JPH028758B2 - - Google Patents

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a device for detecting the amount of bobbin thread remaining on a bobbin thread bobbin in a hook in a pattern stitch sewing machine or other household, professional, and industrial sewing machines. Regarding.

"Prior Art" The conventional bobbin thread detection device disclosed in Japanese Patent Publication No. 54-21786 has a through hole drilled in the axial direction of the hook and the bobbin, and a signal light beam passing through the through hole. Since the structure of the pot is provided with a reflective surface that is inclined so that it can be bent in a direction that intersects with the axial direction, there is a problem that a pot with a special shape and structure different from ordinary pots is required. Ta. Sensors such as a light emitter and a light receiver arranged across the hook are connected to a rotating outer hook that constitutes the hook, a stationary inner hook and a bobbin case, and as the bobbin thread is consumed and drawn out inside the hook. Since the signal beam can only be detected when the through holes match with the bobbin, which rotates independently, the time at which the light beam can be detected is extremely limited. The accuracy must be very high, and there is a problem in that the detection accuracy is poor because the vibration of the rotating pot scatters the light rays on the inclined reflection surface.

For this reason, the present applicant previously proposed a bobbin thread detection device in which the light beam is reflected by the bobbin thread in the bobbin thread bobbin in Utility Application No. 59-159359, but this device does not require a special hook. On the other hand, since the amount of light detected differs depending on the color of the bobbin thread, there was a problem in that the detection accuracy did not improve as a result.

"Problems to be Solved by the Invention" The present invention has been made in view of the above-mentioned problems, and is a sewing machine that does not require a special hook or bobbin case, and has high detection accuracy for bobbin thread residue. The object of the present invention is to provide a quantity detection device.

``Means for Solving the Problems'' According to the present invention, a detector consisting of a light emitting part that emits light toward the flange of the bobbin thread bobbin and a light receiving part close to the light emitting part is installed in a sewing machine. A pair of flanges of the lower thread bobbin are fixed to the machine frame and are provided with mutually opposing light-transmitting parts so that the light emitted from the light-emitting part can pass therethrough, and the light-transmitting parts that have passed through the light-emitting parts are transmitted through the bobbin. A flat reflective surface is provided on the wall of the storage section of the inner pot facing the detection section in order to reflect the light toward the light receiving section through the through hole, and the ideal radiation of the light from the light emitting section and the light toward the light receiving section are There is provided a bobbin thread remaining amount detecting device for a sewing machine, characterized in that the detector is arranged so that an intersection point with an ideal line of incidence is further away from the flat reflective surface in the direction of the rotation axis of the outer hook.

"Operation" According to the above configuration, since the emitted light is reflected by the flat reflective surface provided on the inner pot that does not rotate,
Since there is no vibration that accompanies rotation, the light incident on the light receiving section is easily concentrated at a certain point, and moreover, the light radiation from the light emitting section and the light incident on the light receiving section are Since the light only passes through the light, there are fewer restrictions on when the light can be detected.

Further, according to the above configuration of the present invention, the light reflected by the flat reflective surface generates more output in the light receiving section than the light reflected by the lower thread bobbin, lower thread, etc. interposed between the flat reflective surface and the detector. Since the voltage is increased, malfunctions are less likely to occur and the accuracy of detecting the remaining amount of bobbin thread is increased.

"Background of the Invention" In the process of arriving at the present invention, the configuration of a bobbin thread remaining amount detection device studied by the applicant was as shown in FIG. 7a. In FIG. 7a, the angle at which the light emitting diode 11 forming the light emitting part of the sensor (detector) S and the phototransistor 12 forming the light receiving part are attached to the sensor holder 13 is determined by the focal point F of the lenses 11a and 12a in the drawing. is a flat reflective surface 18
It had been chosen to be tied at the top. However, with this configuration, in the circuit shown in FIG. 7b, the maximum value Vop of the output voltage Vo of the phototransistor 12 is actually as shown in FIG. Since the distance was shorter than the focal point Lf, the bobbin thread remaining amount detection device, which operates when the output voltage Vo exceeds a certain level,
8, the condition of the bobbin thread 8 wound on the bobbin 16 due to one-sided winding, the gloss, color, etc. of the surface of the shaft portion 16a and collar portion 16b of the bobbin 16, Due to reflection of other physical disturbances, an output voltage Vo that is larger than that from reflection from the reflecting surface 18 may be generated, and this has the disadvantage that it is easy to malfunction as a bobbin thread remaining amount detection device.

