JPH07209024A - Rotating angle detecting device - Google Patents

Abstract

PURPOSE:To provide excellent characteristics in a wide temperature range in a rotating angle detecting device in which a light position detecting element and a Hall element are used. CONSTITUTION:The rotating angle detecting device is provided with a light putting-out means to put out an irradiation light source 31 to a light position detecting element 11, a measuring means to measure the dark current of the light position detecting element 11 while the light source is put out, and a comparing means to compare the dark current with a set value. Also it is provided with a selector means which, when the dark current exceeds a set value, is switched over to a detector 7 using the light position detecting element 11, and when the dark current is below the set value, switched over to a detector 8 using a Hall element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle detecting device, for example, a rotation angle detecting device for detecting the opening degree of a throttle valve necessary for controlling the fuel supply amount of an internal combustion engine, and more particularly, The present invention relates to a rotation angle detection device that can obtain good characteristics in a wide temperature range.

[0002]

2. Description of the Related Art As a method of detecting a rotation angle, there is a method of detecting a rotation angle from an output voltage of a Hall element by using a rotating magnetic field that is rotated by being connected to a rotation axis of a Hall element and a throttle valve. The detector by this method is stable over a wide temperature range from low temperature to high temperature, but has a drawback that the output is not proportional to the rotation angle. On the other hand, there is a method in which the light transmission slit is rotated between the light source and the light position detection element to detect the rotation angle from the light arrival position on the light position detection element. This detector can make the output proportional to the rotation angle by the shape of the light transmission slit. However, since this detector uses a reverse-biased photodiode structure, it is stable at low temperatures, but at high temperatures, the dark current sharply increases compared to the photocurrent (output current), and the output is increased. It has the drawback of becoming unstable. Therefore, with these two detectors, a detector that uses an optical position detection element on the low temperature side (hereinafter referred to as a PSD detector) and a detector that uses a hall element on the high temperature side (hereinafter referred to as hall element detection) It is called a vessel).

FIG. 4 is a block diagram of the switching system in each conventional detector, and FIG. 5 is a flow chart showing the processing of the microcomputer associated with the switching in each conventional detector. Hereinafter, description will be given with reference to the drawings. 45 is a microcomputer, P
Thermistor thermometer 4 installed near the SD detector 47
The switching means 46 is instructed to switch between the PSD detector 47 and the hall element detector 48 on the basis of the temperature measurement result of 9, and the PSD detector 47 or the hall element detector 48 input through the switching means 46. Is processed to drive an actuator (not shown).

Next, the processing performed by the microcomputer will be described. In step B1, the temperature in the vicinity of the PSD detector 47 is measured by the output from the thermistor thermometer 49. In step B2, the temperature measured in step B1 is compared with the preset temperature. Then, if the measured temperature is equal to or higher than the set temperature, the process proceeds to step B4 to switch to the hall element detector 48, and if the measured temperature is lower than the set temperature, the process proceeds to step B3 to switch to the PSD detector 47. Then, these processes are performed again (steps B1 to B4)
Is repeated.

In this way, switching between the two detectors is
This is performed by comparing the temperature inside the housing measured by a thermometer with the set temperature.

[0006]

In the conventional method, since the dark current of the optical position detecting element increases due to the temperature rise in the detecting device, the temperature inside the housing is measured by the thermistor thermometer 49, and the temperature is measured. When the set temperature is exceeded, the Hall element detector 48 is switched to the one that operates stably even at a high temperature. But,
The temperature measured by the thermistor thermometer 49 does not necessarily correspond to the dark current of the optical position detection element due to the difference in the installation position of the optical position detection element and the thermometer in the housing, the heat capacity, etc. There is a problem that the switching timing is not appropriate. Further, there is a problem that a new component for temperature measurement is required, the number of components is increased, and the cost is increased.

According to the present invention, the characteristics of the semiconductor portion of the optical position detecting element are directly evaluated to appropriately switch between the PSD detector 47 and the hall element detector 48, and the number of parts is small and the cost is low. With the goal.

