JP4412295B2 - Instrument device - Google Patents

Description

  The present invention relates to an instrument device that rotationally drives a pointer by a drive source including a rotor.

As the above-described instrument device, for example, one described in Patent Document 1 is known. This instrument device is used, for example, as an instrument that indicates a vehicle speed in an automobile, and enables the pointer to turn without a sense of incongruity even when the degree of change in the input analog amount indicating the vehicle speed is large. Specifically, while the difference between the current target instruction angle and the current instruction angle of the pointer is larger than the deceleration start reference value, that is, while the degree of increase or decrease in vehicle speed is large, If the amount of change from the previous target instruction angle is equal to or greater than the sum of the previous drive amount of the step motor and the predetermined acceleration amount, the method of rotating the pointer is accelerated based on the acceleration amount. On the other hand, when the difference between the current target instruction angle and the current instruction angle is equal to or less than the deceleration start reference value, that is, when the increase or decrease of the vehicle speed decreases, the way of turning the pointer based on the acceleration amount described above. To slow down.
Japanese Patent Laid-Open No. 2003-130884

  By the way, in the instrument device as described above, generally, a rotation transmission mechanism such as a reduction gear train that reduces the rotation angle of the pointer with respect to the rotation angle of a drive source such as a step motor is provided. By providing this rotation transmission mechanism, the pointer can be driven almost continuously, not stepwise, so that it can appear to the user as if the pointer is moving smoothly.

  However, when a rotation transmission mechanism comprising a reduction gear train or the like is used, there is always a mechanical play in the meshing of the gears. Therefore, a mechanical play in the rotation transmission path from the drive source including the rotation transmission mechanism to the pointer is included. Will become bigger. As a result, a dead zone in which the pointer does not move even when the drive source rotates is generated by the amount of mechanical play, and hysteresis occurs at the indicated position of the pointer. In other words, when the pointer is rotated in the first direction and when it is rotated in the second direction opposite to the first direction, even if the pointer is driven to the same indicated position, there is a deviation in the indicated position. It ends up.

  This invention is made | formed in view of the point mentioned above, and it aims at providing the measuring device which can reduce the shift | offset | difference of the indication position of a pointer | guide.

In order to achieve the above object, the instrument device according to claim 1 comprises:
Guidelines,
A drive source having a rotor, and rotating the pointer in the first direction or the second direction by rotating the rotor in the first direction or the second direction;
A transmission mechanism that transmits the rotation of the rotor to the pointer;
An instrument device comprising control means for driving and controlling a drive source so as to rotate the rotor to a rotation angle corresponding to a target indication position of the pointer,
There is a mechanical play in the rotation transmission path from the drive source to the pointer through the transmission mechanism, and as a result of the mechanical play, even if the rotor rotates, the pointer does not move, and as a result, there is hysteresis at the indicated position of the pointer. That occurs,
The pointer has a minimum mechanical play in the rotation transmission path when the pointer is rotationally driven in the first direction at a predetermined reference position, and a maximum mechanical play when the pointer is rotationally driven in the second direction. Is coupled to the transmission mechanism,
When the pointer is driven to rotate in the second direction, the control means rotates using the angle obtained by adding the compensation angle for compensating the mechanical play of the rotation transmission path to the rotation angle corresponding to the target indication position of the pointer as the target angle. The child is rotated in the second direction.

  As described above, when the pointer is rotationally driven in the first direction by coupling the pointer to the transmission mechanism with the mechanical play in the first direction being minimized at the reference position, the rotation transmission path There is no need to consider mechanical play. That is, in this case, the pointer changes its indicated position by the amount of rotation of the rotor. On the other hand, when the pointer is driven to rotate in the second direction, an angle obtained by adding a compensation angle that compensates for the mechanical play of the rotation transmission path is set as a target angle, so that the indicated position by the mechanical play of the rotation transmission path is changed. Deviation can be reduced. As a result, when the pointer is driven to rotate in the first direction and when it is driven to rotate in the second direction, it is possible to reduce the deviation of the indicated position when attempting to drive to the same indicated position. .

  Further, as described above, the pointer is coupled to the transmission mechanism in a state where mechanical play in the rotation transmission path is minimized when the pointer is rotationally driven in the first direction at a predetermined reference position. Therefore, since the relationship between the display position of the pointer and the angle of the rotor is uniquely determined using this reference position, the accuracy with respect to the indicated position of the pointer can be improved.

  According to a second aspect of the present invention, the control means moves the pointer in the second direction when the change in the rotation angle according to the target indication position of the pointer is equal to or smaller than the predetermined first threshold angle toward the second direction. When rotating, it is preferable to rotate the rotor in the second direction using the rotation angle corresponding to the target indicated position of the pointer as it is without increasing the compensation angle. In this way, when the target indication position of the pointer changes slightly so as to fluctuate, the pointer can be maintained in an immobile state, thereby preventing the pointer from moving tightly in the second direction. it can.

