JP3662797B2 - Weight detector and microwave oven - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a weight detection device that electrically detects a weight in a thrust direction, and to an improvement in a microwave oven using the weight detection device.
[0002]
[Prior art]
In recent years, in microwave ovens, sensors for measuring temperature and weight are used as sensors for automatic cooking. Conventionally, various types such as a capacitance type and a piezoelectric element type have been adopted as a weight detection device as a weight sensor, but at present, the capacitance type is mainly used. In this weight detection device based on capacitance, a slight displacement amount of an output shaft (thrust shaft) that is displaced by the weight of a cooked product placed on a turntable is based on a change in capacitance between parallel plates. To detect.
[0003]
[Problems to be solved by the invention]
However, the conventional electrostatic capacity type weight detection apparatus includes an oscillation circuit and is configured to change the electrostatic capacity of the variable capacitor according to the distance between the electrodes. Therefore, it may be affected by stray capacitance generated in the wiring pattern on the printed circuit board, and in order to cope with this, it is necessary to secure a certain capacitance or more. In addition, in consideration of variations in component dimensions, a certain distance between electrodes is required. For this reason, the opposing area between electrodes increases and there exists a problem that an apparatus enlarges.
[0004]
Further, when such a conventional weight detection device is applied to a microwave oven, the displacement amount in the thrust direction of the turntable is detected, and a rotation drive means and a weight detection device for driving the turntable to rotate. Each has an independent configuration, and after assembling each separately, the two are combined, so the number of assembly steps is large, and the shape after combining the two is difficult to be compact It tends to be large.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a weight detection device that can be miniaturized and that can stably detect a weight, and a microwave oven using the weight detection device.
[0006]
[Means for Solving the Problems]
In order to achieve such an object, the weight detection device of the present invention includes a thrust shaft that is displaced in the thrust direction according to the weight to be detected, and a rotational displacement member that is displaced in the rotational direction by a predetermined amount according to the displacement amount of the thrust shaft. And a weight conversion means for converting the amount of displacement of the rotational displacement member as a weight, wherein the rotational displacement member is brought into contact with a horizontal axis inserted through the thrust shaft so as to be orthogonal to the thrust shaft. It has a groove that has a slope portion that receives the weight to be detected and converts it into the rotational movement of the rotational displacement member and does not have an undercut portion in the thrust direction.
[0007]
In the above-described weight detection device, when the thrust shaft is displaced in the thrust direction due to weight, the rotational displacement member is displaced in the rotational direction. By this operation, the rotational displacement amount of the rotational displacement member is digitized and converted into weight by the weight conversion means. Specifically, a signal proportional to the displacement amount of the rotational displacement member, for example, the displacement amount is replaced with a distance, which is output as a weight detection signal, and the weight is detected based on the weight detection signal. .
[0008]
Further, in the weight detection device of the present invention, the groove having the slope portion that rotationally displaces the rotational displacement member by receiving the weight of the rotational displacement member is formed, but the undercut portion is formed in the groove having the slope portion. Therefore, when forming the rotational displacement member, it is possible to perform the molding only by removing the mold in the thrust direction without using a special method such as unscrewing. For this reason, manufacture becomes easy.
[0009]
In addition, according to unscrewing, it is necessary to make the slope portion about 60 degrees or more. This is because if the angle is less than that, there is a risk that the groove shape will be collapsed when the wire is pulled out. However, when the groove without an undercut portion is not used and the punching is not performed, the slope portion can be set to 60 degrees or less. When the slope portion is laid at a lower angle in this way, the amount of displacement of the relative rotational displacement member increases with respect to the thrust movement of the thrust shaft. Therefore, the resolution of the weight detection device is increased.
[0010]
The present invention also provides a thrust shaft that is displaced in the thrust direction according to the weight to be detected, a rotational displacement member that is displaced in the rotational direction by a predetermined amount according to the displacement amount of the thrust shaft, and a displacement amount of the rotational displacement member. Weight converting means for converting as a weight, and the rotational displacement member receives a weight to be detected by contacting a horizontal axis inserted through the thrust shaft so as to be orthogonal to the thrust shaft, and this is rotated by the rotational displacement member. The cylindrical wall surface is provided with a groove having a slope portion that converts into motion, and the groove is formed of a slope portion having a predetermined angle with respect to the thrust axis on one side in the circumferential direction, and the edge on the other side is the thrust shaft. Or a slope portion having a predetermined angle with respect to the thrust axis on the opposite side to the slope portion and in the circumferential direction.
[0011]
For this reason, the groove edge on the opposite side to the slope portion on the side that receives the weight in the thrust direction and converts it into rotational motion does not require any particular precision, and therefore can be processed more easily.
[0012]
Further, the weight detection device of the present invention includes a thrust shaft that is displaced in the thrust direction according to the weight to be detected, first and second relative rotational displacement members that are provided to be engaged with the thrust shaft, Rotation displacement means for relatively displacing the two relative rotation displacement members by a predetermined amount according to the displacement amount of the thrust shaft, and rotation for rotating the first and second relative rotation displacement members integrally with the thrust shaft The first and second relative rotational displacement members of the first and second relative rotational displacement members are disposed in the detectable region of the detected body provided on the driving means and the first and second relative rotational displacement members, respectively. A detector that detects the relative amount of displacement using integral rotation of the first and second relative rotational displacement members, and a weight conversion means that converts the amount of displacement as weight, The relative rotational displacement member of the thrust shaft An undercut portion having a slope portion that receives a weight to be detected by abutting against a horizontal shaft inserted through the thrust shaft so as to intersect and converts the weight into a rotational motion of the first relative rotational displacement member and in the thrust direction The second relative rotational displacement member is provided with a thrust-direction groove that does not hinder the operation of the horizontal axis in the thrust direction, and is rotationally displaced between the thrust-direction groove, the slope portion, and the horizontal axis. Means.
