JP2001000769A - Bobbin thread remaining amount detecting device for sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the detecting precision for a remaining thread amount by providing a detecting sensitivity regulating circuit which regulates the detecting sensitivity of a detector to detect the remaining thread amount of a bobbin in a bobbin case, and at the same time, providing a detecting sensitivity regulating circuit which regulates the detecting sensitivity of a lint detector to detect lint in the vicinity of the bobbin. SOLUTION: When a remaining thread amount is detected, on the outside of a shuttle race body 10 arranged in a sewing machine frame 1, a light source LD1 by a light-emitting diode, or the like, and a photo-detector PT1 by a photo-transistor, or the like, are provided in such a manner that an optical axis from the light source LD1 to the photo-detector PT1 may be orthogonal with a hook shaft 18, i.e., the axial section of a bobbin 12. Also, when lint is detected, a photo-interrupter PI using the same optical element is arranged under the bobbin 12. Then, for the sensitivity regulation of a remaining thread amount detecting means and a lint detecting means, variable resistors VR1 and VR3 are provided. Then, the result that the sensitivity regulation of the remaining thread amount detecting means and the lint detecting means has been correctly performed is displayed to a user by the lighting up of light- emitting diodes LD3 and LD4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lower thread remaining amount detecting device for a sewing machine.

[0002]

2. Description of the Related Art A method and apparatus for detecting the remaining amount of the lower thread of a bobbin in order to avoid the danger that the remaining amount of the lower thread is insufficient during sewing in a sewing machine and the necessity of re-sewing will occur. Proposed. A typical example of such a device is a device that detects the amount of yarn remaining on a bobbin using an optical sensor. However, the applicant has further provided a dust detector to eliminate a detection error caused by dust. Detection devices have already been proposed.

[0003]

However, in the above-described apparatus for detecting the remaining amount of bobbin thread, a measuring instrument such as a synchroscope is required in order to adjust the detection sensitivity of the bobbin remaining thread amount detector and the dust detector. In addition, fine work in a narrow space, such as connecting the probe to the terminal of the circuit board of the detector, is required, and there are problems such as the risk of damage to the detector and the need for skilled workers. . Therefore, there is a problem that it is difficult for the user to make adjustments, and it is desired to solve this point. An object of the present invention is to solve the above-mentioned problems of the prior art.

[0004]

In order to achieve the above object, a lower thread remaining amount detecting device for a sewing machine according to the present invention comprises: a detector for detecting a remaining thread amount of a bobbin in a bobbin case; A detection sensitivity adjustment circuit for adjusting detection sensitivity, a display device for displaying an adjustment value of the detection sensitivity adjustment circuit, a dust detector for detecting dust near the bobbin, and detection of the dust detector A detection sensitivity adjustment circuit for adjusting sensitivity, and a display device for displaying an adjustment value of the dust detection sensitivity adjustment circuit are provided. With the above configuration, the sensitivity of the detector can be adjusted without using a synchroscope or the like to connect the probe to the circuit board in a small space. By using a light emitting diode or the like as the display device, it can be installed at a low cost and in a small space.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a sewing machine. A needle bar 3 connected to a drive unit (not shown) and connected to an upper shaft 2 to which rotation is transmitted and supported on a sewing machine frame 1 is vertically movably supported. . The needle bar 3 is provided with a rotatable shaft at the other end of a needle bar crank lot 6 having one end fitted to an eccentric pin 5 fixed to a crank 4 provided at the shaft end of the upper shaft 2.
The upper and lower portions of the needle bar holder are inserted through and fixed to the needle bar support 8 so as to be vertically movable.

Reference numeral 9 denotes a bobbin, which is a needle thread catching means, rotatably supported by a cauldron 10 fixed to the sewing machine frame 1, and a bobbin inside the bobbin which is prevented from rotating by the cauldron 10. The case 11 is held. As shown in FIG. 2, a bobbin 1 in which a bobbin thread is wound inside the bobbin case 11.
2 are held.

The inner hook 9 meshes with a lower shaft gear 16 fixed to the shaft end of a lower shaft 15 which is pivotally rotated via an arm 14 and a crank rod 13 connected to the crank portion of the upper shaft 2. It is configured to be driven in contact with a driver (not shown) provided at the shaft end of a stud shaft 18 to which the stud shaft gear 17 is fixed.