  In the instrument device according to claim 3, when the control unit rotates the pointer in the second direction, the control unit rotates the rotor to the target rotation angle obtained by adding the compensation angle to the first direction. When it is necessary to rotate the rotor, the addition of the compensation angle to the target angle of the rotor is finished, and the rotor is rotated in the first direction with the rotation angle corresponding to the target indicated position of the pointer as it is as the target angle. It is characterized by making it. When the pointer is driven in the first direction, the mechanical play in the rotation transmission path is set to the minimum, so that the target angle of the rotor can be determined without considering any mechanical play. is there.

  However, as described in claim 4, when the change in the rotation angle according to the target indication position of the pointer is equal to or smaller than the predetermined second threshold angle toward the first direction, the control means When rotationally driving in the first direction, the addition of the compensation angle to the target angle of the rotor is continued, and the rotor can be rotated in the first direction so that this compensation angle becomes the added target angle. preferable. This is to prevent the sticking of the pointer in the first direction when the target pointing position of the pointer changes slightly as in the second aspect.

  According to a fifth aspect of the present invention, the compensation angle is preferably set so as to coincide with a dead zone angle in which the pointer does not move even when the rotor rotates due to mechanical play in the rotation transmission path. As a result, the displacement of the pointer indication position can be almost completely eliminated.

  However, in order to set the compensation angle so as to coincide with the dead zone angle, it is necessary to set the compensation angle corresponding to the dead zone angle in each instrument device accurately. However, since the dead zone angle in each instrument device does not completely match due to individual differences, it is necessary to measure the dead zone angle in each instrument device at the time of inspection or the like in order to perform the setting as described above.

  In order to set the compensation angle more simply, the compensation angle may be set as described in claim 6. That is, the compensation angle is set to a value smaller by a predetermined angle than the dead zone angle where the pointer does not move even when the rotor rotates due to mechanical play in the rotation transmission path. In this case, the displacement of the indicated position of the pointer cannot be completely eliminated by the compensation angle, but the displacement of the indicated position of the pointer caused by mechanical play of the rotation transmission path can be reduced at least.

  In order to set the compensation angle to a value smaller than the dead zone angle, for example, the theoretical dead zone angle is determined by calculation from the design value of each component constituting the rotation transmission path, and from the theoretical dead zone angle. Subtract the predetermined angle to determine the compensation angle, measure the actual dead zone angle in multiple instrument devices, adopt the minimum value as the compensation angle, or subtract the predetermined angle from the average value of the actual dead zone angle And determining the compensation angle.

  As described in claim 7, it is preferable that the first and second threshold angles are set equal. As a result, the same sticking prevention effect can be exhibited when the pointer is rotationally driven in the first direction and when it is rotationally driven in the second direction.

  Hereinafter, an instrument device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the instrument device 10 according to the present embodiment. The instrument device 10 can be applied to any quantitative display as long as the pointer is rotationally driven by a drive source including a rotor so that the pointer matches the target indication position. For example, the instrument device according to the present embodiment can be suitably used for displaying speed, engine speed, and the like in a vehicle or the like.

  In FIG. 1, reference numeral 20 denotes a microcomputer, which obtains related data related to the target indicated position of the pointer from a sensor or other control device (not shown). The microcomputer 20 calculates a target rotation angle of the step motor 40 for matching the indicated position of the pointer 60 with the target indicated position based on the acquired related data. Then, a drive amount for rotating the step motor 40 from the current rotation angle to the target rotation angle is calculated, and a drive amount signal corresponding to the drive amount is output to the drive circuit 30. The drive circuit 30 generates a drive signal for rotationally driving the step motor 40 based on the input drive amount signal.

  The step motor 40 serves as a drive source for rotationally driving the pointer 60, and is connected to the pointer 60 via a transmission mechanism 50 that transmits the rotation of the rotor of the step motor 40. The pointer 60 is supported by the pointer shaft, and rotates along the surface of a scale plate (not shown) as the pointer shaft rotates.

  Here, an example of specific configurations of the step motor 40, the transmission mechanism 50, and the pointer 60 will be described with reference to FIG. As shown in FIG. 2, the step motor 40 is a two-phase step motor and incorporates a reduction gear train and a stopper mechanism 70 as the transmission mechanism 50. By the reduction rotation of the reduction gear train accompanying the rotation of the step motor 40, the pointer shaft 61 supported coaxially with the output gear 55 (described later) of the reduction gear train is rotated.

  As shown in FIG. 2, the step motor 40 includes a stator Ms and a magnet rotor Mr as a rotor. The stator Ms includes a yoke 41 and a field winding 43. The yoke 41 includes a pole-shaped magnetic pole 42, and a field winding 33 is wound around the magnetic pole 42. Although not shown in FIG. 2, the stay or the like Ms includes a pair of magnetic poles and a pair of field windings wound around the magnetic poles.

