JP3370451B2 - Electric head rotation angle detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection device capable of detecting the rotation angle of an electric pan head rotating 360 degrees or more.

[0002]

2. Description of the Related Art FIG. 8 is a view showing an example of an electric pan head provided with a rotation angle detecting device, and shows a disassembled state in a perspective view. Two sets of motors 1 are provided in the housings 10a to 10f.
2, 14 and speed reducers 16, 18 are built in, and the output of each speed reducer is transmitted to the rotary bases 28, 30 via the gears 20, 22 and the rotary shafts 24, 26. Rotating shafts 24, 26
Is supported by being passed through an opening 32 provided in the housing 10a, and the rotary bases 28 and 30 are attached to one ends of the rotary shafts 24 and 26. Then, one rotary table 28 is fixed to a wall surface or the like, and the other rotary table 30 is attached with a television camera or the like. As a result, this television camera has two degrees of freedom with respect to the wall surface. That is,
As the motor 12 rotates, the turntable 28 rotates with respect to the housings 10a to 10f, so that the housing 1 is attached to the wall surface.
0a to 10f rotate in the vertical direction and the motor 14 rotates to rotate the turntable 30 with respect to the housings 10a to 10f, so that the television camera rotates in the left-right direction with respect to the housings 10a to 10f.

At the other end of the rotary shafts 24 and 26, the rotary table 2 is attached.
A rotation angle detection device 34 for detecting the rotation angles of 8 and 30,
36 is attached. This rotation angle detection device 3
The rotation angle signals detected by 4 and 36 are fed back to a controller (not shown), whereby the rotation of the motors 12 and 14 is controlled and the angles of the turntables 28 and 30 are set to predetermined values. As described above, since the rotation angle detection devices 34 and 36 are provided, the vertical and horizontal angles of the television camera are set to predetermined values, and a predetermined subject is photographed. Rotation angle detector 3
Reference numerals 4 and 36 include a base portion 38 fixed to the housings 10e and 10f, and a rotating portion 40 fixed to the rotating shafts 24 and 26.

FIG. 9 is a plan view showing the base portion 38.
An annular resistor 42 and an annular conductor 44 are provided on the upper surface of the base portion 38. The annular resistor 42 is divided at one location, and electrodes 46 and 48 are attached to that location, respectively. A constant voltage is applied between the electrode 46 and the electrode 48, and the electrode 48 is connected to the ground. An electrode 50 is attached to the annular conductor 44.

FIG. 10 is a side sectional view showing the structure of the rotation angle detecting devices 34 and 36. The rotary unit 40 is attached to one end of the rotary shafts 24 and 26, and the base unit 38 is attached to the rotary unit 40.
Are facing each other. The brush 52 is arranged so as to straddle both the annular resistor 42 and the annular conductor 44 provided on the base portion 38, and the brush 52 is fixed to the rotating portion 40. Therefore, the brush 52 and the annular conductor 44 are electrically connected to each other, and the position of the point on the annular resistor 42 where the brush 52 is in contact is detected by detecting the potential of the annular conductor 44 (the voltage between the ground and the ground). That is, the rotating unit 40
The rotation angle of can be detected. The rotary shaft 2
The ends of 4, 26 are rotatably supported by a bearing 49 attached to the inner wall and a through shaft 54 attached to the base 38.

[0006]

Here, in the case where the television camera rotates 360 degrees or more, the rotating portion 40 must also rotate 360 degrees or more. But,
The resistor 42 has a dividing portion for taking out the electrodes 46 and 48, and the brush 52 cannot contact this portion.
Therefore, there is no detection data in this portion, and the data becomes discontinuous. Therefore, the rotation angle detection devices 34 and 36 shown in FIGS. 9 and 10 have a problem that they cannot detect a rotation angle of 360 degrees or more.

Further, there is a type of an electric pan head angle detecting device having a control cable through which a signal passes, but such an angle detecting device is structurally capable of detecting a rotation angle of 360 degrees or more. There is a problem that you cannot do it.

On the other hand, if a pulse counting type detector is attached to the rotary table, it is possible to easily detect a rotation angle of 360 degrees or more by counting the number of pulses.
However, this angle detection is relative, and there is a problem that a home position must be provided and a home position search must be performed immediately after the power is turned on in order to detect the absolute position. Moreover, there is a problem that it becomes difficult to secure control accuracy due to the accumulation of pulse count errors.

Therefore, an object of the present invention is to provide a rotation angle detecting device for an electric pan head which can detect a rotation angle of 360 degrees or more without performing a home position search.

