JPH0744974Y2 - Needle type display device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a needle type display device using a step motor as a pointer driving means, and a needle type display device capable of surely correcting a display shift with a particularly simple structure. Regarding display device.

[Conventional technology]

A needle-type display device using a step motor is known as a vehicle-mounted speedometer and tachometer. The step motor has a very accurate rotation angle and can control the number of revolutions and the position control in an open loop, and thus can be used in a needle type display device.

In this type of needle type display device, for example, a signal supplied from a speed detecting means is arithmetically processed by a calculating / controlling means to calculate the number of steps of a step motor corresponding to the speed, and the step motor is supplied to the step motor. Is configured to drive the pointer.

However, in a needle type display device using a step motor, due to its structure, the hands are controlled and driven at relative positions, so if a misstep occurs due to disturbance (such as automobile vibration or erroneous signal), the error is accumulated. It will not be possible to display accurately.

Therefore, conventionally, the needle type display device is provided with a pointer position detecting means (for example, a rotary encoder) for detecting the actual display device of the pointer, and there is a deviation between the speed signal from the speed detecting means and the position signal from the pointer position detecting means. In some cases, arithmetic and control means were configured to correct this.

[Problems to be solved by the invention]

However, in the conventional needle type display device, since the rotary encoder and the photo interrupter as the pointer position detecting means are expensive and the structure is complicated, it is difficult to reduce the cost and miniaturize the needle type display device and further correct the deviation. There was a problem that the control of was complicated.

The present invention was created in view of the above points, and it is an object of the present invention to provide a needle type display device capable of surely correcting a display shift with a simple and inexpensive structure.

[Means for solving problems]

FIG. 1 shows the basic configuration of a needle type display device 1 according to the present invention. In the present invention, in order to solve the above problems, the step motor 3 for driving the pointer 2 and the number of steps of the step motor 3 are used as position data, and the next display position is based on the current position data of the pointer 2. Calculation / control means 4 for driving and controlling the step motor 3 by calculating the number of steps up to
The needle type display device provided with and was constructed as follows.

That is, the needle type display device is provided with the pointer position detecting means 5 for supplying the detection signal to the calculation / control means 4 only when the pointer 2 is at the specified display position, and each time the detection signal is supplied, The calculation / control means 4 is configured to replace the current position data of the pointer 2 with the number of steps of the specified display position and automatically correct the deviation between the position of the pointer 2 and the position data.

[Action]

According to the present invention, by considering the case where the needle type display device 1 is used as a speedometer by configuring the needle type display device 1 as described above, when the pointer 2 indicates the specified display position (0 km / h Is displayed), the current position data of the calculation / control means 4 is replaced with the step number (0 step) of the specified display position.

Therefore, a step error occurs in the step motor 3 due to disturbance, and the pointer 2 is at the specified display position (position at which 0 km / h is displayed).
Even if the current position data of the calculation / control means 4 is different from the number of steps of the specified display position and there is still a misstep (for example, 5 steps), the pointer position Since the current position data is replaced by the number of steps (0 step) of the specified display position by the detection signal from the detecting means 5, the misstep can be automatically corrected.

Further, the pointer position detecting means 5 does not have to detect all the display positions of the pointer 2, but it is sufficient to detect only one pointing position (for example, only the display position of 0 km / h).
The configuration can be simplified.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings. Second
FIG. 1 is a configuration diagram of a needle type display device 6 (hereinafter, simply referred to as a device) which is an embodiment of the present invention. As shown in the figure, the device 6 is roughly composed of a meter display unit 7, a step motor 8,
It is composed of a zero position detection device 9, a calculation / control device 10, etc., and is used, for example, as a vehicle-mounted speedometer.

Meter display unit 7, step motor 8 and zero position detection device 9
Are unitized as shown in FIGS. 3 and 4, and constitute a meter unit 11. Of these, the meter display section 7 is composed of a display (decoration) panel 12 and a pointer 13 as shown in FIG. Display characters 14 are provided on the surface of the display panel 12, and the speed is displayed in cooperation with the rotating pointer 13.

As shown in FIGS. 3A and 3B, a step motor 8 and a zero position detecting device 9 are attached to the rear surface of the meter display portion 7 using a holder 15. Step motor 8
Has a well-known structure, and rotates the rotary shaft 8a by a predetermined angle in response to the supplied drive pulse. This axis of rotation
A gear 16 is attached to 8a.