[0008]

In order to achieve the above object, the present invention has a light transmitting slit provided at a distance from a center of rotation corresponding to a rotation angle, which rotates in association with rotation of a rotating shaft. A slit plate and a light source on one side facing the slit plate and a light position detection element on the other side are arranged, and light from the light source passes through the slit and reaches the light position detection element. A second rotation angle detector that detects a rotation angle from a rotating position, a rotation magnetic field that rotates in conjunction with the rotation of the rotation shaft, and a Hall element that is disposed in the rotation magnetic field. In a rotation angle detection device having a detector, an extinguishing means for extinguishing the light source of the first rotation angle detector for a short time, and the light of the first rotation angle detector within an extinction time of the light source. Dark current measuring means for measuring the dark current of the position detection element The comparing means for comparing the measured dark current with a preset value, and the measured dark current in the first rotation angle detector if the measured dark current is equal to or less than the set value, The present invention is characterized by including switching means for switching to the second rotation angle detector when the set value is exceeded.

[0009]

According to the present invention, the light source is turned off for a short time during rotation angle detection by the rotation angle detector (first rotation angle detector) using the light position detection element, so that the light position detection element Only the dark current of can be measured directly. When the dark current exceeds the set value, it is determined that the characteristics of the optical position detection element have become unstable, and the rotation angle detector (second rotation angle detector) that uses a Hall element that operates stably even at high temperatures is used. Can be switched. Further, when the temperature decreases and the dark current of the optical position detecting element becomes equal to or less than the set value, the rotation angle detector (first rotation angle detector) using the optical position detecting element having good operating characteristics at low temperature is used.
Is switched to. In this way, always the preferred rotation angle detector is automatically selected.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 is an explanatory view of the operation principle of switching of each detector in one embodiment of the present invention. This will be described below with reference to the drawings. Reference numeral 1 is a circuit board in which an optical position detecting element 11, a hall element 14 and a drive circuit (not shown) for them are incorporated. The optical position detecting element 11 is arranged so that the detecting portion extends in the radial direction of the rotary slit plate 2. The anodes 12a and 12b and the cathode 13 are provided as terminals, are connected to the drive circuit, and the Hall element 14 is arranged so as to face the central portion of the rotary slit plate 2. Reference numeral 2 is a non-magnetic rotary slit plate fixed to a rotary shaft 21 connected to the rotary shaft of the throttle valve, and the slit 23 is provided so as to correspond to the rotary angle of the throttle valve as described above, A pair of magnets 22a and 22b for applying a magnetic field to the Hall element 14 are arranged in the peripheral portion. Reference numeral 3 denotes a light source plate, which is a light source 31 that transmits light through the slit 23 and irradiates the light position detection element 11 with light, and a light-shielding plate 3 that is provided on the circumferential portion to prevent light from the light source from leaking to the outside.
2. A rotary bearing 33 that holds the rotary shaft 21.
As shown in the figure, the circuit board 1 and the light source plate 3 are fixed, and only the slit plate 2 is interlocked with the throttle valve to rotate the rotary shaft 2
It is structured to be rotated by 1.

Next, the operation of the rotation angle detector (PSD detector) using the optical position detecting element will be described. The PSD detector 7 includes an optical position detecting element 11, a slit 23 of the slit plate 2, and a light source 31. As the rotary shaft 21 rotates in association with the rotation of the throttle valve, the irradiation position of the light passing through the slit 23 moves on the optical position detecting element 11. The optical position detection element 11 corresponding to this irradiation position
Then, the anode currents Ia and Iba are output, and the light irradiation position (r) on the light position detection element 11 is obtained by the calculation process. Then, the rotation angle (θ) of the rotary shaft 21 and the slit plate 2
If the distance (r) from the center to the slit 23 is made to correspond in advance, the output signal of the optical position detecting element 11 and the rotation angle can be made to have a substantially proportional relationship.

Next, the operation of the rotation angle detector (Hall element detector) using the Hall element 14 will be described. The hall element detector 8 includes a hall element 14 and a pair of magnets 22a,
22b. When the Hall element 14 is placed in a magnetic field with a voltage applied between the electrodes, the Hall element 14 generates a voltage in the direction perpendicular to the electric field and the magnetic field. This output voltage is proportional to the strength of the magnetic field (when the applied voltage is constant). Therefore, the rotary shaft 2
When 1 rotates in association with the rotation of the throttle valve, the magnets 22a and 22b rotate around the hall element 14, so that the angle formed by the magnetic field with respect to the hall element 14 changes and the output voltage of the hall element 14 changes. To do. The rotation angle is detected from this output voltage.