[0013]
When the thrust shaft is displaced in the thrust direction by weight, the above-described weight detection device relatively rotates the first and second relative rotational displacement members by a predetermined rotation angle around the thrust shaft according to the displacement amount of the thrust shaft. . By this operation, the relative displacement amounts of both relative rotational displacement members are digitized and converted to weight by the weight conversion means. Specifically, a signal proportional to the relative displacement amount of the first relative rotational displacement member relative to the second relative rotational displacement member, for example, a signal having a time interval proportion proportional to the relative displacement amount is output as the weight detection signal. The weight is detected based on the weight detection signal.
[0014]
In another aspect of the invention, in addition to the above-described weight detection device, the thrust shaft is rotationally driven only in the direction in which the weight to be detected is received and is pressed against the inclined surface portion that converts the weight to rotation. Therefore, the relative displacement member is securely held with respect to the thrust shaft, and the accuracy of weight detection is improved.
[0015]
Further, the microwave oven of the present invention has a weight detection device that allows the turntable to be displaced in the thrust direction according to the weight applied to the turntable and detects the weight applied to the turntable based on the amount of displacement. Any of the weight detection devices described above is used as the weight detection device.
[0016]
In addition, a microwave oven using such a weight detection device as a weight detection device for measuring the weight of a cooked product placed on a turntable can reduce the weight detection portion, and reduce the size of the entire microwave oven. Can be planned.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. In this embodiment, an example in which the weight detection device is applied to a microwave oven will be described. When applied to a microwave oven, as described above, the amount of displacement of the turntable on which the food is placed is taken out as a signal indicating the weight of the food, and the microwave irradiation time is determined based on the signal indicating the weight. Control such as determination.
[0018]
As shown in FIG. 1, the weight detection device 1 can be broadly divided into rotations that rotate the turntable 11 and rotate first and second relative rotational displacement members 42 and 43 described later together with the thrust shaft 41. The driving unit 12 and a weight detection unit 13 that detects the amount of displacement in the thrust direction of the turntable 11 are configured. Each of these components is housed in a single metal casing 14. The casing 14 includes a case body 14a and a case lid 14b. The first and second relative rotational displacement members 42 and 43 are sandwiched from above and below by the bottom surface of the case body 14a and the inner surfaces of the case lid 14b. It is arranged like this.
[0019]
The rotation driving means 12 includes a motor 20 as a drive source (here, a synchronous motor is used), a first gear 31 as a reduction gear train that decelerates the rotational force of the motor 20 and transmits it to the turntable 11, The second gear 32, the third gear 33, the second relative rotational displacement member 43 serving as the output gear, the reverse rotation preventing lever 34a for preventing the motor 20 from rotating in reverse, and the reverse rotation preventing lever rotation disposed coaxially with the reverse rotation preventing lever 34a. And a gear 34. The reverse rotation prevention lever 34a and the reverse rotation prevention lever rotation gear 34 are urged in the thrust direction by a spring. When the rotor 22 of the motor 20 rotates in the direction opposite to the normal rotation direction, the reverse rotation prevention lever 34a engages with a protrusion formed on the pinion 24 that rotates integrally with the rotor 22, and reverse rotation of the rotor 22 occurs. It comes to prevent.
[0020]
The weight detection unit 13 is fixed to the center of the turntable 11 and has a thrust shaft 41 that is displaced in the thrust direction according to the weight applied to the turntable 11 and a first shaft that is engaged with the thrust shaft 41. And a second relative rotational displacement member 42, 43, a rotational displacement means 44 that relatively rotationally displaces the two relative rotational displacement members 42, 43 by a predetermined amount according to the displacement amount of the thrust shaft 41, and a first An urging spring 45 as a position holding means for holding the positional relationship in the rotation direction of the first and second relative rotational displacement members 42, 43, a weight detection signal output means described later, and a tip end side of the thrust shaft 41 The arranged coil spring 46 is a main component. The signal output from the weight detection signal output means is converted into weight by weight conversion means (not shown) made of a microcomputer.
[0021]
The first and second relative rotational displacement members 42 and 43 are coaxially provided on the thrust shaft 41 so as to make a pair with each other. The first relative rotational displacement member 42 rotates according to the displacement of the thrust shaft 41 in the thrust direction, and the second relative rotational displacement member 43 rotates depending on the displacement of the thrust shaft 41 in the thrust direction. Instead, it is rotated by receiving a rotational driving force from the rotational driving means 12. That is, the second relative rotational displacement member 43 serves as an output gear that is a part of the speed reduction wheel train that constitutes the rotation driving means 12 and that engages with another gear.
[0022]
The rotational displacement means 44 engages the first and second relative rotational displacement members 42, 43 and the thrust shaft 41. When the thrust shaft 41 is displaced in the thrust direction, the first relative rotational displacement member 42 is engaged. When the second relative rotation displacement member 43 is rotated by receiving the driving force from the rotation driving means 12, the second relative rotation displacement member 43 is rotated by a predetermined rotation angle around the thrust shaft 41 according to the displacement amount of the thrust shaft 41. The rotational force can be transmitted to the thrust shaft 41. The rotational displacement means 44 includes “let” -shaped grooves 42 b and 42 c formed in the first relative rotational displacement member 42, and thrust grooves 43 b and 43 c formed in the second relative rotational displacement member 43. When the first and second relative rotational displacement members 42 and 43 are fitted together, the horizontal axis is fitted into the overlapping portions of the grooves 42b and 43b and the grooves 42c and 43c. And a pin 44a. Details of these will be described later.