  The magnet rotor Mr is coaxially supported by the rotating shaft 44 in the yoke 41, and a large number of N poles and S poles are alternately magnetized on the outer circumferential surface of the magnet rotor Mr along the circumferential direction. The magnetic pole part formed is formed. As the magnet rotor Mr rotates, the N pole or S pole of the magnetic pole portion faces the tip surface of each magnetic pole 42 of the yoke 41 through a narrow gap.

  In the step motor 40 configured as described above, when the cosine-wave drive voltages whose phases are different from each other by 90 degrees, for example, are applied to the pair of field windings 42, the current flowing through the pair of field windings 42 As a result, cosine-shaped magnetic fluxes are generated in different phases and flow through the yoke 41 and the magnetic poles of the magnet rotor Mr. As a result, the magnet rotor Mr rotates in one direction. Further, by reversing the phase relationship of the cosine wave drive voltages applied to the pair of field windings 42, the rotation direction of the magnet rotor Mr can be reversed and rotated in the other direction.

  The reduction gear train as the transmission mechanism 50 includes an input stage gear 51 and intermediate gears 52 and 54 fixed to the rotating shaft 44 of the magnet rotor Mr, in addition to the output stage gear 55 described above. These input stage gear 51, intermediate gears 52 and 54, and output stage gear 55 reduce the rotational speed of the magnet rotor Mr of the step motor 40 at a predetermined reduction ratio.

  The intermediate gears 52 and 54 are positioned between the input stage gear 51 and the output stage gear 55 and are coaxially supported by a rotation shaft 53 that is rotatably supported. The intermediate gear 54 meshes with the output stage gear 55, and the diameter of the intermediate gear 54 is smaller than the diameter of the intermediate gear 52 and the diameter of the output stage gear 55. The input stage gear 51 is coaxially supported by the rotating shaft 44, and the input stage gear 51 is meshed with the intermediate gear 52. The diameter of the input gear 51 is smaller than the diameter of the intermediate gear 52. As described above, the rotation of the pointer with respect to the rotation speed (rotation angle) of the step motor 40 is caused by the difference in diameter between the input gear 51 and the intermediate gear 52 and the difference in diameter between the intermediate gear 54 and the output gear 55. The speed (rotation angle) is greatly reduced. Therefore, even when the pointer 60 is rotationally driven using the step motor 40 as a drive source, the pointer 60 can be driven almost continuously, not stepwise, and the pointer 60 moves smoothly with respect to the user. You can make it look like you are.

  The stopper mechanism 70 includes a strip-shaped stopper 71 and an L-shaped arm 73. The stopper 71 projects from the surface of the output gear 55 along the longitudinal direction of the pointer 60 immediately below the pointer 60. That is, the stopper 71 is formed to protrude from the pointer shaft 61 toward the surface of the output stage gear 55 in the radial direction so as to correspond to the extending direction of the pointer 60 from the tip end portion of the pointer shaft 61. The distal end portion 74 of the arm 73 extends toward the surface of the output step gear 55. The end surface 75 of the tip portion 74 of the arm 73 on the side in contact with the stopper 71 described above is disposed so as to correspond to a position that exceeds the zero position of the pointer 60 by a predetermined angle in the minus direction. As a result, when the pointer 60 tries to rotate beyond the zero position by the rotation of the step motor 40, the contact surface 72 of the stopper 71 contacts the end surface 75 of the arm 73, so that the pointer 60 has a predetermined zero position. Stops at a position that exceeds the angle.

  As described above, a transmission mechanism including a reduction gear train is provided between the step motor 40 and the pointer 60, and when the rotation of the step motor 40 is transmitted to the pointer 60 at a reduced speed, the transmission mechanism 50 is transmitted from the step motor 40 to the pointer 60. Therefore, it is inevitable that the mechanical play in the rotation transmission path leading to the pointer 60 increases.

  This point will be described in detail with reference to FIG. FIG. 3 schematically shows the mechanical play in the above-described rotation transmission path. In FIG. 3, the indicated position of the pointer 60 is raised (for example, the indicated position of the pointer 60 is rotated to the high rotation side in the tachometer). The rotation direction of the step motor 40 is the forward rotation direction, and the indicated position of the pointer 60 is lowered. The rotation direction of the step motor 40 (which rotates the indicated position of the pointer 60 to the low rotation side in the tachometer) is defined as the reverse rotation direction.

  Between the gear 1 corresponding to the input stage gear 51 attached to the rotating shaft 44 of the step motor 40 and the gear 2 corresponding to the output stage gear 55 to which the pointer shaft 61 is attached, an output from the input stage gear 51 is provided. There is play corresponding to the cumulative value of mechanical play between the gears reaching the step gear 55. For this reason, there is a dead zone in which the pointer 60 does not move even if the first gear of the step motor 40 rotates by the amount of the mechanical play. As a result, even if the pointer 60 is driven to the same indicated position when the pointer 60 is rotated forward and when it is rotated reversely, the indicated position is displaced. That is, hysteresis occurs at the indicated position of the pointer 60 depending on the rotation direction of the pointer 60.