[0010]

To achieve the above object, the invention according to claim 1 is such that a base portion fixed to a fixed portion of an electric platform and a rotatably supported portion with respect to the base portion. A rotating portion that rotates together with the rotating portion of the electric platform, and three annular resistors that are concentrically provided around the rotation center of the rotating portion on the surface of the base portion that faces the rotating portion. The three first annular resistors are provided in a conductive state, respectively, and the angles about the rotation center of the rotating portion are different from each other by 120 degrees, and the three first resistors are set to a constant first potential. The electrodes and the three annular resistors are respectively provided in a conductive state, and 180 degrees from the position where the first electrode is provided on each annular resistor centering on the rotation center of the rotating portion.
The three second electrodes, which are arranged at a rotated position and are set to a constant second electric potential different from the first electric potential, and the three annular resistors attached to the rotating portion, are in contact with each other. Three first sliders that are electrically connected to each other , a detection unit that detects each potential of the first slider, and the rotation of the electric platform based on each potential.
Angle detecting means for detecting an angle .

According to the second aspect of the present invention, on the surface of the base portion facing the rotating portion, three annular conductors concentrically provided around the rotation center of the rotating portion, Attached to the ring portion, three second sliders that are in contact with each of the annular conductors and are conductive, and are connected to each of the first sliders, and detection signal extraction terminals that are connected to the annular conductors. And are provided in the detection means.

According to a third aspect of the present invention, selection means for selecting one of the three first sliders on the basis of the mutual magnitude relation of the electric potentials of the three first sliders. Based on the electric potential of the first slider selected by the selection means,
The angle detection means detects the rotation angle of the rotating portion .

[0013]

In the present invention, the three first sliders attached to the rotating portion that rotates together with the rotating portion of the electric platform detects the potential at the contact point by contacting the respective annular resistors. The three annular resistors are provided on a base portion fixed to a fixed portion of the electric platform, and each has a first electrode and a second electrode. First electrode and second
Since the electrodes of are set to different potentials, the respective portions of the annular resistor are set to potentials corresponding to their positions. Therefore, the first
The rotation angle of the electric platform is detected by detecting the potential of the contact point between the first slider and the annular resistor through the slider.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the same reference numerals are used for the same or corresponding parts in the drawings.

FIG. 1 is a plan view showing the structure of a base portion 38 of the rotation angle detecting device for an electric pan head constructed according to the present invention. On the surface of the base portion 38 facing the rotating portion 40 (not shown), the three annular resistors 5 are provided.
6, 58, 60 and three annular conductors 62, 64, 66 are provided concentrically around a point O (center of rotation of the rotating portion). And three annular resistors 56, 58, 6
The first electrodes 68a and 68a are electrically connected to 0, respectively.
b and 68c are provided. First electrodes 68a, 68
The angles of b and 68c with respect to the point O are different from each other by 120 degrees. The first electrodes 68a, 68b, 68c are connected to each other as shown in FIG. 1, and a first potential (for example, V _ref volt) is applied from the reference potential applying terminal 70.

Also, three annular resistors 56, 58, 60
To the second electrodes 72a, 72b,
72c is provided. Second electrodes 72a, 72b,
72c is the first electrode 68a, 68b, 6 with respect to the point O.
It is arranged at a position 180 degrees from the position where 8c is provided. The second electrodes 72a, 72b, 72c are connected to each other as shown in the drawing, and are connected to the ground level through the ground terminal 74. This ground level constitutes the second potential. Also, three ring conductors 6
Detection signal extraction terminals 76, 78, 80 are connected to 2, 64, 66, respectively.

FIG. 2 is a side view of the rotation angle detecting device for the electric pan head shown in FIG. A brush 52 is attached to the rotating portion 40. The brush 52 includes a base portion 82 and contacts 84a to 84f, and the contacts 84a to 8f.
4f is arranged on a straight line. Contacts 84a-84
f is the annular resistors 56, 58, 60 and the annular conductor 6 respectively.
Contact 2, 64, 66. The contactor 84a and the contactor 84f are connected to each other by a lead wire (not shown), and the contactor 84b, the contactor 84e, and the contactor 84c.
And the contactor 84d are similarly connected.

FIG. 3 is a view showing another example of the brush 52. This brush 52 has three brushes 52a, 52b and 5
2c, and the brush 52a is an annular resistor 5
6 and the annular conductor 62 to bring them into conduction, the brush 52b contacts the annular resistor 58 and the annular conductor 64 to bring them into conduction, and the brush 52c contacts the annular resistor 60 and the annular conductor 66 to bring them into contact. Is conducted. In this case, since it is impossible to arrange the brushes 52a, 52b, and 52c on a straight line, the brushes 52a, 52b, and 52c are arranged with their angles shifted to some extent as shown in FIG. Therefore, in this case, the electrodes 68a, 68b, 68c and the electrodes 72a, 72b,
It is impossible to evenly arrange the 72c, and the brush 5
2a, 52b, 52c are offset by the angle of electrode 68a
It is necessary to shift etc.