FIG. 1 is a configuration diagram of a switching system in each detector according to an embodiment of the present invention, and FIG. 2 is a flow chart showing a process of a microcomputer associated with the switching in each detector according to an embodiment of the present invention. Hereinafter, description will be given with reference to the drawings. Reference numeral 5 denotes a microcomputer, which controls turning on and off the light source 31 during operation of the PSD detector 7 and during dark current measurement.
Based on the measurement result of the dark current of the PSD detector 7, the switching means 6 is instructed to switch between the PSD detector 7 and the hall element detector 8, and the PSD detector 7 input via the switching means 6 or The signal from the Hall element detector 8 is processed to drive an actuator (not shown).

Next, the processing performed by the microcomputer 5 will be described.
In step A1, the light source 3 for irradiation of the light position detecting element 11
Turn off 1. In step A2, the dark current of the light position detection element 11 is measured while the light source 31 is off. The dark current is the sum of the currents of the anodes 12a and 12b or the current of the cathode 13. In step A3, the dark current of the optical position detecting element 11 measured in step A2 is compared with a preset current value. Then, if the measured dark current is greater than or equal to the set current value, the process proceeds to step A6, and if the measured dark current is lower than the set current value, the process proceeds to step A4. Step A4
Then, the light source 31 is turned on again, the light position detection element 11 is maintained in the operating state, and the process proceeds to step A5. In step A5, the switching means 6 is switched to the PSD detector 7 side, and the PSD
The output of the detector 7 is input as the output of the rotation angle detector, and then the process returns to step A1 to repeat the processing.
In step A6, the switching means 6 is switched to the hall element detector 8 side so that the output of the hall element detector 8 is input as the output of the rotation angle detector, and then step A1.
Return to and repeat the process.

In this way, the switching timing of both detectors is determined by comparing the dark current that determines the characteristics of the optical position detecting element 11 with the set current value. Since the output of the light position detection element 11 is not output while the light source 31 is off, the PSD detector 7 cannot detect the rotation angle, but the off time is very short (for example, 1 ms or less), and during this period, it is abrupt. Since the rotation angle does not fluctuate, there is no problem in practical use. If the data during this period is used for control or the like, this time is short, so the previous value may be stored in the memory and that data may be used.

As described above, according to the present embodiment, the dark current of the optical position detecting element 11 can be directly measured, and before the characteristics of the PSD detector 7 deteriorate, the Hall element detector 8 is switched to a stable one even at high temperature. This is effective for stable operation of the rotation angle detection device. Further, since a new temperature detecting element or the like is not required, it can be realized with almost no increase in cost.

[0017]

As described above, according to the present invention, the dark current that influences the characteristics of the optical position detecting element is directly measured to evaluate the optical position detecting element, and the rotation angle detector is switched. The rotation angle detector can be appropriately switched, and the advantages of both detection elements can be fully exerted.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a switching system in each detector according to an embodiment of the present invention.

FIG. 2 is a flow chart showing the processing of a microcomputer associated with switching in each detector of one embodiment of the present invention.

FIG. 3 is an explanatory diagram of the operation principle of switching of each detector in the embodiment of the present invention.

FIG. 4 is a configuration diagram of a switching system in each conventional detector.

FIG. 5 is a flowchart showing processing of a microcomputer associated with switching in each conventional detector.

[Explanation of symbols]

 5 ... Microcomputer 6 ... Switching means 7 ... PSD detector 8 ... Hall element detector 11 ... Optical position detection element 14 ... Hall element 22 ... Magnet 23 ... Light Transmission slit 31 ... Light source 21 ... Rotation axis

Claims (1)

[Claims] 1. A slit plate which rotates in association with rotation of a rotary shaft and which is provided with a light transmitting slit at a distance from a center of rotation corresponding to a rotation angle, and a light source on one side facing the slit plate. However, the optical position detection element is arranged on the other side,
A first rotation angle detector that detects a rotation angle from a position where light from the light source passes through the slit and reaches the optical position detection element; and a rotating magnetic field that rotates in association with rotation of the rotation shaft. And a second rotation angle detector including a Hall element disposed in the rotating magnetic field, comprising: a turning-off means for turning off the light source of the first rotation angle detector for a short time. And dark current measuring means for measuring the dark current of the optical position detecting element of the first rotation angle detector within the turn-off time of the light source, and comparing the measured dark current with a preset value. Switching to a comparing means and to a first rotation angle detector if the measured dark current is less than or equal to the set value, and to a second rotation angle detector if the measured dark current exceeds the set value. Rotation angle detection, characterized by comprising switching means Apparatus.