[0023]
The biasing spring 45 is a coil spring, and serves as a position holding means for holding the positional relationship between the first and second relative rotational displacement members 42 and 43 in the rotational direction.
[0024]
That is, when the first and second relative rotational displacement members 42 and 43 are fitted together, the biasing spring 45 applies a force in the circumferential direction to the first relative rotational displacement member 42, and both inclined surface portions 42d. , 42e and the pin 44a are made stronger. Thereby, the relative displacement amounts of the first and second relative rotational displacement members 42 and 43 are reliably maintained. That is, by performing the position holding by the biasing spring 45, the accuracy at the time of weight measurement is further stabilized.
[0025]
The weight detection signal output means outputs a signal corresponding to the relative displacement amounts of the first and second relative rotational displacement members 42 and 43 as the weight detection signal. As shown in FIG. 6, the weight detection signal output means includes three magnets B1, B2, and B3 that are to be detected provided on the first relative rotational displacement member 42 side, and a second relative rotational displacement. It consists of three magnets A1, A2, and A3 that are to be detected provided on the member 43 side, and a Hall IC 47 that is a detector that converts the magnetism generated by these magnets B1 to B3 and A1 to A3 into electrical signals. . Details of these will be described later.
[0026]
The weight detector 13 having such a configuration will be described in more detail. As described above, one end (rear end) of the thrust shaft 41 is engaged with or fixed to the turntable 11, the rotational force of the motor 20 is transmitted to the turntable 11, and the cooked product is placed on the turntable 11. As a result, it is lowered together with the turntable 11 in the thrust direction. A bush 48 and a cap member 49 for pushing down the coil spring 46 are attached to the other end (tip) side of the thrust shaft 41.
[0027]
The coil spring 46 is a coil spring called a square coil spring having a quadrilateral cross section, and applies a biasing force against the thrust shaft 41 to the thrust shaft 41. That is, the thrust shaft 41 is supported by the coil spring 46 and is displaced in the thrust direction against the restoring force of the coil spring 46 according to the weight. The coil spring 46 is housed in a protruding cylindrical portion 14c that is fixed to the case body 14a with screws.
[0028]
Further, as shown in FIG. 3, the first relative rotational displacement member 42 has a cylindrical shape, and a hole 42 a through which the thrust shaft 41 passes is formed at the center. A pair of grooves 42b and 42c are formed in the side cylindrical portion at positions facing each other across the central axis. As shown in FIG. 4, the groove 42 b is expanded upward with a sloped portion 42 d having a predetermined angle with respect to the central axis direction and a vertical surface portion 42 f formed in substantially the same direction as the central axis direction. "It is a groove of shape. In addition, the inclination angle θ1 with respect to the reference surface p (surface orthogonal to the thrust axis 41) of the inclined surface portion 42d is about 45 degrees. The angle θ2 of the vertical surface portion 42f with respect to the reference plane p is (90 + α (α ≧ 0), α = about 1 degree is ideal) degrees. Also, the groove 42c has the same shape as the groove 42b, that is, a "le" shape having a sloped part 42e having a predetermined angle with respect to the central axis direction and a vertical surface part 42g formed in substantially the same direction as the central axis direction. It has become a groove.
[0029]
Thus, both grooves 42b and 42c have a “let” shape, and a so-called undercut portion (from the groove bottom toward the thrust direction release end side) It has a shape that does not have a part that hits. For this reason, it is not necessary to perform a special mold molding such as unscrewing, and the cost of the mold can be reduced.
[0030]
It should be noted that the tilt angle θ1 can be further laid down (the tilt angle θ1 can be further reduced) by not performing the punching molding. That is, in the punching molding, in order to prevent the shape of the groove from collapsing until the resin constituting the member is cooled and solidified after molding, the inclination angle θ1 must be set to 60 degrees or more. . However, when there is no undercut portion and the mold can be pulled straight in the thrust direction, naturally, the groove shape does not collapse even if the inclination angle θ1 is configured many times. From another point of view, each of the inclined portions 42d and 42e of the grooves 42b and 42c receives the weight of the turntable 11 by contacting the pin 44a described above, and this is received by the first relative rotational displacement member 42. In order to accomplish this, an angle of at least about 45 degrees is desirable.
[0031]
As described above, when the inclination angle θ1 of the inclined surfaces 42d and 42e is further laid down, the rotation angle of the first relative rotational displacement member 42 due to the thrust shaft 41 sinking in the thrust direction becomes larger. Therefore, the rotation angle with respect to the same distance in the thrust direction is increased, and the resolution of the weight detector 13 as a detector is further improved. In this embodiment, in order to increase the resolution as described above, the inclination angle θ1 of the inclined surface portions 42d and 42e is set to about 45 degrees. It may be about 60 degrees. In the case of such a configuration, there is no effect of increasing the resolution as compared with the case of molding by unscrewing, but there is an effect that the mold can be simplified.
[0032]
Further, as shown in FIG. 3, magnet loading portions 51a and 51b for loading magnets B1, B2 and B3 arranged at intervals of 120 ° are provided outside the side cylindrical portion of the first relative rotational displacement member 42. , 51c are provided. The magnet loading part 51a, which is one of these magnet loading parts 51a, 51b, 51c, is attached to hold the positional relationship in the rotational direction of the first and second relative rotational displacement members 42, 43. A protrusion 51d that locks one end of the spring 45 is provided. Note that the other end side of the biasing spring 45 is loaded into a storage portion including a storage wall 52d and a pressing protrusion 52e provided in the second relative rotational displacement member 43.
