034] (Outline configuration of the electromagnetic brake control system and configuration of the electromagnetic brake) Figure 1 is a block diagram illustrating the schematic configuration of an electromagnetic brake control system 6 according to an embodiment of the present invention. Figure 2 is a cross-sectional view illustrating the configuration of an electromagnetic brake 2 controlled by the electromagnetic brake control device 1 and brake control circuit 4 shown in Figure 1. Figure 3 is a schematic diagram illustrating an example of use of the electromagnetic brake 2 shown in Figure 2.

[0035] The electromagnetic brake control system 6 (hereinafter referred to as "control system 6") in this embodiment is a system for controlling the electromagnetic brake 2, and comprises an electromagnetic brake control device 1 (hereinafter referred to as "control device 1") and a brake control circuit 4 as components for controlling the electromagnetic brake 2. The electromagnetic brake 2 is an unexcited type electromagnetic brake, and when the coil 3 of the electromagnetic brake 2 is in an unexcited state, a braking force is applied, resulting in a braking state, and when the coil 3 is in an excited state, no braking force is applied, resulting in a release state.

[0036] The electromagnetic brake 2 is used attached to the motor 7. The motor 7 is used, for example, as a drive source to drive the arm 8 of an industrial robot. A reduction gear 9 is attached to the output shaft of the motor 7, and the motor 7 is connected to the arm 8 via the reduction gear 9. The electromagnetic brake 2 comprises a rotating plate 12 fixed to the rotation axis of the motor 7 via a boss 11, a braking plate 13 and an armature 14 positioned on either side of the rotating plate 12, a compression coil spring 15 that biases the armature 14 toward the rotating plate 12, and a yoke 16 around which the coil 3 is wound.

[0037] When coil 3 is de-energized, as shown in Figure 2(A), the rotating plate 12 is sandwiched between the braking plate 13 and the armature 14 by the biasing force of the compression coil spring 15, and the electromagnetic brake 2 is in a braking state. On the other hand, when coil 3 is energized, as shown in Figure 2(B), the armature 14 is attracted to the yoke 16 against the biasing force of the compression coil spring 15, and the rotating plate 12 becomes rotatable. That is, the electromagnetic brake 2 is released. In this embodiment, a control board 17 on which the brake control circuit 4 is mounted is built into the electromagnetic brake 2. In other words, the electromagnetic brake 2 is equipped with a control board 17 on which the brake control circuit 4 is mounted. The control board 17 is, for example, a rigid substrate such as a glass epoxy substrate.

[0038] For example, if a motor 7 is used as a drive source to drive the arm 8 of an industrial robot, the control device 1 is included in the industrial robot's control system and constitutes part of the industrial robot's control system. The control device 1 is equipped with a power supply 5 to supply power to apply a DC voltage to the coil 3. The power supply 5 supplies power to the brake control circuit 4. Specifically, the power supply 5 is a DC power supply and supplies DC power to the brake control circuit 4. The brake control circuit 4 applies a DC voltage to the coil 3.

[0039] Power supply 5 is equipped with a battery 19 for use in emergencies such as power outages. The battery 19 stores the regenerative power of the motor 7. For example, the regenerative power of the motor 7 when it is stopped in an emergency, as described later, is stored in the battery 19. Alternatively, the battery 19 stores the power supplied from the main power source to which power supply 5 is connected. Alternatively, the battery 19 stores both the regenerative power of the motor 7 and the power supplied from the main power source.

[0040] When releasing the electromagnetic brake 2, which is in a braking state, power is supplied from the power supply 5 to the brake control circuit 4. That is, the control device 1 supplies power from the power supply 5 to the brake control circuit 4. When the power supply from the power supply 5 to the brake control circuit 4 begins, the brake control circuit 4 applies a first voltage to the coil 3 for a predetermined time T1 (see Figure 6(A)), which is a DC voltage that releases the electromagnetic brake 2 and is the input voltage from the power supply 5 to the brake control circuit 4. After that, it applies a second voltage to the coil 3, which is a DC voltage that maintains the released state of the electromagnetic brake 2. The effective value of the second voltage is lower than the effective value of the first voltage. The specific configuration and operation of the brake control circuit 4 and the operation of the control system 6 will be described below.

