JPS6056516B2 - sewing machine safety device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a swinging needle disposed on the front surface of a sewing machine.
This relates to a safety device for sewing machines that operates on the drive control section to stop or slow down when a part of the human body, such as a hand or finger, is in danger of touching the machine.

Conventionally, there are devices that mechanically provide a guard member on the front of the needle to prevent hands and fingers from touching the needle, but this does not stop the needle electrically, and the guard member also makes it difficult to see the needle tip. It became something that even sewing sumo wrestlers could do.

In addition, there are some models that have a guard member made of conductive material near the needle base that electrically stops the sewing machine when a human body touches it, but the guard member gets in the way during sewing and causes problems with sewing. Ta. The present invention has been improved in view of the above points, and includes an infrared temperature detector installed near the needle base of the sewing machine to detect temperature changes caused by a human body entering the detection range. To provide a device that further improves safety by removing a guard member that has hitherto been a hindrance to sewing by transmitting the information to a motor speed control circuit to control motor drive. With the goal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 is a perspective view of this device mounted on a sewing machine body, FIG. 2 is a block diagram of FIG. 1, and FIG. 3 shows input and output signals of an infrared temperature detector. As shown in FIGS. 1 and 2, an infrared temperature detector 2 is installed near the needle base 1a of the sewing machine body 1,
An actuation switch 3 for actuating the infrared temperature detector 2 is provided on the sewing machine operating section lb and is linked to the presser foot 4. A temperature detector 5 utilizing diode temperature characteristics is provided on the outer surface lc of the sewing machine to detect the ambient temperature of the sewing machine, and a temperature comparison/judgment circuit means 6 is provided on the sewing machine body 1.
will be established. The temperature comparison/judgment circuit means 6 includes a reference voltage generator 6a that generates a voltage serving as a preset criterion for determining an intruder with respect to the sewing machine ambient temperature measured by the temperature detector 5; a level comparator 6b for comparing the output of the detector 6a and the output of the infrared temperature detector 2;
It consists of The level comparator 6b is then connected to a signal latch section 7 having a reset switch. The reset switch is provided in combination with a start switch 8 of the sewing machine, and the output terminal of the signal latch section 7 is connected to a motor control section 10 for applying a brake on the rotation of the sewing machine motor 9. It is connected to a motor speed control circuit 11 that controls the motor speed. Embodiments of the present invention are constructed as described above, and when using the device:
The operating switch 3 interlocked with the presser foot 4 is set to ON. However, when the presser foot 4 is being raised, the infrared temperature detector 2 is always in the operating state regardless of whether the operating switch 3 is ON or OFF. Therefore, even if the start switch 8 of the sewing machine is pressed when the hand or finger approaches the needle base 1a of the sewing machine, the sewing machine motor 9 will not start. However, when the presser foot 4 is lowered, the operation switch 3 is opened and can be switched between ON and OFF, and the infrared temperature detector 2 can be selectively used depending on the sewing skill level. Set the operation switch 3 to the ON state,
When a hand or finger approaches the detection range of the infrared temperature detector 2, the infrared temperature detector 2 detects the intrusion of a human body with a different temperature than before, and generates a pulse-like waveform (as shown in Figure 3A).
Hereinafter referred to as signal output 2a) is output. However, the signal output 2a is generated only when the human body enters the detection range of the infrared temperature detector 2. Here, even when the cloth is brought close to the detection range, the infrared temperature detector 2 detects a temperature change due to the radiation temperature from the cloth. However, the signal output 2b outputted from the infrared temperature detector 2 at this time varies somewhat depending on the color of the cloth, but is smaller than the signal output 2a generated when a human body intrudes, and the output 6 of the reference voltage generator 6a
Peak voltage 2 of signal output 2b output in case of a or cloth
If set to c, the signal output 2b that occurs when cloth enters
is cut out, so that only human intrusion can be detected. At this time, since the radiation temperature from the cloth varies somewhat depending on the ambient temperature of the sewing machine, the temperature is constantly corrected by the temperature detector 5, and the output 6a from the reference voltage generator 6a is
Then, the output 6a'' from the reference voltage generator 6a and the signal output from the infrared temperature detector 2 are compared by a level comparator 6b. Here, when the signal output 2a is larger than the output 6a'', it is output from the level comparator 6b to the signal latch section 7.Then, this latched signal is transmitted to the motor speed control circuit 11 to control the motor braking section 10. The sewing machine motor 9 is activated, and the rotation of the sewing machine motor 9 is braked to stop or decelerate. Then, when it is desired to return the sewing machine motor 9 to its original speed, the start switch 8 of the sewing machine is activated in combination with the reset switch of the signal latch section 7. By pressing the button, the sewing machine returns to its original speed after determining whether there is a human hand or finger within the infrared detection range.Alternatively, as another embodiment, a sound wave or ultrasonic wave is output near the base of the sewing machine needle. Those skilled in the art will be able to detect the change in wavelength caused by the touch of a hand or finger with the sound wave or ultrasonic wave using the Doppler effect and transmit the intrusion of an object to the motor speed control circuit. The present invention has the above-described structure and function, and by installing an infrared temperature detector near the needle base of the sewing machine, it can eliminate the guard that has hitherto been a hindrance to sewing. Since there is no need to attach any members, the sewing surface is easy to see, and since there is no fear that the guard member will get in the way during sewing, sewing can be performed easily, and furthermore, safety can be sufficiently promoted for blind people and beginners.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment in which the safety device according to the present invention is installed near the needle base of a sewing machine, Fig. 2 is a block diagram of Fig. 1, and Fig. 3 is an infrared temperature detection according to the present embodiment. The input and output signals of the device are shown. DESCRIPTION OF SYMBOLS 1...Sewing machine body, 2...Infrared temperature detector, 5...Temperature detector, 6...Temperature comparison and determination circuit means, 6a...・Reference voltage generator,
6b... Lebel comparison/comparator.

Claims (1)

[Claims] 1. In a sewing machine whose motor speed is electrically controlled, an infrared temperature detector is installed near the needle base of the sewing machine, a temperature sensor is installed in the sewing machine body to detect the ambient temperature of the sewing machine, and a reference voltage generator is installed. Temperature comparison and judgment circuit means consisting of a temperature comparison and judgment circuit means is provided to detect changes in the surface temperature of the lower part of the needle swing during sewing of the sewing machine, and to detect changes in the surface temperature of the lower part of the needle swing when the sewing machine is sewing. A sewing machine safety device that controls the rotation of the sewing machine.