[0033]
On the other hand, as shown in FIG. 5, the second relative rotational displacement member 43 that also serves as an output gear has a cylindrical shape with one end having a bottom and the other end having an opening, and the inner diameter thereof is that of the first relative rotational displacement member 42. It has an inner cylindrical portion 43a that is slightly larger than the outer diameter and formed concentrically inside. The outer diameter of the inner cylindrical portion 43a is slightly smaller than the inner diameter of the first relative rotational displacement member 42, and the side cylindrical portion has a pair of thrust directions in positions facing each other across the central axis of the cylinder. Cutout grooves 43b and 43c are formed. The grooves 43b and 43c do not hinder the operation in the thrust direction of the pin 44a inserted through the thrust shaft 41 so as to be orthogonal to the thrust shaft 41, that is, the pin 44a can freely move in the thrust direction. ing.
[0034]
A hole 43 d through which the thrust shaft 41 passes is formed in the center portion on the bottomed end side of the second relative rotational displacement member 43. The second relative rotational displacement member 43 has a gear formed on the outer surface thereof, meshes with the third gear 33 of the rotation driving means 12, and also functions as an output gear.
[0035]
One end of the second relative rotational displacement member 43 is in contact with a leaf spring 50 made of a metal plate-like spring member. The leaf spring 50 is disposed between the first and second relative rotational displacement members 42 and 43 and the inner surface of the case lid 14b. As shown in FIG. 2, the leaf-shaped spring 50 includes an annular portion formed in a flat plate shape, and a spring portion extended outward so as to bend toward the case lid 14b from the outer peripheral portion of the annular portion. The second relative rotational displacement member 43 and the first relative rotational displacement member 42 are urged toward the case main body 14a by abutting each spring portion against the inner surface of the case lid 14b. ing. Thus, the leaf spring 50 is a biasing means that biases the first and second relative rotational displacement members 42 and 43 in the thrust direction.
[0036]
The first relative rotational displacement member 42 and the second relative rotational displacement member 43 include an end portion where the inlet portions of the grooves 42b and 42c of the first relative rotational displacement member 42 are provided, and a second relative rotational displacement member. The first relative rotational displacement member 42 is inserted into the second relative rotational displacement member 43 so as to face the open end of 43. As a result, the inner cylindrical portion 43 a of the second relative rotational displacement member 43 is inserted into the first relative rotational displacement member 42.
[0037]
A cylindrical protrusion 43 e (see FIG. 2) protruding outward is formed at the bottomed end of the second relative rotational displacement member 43, and the cylindrical protrusion 43 e is formed on the leaf spring 50. It is in contact. Thereby, the 2nd relative rotational displacement member 43 is urged | biased by the bottom face side of the case main body 14a. A flat washer 54 is disposed between the inner surface of the case body 14 a and the first and second relative rotational displacement members 42, 43 on the opening end side of the second relative rotational displacement member 43. . Thus, since the second relative rotational displacement member 43 is biased from one side by the leaf spring 50 and the other is pressed against the washer 54, the movement in the vertical direction is restricted. The first relative rotational displacement member 42 is pressed against the washer 54 side by the biasing force of the tooth spring 50 via the second relative rotational displacement member 43. The second relative rotational displacement member 42 is also pressed against the washer 54 by an urging force generated from the urging force of the urging spring 45.
[0038]
As described above, the washer 54 has the first and second relative rotational displacement members 42 when the weight is not applied to the turntable 11 (that is, in the initial state) or when the cooking member is not placed on the turntable 11. 43 are in contact with each other. That is, the washer 54 serves as a reference surface that receives the end surfaces of the first and second relative rotational displacement members 42 and 43 that are biased by the leaf spring 50 serving as a biasing means in the initial state or during cooking. The first and second relative rotational displacement members 42 and 43 are relatively displaced from the reference surface in accordance with the weight applied to the turntable 11. With this configuration, the relative displacement amount of both due to the weight is stabilized, and it is possible to reliably detect the weight without error.
[0039]
Although the end faces of the first and second relative rotational displacement members 42 and 43 biased by the leaf spring 50 are in contact with the washer 54 at the same time, the first relative rotational displacement member Only 42 may be in contact with the washer 54. When only the second relative rotational displacement member 43 is in contact with the washer 54, the first relative rotational displacement member 42 is also in contact with the washer 54 by the biasing force of the biasing spring 45. . The washer 54 is provided so that the first and second relative rotational displacement members 42 and 43 rotate smoothly. However, the washer 54 is eliminated, and the bottom surface of the case body 14a is directly used as a reference plane. Also good.
[0040]
In addition, the pin 44a is attached to the thrust shaft 41 so that the pin 44a crosses the central axis of the thrust shaft 41 at right angles so that both ends of the pin 44a protrude on both sides (referred to as left and right). The left and right protruding portions of the pin 44 a engage with axial grooves 43 b and 43 c formed in the inner cylindrical portion 43 a of the second relative rotational displacement member 43, and the first relative rotational displacement member 42. The grooves 42b and 42c are formed in contact with the inclined surfaces 42d and 42e and are pressed against the contact surfaces by the biasing force of the biasing spring 45 and the rotational driving force of the motor 20. Furthermore, one end of the pin 44a is engaged with a groove 43b formed in the inner cylindrical portion 43a of the second relative rotational displacement member 43 and a slit 43f disposed opposite to the first relative rotational displacement member 42. Yes.