[0041] (Configuration and operation of the brake control circuit and operation of the electromagnetic brake control system) Figure 4 is a circuit diagram of an example of the brake control circuit 4 shown in Figure 1. Figure 5 is a diagram illustrating the function of the brake control circuit 4 shown in Figure 1. Figure 6(A) is a waveform diagram illustrating the operation of the brake control circuit 4 during normal use of the motor 7 shown in Figure 3, and Figure 6(B) is a waveform diagram illustrating the operation of the control system 6 during an emergency stop of the motor 7 shown in Figure 3.

[0042] The brake control circuit 4 includes a semiconductor switch 23 that performs on / off operations based on a first drive signal for generating a first voltage and a second drive signal for generating a second voltage, a first drive signal stop circuit 24 that stops the first drive signal after a predetermined time T1 has elapsed since the start of power supply from the power supply 5 to the brake control circuit 4, and a second drive signal generation circuit 25 that generates the second drive signal. In this embodiment, the semiconductor switch 23 is a transistor. Therefore, hereafter, the semiconductor switch 23 will be referred to as "transistor 23".

[0043] Transistor 23 is a PNP type transistor. The emitter of transistor 23 is connected to the power supply 5, and the collector of transistor 23 is connected to one end of coil 3. No electronic components such as resistors are placed between the emitter of transistor 23 and the power supply 5, or between the collector of transistor 23 and coil 3. The other end of coil 3 is directly grounded. When transistor 23 is turned on, a voltage is applied to coil 3 (i.e., current flows from the power supply 5 to coil 3), and when transistor 23 is turned off, no voltage is applied to coil 3. A resistor 27 and a capacitor 28 are connected in parallel to the base of transistor 23. That is, the brake control circuit 4 is equipped with a resistor 27 connected to the base of transistor 23 and a capacitor 28 connected in parallel to the base of transistor 23.

[0044] The first drive signal stop circuit 24 includes a capacitor 30. A transistor 31 is connected to the first drive signal stop circuit 24. Transistor 31 is an NPN type transistor. The collector of transistor 31 is connected to the base of transistor 23 via a resistor 27 and a capacitor 28. The emitter of transistor 31 is grounded. The base of transistor 31 is connected to the power supply 5 via a capacitor 30, a variable resistor 32 and a diode 33.

[0045] When power is supplied from the power supply 5 to the brake control circuit 4, for a predetermined time T1 until charge is stored in the capacitor 30, the current supplied from the power supply 5 to the brake control circuit 4 and flowing through the diode 33, variable resistor 32, and capacitor 30 is input to the base of the transistor 31. In this embodiment, the current supplied from the power supply 5 to the brake control circuit 4 and flowing through the diode 33, variable resistor 32, and capacitor 30 becomes a first drive signal for generating a first voltage, and this first drive signal is input to the base of the transistor 31.

[0046] Thus, the first drive signal is not a signal output from an integrated circuit or logic circuit, but a signal directly generated from the input voltage from the power supply 5 to the brake control circuit 4. In other words, the first drive signal is directly generated from the input voltage from the power supply 5 to the brake control circuit 4. Therefore, the first drive signal begins to be generated almost simultaneously with the start of power supply from the power supply 5 to the brake control circuit 4. More specifically, the first drive signal begins to be generated immediately when power supply from the power supply 5 to the brake control circuit 4 begins. In other words, the first drive signal begins to be generated in synchronization with the start of power supply from the power supply 5 to the brake control circuit 4. The first drive signal is a continuous signal (analog signal) without on / off states.

[0047] After a predetermined time T1 has elapsed since the start of power supply from power source 5 to brake control circuit 4 and charge has accumulated in capacitor 30, current will no longer flow into the base of transistor 31. In other words, after a predetermined time T1 has elapsed since the start of power supply from power source 5 to brake control circuit 4 and charge has accumulated in capacitor 30, the first drive signal will stop (i.e., the first drive signal stop circuit 24 will stop the first drive signal), and the first drive signal will no longer be input to the base of transistor 31.

[0048] The second drive signal generation circuit 25 includes an oscillator circuit 35. A transistor 36 is connected to the second drive signal generation circuit 25. Transistor 36 is an NPN type transistor. The collector of transistor 36 is connected to the base of transistor 23 via a resistor 27 and a capacitor 28, and transistors 31 and 36 are connected in parallel to the base of transistor 23 via a resistor 27 and a capacitor 28. The emitter of transistor 36 is grounded. The base of transistor 36 is connected to the oscillator circuit 35 via a resistor 37.