In order to eliminate the above-mentioned drawbacks, the present invention has been developed so that the focal point F of the light emitting diode 11 and the phototransistor 12 in the drawing is connected to a distance from the flat reflective surface 18 as shown in FIG. As shown in FIG.
The intersection point (focal point F) of the ideal radiation of light from the light emitting diode 11 and the ideal line of incidence of light to the phototransistor 12, as obtained by reflection at 8, is the rotation axis of the outer pot (or inner pot 14). In the direction,
The sensor S is moved further away from the flat reflective surface 18.
By arranging this, it is possible to eliminate malfunctions of the bobbin thread remaining amount detection device due to physical disturbances, as in the technology studied in the process of arriving at the present invention described above, and improve the detection accuracy of the bobbin thread remaining amount. Ta.

"Example" Next, an example of the present invention will be described with reference to FIGS. 1 to 6. FIGS. 2a and 2b are partially sectional plan views of the bobbin thread remaining amount detection device according to this embodiment, and a schematic plan view that takes into account the directivity of the sensor, and FIG. longitudinal section by line,
Figure 4 A, B, C, and D are front views of the bobbin thread bobbin, Figure 5 is a characteristic diagram showing the relationship between the remaining amount of lower thread and the output voltage, and Figure 6 is a bobbin thread remaining amount detection device. FIG. 3 is a front view showing the mounting position of the display light emitting diode of the sewing machine.

In FIGS. 1 to 6, a pot lid 1 made of synthetic resin is provided on the front surface of a lower arm 3. As shown in FIGS. As is well known, the sewing machine head 4 includes a needle bar 2.
is provided to be movable up and down and swingable left and right, and a sewing machine needle 2a is fixed to the needle bar 2.
A hook shaft 5 is connected by a bevel gear in a direction perpendicular to the lower shaft passing through the lower arm 3, and an outer hook 6 having the same shape and structure as a normal sewing machine is fixed to the hook shaft 5. As a result, the outer hook 6 rotates in synchronization with the rotation of the main shaft of the sewing machine, as is well known, and performs a movement to catch the upper thread 7 threaded through the sewing machine needle 2a. A shaft portion 1a of the pot lid 1 is pressed from below by a pot lid plate spring 9, and is attached to the lower arm 3 so as to be rotatable about the shaft portion 1a and to be detachable. A sensor cover 10 is removably attached to the pot lid 1. A bent portion 10a is formed at the lower part of the sensor cover 10 to sandwich a portion of the shaft portion 1a of the pot lid 1. 1
0 has a protrusion 1b integrally provided on the pot lid 1.
A fitting hole 10b is bored into which the fitting hole 10b is fitted. A sensor holder 13 in which a light emitting diode 11 and a phototransistor 12, etc., which form the light emitting part and the light receiving part of the sensor (detector) S, are fixed in close proximity to each other, is molded integrally with the sensor S, and the sensor holder 13 is attached to the sensor cover. It is fixed at 10.

Light emitting diode 11 and phototransistor 1
2 has hemispherical lenses 11a and 12a, respectively, and the direction in which they are fixed to the sensor holder 13 is inclined with respect to the rotational axis direction of the outer hook 6, as shown in FIG. As shown in FIG. 3, it is parallel to the horizontal axis of the outer hook 6. An inner hook 14 having the same shape and structure as a normal sewing machine is rotatably attached to the outer hook 6 and fixed to the lower arm 3. A support pin 14a is implanted in the inner pot 14, and a bobbin case 15 having the same shape and structure as those for ordinary sewing machines is fitted onto the support pin 14a.
It is fixed to the inner pot 14 in a non-rotating manner. The bobbin case 15 has a needle drop notch 15a.
By the bobbin case 15 and the inner pot 14, the inner pot 14
The lower thread bobbin 1 is stored in the storage portion R formed therein.
6 is removably attached. Lower thread bobbin 16
is molded from synthetic resin such as polycarbonate resin mixed with black dye, and is colored black. The bobbin thread bobbin 16 has a shaft portion 16a on which the bobbin thread 8 is wound, and a pair of flanges 16b provided at both ends of the shaft portion 16a. As shown in FIG. 3, light-transmitting portions consisting of circular arc-shaped elongated holes 17 centered around the shaft portion 16a of the bobbin thread bobbin 16 are provided so as to face each other. The arc-shaped elongated hole 17 can also be replaced with a transparent synthetic resin portion formed into an arc-shaped elongated window. In the storage portion R of the inner pot 14, a flat reflective surface 18 is provided on a wall 14b facing the sensor holder 13. As the flat reflective surface 18, a circular plate 18a made of stainless steel and having a glossy surface is used as the wall 1.
4b, but is not limited thereto.