[0041]
The tip of the thrust shaft 41 passes from the case body 14 through the washer 54 and the bearing member 53 a to reach the cap member 49 disposed in the protruding cylindrical portion 14 c, and pushes the cap member 49 by the weight applied to the turntable 11. An operation of compressing the coil spring 46 is performed. At this time, the tip of the thrust shaft 41 is in contact with the cap member 49 via the bush 48 and is rotatable with respect to the bush 48. The rear end side of the thrust shaft 41 protrudes outward from the case lid 14 b and is engaged with or fixed to the turntable 11.
[0042]
The thrust shaft 41 is attached in such a state. That is, the pin 44a attached to the thrust shaft 41 is formed in the grooves 43b and 43c (formed in the same direction as the central axis, that is, in the thrust direction) on the second relative rotational displacement member 43 side as described above. While being engaged, it is engaged with the slope portion 42d of the groove 42b and the slope portion 42e of the groove 42c on the first relative rotational displacement member 42 side. For this reason, when the thrust shaft 41 is operated so as to be pushed down, the pin 44a tends to move downward along the grooves 43b and 43c on the second relative rotational displacement member 43 side. At this time, the second relative rotational displacement member 43 is not rotated because the movement in the rotational direction is restricted and the grooves 43b and 43c are the same as the axial direction. On the other hand, in the first relative rotational displacement member 42, the slopes 42d and 42e are pressed downward by the pin 44a when the pin 44a moves downward. As a result, a component force acts on the slope portions 42d and 42e, and the first relative rotational displacement member 42 rotates in the rotational direction about the thrust shaft 41.
[0043]
Thus, when a load is applied to the turntable 11, the thrust shaft 41 is displaced (lowered) in proportion to the load, and accordingly, the first relative rotational displacement member 42 can move in the rotational direction. ing.
[0044]
When the turntable 11 is rotationally driven, if the motor 20 is energized, the rotational force is transmitted from the first gear 31 to the third gear 33, and further, the third gear 33 has teeth. It is transmitted to the second relative rotational displacement member 43 that is combined. When the second relative rotational displacement member 43 rotates, the rotational force is transmitted to the thrust shaft 41 via the pin 44a, whereby the turntable 11 can be rotated.
[0045]
As described above, the slopes 42d and 42e of the grooves 42b and 42c provided on the pin 44a and the first relative rotational displacement member 42 side, and the grooves 43b and 43c provided on the second relative rotational displacement member 43 side are: When the thrust shaft 41 is displaced in the thrust direction, the first relative rotational displacement member 42 is rotated by a predetermined rotation angle about the thrust shaft 41 according to the displacement amount of the thrust shaft 41. Then, when the second relative rotational displacement member 43 rotates by receiving the driving force from the rotational driving means 12, the pin 44 a and the like perform an operation that enables the rotational force of the motor 20 to be transmitted to the thrust shaft 41. That is, the pins 44a and the like constitute the above-described rotational displacement means.
[0046]
Next, means for outputting an electrical signal corresponding to the magnitude of the load applied to the turntable 11 by the relative movement of the first relative rotational displacement member 42 with respect to the second relative rotational displacement member 43, that is, a weight detection signal output. Means will be described.
[0047]
In the first relative rotational displacement member 42, three magnets B1, B2, B3 are arranged at equal intervals on the same plane. These magnets are separated by 120 °. On the other hand, on the second relative rotational displacement member 43, three magnets A1, A2, A3 are arranged at equal intervals on the same plane. These magnets are separated by 120 °. In the state where the first and second relative rotational displacement members 42 and 43 are fitted so as to be coaxial as described above, the six magnets A1, A2, A3, B1, B2, B3 described above are Corresponding magnets, that is, magnet A1 and magnet B1, magnet A2 and magnet B2, and magnet A3 and magnet B3 are arranged on the same plane so as to be separated by 33.24 °.
[0048]
In the vicinity of the magnet, a Hall IC 47 that converts the magnetism into an electric signal and outputs it is fixedly arranged. The Hall IC 47 is configured such that a terminal portion protrudes outside the casing 14 through a hole (not shown) provided on the bottom surface of the case body 14a, and this protruding portion is attached on a printed circuit board (not shown). And is covered by a holder. Moreover, components such as connectors are also mounted on the printed circuit board.
[0049]
FIGS. 7A and 7B are diagrams for explaining the positional relationship among these magnets A1, A2, A3, magnets B1, B2, B3, and Hall IC 47, and are schematic diagrams for easy understanding. There are also portions that do not directly represent the structure shown in FIGS. 1 to 6 used in the above description.
[0050]
As shown in FIG. 5, the magnets A1, A2, and A3 are respectively loaded into magnet loading portions 52a, 52b, and 52c provided at equal intervals on the circumferential portion of the second relative rotational displacement member 43. As shown in FIG. 3, the magnets B1, B2, and B3 are loaded in magnet loading portions 51a, 51b, and 51c provided at equal intervals on the circumferential portion of the first relative rotational displacement member 42, respectively. Magnets A1, A2, A3 and magnets B1, B2, B3 are alternately arranged on the same plane. FIG. 7A shows a positional relationship corresponding to the state of FIG. 6, and is a positional relationship in a state where the thrust shaft 41 is in an initial state (a state in which a cooked product is not placed on the turntable 11). FIG. 7B shows the positional relationship when the cooked product is placed on the turntable 11 and the thrust shaft 41 is fully loaded, assuming that the lowered state is about 60%.
[0051]
In FIG. 7A, the interval between a pair of magnets (for example, the magnet A1 and the magnet B1) arranged in the proximity position is 33.24 °. When the cooked product (4 kg) is placed on the turntable 11 and the thrust shaft 41 is lowered by about 60%, the first relative rotational displacement member 42 rotates by about 60%. Then, as shown in FIG. 7B, the magnets B1, B2, B3 of the first relative rotational displacement member 42 each move in the circumferential direction of 20 °. Therefore, as described above, the gap between the pair of magnets (for example, the magnet A1 and the magnet B1) arranged at the close positions in the initial state is opened to 53.24 °.
