JPH0450771A - Speed detector - Google Patents

Abstract

PURPOSE:To output pieces of information on a speed and a direction at the same time without increasing the number of outputs by varying the pulse width of output pulses of the speed detector and multiplexing the direction information with the speed information. CONSTITUTION:When a disk 1 rotates forward at a constant speed, slits of the disk 1 crosses a photointerrupter 4, which sends its output signal 2 to a microcomputer 5. The current waveform of the signal 2 is an output signal waveform 6 in the constant-speed forward rotation, the pulse width of a high- level signal corresponding to slit width varies in the order of W1, W2, W3, W4, W1, W2..., and the pulse width ratio is 1:2:3:4. Further, when the disk 1 reverses at the constant speed, the signal 2 has an output waveform 7 in constant-speed reversing and the width of the pulse signal varies in the reverse order of the forward rotation. For the purpose, the order of variation in the width of the signal pulses is analyzed to decide the rotating direction. When the rotating speed is detected, a microcomputer 5 measures the period T of the edge of the signal 2 corresponding to the rotating direction to detect the speed of the disk 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a speed detector for detecting the speed and direction of a moving part in an apparatus having a moving part that performs movements such as rotation.

[Conventional technology]

Conventionally, as a speed detector, one in which a rotating slit is provided between a light emitting part and a light receiving part has been proposed, for example, as shown in "DC Servo Motor for Mechatronics", p. 211, Sogo Denshi Publishing.

This speed detector is structurally simple and requires only one detection output, but although it can detect speed, it cannot detect direction.

Furthermore, as a device capable of detecting direction, a rotary encoder such as that shown in ``Fundamentals and Applications of Electronic Servo Systems'', p. 103, Sogo Shuppansha, has been proposed. In this rotary encoder, since the aforementioned speed detector requires a ratio slit fixing plate and two photoelectric elements, the number of parts increases and the structure becomes complicated. Furthermore, two outputs are required.

As described above, nothing has been developed that has a simple structure and can output two pieces of information, speed and direction, with a single output.

[Problem to be solved by the invention]

The above-mentioned conventional speed detector has the problem that only speed information can be obtained as an output signal, and in order to detect direction, a comparison must be performed using an independent mechanism.

An object of the present invention is to simultaneously output speed and direction information without increasing the number of outputs from the speed detector.

[Means to solve the problem]

In order to achieve the above object, in a speed detector that outputs a pulse having a period corresponding to the detected speed, the pulse width of the output pulse is changed and direction information is multiplexed.

[Effect]

The pulse period of the speed detector output pulse operates inversely proportional to the speed.

The pulse width of the speed ratio ratio output pulse operates so as to change over time in accordance with the direction.

Thereby, the speed detector output pulse can have both speed and direction information in one signal.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1, 2, 3, and 4. Fig. 1 is a configuration diagram of a speed detector as an embodiment of the present invention, Fig. 2 is a plan view of the disk shown in Fig. 1, and Fig. 3 is an output signal waveform diagram during constant speed forward rotation in Fig. 1. , FIG. 4 is an output signal waveform diagram during constant speed reverse rotation in FIG. 2.

1 is a disk, and as shown in FIG. 2, a slit is provided. One edge of the slit is located at a position radially dividing the center of the disk l into four equal parts, and the length ratio of the slit is 1:2 in the clockwise direction on the concentric circles.
They are formed in order at a ratio of 3:4. Reference numeral 2 designates an output signal from a speed detector, 3 a rotating shaft of the disk 1, and 4 a photointerrupter, which outputs electrical pulses in response to blocking and passing light. 5 is a microcomputer (hereinafter referred to as microcomputer) and its speed.

Make direction decisions.

First, detection of the rotation direction will be explained.

When disk 1 is rotating at a constant speed, photo interrupter 4
is crossed by the slit of disk 1, which causes output signal 2
is input to the microcomputer 5. The waveform of the output signal 2 is the constant speed normal rotation output signal waveform 6 shown in FIG. In the output signal 2, the pulse width of the high level signal corresponding to the slit width of the disk 1 is Wl, W2 . W3. W4. Wl, W2--
Changes in the order of 1. The pulse width ratio is Wl:W2:'
W3:W4=1:2+3:4.

Also, when the disk 1 is rotating in the opposite direction at a constant speed, similarly,
The waveform of the output signal 2 is the output waveform 7 during constant speed reverse rotation shown in FIG. 4, and the width of the high level signal pulse is W4. W3.
W2. Wl, W4. It changes in the order of W3-m-, and changes differently than during normal rotation.

Therefore, the rotation direction of the disk 1 can be determined by the microcomputer 5 by analyzing the order in which the widths of the high-level signal pulses change.

Next, detection of the rotation speed will be explained.

When the disc 1 is rotating in the forward direction at a constant speed, the period T of the output signal 2 from one falling edge of the signal to the next falling edge is constant, as shown in the waveform 6 during constant speed reverse rotation.

Further, during constant speed reverse rotation, the output signal 2 has a constant period T from one rising edge of the signal to the next rising edge, as shown in output waveform 7 during constant speed reverse rotation.

These periods T are proportional to the period of 10 rotations of the disc. Furthermore, there is an inverse relationship between rotation period and speed. Therefore, if the microcomputer 5 measures the period of the edge corresponding to the direction of rotation of the disk 1, the speed of the disk 1 can be determined.