Next, a description will be given of a lower thread remaining yarn detecting device. In FIG. 2, reference numeral 19 denotes a mounting plate disposed outside the cauldron 10 and fixed to the sewing machine frame 1. The mounting plate 19 includes a first light source LD1 formed of a light emitting diode or the like and a first light source LD1 formed of a phototransistor or the like. A photodetector PT1 is mounted, and a first optical axis extending from the first light source LD1 to the first photodetector PT1 is connected to the camera shaft 18 as shown.
When the lower thread is wound around the bobbin so as to be orthogonal to the axis of the built-in bobbin 12, or when there is only a small number of bobbins, the light beam projected from the first light source LD1 emits the first light. It is arranged so as to reach the photodetector PT1. For this reason, the cauldron 10 and the bobbin case 11 are provided with cutouts or holes so that light beams can pass therethrough. Further, the inner hook 9 is provided with a cutout or a hole so that a light beam projected from the first light source LD1 reaches the first photodetector PT1 at least at one position during one rotation. .

Next, means for detecting dust and the like will be described.
A photo interrupter PI is arranged below the bobbin 12. The photo-interrupter PI is a small-sized photo-interrupter having a focal length of about 1 mm, and is arranged in a place where dust easily accumulates. The distance between the photo-interrupter PI and the rotating hook 9 is arranged to be larger than the focal length. As described above, in the arranged photo interrupter PI, no current flows through the phototransistor PT in a state where dust does not accumulate at the focal length position, and when dust accumulates at the focal length position, light is diffusely reflected and partially Is configured to enter the phototransistor PT and allow a current to flow.

As shown in FIG. 3, the photointerrupter PI includes a second light source LD2 and a second photodetector PT2. LD2 is a second light source made of a light emitting diode or the like, like the first light source, and PT2 is a second light source made of a phototransistor or the like like the first photodetector PT1. In FIG. 2, the first signal indicated by VR1
And a second variable resistor indicated by VR3 are similarly fixed to the mounting plate 19.

The circuit configuration will be described with reference to FIG. R2 is a load resistor connected to the emitter of the first photodetector PT1, and this output voltage V1 is supplied to the first comparator C1.
It is input to the inverting input terminal of P1. A resistor R3 and the first variable resistor VR1 are connected in series between a power supply Vcc and a ground Gnd, and a movable terminal of the variable resistor VR1 is connected to a non-inverting input terminal of a comparator CP1. , And a first reference voltage Vs1. The resistance value of the first variable resistor VR1 is used to adjust the reference voltage Vs1 of the first comparator CP1, and the thread is wound so as to have a lower limit of the lower thread remaining amount (reference remaining thread amount X). The bobbin 12 is set to the sewing machine, and the hook wheel 9 is rotated by manually operating the scissor wheel to determine the amount of light when the light of the first light source LD1 reaches the first photodetector PT1. It is adjusted so as to have the same value as the voltage V1.

A resistor R8 and a variable resistor VR3 are connected in series between the collector-side voltage Vcc of the second photodetector PT2, and the collector-side output voltage V2 is supplied to the second comparator CP2. Connected and input to the inverting input terminal. One end of a resistor R9 connected to the power supply Vcc is connected to the inverting input terminal of the second comparator CP2, and a resistor R10 is connected to the ground Gnd. The reference voltage Vs2 of the inverting input terminal of the second comparator connected to the power supply Vcc, the resistor R9, and the resistor R10 is always constant, and the limit amount Y of the dust accumulation amount is set by the variable resistor VR3. Perform by adjustment. That is, a reflector corresponding to the limit amount Y of dust accumulated on the upper surface of the photointerrupter PI is mounted, and the voltage V on the collector side of the second photodetector of the photointerrupter PI is the same as the reference voltage Vs2. The variable resistor VR3 is adjusted so that The relationship between the voltage V2 on the collector side of the second photodetector PT2 of the photointerrupter PI and the dust is such that when there is no dust on the photointerrupter PI, the second light source LD2
V2 is at a high voltage because the light from the second photodetector PT2 does not reach the second photodetector PT2. However, when dust accumulates, the second photodetector PT2 receives light and a current flows. V2 becomes a low voltage. A resistor R6 is a resistor for correcting a detection error of the lower thread remaining amount detecting unit by the first photodetector PT1 due to accumulation of dust, and a resistor R3 connected to the emitter of the second photodetector PT2 and the power supply Vcc. Is connected between. The first light source LD1 and the second light source LD2
And the resistor R1 are connected in series. The resistor R1 is a resistor for setting the amount of light.