Light emitting diode 11 and phototransistor 1
2 and the flat reflective surface 18 is such that when the infrared light U from the light emitting diode 11 is reflected by the flat reflective surface 18 as shown in FIGS. selected to be obtained. Therefore, in this embodiment, as shown in FIG. 2b, the ideal radiation IU of the infrared light U from the light emitting diode 11 and the phototransistor 12
The sensor S is arranged so that the focal point F, which is the point of intersection of the ideal line of incidence IU of the infrared light U onto the rotor, is further away from the flat reflective surface 18 in the direction of the rotation axis of the outer hook 6. In Figure 2b, infrared light U
is illustrated like a bundle of light, taking into consideration that the directivity of the light emitting diode 11 has a certain width.

In addition, as shown in FIG. 6, the sewing machine head 4
A display light emitting diode 19 that emits light based on the output voltage of the phototransistor 12 is provided.

"Operation" When the sewing machine starts sewing, the bobbin 16 rotates as the bobbin thread 8 is drawn out. light emitting diode 11
The infrared light U emitted from the bobbin 1 passes through the needle drop notch 15a of the stationary bobbin case 15.
It is radiated to the side of 6. If a large amount of bobbin thread 8 remains in the bobbin 16, the arc-shaped long hole 17
, the infrared light U emitted to the side of the bobbin 16 does not reach the flat reflective surface 18 and is blocked by the side of the black bobbin 16 and the bobbin thread 8.
Since the phototransistor 12 has no great sensitivity to the infrared light U reflected in front of such a flat reflective surface 18, As shown in FIG. 5, the output voltage Vo of the phototransistor 12 is almost zero (=0).

When the remaining amount of the bobbin thread 8 in the bobbin 16 decreases and the uppermost surface of the bobbin thread 8 falls below the arc-shaped elongated hole 17, the amount of infrared light U transmitted through the elongated hole 17 gradually increases. This infrared light U is transmitted to a stationary flat reflecting surface 18.
The output voltage Vo of the phototransistor 12 is the fifth
gradually increases as shown in the figure. After detecting that the bobbin thread 8 has decreased to a predetermined remaining amount (approximately 6 m) as shown in FIG. 4B using the output voltage Vom shown in FIG. 5, the detection circuit (not shown) is activated. Through this, the display light emitting diode 19 blinks or lights up continuously, giving a warning that the remaining amount of the bobbin thread 8 has decreased to a predetermined amount. Therefore,
The sewing machine user can stop the sewing machine as early as possible based on the alarm from the display light emitting diode 19, and wind the bobbin 16 with the bobbin thread 8 to replenish it. Damage to sewn products can be prevented.

Here, as shown in FIG. 7, when the light emitting diode 11 and the phototransistor 12 are attached to the sensor holder 13 so that the focal point F of the infrared light U is on the flat reflective surface 18, the output voltage Vo of the phototransistor 12 is Since the position where the maximum value Vop is obtained is closer to the sensor S than the position of the reflective surface 18, the output voltage Vo due to the reflection of one-sided winding of the bobbin thread 8 or other physical disturbances is due to the infrared rays reflected by the reflective surface 18. Although there is a risk that the value of the output voltage Vo due to the light U may become larger than the value of the output voltage Vo, causing a malfunction, in the above embodiment, as shown in FIG. 1, the phototransistor 12 is Since the maximum value Vop of the output voltage Vo is obtained, malfunctions due to one-sided winding of the bobbin thread 8, the condition of the side surface of the flange portion 16b of the bobbin 16, the color of the bobbin thread 8, the condition of the needle drop notch 15a, and other physical disturbances may occur. It has the advantage of being extremely small. Further, according to the above embodiment, there is no need for a special hook or bobbin case;
Moreover, since there are fewer restrictions on the time point at which light can be detected, there is an advantage that the sensor mounting accuracy does not have to be as strict as shown above. Therefore, the detection device of this embodiment can be easily attached to a normal sewing machine, and has the advantage of high compatibility.