Next, the voltage of the detection signal extracting terminals 76, 78, 80 which changes with the rotation of the rotating portion 40 will be described. First, the annular resistor 56 is provided with two electrodes 68a and 72a, to which V _ref volt and 0 volt are applied, respectively. Therefore, the potential of each point on the annular resistor 56 becomes a potential between 0 volt and V _ref volt depending on the position of the point. Therefore, the electric potential of the contactor 84a that contacts the annular resistor 56 is
It will change linearly with the rotation of. Figure 4 (
The solid line shown in a) represents the change in the potential of the contact 84a, that is, the change in the voltage Va at the terminal 76. As described above, the voltage Va linearly increases from 0 volt to V _ref volt from the rotation angle of 0 to 180 degrees, and linearly decreases from V _ref volt to 0 volt from 180 to 360 degrees.

The alternate long and short dash line shown in FIG. 4A shows the change in the voltage Vb at the terminal 78, and the alternate long and two short dashes line shows the change in the voltage Vc at the terminal 80. These changes are the same as the changes in the voltage Va except that the phases are advanced by 120 degrees and 240 degrees, respectively, as compared with the changes in the voltage Va.

Thus, for one rotation angle, V
Although three voltage outputs of a, Vb, and Vc are obtained, the contacts are electrodes 68a, 68b, 68c and electrode 72.
It is not convenient to use the voltage output (V _ref volt or 0 volt) when the voltage reaches a, 72b, or 72c because the electrode 68a and the like have a certain width and the angle cannot be detected. Therefore, in this embodiment, of the three voltage outputs of Va, Vb, and Vc, the one that does not become V _ref volt or 0 volt is used. For example, in FIG.
In the above, Vc is selected and used when the rotation angle is between 0 and 60 degrees, and Va that becomes 0 volt and Vb that becomes V _ref volt are not used. In addition, Va is selected and used between 60 degrees and 120 degrees, and V becomes 0 volt.
Vb, which is the c or V _ref volt, is not used.

In order to select an appropriate voltage output as described above, first, the voltage outputs Va and V are generated by the circuit shown in FIG.
Create bit1 to bit3 from b and Vc. Va and Vb are input to the comparator 86, and when Va is larger than Vb, bit1 becomes "1". Similarly, Vb
Is larger than Vc, the output bit2 of the comparator 88 is "1", and when Vc is larger than Va, the output bit3 of the comparator 90 is "1". FIG. 4B shows changes in the bit1 to bit3 depending on the rotation angle.

FIG. 6 is a diagram showing the configuration of the entire system including the circuit shown in FIG. Annular resistors 56, 58, 6
The voltages Va and Vb output from the circuit 92 including 0,
Vc is converted into bit1 to bit3 by the circuit of FIG. Further, bit1 to bit3 are bit-a to bit by an inverter, an AND gate, and an OR gate.
Converted to -c. The circuit 96 is composed of the comparators 86 to 90, the inverter, the AND gate, and the OR gate. Bit-a to bit-c are input to the circuit 94 including a switching element. This switching element is a semiconductor switching element such as a relay or a FET.

Bits 1 to 3 are output by the circuit 96 to b.
converted to it-a to bit-c and converted to bit-a to bi
As a result of the switching elements in the circuit 94 being turned on and off by t-c, the selected voltage output becomes as shown in FIG. For example, Vc is selected when the rotation angle is between 0 and 60 degrees, and Va is selected when the rotation angle is between 60 and 120 degrees. Due to such selection, as shown in FIG. 4 (a), the voltage output selected at an arbitrary rotation angle, that is, the sensor output voltage becomes an intermediate voltage which is neither 0 volt nor V _ref volt. Become.

The sensor output voltage, that is, the output of the circuit 94 is further converted into a digital signal by an A / D converter and then input to the CPU, as shown in FIG. On the other hand, bit1 to bit3 are also input to the CPU, and the CPU determines which range the rotation angle is in from these values and the conversion table shown in FIG.
Therefore, the CPU uses the input value from the A / D converter and b
The rotation angle of the rotating body 40 can be detected based on it1 to bit3.

In this way, the CPU can detect the rotation angle of the rotating body 40, that is, the rotation angle of the electric platform, so that the rotation angle signal is used as a feedback signal to change the input signal of the motor driver 98. The X-axis motor 12 can be feedback-controlled.