  Therefore, in the present embodiment, it is possible to reduce the deviation of the indication position of the pointer 60 by taking the measures described below.

  First, in this embodiment, when the pointer 60 is mounted on the pointer shaft 61, the mechanical play in the forward rotation direction (first direction) is minimized, that is, zero, and the mechanical play in the reverse rotation direction (second direction) is reduced. Try to maximize play. For this purpose, first, the step motor 40 is driven in the reverse direction until the output stage gear 55 is stopped by the stopper mechanism 70 in a state where the pointer 60 is not attached to the pointer shaft 61. Thus, if the pointer 60 is attached, the pointer 60 indicates the lowest point.

  Next, for example, the step motor 40 is rotated forward by an angle necessary for the pointer 60 to rotate from the lowest point to a position indicating the zero position. However, what is important at this time is that the mechanical play between the first gear and the second gear shown in FIG. 3 is expected as the angle necessary for the pointer 60 to rotate from the lowest point to the position indicating the zero position. It is an angle. That is, simply rotating the step motor 40 forward by an angle corresponding to the rotation of the pointer 60 from the lowest point to the position indicating the zero position, the dead zone angle corresponding to the dead zone due to mechanical play, The forward rotation angle of the step motor 40 is substantially reduced. Therefore, the step motor 40 is rotated forward by an angle obtained by adding the dead zone angle to the angle corresponding to the rotation of the pointer 60 from the lowest point to the position indicating the zero position.

  As shown in the schematic diagram of FIG. 4, the rotation position of the rotation transmission path from the step motor 40 to the pointer 60 is set to a position corresponding to the zero position of the pointer 60 by forward rotation of the step motor 40 as described above. In the forward rotation direction of the step motor 40, the mechanical play between the first gear on the step motor 40 side and the second gear on the pointer shaft 61 side is minimized, that is, the mechanical play is made zero. Can do. In this state, if the pointer 60 is attached to the pointer shaft 61 so as to indicate the zero position, the mechanical play in the forward rotation direction is minimized and the mechanical play in the reverse rotation direction is maximized. The pointer 60 can be attached to the pointer shaft 61.

  As a result, when the pointer 60 is driven to the target instruction position, mechanical play in the rotation transmission path from the step motor 40 to the pointer 60 occurs only on the side where the pointer 60 is lowered. Therefore, when the process for reducing the mechanical play is performed when the pointer 60 is lowered by the control logic for controlling the indicated position of the pointer 60, the hysteresis of the indicated position of the pointer 60 can be reduced.

  In the above-described example, the zero position of the pointer 60 is set as a reference position when the pointer 60 is mounted on the pointer shaft 61. However, an indication position other than the zero position may be set as the reference position. However, at the reference position, the mechanical play between the first gear on the step motor 40 side and the second gear on the pointer shaft 61 side needs to be minimal with respect to the forward rotation direction. For this reason, it is necessary to set the position where the step motor 40 is rotated in the forward rotation direction by at least the angle corresponding to the dead zone angle due to mechanical play from the lowest point as the reference position. In the above-described example, the lowest point is provided at a position that exceeds the zero position of the pointer 60 by a predetermined angle in the minus direction. However, the lowest point may be provided so as to coincide with the zero position.

  Next, the control logic for controlling the indicated position of the pointer 60 according to the present embodiment will be described based on the flowchart of FIG. The control processing shown in the flowchart of FIG. 5 is repeatedly executed with a predetermined time (for example, 20 ms) as a control cycle.

  First, in step S110, a related data signal related to the target indicated position of the pointer is input from a sensor (not shown) or another control device. In step S120, a target rotation angle of the step motor 40 for making the indicated position of the pointer 60 coincide with the target indicated position is calculated based on the input related data signal. In calculating the target rotation angle, for example, it may be extracted from a preset map indicating the relationship between the input related data signal and the target rotation angle, or calculated by calculation using a predetermined calculation formula. You may do it.

  In step S130, it is determined whether or not the calculated target angle is equal to or greater than the swing-off angle corresponding to the upper limit of the indicated position of the pointer 60. In this determination process, if it is determined that the target angle is greater than or equal to the swing angle, the target angle is replaced with the swing angle so that the pointer 60 is not rotated beyond the upper limit instruction position in step S140. Thereafter, the process proceeds to step S200, and a drive amount signal corresponding to the target angle is output to the drive circuit 30 in order to rotate the step motor 40 by the target angle. Then, the drive circuit 30 applies the above-mentioned cosine wave drive voltage to the step motor 40 so that the display position of the pointer 60 matches the upper limit position according to the drive amount signal.