[0049] The oscillator circuit 35 is a timer IC. When power is supplied from the power supply 5 to the brake control circuit 4, the oscillator circuit 35 generates and outputs a second drive signal to generate a second voltage. The second drive signal is a PWM signal that switches on and off at a predetermined period. The second drive signal is input to the base of the transistor 36. After power supply from the power supply 5 to the brake control circuit 4 begins, the oscillator circuit 35 generates and outputs the second drive signal when the input voltage of the brake control circuit 4 reaches a predetermined value and the oscillator circuit 35 is reset (see Figure 6(A)).

[0050] The oscillation circuit 35 starts generating and outputting the second drive signal before a predetermined time T1 has elapsed after power supply from the power supply 5 to the brake control circuit 4 has started (i.e., before the first drive signal stops) (see Figure 6(A)). In other words, the second drive signal generation circuit 25 starts generating the second drive signal before the first drive signal stops. Furthermore, the oscillation circuit 35 continues to generate and output the second drive signal until power supply from the power supply 5 to the brake control circuit 4 stops.

[0051] To release the electromagnetic brake 2, which is in a braking state, when power is supplied from the power supply 5 to the brake control circuit 4, a first drive signal is input to the base of transistor 31 for a predetermined time T1, and transistor 31 turns on. When transistor 31 turns on, current flows from the emitter of transistor 23 to the base of transistor 23, and transistor 23 turns on. Also, because current flows from the base of transistor 23 to transistor 31, a first voltage is applied to coil 3. That is, the input voltage to the brake control circuit 4 is directly applied to coil 3. When the first voltage is applied to coil 3, as shown in Figure 6(A), a voltage is continuously applied to coil 3, and the electromagnetic brake 2 is released.

[0052] As described above, the first drive signal is generated immediately when power is supplied from the power supply 5 to the brake control circuit 4. Therefore, when power is supplied from the power supply 5 to the brake control circuit 4, transistors 23 and 31 immediately turn on, and voltage is applied to coil 3 immediately after power is supplied from the power supply 5 to the brake control circuit 4. In other words, the brake control circuit 4 starts applying voltage to coil 3 in synchronization with the start of power supply from the power supply 5 to the brake control circuit 4. Specifically, the brake control circuit 4 starts applying the first voltage to coil 3 in synchronization with the start of power supply from the power supply 5 to the brake control circuit 4.

[0053] After a predetermined time T1 has elapsed since the power supply 5 began supplying power to the brake control circuit 4, the first drive signal input to the base of transistor 31 stops, and transistor 31 turns off. As described above, the oscillation circuit 35 generates and outputs the second drive signal even before the first drive signal stops, so the second drive signal is input to the base of transistor 36 even before the predetermined time T1 has elapsed, and transistor 36 turns on. Therefore, even after the predetermined time T1 has elapsed and transistor 31 turns off, the on state of transistor 23 continues.

[0054] Furthermore, after a predetermined time T1 has elapsed since the start of power supply from power source 5 to brake control circuit 4, current flows from the base of transistor 23 to transistor 36 without current flowing from the base of transistor 23 to transistor 31, and a second voltage is applied to coil 3. When the second voltage is applied to coil 3, as shown in Figure 6(A), the voltage is intermittently applied to coil 3, maintaining the released state of the electromagnetic brake 2. Thus, transistor 23 is ON when at least one of the first drive signal and the second drive signal is output, and OFF when neither the first drive signal nor the second drive signal is output. In other words, functionally, in the brake control circuit 4, as shown in Figure 5, transistor 23 performs ON / OFF operation based on the first drive signal and the second drive signal which are input in parallel. When the electromagnetic brake 2, which is in the released state, is to be put into a braking state, the control device 1 stops the power supply from power source 5 to brake control circuit 4.