[0052]
In such a configuration, the operation will be described. First, when a cooked product is not placed on the turntable 11, the relationship between the first relative rotational displacement member 42 and the second relative rotational displacement member 43 is as shown in FIG. ing.
[0053]
If the motor 20 rotates in this state, the second relative rotational displacement member 43 also starts to rotate, and an output as shown in FIG. In other words, signals are output from the Hall IC 47 at time intervals proportional to the angle between adjacent magnets.
[0054]
Here, considering only the magnets A1, A2 and A3 in the second relative rotational displacement member 43, as the turntable 11 rotates, the signal As1 of the Hall IC 47 by the magnet A1 and the signal As2 of the Hall IC 47 by the magnet A2. If the time until (the time between the centers of the time widths in each signal) is t, this time t is invariable and corresponds to an angle of 120 °. Therefore, when there is no food on the turntable 11, the signal As1 is first output from the Hall IC 47 between the magnet A1 and the magnet B1, and when time = 0.28t corresponding to an angle of 33.24 ° has elapsed, A signal Bs1 is output.
[0055]
Next, between the magnet B1 and the magnet A2, a signal Bs1 is output from the Hall IC 47, and a signal As2 is output when a time corresponding to an angle of 86.76 ° = 0.72 t elapses.
[0056]
In addition, as a method of measuring the time between signals output from the Hall IC 47, as described above, the length between the signal centers (signal width centers) is measured. This is because the output signal width of the Hall IC 47 may change depending on the temperature. In order to cope with this, the center of the output signal is measured.
[0057]
On the other hand, when some cooked product is placed on the turntable 11 and cooking is started, the turntable 11 starts rotating, and the thrust shaft 41 is lowered together with the turntable 11 by the weight of the cooked product.
[0058]
As a result, the first relative rotational displacement member 42 rotates in proportion to the descending amount of the turntable 11, and the angle between the adjacent magnets changes, such as the magnet B1 with respect to the magnet A1 and the magnet B2 with respect to the magnet A2. To do.
[0059]
For example, when a 4 kg cooked product is placed on the turntable 11, the relationship between the magnets A1, A2, A3 on the second relative rotational displacement member 43 side and the magnets B1, B2, B3 on the first relative rotational displacement member 42 side. Is in a positional relationship as shown in FIG. That is, the angle between the magnets in the close position in the initial state of the magnet on the first relative rotational displacement member 42 side and the magnet on the second relative rotational displacement member 43 side (for example, the angle between the magnets of the magnet A1 and the magnet B1). , 53.24 °, and the angle with the magnet (for example, magnet A2 for magnet B1) arranged at a position not close to each other is reduced to 66.76 °. Such an output is obtained.
[0060]
As can be seen from FIG. 8B, the time interval between the signal As1 for the magnet A1 and the signal Bs1 for the magnet B1 is about 44% of the time interval t between the signal As1 for the magnet A1 and the signal As2 for the magnet A2. Becomes 0.44t. That is, signals at different time intervals can be extracted from the Hall IC 47 in accordance with the weight of the cooked product. Therefore, the weight of the cooked product can be measured using the output of the Hall IC 47. The displacement amount is converted into weight by a microcomputer (not shown).
[0061]
FIG. 9 shows the load applied to the turntable (the weight of the cooked product) and the time interval of the Hall IC output by the magnet B1 with respect to the Hall IC output by the magnet A1, expressed as a percentage between the magnets A1, A2 and A3. Each time interval t is defined as 100%, which is a percentage with respect to t. The relationship between the magnet B2 for the magnet A2 and the magnet B3 for the magnet A3 is the same. As can be seen from FIG. 9, when the load is 0, it is 28% (0.28 t), when the load is 1 kg, it is about 32% (0.32 t), and when the load is 4 kg, it is about 44% (0. 44t), the time interval becomes longer in proportion to the load. At the maximum load (7 kg), the time interval is about 56% (0.56 t).
[0062]
On the other hand, FIG. 10 shows the load (the weight of the cooked product) applied to the turntable and the time interval of the Hall IC output by the magnet A2 with respect to the Hall IC output by the magnet B1, expressed as a percentage, and the magnets A1, A2, A3. Each time interval t between them is defined as 100%, which is a percentage with respect to t. The relationship between the magnet A3 with respect to the magnet B2 and the relationship between the magnet A1 with respect to the magnet B3 is the same. As can be seen from FIG. 10, when the load is 0, it is 72% (0.72 t), when the load is 1 kg, it is about 68% (0.68 t), and when the load is 4 kg, it is about 56% (0. 56t), the time interval becomes shorter in proportion to the load. At the maximum load (7 kg), the time interval is about 44% (0.44 t).
[0063]
Based on such a relationship, the weight of the cooked product can be detected, and if the weight of the cooked product is known, the cooking time or the like considering that can be automatically set.
[0064]
By the way, in the description so far, the magnet on the second relative rotational displacement member 43 side and the magnet on the first relative rotational displacement member 42 side are each composed of three pairs of three, but more may be used. And it is good also as a pair. In principle, the amount of displacement of the turntable 11 is determined by the time interval of the Hall IC 47 even if the magnet on the second relative rotational displacement member 43 side and the magnet on the first relative rotational displacement member 42 side are only one pair. It can be taken out as a displacement. However, in order to enable use regardless of the difference between the 50 kHz region and the 60 kHz region, the reference time (in this case, the time between the magnets A1, A2, and A3 on the second relative rotational displacement member 43 side). It is preferable to express the displacement (= ratio) with respect to the interval t). Therefore, in order to obtain the displacement amount, it is desirable to provide at least three magnets of the first and second relative rotational displacement members 42 and 43 in total.