  On the other hand, if it is determined in step S130 that the target angle is smaller than the swing-off angle, the process proceeds to step S150, and when the pointer 60 is driven downward, the mechanical play described above is performed. In order to compensate for the dead zone angle corresponding to the dead zone, it is determined whether or not the target angle needs to be corrected. This correction determination process will be described later in detail.

  If it is determined in step S150 that the target angle needs to be corrected, the correction flag is turned on. On the other hand, if it is determined that the target angle does not need to be corrected, the correction flag is turned off. . In step S160, it is determined whether this correction flag is on. If it is determined in step S160 that the correction flag is OFF, the process proceeds to step S200, and the drive angle signal corresponding to the target angle is output using the target angle calculated in step S120 as it is. .

  On the other hand, if it is determined in step S160 that the correction flag is on, the process proceeds to step S170, where the target angle is corrected to the lowest point angle corresponding to the lowest point of the pointer 60. It is determined whether or not the angle is equal to or greater than the angle obtained by adding the compensation angle. If “No” is determined in the determination processing of step S170, if the target angle is corrected by the compensation angle, the pointer 60 is driven so as to be lower than the lowest point. The lowest point angle corresponding to the lower point is set as the target angle. Conversely, if “Yes” is determined in the determination process of step S170, the process proceeds to step S190, and the correction target angle is obtained by subtracting the compensation angle for compensating the dead zone angle due to mechanical play from the target angle. Is calculated. In step S200, a drive amount signal corresponding to the correction target angle is output to the drive circuit 30.

  Here, the compensation angle will be described. This compensation angle is set to a value smaller by a predetermined angle than the dead zone angle due to mechanical play in the rotation transmission path. In this case, the displacement of the indicated position of the pointer 60 cannot be completely eliminated by the compensation angle, but at least the displacement of the indicated position of the pointer caused by the mechanical play of the rotation transmission path can be reduced.

  In order to set the compensation angle to a value smaller than the dead zone angle, for example, a theoretical dead zone angle is determined by calculation from the design value of each component constituting the rotation transmission path, and the predetermined angle is determined from the theoretical dead zone angle. Subtract the compensation angle, measure the actual dead zone angle in multiple instrument devices, adopt the minimum value as the compensation angle, or subtract the predetermined angle from the average of the actual dead zone angle to compensate An angle should be determined.

  As described above, the reason why the compensation angle is set to a value smaller than the dead zone angle due to mechanical play is that the dead zone angle varies due to individual differences in individual instrument devices. That is, by making the compensation angle smaller than the dead zone angle, even if the dead zone angle varies among individual instrument devices, it is possible to prevent excessive correction while using the compensation angle common to each instrument device.

  However, if the compensation angle can be set so as to match the dead zone angle of each instrument device, the displacement of the indicated position of the pointer 60 can be almost completely eliminated. Therefore, the dead zone angle in each instrument device may be measured at the time of inspection or the like, and the compensation angle of each instrument device may be individually set based on the measured value.

  Next, the correction determination process will be described with reference to the flowchart of FIG. When the correction determination process is started, first, in step S210, it is determined whether or not the target angle exceeds the upper peak value. If “No” is determined in the determination process of step S210, the process proceeds to step S270, and it is determined whether or not the target angle is below the lower peak value. These upper peak value and lower peak value are updated by the target angle in the previous control cycle in principle. Therefore, the target angle in the current control cycle is compared with the target angle in the previous control cycle by comparing the target angle in the current control cycle with the upper peak value and / or the lower peak value. It can be determined whether it changes in the forward rotation direction, the reverse rotation direction, or the same. When the target angle in the current control cycle is the same as the target angle in the previous control cycle, the determination results in step S210 and step S270 are both “No”, and the correction determination process is terminated.

If it is determined in step S210 that the target angle exceeds the upper peak value, the process proceeds to step S220, and the upper peak value is updated in preparation for determination in the next control cycle. Specifically, the target angle in the current control cycle is stored as a new upper peak value. In the subsequent step S230, the angle difference between the target angle and the lower peak value is calculated. In step S240, the calculated angle difference is compared with a predetermined first threshold angle θ _T1 . The first threshold angle θ _T1 is set to an angle smaller than the dead zone angle due to mechanical play in the rotation transmission path described above. For example, when the dead zone angle is about 0.8 ° in terms of the rotation angle of the pointer 60, the first threshold angle θ _T1 is set to about 0.2 °.

Here, calculating the angle difference between the target angle and the lower peak value and comparing it with the first threshold angle θ _T1 reacts sensitively when the target indication position of the pointer 60 changes slightly so as to fluctuate. This is to prevent the pointing position of the pointer 60 from changing tightly.