[0055] In this embodiment, when the electromagnetic brake 2 is released and the motor 7 is rotating (i.e., when the arm 8 is being driven), if an emergency such as a power outage occurs and the rotating motor 7 needs to be stopped, the control device 1, as shown in Figure 6(B), alternately supplies power from the power source 5 to the brake control circuit 4 and then temporarily stops the power supply to the brake control circuit 4, so that the braking state and the release state of the electromagnetic brake 2 alternate. Finally, the control device 1 stops the power supply from the power source 5 to the brake control circuit 4. When power supply and power supply stoppage alternate, a voltage is intermittently applied to the coil 3, and when the power supply from the power source 5 to the brake control circuit 4 is stopped, the application of voltage to the coil 3 is stopped.

[0056] In the control device 1, the power supply time T2, which is the time during which power is supplied from the power supply 5 to the brake control circuit 4 when the motor 7 is brought to an emergency stop, and the power supply stop time T3, which is the time during which power is temporarily suspended from the power supply 5 to the brake control circuit 4 when the motor 7 is brought to an emergency stop, can be arbitrarily set. In addition, the control device 1 can also arbitrarily set the number of times power is supplied to the brake control circuit 4 before the power supply from the power supply 5 to the brake control circuit 4 is completely stopped. These settings can be made manually by, for example, an industrial robot operator in the control device 1.

[0057] In the example shown in Figure 6(B), power is supplied to the brake control circuit 4 three times before the power supply from the power source 5 to the brake control circuit 4 is completely stopped. Also, in the example shown in Figure 6(B), the power supply time T2 and the power supply stop time T3 gradually increase after the emergency stop of the motor 7 begins. Note that if a power outage occurs and the motor 7 is brought to an emergency stop, power is supplied to the brake control circuit 4 from the storage battery 19.

[0058] (Main effects of this form) As explained above, in this embodiment, when the electromagnetic brake 2, which is in a braking state, is released, the power supply from the power source 5 to the brake control circuit 4 begins. The brake control circuit 4 then applies a first voltage to the coil 3 for a predetermined time T1 to release the electromagnetic brake 2, and then applies a second voltage with a lower effective value than the first voltage to the coil 3 to maintain the released state of the electromagnetic brake 2. Therefore, in this embodiment, it is possible to reduce the power consumption when the electromagnetic brake 2 is released.

[0059] Furthermore, in this embodiment, the brake control circuit 4 starts applying the first voltage to the coil 3 in synchronization with the start of power supply from the power source 5 to the brake control circuit 4. As shown in Figure 6(A), this eliminates the time lag between the start of power supply from the power source 5 and the start of voltage application to the coil 3. In other words, in this embodiment, even if it is possible to reduce the power consumption when the electromagnetic brake 2 is released, it is possible to eliminate the time lag between the start of power supply from the power source 5 to the brake control circuit 4 and the start of voltage application to the coil 3.

[0060] In this configuration, the second drive signal generation circuit 25 begins generating the second drive signal even before the first drive signal stops. Therefore, in this configuration, it is possible to prevent situations where no voltage is applied to the coil 3 immediately after the first voltage has finished being applied to the coil 3. Consequently, in this configuration, it is possible to prevent malfunction of the electromagnetic brake 2. In addition, in this configuration, since the capacitor 28 is connected in parallel with the resistor 27 connected to the base of the transistor 23, it is possible to improve the responsiveness of the transistor 23 even if the second drive signal is a PWM signal.

[0061] In this configuration, when the motor 7 is brought to an emergency stop, the control device 1 alternately supplies power from the power source 5 to the brake control circuit 4 and then temporarily stops the power supply to the brake control circuit 4, so that the braking state and the release state of the electromagnetic brake 2 alternately repeat. Finally, the control device 1 stops the power supply from the power source 5 to the brake control circuit 4. Therefore, in this configuration, even when the motor 7 is brought to an emergency stop, it is possible to stop the motor 7 while gradually reducing its rotational speed, thereby preventing the motor 7 from coming to a sudden stop. Consequently, in this configuration, even when the motor 7 is brought to an emergency stop, it is possible to suppress the excessive load caused by the moment of inertia of the arm 8 from acting on the reduction gear 9.