Further, the holder 15 is provided with a rotary shaft 17, and the pointer 13 and a large-diameter gear 18 are attached to the rotary shaft 17. Further, a protrusion 18a is provided near the outer peripheral edge of the lower surface of the gear 18. Therefore, the rotation of the step motor 8 is the gear 1
The pointer 13 is transmitted via 6 and 18 to the rotary shaft 17, and the pointer 13 is driven to rotate.

The zero position detection device 9 (hereinafter referred to as a zero position switch)
For example, a micro switch is attached and fixed to a predetermined position on the side surface of the step motor 8. At this time, the zero position switch 9 is configured to face the gear 18 and engage with the protrusion 18a as the gear 18 rotates to be closed. Furthermore, the position where the protrusion 18a closes the zero position switch 9 is the pointer 1
3 is selected as a position (position shown in FIG. 4) for displaying 0 km / h on the display panel 12. That is, the zero position switch 9 is closed only when the pointer 13 displays 0 km / h, and the zero position of the pointer 13 can be detected. The step motor 8 and the zero position switch 9 are connected to the arithmetic / control unit 10.

As shown in FIG. 2, the arithmetic / control unit 10 is composed of an input processing circuit 18, an instruction value conversion circuit 19, a motor drive amount arithmetic circuit 20, a motor control circuit 21, a motor drive circuit 22, and the like. This device controls the drive of the pointer 13 by using the number of steps of the motor 8 as display position data. The input processing circuit 18 is a circuit for performing waveform shaping processing and amplification processing of a speed signal supplied from speed detection means (not shown) provided on, for example, an axle of an automobile. The instruction value conversion circuit 19 converts the signal supplied from the input processing circuit into a numerical value and also converts the next display position into the number of steps of the step motor 8 to generate next display position data.

The motor drive amount calculation circuit 20 stores the position currently indicated by the pointer 13 in a memory (not shown) as the number of steps of the step motor 8 (this is referred to as current display position data M), and A circuit for calculating the number of steps and the rotation direction of the drive step motor 8 for driving the pointer 13 to the next display position from the display position data M and the next display position data N.

The motor control circuit 21 is a circuit for controlling the step motor 8 to appropriately rotate by the number of steps calculated by the motor drive amount calculation circuit 20, and the motor drive circuit 22 directly drives the step motor 8 corresponding to the number of steps. It is a circuit that supplies a drive pulse signal that causes the drive pulse signal.

The calculation / control device 10 described above has a predetermined unit time (for example,
The speed is displayed by updating the display position of the pointer 13 every 90 ms seconds (hereinafter referred to as update time T). This will be described with a specific example.

Now, assume that the display position of the pointer 13 is 10 km / h and the current display position data M is 10 steps (when one step corresponds to 1 km / h). Further, as a result of processing the speed detection signal by the input processing circuit 18 and the indicated value conversion circuit 19,
Assuming that the next display position is 25 km / h and therefore the next display position data N is 25 steps, the motor drive amount conversion circuit 20 uses the current display position data M as a reference to determine the number of steps to the next display position. Is calculated (N−M). Then, the step motor 8 is driven by the calculated 15 steps through the motor control circuit 21 and the motor drive circuit 22 to rotate the pointer 13 to display 25 km / h. When the unit time T elapses, the next display position data N (25 steps) becomes the current display position data M.
The speed display is performed by repeating the same processing as described above with respect to the next speed detection signal.

The zero position switch 9 is connected to the motor drive amount calculation circuit 20 of the calculation / control means 4.

Next, the operation of the device 6 will be described, and the correction of the instruction deviation, which is a feature of the present invention, will be described.

First, about the operation when the power is turned on (when the car is started)
It will be described with reference to the drawings. Before the power is turned on, the pointer 13 is at the stop position further rotated counterclockwise from the zero display position as shown in FIG. This is performed in order to match the excitation layer of the step motor 8 at the end of the operation described later with the excitation layer at the time of turning on the power (hereinafter, this excitation layer is referred to as an initial excitation layer). Therefore, when the step motor 8 is activated, the initial excitation layer is always excited and rotationally driven, so that the initial excitation layer can be used as a reference for the display position data. As a result, it is possible to prevent a misstep from occurring when the power is turned on.

Referring back to FIG. 5, when the power is turned on, it is first determined whether or not the output signals of the arithmetic / control unit 10 and the zero position switch 9 (hereinafter simply referred to as the zero position signal) are obtained (S
1).