This point will be described in detail below. When the angle difference calculated in step S230 is equal to or smaller than the predetermined first threshold angle θ _T1 , the correction determination process is terminated without executing the processes after step S250 by the determination branch process in step S240. In step S250, processing for setting the correction flag to OFF is executed. Therefore, in a state in which the correction flag is turned on and the rotation angle of the step motor 40 is controlled according to the correction target angle subtracted by the compensation angle, a target that slightly drives the step motor 40 to the forward rotation side. Even when an angle change (change below the first threshold angle θ _T1 ) occurs, the correction flag remains on. Then, even if the step motor 40 is driven to the normal rotation side according to a slight change in the target angle to the normal rotation side, the rotation angle of the step motor 40 is within the dead zone angle due to mechanical play in the rotation transmission path. Therefore, the indicated position of the pointer 60 does not substantially change. Therefore, even if the target indication position of the pointer 60 slightly changes so as to fluctuate, it is possible to suppress the movement of the pointer 60 sticking to it.

In step S240, the angular difference calculated in step S230 when it is determined to be greater than a predetermined first threshold angle theta _T1, the process proceeds to step S250 described above, turning off the correction flag. As a result, when the step motor 40 is driven in the reverse rotation direction to switch to the state in which the step motor 40 is driven in the normal rotation direction by the rotation angle equal to or greater than the first threshold angle θ _T1 described above, the correction is performed by subtracting the compensation angle Correction processing using the target angle can be terminated.

In the subsequent step S260, the lower peak value is updated. Specifically, the target angle in the current control cycle is stored as a new lower peak value. Thus, in step S260, the lower peak value is updated based on the target angle in the current control cycle because the change in the normal rotation direction of the target angle has exceeded the first threshold angle θ _T1 , so in the next control cycle. This is because it is determined whether or not the change in the target angle is a minute change equal to or smaller than the first threshold angle θ _T1 on the basis of the target angle after the change.

Note that, when the target angle of the step motor 40 changes in the forward rotation direction by the determination processing in step S240, the change in the target angle calculated as the angle difference between the target angle and the lower peak value is the first. The lower peak value is not updated unless the threshold angle θ _T1 is exceeded. As will be described later, the same applies to the case where the target angle of the step motor 40 changes in the reverse direction, and the change in the target angle calculated as the angle difference between the target angle and the upper peak value is the second threshold value. The upper peak value is not updated unless the angle θ _T1 is exceeded. For this reason, the upper peak value and the lower peak value may deviate by the first threshold angle θ _T1 (second threshold angle θ _T2 ) at the maximum. When the target angle changes in the range between the deviated upper peak value and lower peak value, even if the rotation angle of the step motor 40 changes, the change is a dead zone due to mechanical play. Since it falls within the angle, the indicated position of the pointer 60 is maintained at a fixed position.

If it is determined in step S270 that the target angle is smaller than the lower peak value, the process proceeds to step S280. In step S280, the lower peak value is updated by storing the target angle in the current control cycle as a new lower peak value in preparation for determination in the next control cycle. In subsequent step S290, an angle difference between the target angle and the upper peak value is calculated, and in step S300, the calculated angle difference is compared with a predetermined second threshold angle θ _T2 . The second threshold angle θ _T2 is preferably set to an angle value equal to the first threshold angle θ _T1 described above. As a result, the same sticking prevention effect can be exhibited when the pointer 60 is rotationally driven upward and when it is rotationally driven downward.

In step S300, the calculated angle difference when it is determined to be equal to or less than a second threshold angle theta _T2 without executing the processes of steps S310 and S320, and ends the correction determination process. On the other hand, in step S300, the calculated angle difference when it is determined to be greater than the second threshold angle theta _T2, the process proceeds to step S310, the turns on the correction flag. That is, in this case, since a change in the target angle larger than the second threshold angle θ _T2 has occurred in the reverse direction of the step motor 40, it is necessary to compensate the dead zone angle due to mechanical play with the compensation angle. The correction flag is turned on.

In the subsequent step S320, the upper peak value is updated. Specifically, the target angle in the current control cycle is stored as a new upper peak value. As in step S260, since the change in the reverse direction of the target angle has exceeded the second threshold angle θ _T2 , in the next control cycle, the change in the target angle with reference to the changed target angle. There is for determining whether a small change in the following second threshold angle theta _T2.

  An example of the pointer control process shown in the flowcharts of FIGS. 5 and 6 will be described with reference to the time charts of FIGS. 7 to 12 represent the target angle of the step motor 40, the upper peak value, the lower peak value, the indication position of the pointer, and the like that change with the passage of time.

  First, in the time chart of FIG. 7, the state immediately after the display in the instrument apparatus 10 is started is shown. At the display start time in the instrument device 10, the step motor 40 is driven to the lowest point angle corresponding to the lowest point of the pointer 60, and then the pointer 60 is driven, as when the pointer 60 is mounted on the pointer shaft 61. Is the state in which the step motor 40 is rotated in the forward direction until the angle indicating the zero position A. In this case, the correction flag is initially turned off. Moreover, as shown in FIG. 7, since the target angle remains unchanged at A, the upper peak value and the lower peak value are not updated and are in a state that matches the target angle.

