JPH06327875A - Pedal sensor for sewing machine - Google Patents

Abstract

PURPOSE:To provide a pedal sensor which can detect the position of a pedal by a contactless system, which has a long use life while having a high operational reliability, and which has a simple and inexpensive mechanism. CONSTITUTION:A pedal sensor for a sewing machine, which delivers a drive output in accordance with a position of a pedal 4, comprises a light emitting element 10, light receiving elements PH1, PH2, and a movable polarizer 12 and a stationary polarizer 11 provided in an optical path extending from the light emitting element 10 to the light receiving elements PH1, PH2, and partly overlapped with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the driving state of a drive motor of a sewing machine according to the amount of pedal depression.
The present invention relates to a pedal sensor of a sewing machine that generates a driving output according to the position of the pedal.

[0002]

2. Description of the Related Art Generally, a sewing machine equipped with a drive motor is
Adjust the pedal position by stepping on the pedal,
The drive state of the drive motor can be set to variable speed rotation, stop, thread trimming,
It is formed so that it can be freely selected and changed such as lifting the work clamp.

Various proposals have hitherto been made in order to take out the fluctuation of the position of the pedal as an electric signal and output it as an output for driving.

For example, CC that controls the driving state by changing the resistance value of the contact type variable resistor according to the change of the position of the pedal, and the luminous body which moves with the change of the position of the pedal is CC.
One that controls the driving state by detecting with a D-type sensor, and one that controls the driving state by a magnet that moves relative to the position of the pedal and a magnetic sensor such as a magnetoresistive element (Japanese Patent Publication No. 60-39397). Gazette and Japanese Patent Publication Sho 61
No. 24,955), which transmits the fluctuation of the pedal position to a contact type or non-contact type rotary encoder to control the driving state (see Japanese Patent Publication No. 60-44954), and a plurality of light emitting / receiving element pairs. A drive state is controlled by moving a shield plate having a slit disposed between the two in accordance with a change in the position of the pedal to turn on / off the light receiving element and generate a plurality of digital signals. (See Japanese Examined Patent Publication No. 60-44952),
For example, the one that controls the driving state by sequentially turning on / off a plurality of reed switches according to the change in the position of the pedal is used.

[0005]

However, each of the conventional examples has the following problems.

That is, the contact type variable resistor has an advantage that the number of parts is small and the cost is low, but the contact type has a problem that the life is short.

Further, in the case of using a light emitting body and a CCD type sensor, there is a problem that the cost is high although the life is long because of non-contact.

Also, a magnet using a relative moving magnet and a magnetic sensor such as a magnetoresistive element (Japanese Patent Publication No. 60-39397).
In Japanese Patent Publication No. 61-24955 and Japanese Patent Publication No. 61-24955), the life is long due to non-contact, but the setting work is complicated because there are many adjustment points, and the accuracy changes when the temperature changes, so it is appropriate. There is a problem in that it is impossible to perform various drive controls.

Further, in the case of using a rotary encoder (see Japanese Patent Publication No. 60-44954), the manufacturing precision of the slit or the like for determining the rotation angle of the rotary encoder must be extremely high, and the cost is high. There was a point.

Also, a device using a plurality of light emitting / receiving elements and a shield plate having slits (Japanese Patent Publication No. 60-44952).
However, there is a problem in that the number of control patterns exceeding a preset number of digital signals cannot be executed and the resolution cannot be increased.

Further, even in the case of using a plurality of reed switches, there is a problem in that the resolution cannot be improved similarly.

The present invention has been made in view of these points, and it is possible to detect the position of the pedal by a non-contact method, have a long life, and perform drive control with high resolution, and reliable operation. It is an object of the present invention to provide a pedal sensor for a sewing machine, which is highly flexible, has a simple mechanism, and is inexpensive.

[0013]

To achieve the above object, a pedal sensor for a sewing machine according to the present invention is a pedal sensor for a sewing machine that generates a driving output according to the position of the pedal. And a movable polarization plate that is displaced according to the position of the pedal in the middle of an optical path from the light emitter to the light receiver, and a fixed polarization. It is characterized in that the plate and the plate are provided so as to at least partially overlap each other.

[0014]

According to the pedal sensor of the sewing machine of the present invention, when the operator changes the position of the pedal, the movable polarizing plate is displaced according to the position of the pedal, and in response to this, the movable polarizing plate is emitted from the light emitting body. The amount of transmitted light that passes through the overlapping portion between the fixed polarizing plate and the fixed polarizing plate and reaches the light receiving body changes, and a drive output corresponding to this transmitted light amount is generated from the light receiving body and used for drive control of the sewing machine.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

1 to 6 show an embodiment of the present invention.