[0065]
As described above, in the above-described embodiment, the displacement amount in the thrust direction of the turntable 11 is converted into the displacement amount in the rotation direction of the first relative rotational displacement member 42, and the hall is proportional to the displacement amount in the rotation direction. The output of the IC 47 is obtained, and the weight of the cooked product placed on the turntable 11 is detected based on the displacement amount of the output of the Hall IC 47. Thus, unlike the capacitance type weight detection device, the weight detection device of the present invention has various problems that the capacitance type conventionally has, for example, floating that occurs in a wiring pattern on a printed circuit board. In order to cope with the influence on the capacity, it is necessary to secure a certain capacitance or more, so that the facing area between the electrodes increases, the problem of increasing the size of the apparatus does not occur, and the weight is small and accurate. Detection is possible. In addition, these weight detection operations can be performed while the turntable 11 is rotating by placing a cooked product on the turntable 11 and starting cooking, and is performed at the maximum while the turntable 11 makes one round. Therefore, efficient weight detection becomes possible.
[0066]
Further, the rotation drive means 12 for rotating the turntable 11 and the weight detection unit 13 for detecting the weight are housed in one casing 14, in other words, the weight detection unit 13 is connected to the rotation drive means 12. Since the weight detection unit 13 and the rotation driving means 12 are assembled separately and then combined together, the number of assembly steps can be reduced and the overall size can be reduced. It is possible to reduce the cost.
[0067]
The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the grooves 42b and 42c provided in the first relative rotational displacement member 42 have a “let” shape, and the angle θ2 of the vertical surface portions 42f and 42g is (90 + α) degrees. θ2 may be exactly 90 degrees. In addition, the angle θ2 is not set to about 90 degrees, but a large obtuse angle (for example, 100 degrees, 110 degrees, 135 degrees, etc. may be used as many times), and the grooves 42b and 42c have a “V” shape instead of a “let” shape. It is good.
[0068]
Further, in the above-described embodiment, the displacement amount is detected by the magnetic detection means by the magnets A1, A2, A3, B1, B2, B3 and the Hall IC 47. It is feasible. For example, a plurality of overlapping slits are provided on both the first relative rotational displacement member 42 and the second relative rotational displacement member 43 so that the length of the overlapping slits changes as the thrust shaft is displaced in the thrust direction. Anyway.
[0069]
In the case of this configuration, the photoelectric conversion means such as a photodiode and a phototransistor are arranged to face each other with the slit interposed therebetween, and the thrust shaft is displaced in the thrust direction, whereby the slit length of the overlapping slit is changed. Then, a change in the slit length of the overlapping slits can be taken out as an interval of output signals from the phototransistor, and weight detection can be performed based on this. Also by this, the weight can be detected as in the above-described embodiment.
[0070]
In the above-described embodiment, the first relative rotational displacement member 42 is rotationally displaced by the displacement of the thrust shaft 41 in the thrust direction, and the second relative rotational displacement member 43 is not displaced. The members 42 and 43 may be displaced together, or only the second relative rotational displacement member 43 may be displaced. Moreover, you may employ | adopt other shapes and structures, such as making the magnet into the structure which made the outer peripheral part of the circular rubber magnet convex. Further, the coil spring 46 may be a circular or other shape coil spring instead of a square coil spring. Furthermore, instead of a coil spring, another spring such as a plate spring or a disc spring may be used, or another elastic member such as a rubber material or a plastic material may be used.
[0071]
Furthermore, in the above-described embodiment, the case where the weight of the cooked product in the microwave oven is detected has been described as an example. However, the present invention is not limited to the microwave oven, and the weight of other devices such as an oven and a toaster are not limited. It can also be applied to detection. The present invention can also be applied to detection of the weight of other articles other than cooked products.
[0072]
【The invention's effect】
As described above, the weight detection device of the present invention includes the rotational displacement member that rotates and displaces according to the thrust direction displacement of the thrust shaft that displaces in the thrust direction according to the weight to be detected. Since a signal corresponding to the amount of displacement is output as a weight detection signal, highly accurate weight detection is possible with a simple configuration, and the size can be reduced as compared with a conventional electrostatic capacitance type weight detection device. In addition, since the groove including the inclined surface portion that rotates the rotational displacement member in response to the thrust load has no undercut portion, a special construction method such as unscrewing is not used in molding the rotational displacement member, and the thrust direction is not used. It is possible to mold by simply removing the mold. For this reason, manufacture becomes easy.
[0073]
In another invention, two rotational displacement members are rotated relative to each other in accordance with the displacement in the thrust direction of the thrust shaft that is displaced in the thrust direction according to the weight to be detected, and a signal corresponding to the relative displacement is detected by weight. Since it is output as a signal, it is possible to detect a weight with high accuracy with a simple configuration by using a magnet and a Hall element, and the size can be reduced as compared with a conventional capacitance type weight detection device.
[0074]
Moreover, since the microwave oven of this invention can make the weight detection apparatus which detects the weight of a cooked product small, a microwave oven itself is reduced in size. In addition, since it is possible to detect the weight with high accuracy, it is possible to set an appropriate cooking time when performing control for automatically setting the cooking time with respect to the weight of the cooked product.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing an embodiment of a weight detection device of the present invention.
FIG. 2 is an exploded perspective view of the weight detection apparatus shown in FIG.
