JPH0545977Y2 - - 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 drive source, and particularly to a needle-type display device in which the movement of the pointer is smooth and the visibility is improved.

[Conventional technology]

2. Description of the Related Art Needle-type display devices using a step motor are known as vehicle-mounted speedometers and revolution counters. Step motors can be used in needle-type display devices because the rotation angle is very accurate and the rotation speed and position can be controlled in an open loop.

This type of needle-type display device uses, for example, arithmetic processing of a speed signal supplied from a speed detection means by a calculation/control means, calculates the number of steps of a step motor corresponding to the speed, and generates a drive pulse. The pointer is driven by supplying it to the step motor. The drive operation of the pointer is repeatedly updated at every predetermined unit time (hereinafter referred to as update time T), whereby the pointer is driven and displaced in response to a speed signal that changes sequentially.

[Problem that the invention attempts to solve]

However, in the above-mentioned conventional needle-type display device, the pulse frequency of the drive pulse is always constant and cannot be changed, so the movement of the pointer becomes gradual, resulting in poor visibility (visibility of the pointer display). There was a problem that the recognizability (recognizability through the image) deteriorated.

This problem will be explained using a specific example. Now let's assume that the update time T is 1 sec and the drive pulse period t is
Set to 0.01sec. Further, it is assumed that the needle-type display device is used as a speedometer for a car, and when one drive pulse is supplied to the step motor, the needle moves in a direction corresponding to 1 km/h.

Here the speed of the car is from 0km/h to 20km/h
h, the calculation/control means detects this speed change from the speed signal and calculates the number of driving pulses that can correspond to this speed change (in this case, the speed change is 20 km/h, so the number of driving pulses N calculates 20) and supplies it to the step motor. The step motor is driven by this drive pulse to move the pointer 20
Move to the position where Km/h is displayed. At this time, if T ₁ is the time required for the pointer to move to the position where it displays 20 km/h, then T ₁ = t×N, and T ₁
=0.2sec. Therefore, after the pointer displays 20km/h, the T-
During the time _T1 (0.8sec), the pointer remains in a stopped state.

In this way, in the conventional needle-type display device, there is a stop time of the pointer within the update time T, and for the person viewing the needle-type display device, the pointer is displaced in stages due to this stop time. There was a problem that visibility was poor.

The present invention was created in view of the above points, and an object of the present invention is to provide a needle-type display device with improved visibility.

[Means and actions for solving problems]

In order to solve the above problems, the present invention uses a step motor that drives the pointer and the number of steps of this step motor as position data, and calculates the number of driving steps to the next display position based on the current position data of the pointer. Then, by supplying drive pulses corresponding to the number of drive steps, the step motor is driven and controlled every predetermined update time unit.
The present invention is characterized in that a needle-type display device comprising a control means is provided with drive pulse frequency modulation/control means.

The drive pulse frequency modulation/control means modulates the pulse frequency of the drive pulse in accordance with the number of drive steps, and controls the timing of generating the first drive pulse within the update time.

By configuring the hand-type display device as described above, the period of the drive pulse is averaged, and it is possible to eliminate the stop time of the hand within the update time.

〔Example〕

Next, an embodiment of the needle-type display device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a needle-type display device 1 (hereinafter simply referred to as the device), which is an embodiment of the present invention. As shown in the figure,
The device 1 roughly consists of a meter display section 2, a step motor 3, an arithmetic/control device 4, etc.
A drive pulse frequency modulation/control circuit 5 (hereinafter simply referred to as a modulation/control circuit), which is the essential part of the present invention, is incorporated in the arithmetic/control device 4. This device 1
is used, for example, as an in-vehicle speedometer.

The meter display section 2 and step motor 3 are shown in Fig. 2.
As shown in FIG. 3, the meter unit 6 is formed into a unit. Of these, the meter display section 2 is comprised of a display (decorative) panel 7 and a pointer 8, as shown in FIG. Display characters 9 are arranged on the surface of the display panel 7, and cooperate with the rotating pointer 8 to display the speed.

As shown in FIG. 3, a step motor 3 is attached to the back of the meter display section 2 using a holder 10. As shown in FIG. The step motor 3 has a well-known structure, and rotates the drive shaft 3a by a predetermined angle in response to supplied drive pulses. A gear 11 is attached to this drive shaft 3a.

A gear 13 is attached to the rotating shaft 12 to which the pointer 8 is attached.
is provided, and this gear 13 is fitted with the gear 11. Therefore, the rotation of the step motor 3 drives the pointer 8.