The circuit 96 constitutes the selecting means, and the A / D converter and the CPU constitute the angle detecting means.

FIG. 6 shows a system having two X and Y axes, and a Y-axis circuit similar to the X-axis circuit described above is provided. That is, the circuit 102 is the circuit 92, the circuit 104 is the circuit 94, and the circuit 106 is the circuit 9.
6, the motor driver 108 is the motor driver 98,
The motor 14 is similar to the motor 12, respectively. However, the output of the circuit 104 is input to the X-axis A / D converter, and the A / D converter is in service. Here, the output of the A / D converter is 2
However, if the signal indicating which of the X-axis signal and the Y-axis signal is converted is transmitted to the CPU, one output of the A / D converter can be used.

[0029]

As described above, according to the present invention, the three first sliders attached to the rotating portion respectively contact the annular resistor to detect the potential of the contact portion. The three annular resistors are provided on the base portion and each have a first electrode and a second electrode. Since the first electrode and the second electrode have different potentials, each part of the annular resistor has a potential corresponding to its position. Therefore,
The rotation angle of the electric platform is detected by detecting the potential of the contact point between the first slider and the annular resistor through the first slider. In this way, it is possible to obtain a rotation angle detection device for an electric pan head that can detect a rotation angle of 360 degrees or more without performing a home position search.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a base portion in a rotation angle detecting device for an electric pan head constructed according to the present invention.

FIG. 2 is a side view of the rotation angle detection device for the electric tripod head shown in FIG.

FIG. 3 is a diagram showing another example of a brush.

FIG. 4A shows terminal voltages Va, Vb, and
It is a figure which shows the change of Vc, (b) is b by rotation angle.
It is a figure which shows the change of it1-bit3.

FIG. 5 shows voltage outputs Va, Vb, and Vc as bit1 to bit.
It is a figure which shows the circuit converted into 3.

FIG. 6 is a diagram showing a configuration of the entire system.

FIG. 7 shows bit1 to bit3 that change depending on the rotation angle.
It is a figure which shows the value of, and the selected voltage outputs Va, Vb, and Vc.

FIG. 8 is a diagram showing an example of an electric pan head provided with a rotation angle detection device.

FIG. 9 is a plan view showing a base portion in a conventional rotation angle detection device.

FIG. 10 is a side sectional view showing a structure of a conventional rotation angle detection device.

[Explanation of symbols]

38 ... Base part, 40 ... Rotating part, 56, 58, 60 ... Annular resistor, 62, 64, 66 ... Annular conductor, 68a, 68
b, 68c ... 1st electrode, 72a, 72b, 72c ... 2nd electrode, 76, 78, 80 ... Detection signal extraction terminal, 84a, 84b, 84c ... 1st slider, 84d,
84e, 84f ... Second slider, 96 ... Circuit (selecting means).

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01B 7/30 G01D 5/165

Claims (3)

(57) [Claims] 1. A base portion fixed to a fixed portion of the electric platform, a rotating portion which is rotatably supported with respect to the base portion, and rotates together with a rotating portion of the electric platform, and a surface of the base portion. Of the three annular resistors, which are concentrically provided around the rotation center of the rotating portion, are provided on the surface facing the rotating portion, and the three annular resistors are electrically connected to each other. , The angles about the center of rotation of the rotating part are 1
They are provided in a state of being electrically connected to three first electrodes which are different from each other by 20 degrees and have a constant first potential, and three annular resistors which are respectively provided in a conductive state, and each of which is centered on the rotation center of the rotating portion. 180 degrees from the position where the first electrode on the annular resistor is provided
Three second electrodes which are arranged in a rolled position and have a constant second electric potential different from the first electric potential; and three annular resistors which are attached to the rotating portion. Three first sliders that are in contact with each other and are conductive, a detection unit that detects each potential of the first slider, and a rotation angle of the electric pan head based on each potential.
And a rotation angle detecting device for an electric pan head. 2. Three annular conductors concentrically provided around the rotation center of the rotating portion on a surface of the base portion facing the rotating portion, and attached to the rotating portion. Three second sliders connected to each of the first sliders and brought into contact with each of the annular conductors, and terminals for detection signal extraction connected to the annular conductors. The rotation angle detecting device for an electric pan head according to claim 1, wherein: 3. A selection means for selecting one of the three first sliders on the basis of mutual magnitude relations of electric potentials of the three first sliders , On the basis of the electric potential of the first slider selected by the selection means, the angle detection means causes the rotation angle of the rotating portion to change.
Rotation angle detecting device for an electric pan head according to claim 1 or 2, characterized by detecting a degree.