Electric scissors

Patent metadata

Field	Value
Publication number	US-10099392-B2
Application number	US-201615221253-A
Country	US
Kind code	B2
Filing date	Jul 27, 2016
Priority date	Aug 4, 2015
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

Electric scissors comprise a motor, a movable blade, a transmission mechanism, an operation device, an operation signal output device, a control device, a drive circuit, and a forced stop device. The forced stop device is configured to stop the motor when an abnormal state is present in which the value of the operation signal output from the operation signal output device is a value determined in the control device to rotate the motor in a specific rotation direction out of the first and the second rotation directions or to stop the motor, and in which the motor is rotating in a direction opposite to the specific rotation direction.

First claim

What is claimed is:

1. Electric scissors comprising:
a motor;
a movable blade for cutting a cutting object, the blade configured to be rotatable in a closing direction and in an opening direction opposite to the closing direction, the closing direction being a direction in which the cutting object can be cut;
a transmission configured to transmit a rotational force of the motor to the movable blade, the transmission configured to rotate the movable blade in the closing direction when the motor rotates in a first rotation direction, and rotate the movable blade in the opening direction when the motor rotates in a second rotation direction opposite to the first rotation direction;
an actuator configured to be operated by a user for operation of the motor;
an operation signal output device comprising a sensor configured to output an operation signal having a value corresponding to an operation state of the actuator;
a controller configured to determine whether to rotate the motor in the first rotation direction or in the second rotation direction, or stop the motor, based on the value of the operation signal output from the operation signal output device, and output a control signal corresponding to a determination result;
a drive circuit configured to supply electric power to the motor in accordance with the control signal output from the controller to actuate the motor in response to the control signal; and
a force stopper comprising a circuit configured to stop the motor when an abnormal state is present in which the value of the operation signal output from the operation signal output device is a value determined in the controller to rotate the motor in a specific rotation direction out of the first and the second rotation directions or to stop the motor, and in which the motor is rotating in a direction opposite to the specific rotation direction.

2. The electric scissors according to claim 1 , wherein
the specific rotation direction is the second rotation direction.

3. The electric scissors according to claim 1 , wherein
the force stopper comprises:
a stop signal output unit configured to output a stop signal for stopping the motor when the abnormal state is present; and
a stop circuit configured to stop the motor by stopping power supply to the motor regardless of contents of the control signal while the stop signal is output from the stop signal output unit.

4. The electric scissors according to claim 3 ,
wherein the stop signal output unit is configured by a hardware circuit.

5. The electric scissors according to claim 3 ,
wherein the stop signal output unit comprises:
a first signal output section configured to receive the operation signal output from the operation signal output device and output a first signal when the value of the operation signal is a value determined in the controller to rotate the motor in the specific rotation direction or to stop the motor;
a second signal output section configured to acquire actual operation information indicating an actual operating state of the motor and output a second signal when the acquired actual operation information indicates that the motor is rotating in a direction opposite to the specific rotation direction; and
a third signal output section configured to output the stop signal when the first signal is output from the first signal output section and the second signal is output from the second signal output section.

6. The electric scissors according to claim 3 ,
wherein the stop signal output unit is configured to continue outputting the stop signal due to presence of the abnormal state until a specific condition is satisfied, and stop the output when the specific condition is satisfied.

7. The electric scissors according to claim 6 ,
wherein the specific condition is a condition in which the actuator is operated in such a manner that the operation signal having a value determined in the controller to rotate the motor in the direction opposite to the specific direction is output from the operation signal output device.

8. The electric scissors according to claim 3 ,
wherein the stop circuit comprises:
a switch section provided separately from the drive circuit in a power supply path to the motor from a power source that supplies electric power to the motor and configured to complete/interrupt the power supply path; and
a switch driving section configured to cause the switch section to interrupt the power supply path while the stop signal is output from the stop signal output unit.

9. The electric scissors according to claim 3 ,
wherein the stop circuit is configured to disable the control signal input to the drive circuit from the controller to stop power supply to the motor from the drive circuit while the stop signal is output from the stop signal output unit.

10. The electric scissors according to claim 1 ,
wherein the motor is a direct current (DC) motor configured such that the motor rotates as a DC voltage is applied to between a pair of terminals and that its rotation direction is switched by a polarity of the applied DC voltage, and
the force stopper is configured to be able to determine, based on the DC voltage applied to the pair of terminals of the motor, whether the motor is rotating in the direction opposite to the specific rotation direction.

11. The electric scissors according to claim 10 ,
wherein the drive circuit comprises an H-bridge circuit having four switching elements, and is configured to apply a DC voltage from the H-bridge circuit to between the pair of terminals of the motor.

Assignees

• Makita Corp

Inventors

• Suda Hidekazu
• Omura Motohiro

Classifications

• H02P7/04

  by means of a H-bridge circuit · CPC title

• H02K7/06

  Means for converting reciprocating motion into rotary motion or vice versa · CPC title

• A01G3/02

  Secateurs; Flower or fruit shears · CPC title

• A01G3/037

  the driving means being an electric motor · CPC title

• B26B15/00 Primary

  Hand-held shears with motor-driven blades · CPC title