[0062] Furthermore, in this embodiment, when the motor 7 is brought to an emergency stop, power is supplied from the power source 5 to the brake control circuit 4, and power is temporarily stopped, alternating between these two states. However, in this embodiment, it is possible to eliminate the time lag between the start of power supply from the power source 5 to the brake control circuit 4 and the start of voltage application to the coil 3. As a result, when the motor 7 is brought to an emergency stop, it becomes possible to release the electromagnetic brake 2 even if the power supply time T2 is short. Consequently, it becomes possible to alternately repeat the braking state and the release state of the electromagnetic brake 2 as a linear braking control with a higher operating frequency of 1 / (T2+T3).

[0063] In this configuration, the power supply time T2 and the power supply stop time T3 can be set arbitrarily. Therefore, in this configuration, it is possible to set the power supply time T2 and the power supply stop time T3 according to the operating environment of the motor 7. Furthermore, in this configuration, it is possible to adjust the power supply time T2 and the power supply stop time T3 while operating the arm 8.

[0064] In this configuration, when a power outage occurs and the motor 7 is brought to an emergency stop, power is supplied from the battery 19 to the brake control circuit 4. Therefore, in this configuration, even when a power outage occurs and the motor 7 is brought to an emergency stop, it is possible to intermittently apply voltage to the coil 3 so that the braking state and the release state of the electromagnetic brake 2 alternately repeat. Furthermore, in this configuration, since the control board 17 on which the brake control circuit 4 is mounted is built into the electromagnetic brake 2, it is possible to increase the added value of the electromagnetic brake 2 compared to the case where a separate control board on which the brake control circuit 4 is mounted is provided.

[0065] (A modified example of an electromagnetic brake control device) Figure 7 is a circuit diagram illustrating the configuration of a control device 1 according to another embodiment of the present invention, showing a case where a power on / off circuit 41 is provided to speed up the on / off switching of power supply from the power source 5 to the brake control circuit 4. Figure 8 is a waveform diagram illustrating the operation of the control system 6 during an emergency stop of the motor 7 when the power on / off circuit 41 shown in Figure 7 is used.

[0066] In the above-described configuration, the control device 1 may also include a power on / off circuit 41 that controls the on / off of the power supply from the power supply 5 to the brake control circuit 4. The power on / off circuit 41 is located between the power supply 5 and the brake control circuit 4. The power on / off circuit 41 includes two transistors 42 and 43. Transistor 42 is a PNP type transistor, with its emitter connected to the power supply 5 and its collector connected to the brake control circuit 4. When transistor 42 is turned on, power is supplied to the brake control circuit 4, and when transistor 42 is turned off, the power supply to the brake control circuit 4 is stopped.

[0067] Transistor 43 is an NPN type transistor. The collector of transistor 43 is connected to the base of transistor 42 via resistor 44 and capacitor 45. The emitter of transistor 43 is grounded. A drive signal is input to the base of transistor 43. The drive signal is, for example, a square wave on / off signal. Transistor 42 switches the power supply from the power supply 5 to the brake control circuit 4 in response to the drive signal input to the base of transistor 43. In this modification, transistor 42 is a second semiconductor switch.

[0068] When the control device 1 is equipped with a power on / off circuit 41, the waveforms of the input voltage, etc., of the brake control circuit 4 when the motor 7 is brought to an emergency stop are as shown in Figure 8. The power supply time T2 and the power supply stop time T3 when the motor 7 is brought to an emergency stop are determined according to the drive signal input to the base of the transistor 43. When the control device 1 is equipped with a power on / off circuit 41, it becomes possible to rapidly raise the input voltage of the brake control circuit 4 after the start of power supply from the power source 5 to the brake control circuit 4, compared to when the control device 1 is not equipped with a power on / off circuit 41. As a result, it becomes possible to rapidly raise the voltage applied to the coil 3 and release the electromagnetic brake 2 in the braking state earlier. Therefore, in this modified example, it becomes possible to release the electromagnetic brake 2 even if the power supply time T2 is shorter, and as a result, it becomes possible to realize linear braking control with an even higher operating frequency of 1 / (T2+T3).

[0069] (Other embodiments) In the above-described configuration, transistor 23 may be an NPN type transistor. In this case, for example, the collector of transistor 23 is connected to one end of coil 3, and the emitter of transistor 23 is grounded. The other end of coil 3 is connected to the power supply 5. The base of transistor 23 is connected to, for example, the emitter of transistor 31 and the emitter of transistor 36. If transistor 23 is an NPN type transistor, the first drive signal and the second drive signal may be directly input to the base of transistor 23.