In this embodiment, a detection error correction resistor R6 is disposed and connected between the emitter of the second photodetector PT2 and the resistor R3, and responds to a change in the output voltage V2. The voltage Vs1 input to the non-inverting input terminal of the first comparator CP1 changes. That is, the resistance value of the correction resistor R6 changes according to the amount of accumulated dust. The change in the output voltage of the second photodetector PT2 causes the voltage input to the non-inverting input terminal of the first comparator CP1. Vs1 is set so as to change correspondingly. As described above, the voltage Vs1 input to the non-inverting input terminal of the first comparator CP1 decreases due to the decrease in the output voltage of the second photodetector PT2, which is a dust detection device. That is, the first comparator CP1
The voltage Vs1 input to the non-inverting input terminal changes in accordance with the amount of dust, thereby making it possible to correct a detection error due to accumulation of dust.

With the above configuration, the lower thread remaining amount detection signal in which the error due to the dust is corrected can be obtained from the comparator CP1. In this embodiment, in addition to the above configuration, a lower thread remaining amount detection sensitivity adjustment display circuit 30 and a dust detection sensitivity adjustment display circuit 40 are further added. These light emitting diodes LD3 and L
D4 is fixed to the mounting plate 19, as shown in FIG. 2, so that the operator can visually recognize it during adjustment.

The bobbin thread remaining amount detection sensitivity adjustment display circuit 30 is configured such that the light emitting diode LD3 and the resistor R11 are connected to the output terminal of the comparator CP1 so that an adjuster can know the adjustment state of the bobbin thread remaining amount sensor. I have. In FIG. 2, for example, a bobbin wound with a lower thread of 9 m is put into a bobbin case,
By rotating the sewing machine motor and adjusting the volume VR1 so that the light emitting diode LD3 blinks, the lower thread 9
It can be adjusted to detect with m.

The dust detection sensitivity adjustment display circuit 40 includes a resistor R1.
3, the reference voltage 9V is connected to the inverting input terminal of the comparator CP3 by R14, the output voltage V2 is connected to the non-inverting input terminal, and the light emitting diode LD4 and the resistor R12 are connected to the output terminal of the comparator. The configuration is such that the adjustment state of the dust sensor can be understood. FIG.
, The output voltage V2 can be adjusted to the reference voltage 9V by adjusting the volume VR3 so that the light emitting diode LD4 blinks.

With the above configuration, the adjustment values of the detection sensitivity adjustment circuit for adjusting the detection sensitivity of the lower thread remaining amount detector and the dust detector can be visually recognized by the light emitting diodes LD3 and LD4. Since there is no need to bring the probe into contact with the circuit, adjustment is easy and there is no danger of breaking the circuit.

[0018]

As described above, according to the apparatus for detecting the remaining amount of lower thread of the sewing machine of the present invention, there is an effect that the detection sensitivity can be easily adjusted.

[Brief description of the drawings]

FIG. 1 is a schematic view of an entire sewing machine showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a mechanical configuration of one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a circuit configuration of one embodiment of the present invention.

[Explanation of symbols]

1: sewing machine frame, 2: upper shaft, 3: needle bar, 4: crank,
5: Eccentric pin, 6: Needle bar crank lot, 7: Needle bar holder, 8: Needle bar support, 9: Middle hook, 10: Cauldron, 11: Bobbin case, 12: Bobbin, 13: Crank lot, 1
4: arm, 15: lower shaft, 16: lower shaft gear, 17: lower shaft gear, 18: lower shaft, 19: mounting plate, 30: lower thread remaining amount detection sensitivity adjustment display circuit, 40: cotton dust detection sensitivity adjustment Display circuit.

Claims (2)

[Claims] 1. A detector for detecting the amount of yarn remaining on a bobbin in a bobbin case, a detection sensitivity adjustment circuit for adjusting the detection sensitivity of the detector, and a display device for displaying an adjustment value of the detection sensitivity adjustment circuit. A dust detector for detecting dust near the bobbin; a detection sensitivity adjustment circuit for adjusting the detection sensitivity of the dust detector; and a display device for displaying an adjustment value of the dust detection sensitivity adjustment circuit. A lower thread remaining amount detecting device for a sewing machine, comprising: 2. The display device is a light emitting diode.
The lower thread remaining amount detecting device according to claim 1.