When the target angle of the step motor 40 changes in the forward direction beyond the first threshold angle θ _T1 from the state shown in FIG. 7 as in the state shown in FIG. 8, both the upper peak value and the lower peak value are It is updated according to the target angle after the change. Since the step motor 40 is driven in the forward direction so that the target angle is reached, the mechanical play in the forward direction of the step motor 40 is zero. It is rotated by an angle corresponding to the change in the target angle.

Furthermore, when the target angle of the stepping motor 40 changes in the reverse direction within the range of the second threshold angle θ _T2 as in the state shown in FIG. 9 from the state shown in FIG. 8, only the lower peak value is It is updated with the target angle after the change, and the upper peak value is maintained as the target angle in the previous control cycle. Even if the target angle of the step motor 40 changes within the range of the second threshold angle θ _T2 and the step motor 40 is driven in the reverse direction so as to be the target angle after the change, the step motor at that time Since the rotation angle of 40 falls within the dead zone angle θh, the display position of the pointer 60 does not change. Thus, also the target angle of the step motor 40 is changed by a slight angle below the second threshold angle theta _T2, since thereby no change is indicated position of the pointer 60, with pointer 60 Gapiku by fluctuation of the target angle Can be suppressed.

As in the state shown in FIG. 10 from the state shown in FIG. 9, the target angle of the step motor 40 further changes in the reverse direction, and the change in the target angle calculated as the angle difference from the stored upper peak value is When the second threshold angle θ _T2 is exceeded, the upper peak value and the lower peak value are updated according to the target angle after the change.

In this case, even if the stepping motor 40 is simply driven to the target angle after the change, the indicated position of the pointer 60 does not change due to the dead zone angle θh due to mechanical play existing on the lower side of the pointer 60. Alternatively, when there is a change in the target angle exceeding the dead zone angle θh, the indication position of the pointer 60 changes, but the indication position of the pointer 60 is shifted by the dead zone angle θ _T2. .

  For this reason, as shown in FIG. 10, a corrected target angle obtained by correcting the target angle in the current control cycle with the compensation angle is calculated, and the step motor 40 is rotationally driven in the reverse rotation direction based on the corrected target angle. Thus, regardless of the presence of the dead zone angle θh, the indicated position of the pointer 60 can be changed toward the lower side by an angle corresponding to the change in the target angle. FIG. 10 shows an example in which a value smaller than the dead zone angle θh by a predetermined angle is used as the compensation angle.

  The above-described corrected target angle is used for convenience to rotationally drive the step motor 40, and the target angle in the current control cycle is stored by the updated upper peak value and lower peak value. By using these upper peak value and lower peak value, it is possible to accurately determine the direction and magnitude of the next target angle change.

When the target angle is corrected by the compensation angle as in the state shown in FIG. 11 from the state shown in FIG. 10, the target angle of the step motor 10 becomes the first threshold angle θ toward the normal rotation direction. _When it changes in the range of _T1 , the upper peak value is updated with the new target angle, but the lower peak value does not change, and the state where the correction flag is on is also maintained. Accordingly, the step motor 40 is driven in the forward rotation direction so that the corrected target angle is obtained by subtracting the compensation angle from the new target angle. However, since the rotation angle of the step motor 40 by this drive falls within the dead zone angle θh, the indicated position of the pointer 60 does not change.

As shown in the state shown in FIG. 12 from the state shown in FIG. 11, the target angle of the step motor 40 further changes in the forward rotation direction, and the target angle changes calculated as the angle difference from the stored lower peak value. Exceeds the first threshold angle θ _T1 , the upper peak value and the lower peak value are updated according to the target angle after the change.

  Further, in this case, the correction flag is turned off, and the target angle correction process using the compensation angle is completed. Therefore, the drive amount signal corresponding to the target angle in the current control cycle is output to the step motor 40 as it is. Then, since the stepping motor 40 is driven excessively by the compensation angle toward the reverse direction, when it is driven to the current target angle, the stepping motor 40 is moved to the forward rotation side by the amount corresponding to the compensation angle. Will be driven. For this reason, even when the step motor 40 is switched from the state of driving in the reverse direction to the state of driving in the forward direction, the indicated position of the pointer 60 is raised to the target position regardless of the dead zone angle θh. Can be changed.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the embodiment described above, the forward direction of the step motor 40 is the first direction, the reverse direction is the second direction, the mechanical play of the rotation transmission path in the forward direction is minimized, and the mechanical play in the reverse direction is reduced. The pointer 60 is attached to the pointer shaft 61 so as to maximize the distance. However, the pointer 60 may be attached to the pointer shaft 61 so that the mechanical play of the rotation transmission path in the reverse rotation direction is minimized by setting the normal rotation direction as the second direction and the reverse rotation direction as the first direction. For example, if the step motor 40 is not rotated excessively by the dead zone angle due to mechanical play when the pointer is mounted, the pointer 60 is attached to the pointer shaft 61 with the mechanical play of the rotation transmission path in the reverse direction minimized. be able to. Then, when the step motor 40 is driven in the forward rotation direction, if the target angle correction process using the compensation angle described above is performed, the hysteresis related to the indicated position of the pointer 60 can be reduced as in the above-described embodiment. .