FIG. 3 is a perspective view illustrating in detail the first relative rotational displacement member shown in FIGS. 1 and 2;
4 is a schematic view showing a groove of the first relative rotational displacement member shown in FIG. 3 in a plan view. FIG.
5 is a perspective view for explaining in detail the second relative rotational displacement member shown in FIGS. 1 and 2. FIG.
6 is a sectional view taken along line VI-VI in FIG.
7 is a diagram for explaining the positional relationship between the magnets on the first relative rotational displacement member side and the magnets on the second relative rotational displacement member side of the weight detection apparatus shown in FIG. 1 and the arrangement of the Hall ICs. (A) is a figure which shows the case where the load is not applied to the turntable, (B) is a figure which shows the case where the load of about 4 kg is added to the turntable.
8 is a diagram showing an output signal of the Hall IC used in the weight detection device shown in FIG. 1, and FIG. 8 (A) is a diagram showing an output signal when no load is applied to the turntable; ) Is a diagram showing an output signal when a load of about 4 kg is applied to the turntable.
FIG. 9 shows a load applied from the turntable to the weight detection device shown in FIG. 1 on the horizontal axis, and a hole by the magnet on the first relative rotational displacement member side with respect to the Hall IC output by the magnet on the second relative rotational displacement member side. It is the graph which made the vertical axis | shaft the value (= phase difference of magnet A, B) which showed the time interval of IC output in percentage.
FIG. 10 shows a load applied from the turntable to the weight detection device shown in FIG. 1 on the horizontal axis, and a hole by a magnet on the second relative rotational displacement member side with respect to a Hall IC output by the magnet on the first relative rotational displacement member side. It is the graph which made the vertical axis | shaft the value (= phase difference of magnet A, B) which showed the time interval of IC output in percentage.
[Explanation of symbols]
1 Weight detector
11 Turntable
12 Rotation drive means
13 Weight detector
20 Motor (part of rotation drive means)
31 1st gear (a part of rotation drive means)
32 Second gear (part of rotation drive means)
33 Third gear (part of rotation drive means)
41 Thrust shaft
42 1st relative rotational displacement member
42b, 42c groove
42d, 42e Slope portion (part of rotational displacement means)
43 Second relative rotational displacement member
43a Internal cylindrical part
43b, 43c Thrust direction groove (part of rotational displacement means)
44 Rotating displacement means
44a pin
47 Hall IC (detector)
AI, A2, A3 Magnet on second relative rotational displacement member side (detected body)
B1, B2, B3 First relative rotational displacement member side magnet (detected body)

Claims (5)

A thrust shaft that is displaced in the thrust direction according to the weight to be detected, a rotational displacement member that is displaced in the rotational direction by a predetermined amount according to the displacement amount of the thrust shaft, and a weight conversion that converts the displacement amount of the rotational displacement member as a weight And the rotational displacement member receives the weight to be detected by coming into contact with a horizontal axis inserted through the thrust shaft so as to be orthogonal to the thrust shaft, and receives the weight to be detected by the rotational movement of the rotational displacement member. A weight detecting device comprising a groove portion having a slope portion to be converted into a groove and having no undercut portion in a thrust direction. A thrust shaft that is displaced in the thrust direction according to the weight to be detected, a rotational displacement member that is displaced in the rotational direction by a predetermined amount according to the displacement amount of the thrust shaft, and a weight conversion that converts the displacement amount of the rotational displacement member as a weight And the rotational displacement member receives the weight to be detected by coming into contact with a horizontal axis inserted through the thrust shaft so as to be orthogonal to the thrust shaft, and receives the weight to be detected by the rotational movement of the rotational displacement member. A groove having a slope portion to be converted into the cylindrical side surface, and the groove is configured by the slope portion having a predetermined angle with respect to the thrust shaft on one side in the circumferential direction, and the edge on the other side. A weight detection device comprising a slope portion having a predetermined angle with respect to the thrust shaft substantially parallel to the thrust shaft or opposite to the slope portion in the circumferential direction. Thrust shafts that are displaced in the thrust direction according to the weight to be detected, and first and second relative rotational displacement members that are respectively engaged with the thrust shafts and are rotated relative to each other when the weight is applied. A rotational displacement means for relatively rotating the two relative rotational displacement members by a predetermined amount in accordance with a displacement amount of the thrust shaft, and the first and second relative rotational displacement members as the thrust shaft. Rotation driving means for rotating integrally, and the first and second relative rotational displacement members are arranged in the detectable areas of the detected bodies respectively provided on the first and second relative rotational displacement members, and the first and the second are detected by detecting the detected bodies. A detector that detects the relative displacement amount of the second relative rotational displacement member by utilizing the integral rotation of the first and second relative rotational displacement members, and a weight that converts the displacement amount as a weight. Conversion means The first relative rotational displacement member receives the weight to be detected by contacting the horizontal shaft inserted through the thrust shaft so as to be orthogonal to the thrust shaft, and receives the weight to be detected. The second relative rotational displacement member has a thrust direction that does not hinder the operation of the horizontal axis in the thrust direction. A weight detection device comprising a groove, wherein the rotational displacement means is constituted by the groove in the thrust direction, the slope portion, and the horizontal axis. The weight according to claim 1, 2 or 3, wherein the thrust shaft is rotationally driven only in a direction in which the horizontal axis receives the weight to be detected and converts the weight into a rotational motion that is pressed against the inclined portion. Detection device. In the microwave oven having a weight detection device for detecting the weight applied to the turntable based on the displacement amount, the turntable can be displaced in the thrust direction according to the weight applied to the turntable. A microwave oven provided with the weight detection device according to claim 1, 2, 3 or 4.

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