When the zero position signal is not detected, the step motor 8 is rotated in the forward direction (clockwise is defined as the forward direction) by one step (S2), and the predetermined drive time of the next drive pulse signal is waited for. (S2- ₁₎ S1, S2, and repeats the processing of S2- _1.

If the in S1 is null position detection is performed, then one step rotation of the step motor 8 in the forward direction (S3), after waiting a predetermined time (S3- _1), it is determined whether the zero position signal is obtained again (S3- _2).

If here the zero position signal detection is performed S3, S3- _1, S3- ₂
The process of is repeated.

Further, after if S3- ₂ in not performed the zero position signal detection is rotated one step stepper motor 8 in the reverse direction (S3
- ₃₎ to end the wait a predetermined time (S3- ₄₎ processing.

Therefore, the pointer 13 is moved from the stop processing end position (position shown in FIG. 6) to the zero display position (position shown in FIG. 4), and the speed display processing is started in this state.

Next, the operation of the device 6 during speed display will be described with reference to FIG. First, the calculation / control means 4 calculates the next display position data N from the speed signal supplied from the speed detection means (S4). Next, it is judged whether the next calculated display position data N is N = 0 (S5). N in S5
= 0 means that the vehicle is stopped. Therefore, when N = 0 in S5, the zero position switch 9 detects the zero position (the output signal from the zero position switch 9 is obtained, and at the drive position one step before,
The state where the output signal from the zero position switch 9 is not obtained is shown. ) Is performed (S6), and if the zero position is not detected, the step motor 8 is rotated in the reverse direction by one step (S7) and a predetermined time is waited until the next drive pulse signal is supplied ( S8) and S6 to S8 are repeated. Therefore, even if the pointer 13 is displaced from the zero display position when the vehicle is stopped due to application of vibration to the vehicle,
The shift of the pointer 13 is corrected by the processing of S6 to S8.

On the other hand, when the zero position is detected in S6, the pointer 13 properly displays the zero position, waits for the display update time T to elapse (S9), and returns to the process of S4 again. That is, S4
~ The processing of S9 is a guideline 13 when the car is stopped.
Is a correction process for properly performing zero display.

Next, a case where N = 0 in S5 will be described.
In this case, the car is running. At this time, the arithmetic / control unit 10 calculates the number of driving steps of the step motor 8 from the current display position data M and the next display position data N (S10), and also rotates the step motor 8 to perform the next display. Determine the direction (S11).

When it is determined in S11 that the rotation direction of the step motor 8 is the forward direction (direction in which the speed increases), the arithmetic / control unit 10
Rotates the step motor 8 in the forward direction by one step (S12), and determines whether or not all the calculated driving steps have been rotated (S13). When the step motor 8 has not rotated the entire number of steps, the process waits for a predetermined time until the next drive pulse signal is supplied (S14), and the processes of S12 and S13 are repeated. On the other hand, when it is determined in S13 that the total number of driving steps has been completed, the next display position data N is replaced with the current display position data M and after waiting for the update time (S15), the process returns to S4 again. Step motor 8 in S13
When it is determined that the drive has rotated the entire number of drive pulses,
13 is located at the display update end position, and the speed display corresponding to the speed signal is displayed.

Let us return to S11 and explain. When it is determined in S11 that the rotation direction of the step motor 8 is the negative direction (direction in which the speed decreases), the arithmetic / control unit 10 rotates the step motor 8 in the reverse direction by one step (S16), and the zero position. It is determined whether or not the switch 9 is performing the zero position detection (S17).

If the zero position is not detected in S17, the calculation / control means 10 determines whether or not the step motor 8 has rotated the total number of driving steps calculated (S18). Wait for a predetermined time until the drive pulse signal is supplied (S19), and repeat the processing of S16 to S18. On the other hand, when it is determined in S18 that the total number of driving steps has been completed, the next display position data N is replaced with the current display position data M and after waiting for the update time (S15), the process returns to S4 again.

The operation of the device 6 when the zero position is detected in S17, which is a feature of the present invention, will be described below.

The fact that the zero position is detected in S17 means that the pointer 13 is at the zero display position. At this time, arithmetic / control device
10 replaces the current display position data M stored in the memory with M = 0 (S20). At this time, even if the misstep occurs due to the vibration of the vehicle or the mixing of an erroneous signal in the stepping motor 8, the misstep is corrected at the time of M = 0, so that the current display position data M
Corresponds to the displayed value on the pointer 13.