[0070] In the above-described configuration, the brake control circuit 4 may be configured such that there is a time lag between the start of power supply from the power source 5 to the brake control circuit 4 and the start of voltage application to the coil 3. For example, the brake control circuit 4 may be configured as in the DC voltage control circuit of Patent Document 1 described above. Even in this case, if the power supply time T2 is long, it becomes possible to release the electromagnetic brake 2 when the motor 7 is brought to an emergency stop, and as a result, it becomes possible to alternately repeat the braking state and the release state of the electromagnetic brake 2.

[0071] In the above-described configuration, when the motor 7 is brought to an emergency stop, the brake control circuit 4 may be configured to continue applying the first voltage to the coil 3 and maintain the release state of the electromagnetic brake 2 even after a predetermined time T1 has elapsed since the start of power supply from the power source 5 to the brake control circuit 4.

[0072] In the above-described configuration, the control system 6 does not necessarily need to include a brake control circuit 4. In this case, voltage is applied directly from the control device 1 to the coil 3. Even in this case, when the motor 7 is brought to an emergency stop, the control device 1 alternately supplies power from the power source 5 to the coil 3 and then temporarily stops the power supply, so that the braking state and the release state of the electromagnetic brake 2 alternately repeat. This allows the power supply from the power source 5 to the coil 3 to be stopped, thereby preventing excessive load caused by the moment of inertia of the arm 8 from acting on the reduction gear 9, even when the motor 7 is brought to an emergency stop, similar to the above-described configuration.

[0073] In the above configuration, if there is no risk of damage to the reduction gear 9 even if the motor 7 is stopped abruptly, the power supply to the brake control circuit 4 may be immediately and completely stopped when the motor 7 is stopped in an emergency, without repeatedly alternating between supplying and stopping power. In this case, the power supply 5 does not need to be equipped with a battery 19. Also, in the above configuration, the semiconductor switch 23 may be something other than a transistor. For example, the semiconductor switch 23 may be a MOS-FET or thyristor with excellent high-speed response. Also, in the above configuration, if there is no risk of the electromagnetic brake 2 malfunctioning, the oscillation circuit 35 may start generating and outputting the second drive signal at the timing when the first drive signal stops.