It is a block diagram which shows the whole structure of the meter apparatus 10 by embodiment. FIG. 4 is a perspective view showing an example of specific configurations of a step motor 40, a transmission mechanism 50, and a pointer 60. It is the schematic diagram which showed typically the mechanical play in the rotation transmission path | route from the step motor 40 to the pointer 60. FIG. FIG. 4 is an explanatory diagram showing a state in which the mechanical play of the rotation transmission path is minimized in the forward rotation direction of the step motor 40 and the mechanical play is maximized in the reverse rotation direction, corresponding to the schematic diagram of FIG. 3. . 5 is a flowchart showing a control logic for controlling the indicated position of the pointer 60. It is a flowchart which shows the detailed process of the correction | amendment determination process in the flowchart of FIG. FIG. 7 is a first time chart for explaining an example of control of a pointer position by a pointer control process shown in the flowcharts of FIGS. 5 and 6. FIG. FIG. 7 is a second time chart for explaining an example of control of the pointer position by the pointer control processing shown in the flowcharts of FIGS. 5 and 6. FIG. FIG. 7 is a third time chart for explaining an example of control of the pointer position by the pointer control processing shown in the flowcharts of FIGS. 5 and 6. FIG. FIG. 7 is a fourth time chart for explaining an example of control of the pointer position by the pointer control processing shown in the flowcharts of FIGS. 5 and 6. FIG. FIG. 7 is a fifth time chart for explaining an example of control of the pointer position by the pointer control processing shown in the flowcharts of FIGS. 5 and 6; FIG. FIG. 7 is a sixth time chart for explaining an example of control of the pointer position by the pointer control processing shown in the flowcharts of FIGS. 5 and 6; FIG.

Explanation of symbols

10 Instrument Device 20 Microcomputer 30 Drive Circuit 40 Step Motor 50 Transmission Mechanism 60 Pointer

Claims (7)

Guidelines,
A drive source having a rotor and rotating the pointer in the first direction or the second direction to rotate the pointer in the first direction or the second direction;
A transmission mechanism for transmitting rotation of the rotor to the pointer;
An instrument device comprising control means for driving and controlling the drive source so as to rotate the rotor to a rotation angle corresponding to a target indication position of the pointer,
There is a mechanical play in the rotation transmission path from the drive source to the pointer through the transmission mechanism, and the needle does not move even if the rotor rotates due to the mechanical play. Hysteresis occurs at the indicated position,
The pointer has a minimum mechanical play in the rotation transmission path when the pointer is rotated in the first direction at a predetermined reference position, and a machine for rotating in the second direction. Coupled with the transmission mechanism in a state where the maximum play is
The control means, when rotationally driving the pointer in the second direction, a target angle is an angle obtained by adding a compensation angle for compensating the mechanical play to a rotation angle according to a target instruction position of the pointer, An instrument device that rotates the rotor in the second direction.   The control means is configured to rotate the pointer in the second direction when a change in the rotation angle according to the target indication position of the pointer is equal to or less than a predetermined first threshold angle toward the second direction. 2. The rotor according to claim 1, wherein the rotor is rotated in the second direction using the rotation angle corresponding to the target instruction position of the pointer as it is without increasing the compensation angle. Instrument device.   When the pointer is rotated in the second direction, the control means rotates the pointer in the first direction while rotating the rotor to a target rotation angle obtained by adding the compensation angle. When necessary, the addition of the compensation angle to the target angle of the rotor is finished, and the rotation angle according to the target indication position of the pointer is set as the target angle as it is, and the rotor is moved in the first direction. The instrument device according to claim 1, wherein the instrument device is rotated.   The control means is configured to rotate the pointer in the first direction when a change in the rotation angle according to the target indication position of the pointer is equal to or smaller than a predetermined second threshold angle toward the first direction. Further, the addition of the compensation angle to the target angle of the rotor is continued, and the rotor is rotated in the first direction so that the compensation angle becomes the added target angle. Item 4. The instrument device according to Item 3.   The compensation angle is set so as to coincide with a dead zone angle in which a pointer does not move even when the rotor rotates due to mechanical play in the rotation transmission path. 4. The instrument device according to any one of 4.   2. The compensation angle is set to a value smaller by a predetermined angle than a dead zone angle in which a pointer does not move even when the rotor rotates due to mechanical play in the rotation transmission path. The instrument device according to any one of claims 4 to 4.   The instrument device according to claim 4, wherein the first and second threshold angles are set equal.

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