Subsequently, the calculation / control device 10 calculates the number of driving steps of the step motor 8 for performing the next display from the next display position data N, using the corrected current display position data M as a reference (S21). Next, the processes of S12 to S14 described above are performed, and the step motor 8 is operated for all the calculated driving steps.
When the rotation of all the driving steps is completed, the next display position data N is replaced with the current display position data M, the update time is waited (S15), and the process returns to S4 again.

Through the series of operations and processes of the device 1, the current display position data M is set to M = 0 every time the pointer 13 reaches the zero display position. That is, each time the pointer 13 reaches the zero display position, the misstep of the step motor 8 is corrected. This gives a guideline
Display deviation of 13 is prevented, and accurate speed display can be realized.

Next, the operation of the device 6 when it is stopped (when the engine of the automobile is turned off) will be described with reference to FIG. When the engine key is turned off, the device 6 performs the process shown in FIG. When the engine key is turned off, the arithmetic / control device 10 reversely rotates the step motor 8 (S22), and determines whether or not the zero position switch 9 is performing zero position detection (S23). When the zero position is not detected, the process waits until the next drive pulse signal is supplied (S24), and the processes of S22 and S23 are repeated. on the other hand,
When the zero position is detected in S23, the arithmetic / control unit 10
Determines whether the current excitation phase of the step motor 8 matches the initial excitation phase (S25). This is to prevent a misstep from occurring when the device 6 is started, as described above. When the current excitation phase and the initial excitation phase do not match in S25, the step motor 8 is again rotated in the opposite direction (S22, S24). Therefore, the pointer 13 rotates again counterclockwise from the zero display position. When both excitation phases match in S25, power supply to the device 6 is stopped (S26).

In the above embodiment, the pointer position detecting means 4 is used as the pointer 13
Although it is arranged at the position corresponding to the zero display position of, the present invention is not limited to this, and it is obvious that the present invention can be realized even if it is arranged at another display position. Therefore, if the sensor is attached at a position where the position detection signal can be obtained even at one place, even if the position detection signal is output for 10 steps, it can be corrected. Therefore, the mounting accuracy of the sensor can be maximized, and the system is easy and easy to assemble.

Further, although the micro switch is used as the zero position switch 9 in the present embodiment, other switch means (for example, an optical switch or the like) can be used.

Further, in the present embodiment, the example in which the device 6 is applied to the speedometer has been shown, but it is needless to say that the device 6 can be applied to various measuring instruments for displaying by the other hands 13.

[Effect of device]

As described above, according to the needle type display device (device) of the present invention, since the position of the pointer is detected at only one position, a simple and frequently used switch such as a micro switch is used as the pointer position detecting means. It is possible to reduce the size and cost of the device, and the calculation / control means replaces the current position data with the number of steps of the pointer position each time the pointer position detecting means detects the pointer position. Since the calculation / control processing is performed by the above, the misstep occurring in the step motor at this time is automatically corrected, and an accurate pointer display without display deviation can be performed.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of the device according to the present invention, FIG. 2 is a configuration diagram of an embodiment of the device according to the present invention, FIG. 3 is a front view and a side view of a meter unit, and FIG. 4 is a meter display section. 5 is a flow chart showing the processing of the arithmetic / control unit when the power is turned on, FIG. 6 is a front view of the meter display section with the pointer at the stop position, and FIG. 7 is the arithmetic / control during speed display. FIG. 8 is a flowchart showing the processing of the apparatus, and FIG. 8 is a flowchart showing the processing of the arithmetic / control apparatus when the apparatus is stopped. 1,6 …… Needle type display device (device), 2, 13 …… Pointer, 3, 8 ……
Step motor, 4 ... Calculation / control means, 5 ... Pointer position detection means, 7 ... Meter display section, 9 ... Zero position detection device (zero position switch), 10 ... Calculation / control device, 11 ...
Meter unit, 18 ... input processing circuit, 19 ... indicated value conversion circuit, 20 ... motor drive amount calculation circuit. 21 …… Motor control circuit, 22 …… Motor drive circuit.

Claims (1)

[Scope of utility model registration request] 1. A step motor for driving a pointer and the step number of the step motor as position data, and the step number up to the next display position is calculated based on the current position data of the pointer to drive and control the step motor. Calculation
A needle type display device provided with a control means is provided with a pointer position detection means for detecting the pointer only when the pointer is at a specified display position and supplying a detection signal to the calculation / control means, and the detection signal Every time the power is supplied, the arithmetic / control means replaces the current position data of the pointer with the number of steps of the specified display position, and automatically corrects the deviation between the position of the pointer and the position data. Needle-type display device.