[0074] In the above-described configuration, the brake control circuit 4 may, instead of transistor 23, separately include a transistor that performs on / off operation based on a first drive signal and a transistor that performs on / off operation based on a second drive signal. That is, the brake control circuit 4 may separately include a semiconductor switch connected to coil 3, which performs on / off operation based on a first drive signal and a semiconductor switch that performs on / off operation based on a second drive signal. Furthermore, in the above-described configuration, the control board on which the brake control circuit 4 is mounted may be installed outside the electromagnetic brake 2. That is, the electromagnetic brake 2 does not need to have a control board on which the brake control circuit 4 is mounted. Moreover, in the above-described configuration, the motor 7 may be used as a drive source to drive something other than the arm 8. The present invention can also be realized in the following application examples. <Application Example 1> In a brake control circuit for controlling a de-excitation type electromagnetic brake, which is in a braking state where a braking force is applied when the coil is de-excited, and in a release state where no braking force is applied when the coil is excited, When power supply to the brake control circuit is started, a first voltage, which is a DC voltage that causes the electromagnetic brake to be in the released state and is the input voltage to the brake control circuit, is applied to the coil for a predetermined time, and thereafter, a second voltage, which is a DC voltage that maintains the released state of the electromagnetic brake, is applied to the coil, and the application of the first voltage to the coil is started in synchronization with the start of power supply to the brake control circuit. Furthermore, after a predetermined time has elapsed since the start of power supply to the brake control circuit, the system includes a first drive signal stop circuit that stops the first drive signal for generating the first voltage, and a second drive signal generation circuit that generates a second drive signal for generating the second voltage. The brake control circuit is characterized in that the second drive signal generation circuit starts generating the second drive signal before the first drive signal stops. <Application Example 2> The semiconductor switch is provided which performs on / off operation based on the first drive signal, When the semiconductor switch is turned on, a voltage is applied to the coil. The brake control circuit according to Application Example 1, characterized in that the first drive signal is generated directly from the input voltage to the brake control circuit. <Application Example 3> The brake control circuit according to application example 1 or 2, characterized in that the semiconductor switch performs an on / off operation based on the first drive signal and the second drive signal. <Application Example 4> The semiconductor switch is a transistor, The brake control circuit according to Application Example 3, characterized in that a resistor and a capacitor are connected in parallel to the base of the transistor. <Application Example 5> In an electromagnetic brake control device for controlling an unexcited electromagnetic brake, which is in a braking state where a braking force is applied when the coil is unexcited, and in a release state where no braking force is applied when the coil is excited, A control device for an electromagnetic brake, comprising a power supply that supplies power for applying a DC voltage to the coil, wherein when the motor to which the electromagnetic brake is attached is brought to an emergency stop, the device alternately supplies power from the power supply and temporarily stops the power supply, so that the braking state and the release state of the electromagnetic brake alternately repeat, and then stops the power supply from the power supply. <Application Example 6> The control device for an electromagnetic brake according to Application Example 5, characterized in that a power supply time, which is the time during which power is supplied from the power source when the motor is at least brought to an emergency stop, and a power supply interruption time, which is the time during which power is temporarily suspended from the power source when the motor is at least brought to an emergency stop, can be arbitrarily set. <Application Example 7> The control device for an electromagnetic brake according to application example 5 or 6, further comprising a second semiconductor switch that performs an on / off operation of the power supply from the aforementioned power source. <Application Example 8> The electromagnetic brake control device according to any one of Application Examples 5 to 7, characterized in that the power supply comprises a storage battery that stores at least one of the regenerative power of the motor and the power supplied from the main power source to which the power supply is connected. <Application Example 9> The electromagnetic brake control device is as described in any of Application Examples 5 to 8, and the brake control circuit is supplied with power from the power source and applies a DC voltage to the coil, The electromagnetic brake control system is characterized in that the brake control circuit starts applying voltage to the coil in synchronization with the start of power supply from the power source to the brake control circuit. <Application Example 10> The brake control circuit includes a semiconductor switch that performs on / off operation based on a first drive signal for generating a first voltage, which is a DC voltage that puts the electromagnetic brake into the released state and is an input voltage from the power supply to the brake control circuit. When the semiconductor switch is turned on, a voltage is applied to the coil. The electromagnetic brake control system according to Application Example 9, characterized in that the first drive signal is generated directly from the input voltage from the power supply to the brake control circuit. <Application Example 11> An electromagnetic brake comprising a coil to which a DC voltage is applied by a brake control circuit described in any of Application Examples 1 to 4, or a brake control circuit described in Application Example 9 or 10, An electromagnetic brake characterized by having a built-in control board on which the aforementioned brake control circuit is mounted. <Application Example 12> In a control method for an electromagnetic brake that operates in a de-excitation state, where a braking force is applied when the coil is de-excited, and a release state is reached when the coil is excited, where no braking force is applied, When power supply to the brake control circuit that applies a DC voltage to the coil is started, a first voltage, which is the input voltage to the brake control circuit and is a DC voltage that causes the electromagnetic brake to be in the released state, is applied to the coil for a predetermined time, and thereafter, a second voltage, which is a DC voltage that maintains the released state of the electromagnetic brake, is applied to the coil, and the application of the first voltage to the coil is started in synchronization with the start of power supply to the brake control circuit, and, A method for controlling an electromagnetic brake, characterized in that, after a predetermined time has elapsed since the start of power supply to the brake control circuit, the first drive signal for generating the first voltage is stopped, and the generation of the second drive signal for generating the second voltage is started even before the first drive signal is stopped. <Application Example 13> In a control method for an electromagnetic brake that operates in a de-excitation state, where a braking force is applied when the coil is de-excited, and a release state is reached when the coil is excited, where no braking force is applied, A method for controlling an electromagnetic brake, characterized in that, when an electromagnetic brake is to be brought to at least an emergency stop, the braking state and the release state of the electromagnetic brake are alternately repeated, by alternately supplying power from a power source that supplies power to apply a DC voltage to the coil, and then temporarily stopping the power supply, and then stopping the power supply from the power source. [Explanation of Symbols]