As shown in FIGS. 1 to 4, the mechanical portion of the present embodiment is formed by providing each component on a support base 1 which is vertically fixed inside a control box or the like (not shown). A rotating shaft 2 is rotatably supported in a lower portion of the support base 1 in a penetrating state. A lever 3 is fixed to the end of the rotary shaft 2 projecting to the front side with its base. Below the lever 3, the pedal 4
Is swingably provided on the rotary shaft 5 with its intermediate portion, and the tip end portion of the lever 3 and the tip end portion of the pedal 4 are connected by a connecting rod 6. Between the intermediate portion of the lever 3 and the pin 7 fixed to the upper portion of the support base 1, the lever 3
In FIG. 1, a tension spring 8 is urged to urge it in the counterclockwise direction. A known biasing mechanism 9 for biasing the lever 3 in the clockwise direction in FIG. 1 is provided on the support base 1 so as to be adjacent to the tension spring 8. This makes pedal 4
The lever 3 is swung about the rotation shaft 2 by stepping the front side (clockwise direction in FIG. 1) or the rear side. On the other hand, on the back side of the support 1, one light-emitting body 10 composed of an LED and the like, and two light-receiving bodies arranged above and below composed of a phototransistor for receiving light emitted from the light-emitting body 10 PH1 and PH2 are fixed to the support base 1 using an appropriate fixing method. In the middle of the optical path between the light emitter 10 and the two photoreceptors PH1 and PH2, both photoreceptors P
A substantially rectangular fixed polarizing plate 11 is fixed to the support base 1 by an appropriate fixing method so as to block both the optical paths to H1 and PH2, and blocks the optical path to only the photoreceptor PH1 below. The movable polarizing plate 12 having a substantially rectangular shape is used as the rotating shaft 2
Is fixed to the end projecting to the back side with its lower end. The movable polarizing plate 12 is swung together with the lever 3 and the rotating shaft 2 to change the overlapping state with the fixed polarizing plate 11. The two polarizing plates 11 and 12 will be further described with reference to FIG. 4. One of the fixed polarizing plates 11 has its polarization direction (hatched direction in the figure) set to 45 with respect to the vertical direction.
It is arranged so as to incline downward to the left. The other movable polarizing plate 12 is fixed to the rotating shaft 2 such that its polarization direction (hatching direction in the same figure) is oriented in the vertical direction at the upward position shown by the solid line in the same figure. The operating range of the movable polarizing plate 12 is between the left and right symmetrical positions as shown by the chain line in the figure.

The circuit components of this embodiment are formed as shown in FIG.

The light emitter 10 is connected in series with the resistor R1 on the power supply voltage Vcc side. One photoreceptor PH1 is
The light transmitted through the overlapping portion of the movable polarizing plate 12 and the fixed polarizing plate 11 is input, the collector is connected to the power supply voltage Vcc side, and the emitter is grounded via the resistor R2. The emitter on the output side of the photodetector PH1 is connected to the positive input terminal of the operational amplifier OP1. This operational amplifier OP1 forms a negative feedback type amplifier circuit 13 that amplifies the output of the photoconductor PH1. The negative input terminal is grounded via the resistor R3 and the resistor R3 is connected to the ground.
It is connected to the output terminal through 4. The other photoreceptor P
The light transmitted through only the fixed polarization plate 11 is input to H2, the collector is connected to the power supply voltage Vcc side, and the emitter is grounded via the resistor R5. The emitter on the output side of the photodetector PH2 is connected to the positive input terminal of the operational amplifier OP2. This operational amplifier OP2 forms a negative feedback type amplifier circuit 14 for amplifying the output of the photodetector PH2, and the negative input terminal is grounded via the resistor R6 and connected to the output terminal via the resistor R7. ing. The output side of one amplifier circuit 13 is connected to the positive input terminal of an operational amplifier OP3 forming the differential amplifier circuit 15 via a resistor R8. The output side of the other amplifier circuit 14 is connected to the negative input terminal of the operational amplifier OP3 of the differential amplifier circuit 15 via the resistor R9. The positive input terminal of the operational amplifier OP3 is grounded via the resistor R10, and the negative input terminal is connected to the output terminal via the resistor R11 for negative feedback. Then, the operational amplifier OP3 is formed so as to perform differential amplification based on the outputs of both amplifier circuits 13 and 14 and output it.

Next, the operation of this embodiment will be described.

When the operator of the sewing machine depresses the pedal 4 forward or backward in order to perform the desired sewing, the displacement of the position of the pedal 4 is transmitted to the lever 3 via the connecting rod 6 and the position of the pedal 4 changes. According to the displacement, the movable polarizing plate 12 swings about the rotation shaft 2 within the operation range α shown in FIG.

