JPH05269285A - Cloth hem or cloth stage detector - Google Patents

Abstract

PURPOSE:To correctly detect the cloth hem and cloth stage of a sewn article independently of the color or thickness of the sewn article. CONSTITUTION:At the jaw part set close to the needle drop part of the head part of a sewing machine 1, a height sensor 2 which dedects the height of a light flux reflection plane by collecting the reflection light flux supplied from a luminous part 3, having a position detecting element (PSD) 17 as light receiving part 4, is fixedly installed. The reflection plane of the light flux supplied from the luminous part 3 is set on a sewn article (a) or a cloth pressing part 5, and the detection signal supplied from the height sensor 2 is inputted into a signal processing control circuit 11 for the detection in the synchronous timing to the bottom dead center of a sewing needle 10, by the signal supplied from a main shaft detector 13 installed on a main shaft 9, and the cloth hem or cloth stage detection signal is outputted according to the height change paint of the detection signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting a cloth edge or a step of an article to be sewn in sewing with a sewing machine, and in particular, an error caused by disturbance such as color and pattern of the article to be sewn and unevenness of cloth. The present invention relates to a cloth edge and cloth level detector capable of accurately detecting a cloth edge or a cloth level without detection.

[0002]

2. Description of the Related Art As a structure for detecting a cloth edge and a step of a cloth to be sewn when sewing with a sewing machine, a light emitting element 50 and a light receiving element 51 are opposed to each other as shown in FIG. It is configured to pass between both elements 50 and 51 at the time of sewing, and a transmitted light type detector for detecting the cloth edge a1 or the cloth step a2 by a change in the amount of light received by the light receiving element 51, or as shown in FIG. The amount of rise of the cloth presser 52 is interlocked with the variable resistor 53, and the amount of displacement of the presser foot 52, which rises in proportion to the cloth thickness of the cloth to be sewn a, is taken out as the electric quantity of the variable resistor 53 to be sewn. A cloth clamp elevating type detector for detecting the cloth edge a1 or the cloth step a2 of a is used.

[0003]

However, in the case of the above-mentioned transmitted light type detector, when the material to be sewn is extremely thick or conversely thin, since the change in the amount of received light is small, the cloth edge or the cloth step is reduced. Will be impossible to detect. When actually sewing, most of the beginning or end of sewing is from the cloth edge or the cloth step, and in order to avoid errors due to expansion and contraction of the sewn item,
It is necessary to detect as close as possible to the sewing machine needle, but due to the mechanical structure of the sewing machine such as the bobbin thread hook, there is a limit to mounting the detector in the vicinity of the sewing machine needle. The detection accuracy is poor. Furthermore, if the sewn product is of a single color, no problem will occur, but since the amount of transmitted light is affected by the color of the sewn product, the sewn product has a pattern (for example, a black and white striped pattern). In the case of the above-mentioned cloth, there is a defect that the false detection of the cloth edge or the cloth row occurs.

On the other hand, in the case of the cloth presser lifting type detector, the cloth presser moves up and down with the vertical displacement of the feed dog due to the driving of the sewing machine. However, the cloth presser is elastically pressed to the upper part in the direction of the workpiece. Since the bar is attached, the cloth presser always bounces up and down, and when the material to be sewn is thin, the displacement of the presser foot is larger than the displacement of the presser foot due to the step of the cloth. There was a problem that it was impossible to detect the cloth floor.

The present invention has been made in view of the above problems, and can accurately detect a cloth edge and a cloth step regardless of a color or a thickness of a material to be sewn, thereby enabling automatic sewing of a sewing machine. It is an object of the present invention to provide a cloth edge or step detector.

[0006]

That is, a cloth edge or cloth stage detector according to the present invention detects a predetermined rotation position of a sewing machine spindle and outputs a spindle signal, and a reflected light flux toward a cloth. It has a light emitting part that emits light and a light receiving part that detects the position of the light beam reflected from the cloth and outputs a light beam position signal, and the light emitting part and the light receiving part are arranged facing the cloth on the jaw of the sewing machine head. It is provided with a cloth height sensor and a judging means for reading the light beam position signal from the cloth height sensor in synchronization with the main axis signal, judging the amount of movement of the light beam position, and outputting a cloth edge signal. It is what

[0007]