[0075] 1. Control device (control device for electromagnetic brakes) 2. Electromagnetic brake 3 coils 4. Brake control circuit 5 Power supply 6. Control System (Electromagnetic Brake Control System) 17 Control board 19. Storage batteries 23. Transistors (semiconductor switches) 24. First drive signal stop circuit 25. Second drive signal generation circuit 27 Resistors 28 Capacitors 42. Transistors (second semiconductor switch) T1 Scheduled time T2 Power Supply Time T3 Power outage time

Claims

1. In a brake control circuit for controlling a de-excitation type electromagnetic brake, which is in a braking state where a braking force is applied when the coil is de-excited, and in a release state where no braking force is applied when the coil is excited, A first drive signal stop circuit that generates and then stops the first drive signal, A second drive signal generation circuit that generates a second drive signal, A semiconductor switch that turns on when at least one of the first drive signal and the second drive signal is output, causing the coil to be in the excited state, Equipped with, The first drive signal stop circuit is configured to release the electromagnetic brake by starting to generate the first drive signal in synchronization with the start of power supply to the brake control circuit, and to stop the first drive signal after a predetermined time has elapsed since the start of power supply to the brake control circuit. The second drive signal generation circuit is configured to start generating the second drive signal before the first drive signal stops, and to continue generating the second drive signal even after the first drive signal stops, thereby maintaining the electromagnetic brake in the released state. The brake control circuit is characterized in that the first drive signal is an analog signal corresponding to the current flowing from a DC power supply through the series connection of a resistor and a capacitor in the first drive signal stop circuit, and the predetermined time is the time from when the capacitor is charged until the first drive signal stops.

2. In a brake control circuit for controlling a de-excitation type electromagnetic brake, which is in a braking state where a braking force is applied when the coil is de-excited, and in a release state where no braking force is applied when the coil is excited, A first drive signal stop circuit that generates and then stops the first drive signal, A second drive signal generation circuit that generates a second drive signal, A semiconductor switch that turns on when at least one of the first drive signal and the second drive signal is output, causing the coil to be in the excited state, Equipped with, The first drive signal stop circuit is configured to release the electromagnetic brake by starting to generate the first drive signal in synchronization with the start of power supply to the brake control circuit, and to stop the first drive signal after a predetermined time has elapsed since the start of power supply to the brake control circuit. The second drive signal generation circuit is configured to start generating the second drive signal before the first drive signal stops, and to continue generating the second drive signal even after the first drive signal stops, thereby maintaining the electromagnetic brake in the released state. The first drive signal is an analog signal corresponding to the current flowing from the DC power supply through the series connection of the resistor and capacitor in the first drive signal stop circuit. The second drive signal generation circuit includes an oscillator circuit. The oscillation circuit is configured to generate and output the second drive signal when the input voltage of the brake control circuit reaches a predetermined value and the oscillation circuit is reset after power supply from the DC power supply to the brake control circuit is started.

3. The brake control circuit according to claim 1 or 2, characterized in that the second drive signal is a signal that repeatedly switches on and off at a predetermined cycle, and the off period of each cycle is also a signal that maintains the electromagnetic brake in the released state.

4. The semiconductor switch is a transistor, The brake control circuit according to claim 1, characterized in that a second resistor and a second capacitor are connected in parallel to the base of the transistor.

5. In a control method for an electromagnetic brake that operates in a de-excitation state, where a braking force is applied when the coil is de-excited, and a release state is reached when the coil is excited, where no braking force is applied, (a) The process of releasing the electromagnetic brake by starting to generate a first drive signal to turn on a semiconductor switch that energizes the coil, in synchronization with the start of power supply to the brake control circuit that applies a DC voltage to the coil, and stopping the first drive signal after a predetermined time has elapsed since the start of power supply to the brake control circuit, (b) After power supply to the brake control circuit is started, a step of generating a second drive signal to turn on the semiconductor switch to bring the electromagnetic brake to the released state, Equipped with, The above step (b) is, A step of starting to generate the second drive signal before the first drive signal stops, The process of continuously generating the second drive signal even after the first drive signal has stopped to maintain the electromagnetic brake in the released state, Includes, A control method for an electromagnetic brake, characterized in that the first drive signal is an analog signal corresponding to the current flowing from a DC power supply to a series connection of a resistor and a capacitor in a first drive signal stop circuit that stops the first drive signal after it has been generated, and the predetermined time is the time from when the capacitor is charged until the first drive signal stops.

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