"Other Embodiments" Although the above embodiment is a bobbin thread remaining amount detection device applied to a sewing machine having a vertical hook, the present invention can also be applied to a sewing machine having a horizontal hook in the same manner as in the above embodiment. It can be easily implemented.

"Effects" As described above, since the bobbin thread remaining amount detection device of the present invention has the above configuration, it does not require a special hook or bobbin case, is relatively inexpensive, and has a flat reflective surface. Since it is stationary, the reflected radiation light is easily concentrated in a certain place, and there are few restrictions on the point of detection, so the detection accuracy of the remaining amount of bobbin thread is high.Also, since the reflection is from a flat reflective surface, Detection accuracy does not change depending on the color of the sensor, resulting in stable operation. Furthermore, in the device of the present invention, the detector is arranged so that the intersection of the ideal radiation and the ideal line of incidence is further away from the flat reflecting surface in the direction of the rotation axis of the outer pot, so malfunctions due to physical disturbances are extremely reduced. It has many excellent effects, such as extremely high accuracy in detecting the amount of yarn remaining.

[Brief explanation of drawings]

FIGS. 1a and 1b are cross-sectional views schematically showing a bobbin thread remaining amount detection device according to an embodiment of the present invention, and output voltage characteristic diagrams of the sensor, and FIGS. A partially sectional plan view and a schematic plan view taking into account the directivity of the sensor, Part 3
The figure is a longitudinal cross-sectional view taken along the line - in Fig. 6, Fig. 4 A, B, C, and D are front views of the bobbin thread bobbin, and Fig. 5 is a characteristic diagram showing the relationship between the remaining amount of bobbin thread and the output voltage. 6th
The figure is a front view showing the mounting position of the display light emitting diode of a sewing machine equipped with a bobbin thread remaining amount detection device. FIG. 1 is a cross-sectional view schematically showing a remaining amount detection device, a circuit diagram of a sensor, and an output voltage characteristic diagram of the sensor. 3...Lower arm, 6...Outer hook, 8...Bobbin thread, 11...
Light emitting diode, 11a... Lens, 12... Phototransistor, 12a... Lens, 13... Sensor holder, 14... Inner hook, 14b... Wall, 16... Lower thread bobbin, 16a... Shaft, 16b... Flange, 17... Arc shape Elongated hole, 18...flat reflective surface, F...focal point, R...storage section, S...sensor, U...infrared light, IU...ideal radiation, ideal line of incidence.

Claims (1)

[Scope of Claims] 1. An outer hook that rotates in synchronization with the main shaft of the sewing machine, an inner hook that is attached to the outer hook so as to be relatively rotatable, and a lower hook that is removably attached to a storage portion formed in the inner hook. For detecting the remaining amount of bobbin thread wound on the bobbin thread bobbin in the storage part in a sewing machine equipped with a shaft part around which thread is wound and a bobbin thread bobbin consisting of a pair of flanges on both sides of the shaft part. A detector consisting of a light-emitting part that emits light toward the flange of the bobbin thread bobbin and a light-receiving part close to the light-emitting part is fixed to the sewing machine frame, and the light emitted from the light-emitting part can pass through. The pair of flanges of the bobbin thread are each provided with a light-transmitting portion facing each other, and the inner hook is configured to reflect the emitted light that has passed through the light-transmitting portion toward the light-receiving portion through the light-transmitting portion. A flat reflective surface is provided on a wall of the storage section facing the detector, and the intersection of the ideal radiation of light from the light emitting section and the ideal line of incidence of light to the light receiving section is in the direction of the rotation axis of the outer pot. . A bobbin thread remaining amount detection device for a sewing machine, characterized in that the detector is arranged so as to be farther away than the flat reflective surface.