It is possible to always measure the height position of the light flux reflecting surface from the position of the light flux condensed on the light receiving portion of the height sensor, and the light quantity of the received light flux is not related to this measurement. The measured value does not change even if the color or pattern of the changes. During sewing by the sewing machine, only the displacement in the thickness direction of the workpiece can be measured by tracking the output of the height sensor at the timing synchronized with the main shaft of the sewing machine.
Therefore, by detecting the change point of the measurement output by the signal processing control circuit, the detection output can be detected as the cloth edge or the cloth step of the sewing object.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the cloth edge or cloth step detector according to the present invention will be described below with reference to FIGS. As shown in FIG. 1, the light emitting part 3 and the light receiving part 4 are optically opposed to the jaw part of the head of the sewing machine 1 at the jaw position facing the needle drop part 1 a through the needle drop notch 6 of the work clamp 5. The height sensor 2 is fixed so as to be fixed. That is, the luminous flux L1 from the light emitting unit 3
The light beam L2 reflected by the surface of the workpiece a sandwiched by the feed dog 7 from above and below and reflected in the direction of the light receiving portion 4 is received. Reference numeral 8 is a pulley mounted on the main shaft 9 of the sewing machine 1, and a main shaft detector 13 that detects a mark provided on the outer circumference of the pulley 8 and outputs a main shaft signal so as to detect the rotational position of the main shaft is a machine frame. It is fixed to.

The light emitting portion 3 and the light receiving portion 4 of the height sensor 2 are, as shown in FIG. 2, a monochromatic light beam L1 from the LED element 14.
Is radiated to the surface of the material to be sewn a that is exposed in the needle drop notch 6 of the presser foot 5 through the light emitting portion lens system 15, and the reflected light flux L2 from the material to be sewn a is received through the light receiving portion lens system 16. The light is condensed on the surface of the position detecting element 17. The position detecting element 17 can specify the position of the condensed light flux on the element surface according to the principle described later.

Further, FIG. 3A shows the principle of specifying the position of the position detecting element 17, and the currents IA and IB generated at the A and B positions when the light is focused at the P position are shown in FIG. IA = Io [(RL-Rx) / (Rx + RL-Rx)] = Io [(RL-Rx) / RL] IB = Io (Rx / RL)
(1) and considering that the length and the resistance value are proportional, IA = Io [(L−x) / L] IB = Io (x / L)
(2) Therefore, the ratio of IA and IB is: IA / IB = (L−x) / x = L / x−1
(3) The expression (3) shows that the incident position of the reflected light beam L2 can be known regardless of the energy of the incident light beam.

That is, the cloth edge or rung detector having the above structure is the height sensor 2 based on the measuring method shown in FIG. 2, and detects a change in the height h of the cloth edge or rung. can do. Therefore, in principle, the change in color of the sewn object a is not affected. Further, since the detector is provided on the head of the sewing machine 1 above the needle drop portion and uses light, the detection position can be set at the needle drop position, and thus there is a great degree of freedom in setting the detection position.

Further, according to the above construction, by increasing the resolution of the height sensor 2 in the height direction, it is possible to deal with a wide range of objects to be sewn, from thin ones to thick ones. Furthermore, even if it is a sewn object in which a large number of cloths are staggered and overlapped, by counting the number of height change points, it is possible to automatically start or end sewing from an arbitrary overlapping point. It will be possible.

FIG. 4 shows an embodiment of the signal processing control circuit 11 of the cloth edge or cloth stage detector, and FIG. 5 is a timing chart showing the signals of the respective parts.

In order to detect a change in the thickness (height) of the material to be sewn, the material to be sewn a is constantly fed by being sandwiched between the feed dog 7 and the presser foot 3. Since it is moved up and down by the tooth 7, it is necessary to detect the change in the height of the feed dog below the needle plate 19, that is, the height change at the bottom dead center of the sewing machine needle.

Reference numeral 20 is a division circuit for detecting the incident position of the light beam to the position detecting element 17 regardless of the incident energy of the light beam, and the voltages Va and Vb inputted from the A terminal and the B terminal of the position detecting element 17, The dividing circuit 20 converts into Va / Vb shown in (a) of the timing chart and outputs it to the sample hold circuit 21.