As a result, the overlapping state of the movable polarizing plate 12 and the fixed polarizing plate 11 changes, the amount of light emitted from the light emitting body 10 passing through both polarizing plates 12 and 11 also changes, and the output of the light receiving body PH1 also changes. .

Therefore, the displacement of the position of the pedal 4 can be detected based on the change in the output of the photodetector PH1, and the drive control can be performed based on the detected displacement.

In this embodiment, another photodetector PH is used.
By using the output of 2, the position of the pedal 4 is detected with various corrections.

This detection operation will be described with reference to FIGS. 4 to 6. The output of one photoreceptor PH1 is amplified by the amplifier circuit 13 and input to the differential amplifier circuit 15, and the output of the other photoreceptor PH2 is amplified. The signal is amplified by 14 and input to the differential amplifier circuit 15. The differential amplifier circuit 15 differentially amplifies both inputs and outputs an output voltage that varies in an analog manner as shown in FIG. This output voltage changes according to the change in the amount of transmitted light in the overlapping portion of the fixed polarizing plate 11 and the movable polarizing plate 12. The change in the transmitted light amount X is X = kCos ² in accordance with the overlapping state of the fixed polarizing plate 11 and the movable polarizing plate 12, that is, the change in the included angle θ formed between the polarization directions of the respective polarizing plates. It changes depending on θ (k is a coefficient).

Therefore, the neutral position (N), the front stepping range, and the rear stepping range are applied to the analogly varying output voltage shown in FIG. 6, and further the rotation start voltage, the speed shift instruction, and the thread cutting operation start. It is preferable that the presser foot lift and the like be applied according to the displacement of the position of the pedal 4 so that the position of the pedal 4 is detected and drive control is performed.

Further, in this embodiment, since the light receiving body PH2 corresponding to only the fixed polarizing plate 11 is provided,
The following corrections are made at the same time.

That is, the photodetector PH2 captures changes in the amount of light emitted from the light emitter 10 and changes in sensitivity of both photodetectors PH1 and PH2 with respect to temperature, and compensates for changes in the input light amount and sensitivity of the other photodetector PH1. is there. The change in the light emission amount of the light emitting body 10 occurs due to the fluctuation of the power supply voltage Vcc, the light emitting amount of the light emitting body 10 itself changes due to the temperature change, the life, and the like. The position of the pedal 4 can be detected.

Therefore, according to the present invention, the movable polarizing plate 12 and the fixed polarizing plate 11 are displaced in accordance with the fluctuation of the position of the pedal.
Since the driving output is generated based on the amount of transmitted light that passes through the overlapping portion of and reaches the photoreceptor PH1,
By the non-contact method, the position of the pedal 4 can be detected as an analog amount, the life is extended, drive control with high resolution can be performed, the operation reliability is high, the mechanism is simple, and the cost is low. . Furthermore, the light receiving body P for correction
By using H2, proper drive control can always be performed without being affected by disturbance.

The present invention is not limited to the above embodiment, but can be modified as necessary.

[0031]

As described above, since the pedal sensor of the sewing machine of the present invention is constructed and operates, the position of the pedal can be detected by the non-contact method, the life is long, and
The drive control can be performed with high resolution, the operation reliability is high, the mechanism is simple, and the cost is low.

[Brief description of drawings]

FIG. 1 is a front view showing a mechanical portion of an embodiment of a pedal sensor of a sewing machine of the present invention.

FIG. 2 is a right side view of FIG.

FIG. 3 is a rear view of FIG.

FIG. 4 is an enlarged view of a light emitting body, a light receiving body, a fixed polarizing plate and a movable polarizing plate portion.

FIG. 5 is a circuit diagram showing a signal processing portion of one embodiment of the pedal sensor of the sewing machine of the present invention.

FIG. 6 is an output characteristic diagram obtained by the pedal sensor of the sewing machine of the present invention.

[Explanation of symbols]

 4 pedal 10 light emitter 11 fixed polarizing plate 12 movable polarizing plate PH1, PH2 light receiving body

Claims (1)

[Claims] 1. A pedal sensor of a sewing machine, which generates a driving output according to the position of a pedal, is provided with a light emitting body and a light receiving body which generates the driving output according to the amount of light received from the light emitting body. A pedal of a sewing machine, characterized in that a movable polarization plate and a fixed polarization plate that are displaced according to the position of the pedal are provided in the optical path from the light emitter to the light receiver so that at least a part of them overlaps each other. Sensor.