Therefore, according to this embodiment, by making the shape of the disc 1 a specific shape, the microcomputer 5 can be operated by only one output of the speed detector.
can know both the speed and rotation direction of the disk l.

Further, in this embodiment, the only structural difference from the conventional speed detector is the shape of the slit in the disk, so the cost of the device does not increase.

For comparison, the disk 8 in a conventional speed detector is shown in FIG. 5, and the output signal waveform 9 at constant speed when using the disk 8 is shown in FIG. 6.

Now, in the above example, we have shown an example in which the slit widths are arranged regularly on the disk 1, but even if the slit width is irregular, one edge of the slit is arranged radially evenly with respect to the center of the disk. If the output pulses are located at separate positions and the train of output pulses can be distinguished between forward rotation and reverse rotation, the speed and direction can be determined in the same way.

For example, if the disk 10 shown in FIG. 7 is used, the slits will be arranged irregularly, but as the output signal 2, the slits shown in FIGS.
Since a constant speed forward rotation output signal 11 or a constant speed reverse rotation output signal 12 as shown in yA is obtained, the speed and direction can be determined.

Furthermore, the same effect can be achieved even if something other than a disk is used to generate the output signal pulse.

As shown in FIG. 10, a light reflecting surface 14 and a non-reflecting surface 15 are provided on the surface of a cylinder 19, and a photosensor comprising a light emitting section 16 and a light receiving section 17 obtains the state of the cylinder surface as an output signal 18. When the cylinder 19 rotates around the rotating shaft 13, the output signal 18 is similar to that in the previous embodiment using a disk, so the speed and direction can be determined.

Furthermore, the present invention can be applied not only to rotational motion but also to linear motion.

For example, as shown in FIG. 11, a movable plate 26 that is movable along the shaft 20 is provided, and a photo sensor consisting of a light emitting part 21 and a light receiving part 22 is connected to a light reflecting surface 25 provided on the end surface of the movable plate 26 and a non-reflective tip. By determining the surface 24, the movement of the movable plate can be obtained as the output signal 23, so it is possible to detect the speed and direction in the same manner as in the previous embodiment.

Furthermore, the speed and direction can be similarly detected by using a magnetic pattern as the output signal generating means and a detector such as a coil to detect the pattern.

Next, a method for improving the performance of the present invention will be described.

When detecting direction using the speed detector of the present invention, the minimum number of pulses required for this is determined by the pattern of the slits, etc. For example, when using the disk shown in FIG. 2, the number of pulses required for direction detection is three pulses. It is clear that the rotation angle with respect to the number of pulses is inversely proportional to the number of slits in the disk 1, so in order to reduce the rotation angle of the disk 1 required for direction detection, the number of slits in the disk 1 can be increased.

In addition, when the angular acceleration of the disk 1 in Fig. 2 is large, for example, the disk 1 accelerates in the forward rotation direction, and the rate of change in speed is greater than the rate of change in the width of the output pulse when rotating at a constant speed. It is clear that if the pulse width becomes large, the pulse width change pattern becomes abnormal and direction detection becomes impossible. In order to increase the upper limit of the angular acceleration that can detect the direction, the ratio of the slit widths may be increased so that the ratio of pulse change widths during constant speed rotation becomes larger.

〔Effect of the invention〕

According to the present invention, since speed information and direction information can be output simultaneously in the output signal of the speed detector, the direction can be detected only by the speed detector output without the need to provide an independent direction detector. There is an effect that can be done.

Furthermore, since the only structural difference from conventional speed detectors is the shape of the slit in the disc, the cost of the device does not increase.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a speed detector as an embodiment of the present invention, Fig. 2 is a plan view of the disk in Fig. 1, Fig. 3 is an output signal waveform diagram during normal rotation in Fig. 1, Figure 4 is an output signal waveform diagram during reverse rotation in Figure 1, Figure 5 is a plan view of a disk in a conventional speed detector, Figure 6 is an output signal waveform diagram at constant speed in a conventional speed detector, Fig. 7 is a plan view of another specific example of the disc shown in Fig. 1, Fig. 8 is an output signal waveform diagram during normal rotation in Fig. 1 when the disc shown in Fig. 7 is used, and Fig. 9 is a diagram of the output signal waveform of the disc shown in Fig. 7. FIG. 1 is a diagram of the output signal waveform during reverse rotation when the disc shown in the figure is used, FIG. It is a perspective view of the principal part of a speed detector as another example. 1-m-Disc 6----Output signal waveform during forward rotation 7---Output signal waveform during reverse rotation

Claims (1)

[Claims] 1. A speed detector that detects the speed of a moving object and outputs a pulse with a period corresponding to the speed, which also detects the direction of the object's movement and detects the movement. A speed detector characterized in that direction information is multiplexed onto the pulse as a change in pulse width. 2. In the speed detector according to claim 1, a movable part that moves in conjunction with the object and has a plurality of first regions and second regions alternately along the direction of movement; a detection unit fixed near the movable part that moves, and outputs a high level as the pulse when the first area is detected and a low level when the second area is detected. and the length of each of the first regions in the movable part in the movement direction and the second A speed detector characterized in that a length in the movement direction of each region is set.