The sample and hold circuit 21 samples the input of the circuit when the control signal (f) is "1", and when the control signal (f) is "0", it becomes "0" as an analog quantity. It is something to remember. In the comparison circuit 22A and the comparison circuit 22B, when the voltage applied to the inverting input “−” is larger than the voltage applied to the non-inverting input “+”, the output of the circuit is “0”, and the non-inverting input “+” is input from the inverting input “−”. When the voltage applied to is large, the output of the circuit is "1". The comparison circuit 22A is used to detect that the sewing target a has become thicker, and the comparison circuit 22B is used to detect that it has become thinner.

The control signal (f) from the control circuit 23 to the sample and hold circuit 21 is generated in synchronization with the falling edge of the bottom dead center signal (e) from the spindle detector 13 as shown in the timing chart. It

As shown in the timing chart, when the bottom dead center signal (e) is "1", the output signal (g) from the comparison circuit 22A or the output signal (h) from the comparison circuit 22B is "1". If so, it is determined that the thickness of the sewing target a has changed.

R1 and R2 are resistors. Further, the sample hold circuit 21 is changed to an A / D converter,
The output data is taken into the central control circuit (CPU), and the displacement amount is determined by comparing the movement amount with a reference value. For example, the same operation is performed even if the software algorithm is used to compare the displacement amount and the reference value. It goes without saying that the cloth edge a1 or the cloth step a2 can be detected.

In the above embodiment, the detection point is set near the cloth presser for detection, but the present invention is not limited to this. For example, the height sensor may be detected by the operator side rather than the cloth presser. By providing 2 on the jaw of the sewing machine 1, it can also be used as a fixed-position stop device that automatically stops sewing before a predetermined position when the cloth edge or step of the cloth to be sewn a is sent to the stitch forming portion by the needle. You can

In this case, the spindle signal of the sewing machine spindle detector is output at a constant interval during the cloth feeding period so that the cloth edge or the passage of the cloth can be detected during the cloth feeding period of the sewing machine. In addition, by reading the luminous flux position luminous flux position signal of the light receiver in synchronization with this, it is possible to detect at which timing during the cloth feed period the cloth edge or the cloth rung has passed the detection position.

[0022]

As described above, in the cloth edge or step detector according to the present invention, the height is measured by the height sensor that reflects the light flux on the surface of the sewing object, and the disturbance is eliminated by the control circuit. Since the structure is such that the edge of the cloth or the cloth step is detected, and the structure of the detector does not have to be arranged under the needle plate, the detection position can be set to the needle drop position, so that the detection accuracy can be improved.

Further, since the reflected light flux is used and is not affected by the light flux energy, it has a feature that highly accurate detection can be performed irrespective of the color or pattern of the sewing object. The effect after implementation is extremely large.

[Brief description of drawings]

FIG. 1 is a perspective view of a sewing machine head (a) and a pulley portion (b) showing an embodiment of a cloth edge or cloth stage detector according to the present invention.

FIG. 2 is an explanatory diagram showing the principle of a triangulation method using the same height sensor.

FIG. 3 is an explanatory view showing the operating principle of the position detection element (a).
And the equivalent circuit diagram (b).

FIG. 4 is a circuit diagram showing an embodiment of a signal processing control circuit of a detector.

FIG. 5 is a timing chart showing signals of respective parts in the circuit diagram.

FIG. 6 is a cross-sectional view of essential parts showing a conventional transmitted light type cloth edge or cloth level detector.

FIG. 7 is a sectional view of an essential part showing a conventional cloth presser lifting type cloth edge or cloth stage detector.

[Explanation of symbols] 1 Sewing machine 2 Height sensor 3 Light emitting part 4 Light receiving part 5 Cloth foot 7 Feed tooth 9 Spindle 8 Pulley 10 Sewing machine needle 11 Signal processing control circuit 13 Spindle detector 14 LED element 17 Position detecting element (PSD) 19 Needle plate 23 control circuit a sewn product a1 end a2 step

Claims (1)

[Claims] 1. A spindle detector that detects a predetermined rotation position of a sewing machine spindle and outputs a spindle signal, a light emitting unit that emits a reflected light flux toward a cloth, and a light flux that detects a light flux position reflected from the cloth. A light receiving unit that outputs a position signal, a cloth height sensor in which the light emitting unit and the light receiving unit are arranged on the jaw of the sewing machine facing the cloth, and a light beam position signal from the cloth height sensor is A cloth edge or cloth edge detector, comprising: a reading means which reads in synchronization with a main axis signal, judges a movement amount of a light beam position, and outputs a cloth edge signal.