As shown in FIG. 1, the arithmetic/control device 4 includes an input processing circuit 14, an instruction value conversion circuit 15, a motor drive amount calculation circuit 16, a motor control circuit 17, a motor drive circuit 18, an oscillation circuit 19, and an oscillation circuit 19 according to the present invention. This device is composed of a modulation/control circuit 5 and the like as the main part, and controls the drive of the pointer 8 using the number of steps of the step motor 3 as display position data. The input processing circuit 14 is a circuit that performs waveform shaping processing and amplification processing of a speed signal supplied from speed detection means (not shown) provided, for example, on an axle of an automobile. The instruction value conversion circuit 15 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 3 to generate the next display position data.

The motor drive amount calculation circuit 16 stores the position currently indicated by the pointer 8 in a memory (not shown) as the number of steps of the step motor 3 (this is referred to as current display position data M). From the display position data M and the next display position data N,
This circuit calculates the number of drive steps and rotation direction of the drive step motor 3 to drive the pointer 8 to the next display position.

The modulation/control circuit 5 is a circuit that generates drive pulses for driving the step motor 3 based on the oscillation signal supplied from the oscillation circuit 19 and the number of drive steps supplied from the motor drive amount calculation circuit 16.
As will be described in detail later, this modulation/control circuit 5 modulates the period of the oscillation signal from the oscillation circuit 19 in accordance with the number of drive steps, and also modulates the period of the oscillation signal from the oscillation circuit 19 so that it is first supplied to the step motor 3 at a predetermined update time. This is a circuit that controls the timing of supply of drive pulses.

The motor control circuit 18 is a circuit that controls the rotation of the step motor 3 so that it rotates accurately in response to an appropriate pulse frequency generated by the modulation/control circuit 5. This is a circuit for directly driving the step motor 3.

The above device 1 has a pointer 8 at every predetermined update time T.
The speed is displayed by updating the display position of the vehicle. This will be explained using a specific example.

Assume now that the display position of the pointer 8 is 10 km/h, and the current display position data M is 10 steps (when 1 step corresponds to 1 km/h). Further, as a result of processing the speed detection signal by the input processing circuit 14 and the instruction value conversion circuit 15, if the next display position is 25 km/h, and therefore the next display position data N is 25 steps, the motor drive The amount conversion circuit 16 calculates the number of drive steps to the next display position (N-M) using the current display position data M as a reference. Then, the step motor 3 is driven by the calculated 15 steps via the modulation/control circuit 5, motor control circuit 17, and motor drive circuit 18 to rotate the pointer 8, thereby displaying 25 km/h. ing. Furthermore, when the above update time T has elapsed, the next display position data N (25
Step) is replaced by the current ideographic position data M, and the speed is displayed by repeating the same process as above for the next incoming speed detection signal.

Next, the operation of the modulation/control circuit 5, which is the main part of the present invention, will be explained using FIGS. 1, 4, and 5. FIG. 4 shows the procedure of processing performed by the modulation/control circuit 5, and FIG. (indicated by the arrow in the book) shows the output timing.

When the motor drive amount calculation circuit 16 supplies the number of drive steps (hereinafter denoted by K), the modulation/control circuit 5 first determines whether K=0 (denoted by S1 in FIG. 4). If K=0, there is no change in the speed signal and there is no need to drive the pointer 8. Therefore, in this case, the modulation/control circuit 5 waits for the update time T to elapse (S2), and the process ends.

On the other hand, if it is determined that K≠0 in S1,
The modulation/control circuit 5 determines an appropriate period t for driving the step motor 3. This appropriate period t is determined by dividing the update time T by the number of drive steps K (t=T/
K) is obtained by (S3). Also, modulation and
The control circuit 5 divides the period t obtained in S3 by 2,
Calculate delay time Δt (S4).

Subsequently, the modulation/control circuit 5 modulates the clock pulse frequency supplied from the oscillation circuit 19 to generate a drive pulse with a period t (S5). After waiting for a delay time Δt from the update start time (S6), the modulated drive pulse is supplied to the motor control circuit 17 (S7). At this time, the modulation control circuit 5 counts the number of supplied drive pulses (indicated by code k) (S8), and supplies drive pulses until the number of drive pulses k becomes equal to the number of drive steps K (S7 to
(loop indicated by S10), and when k=K, the supply of drive pulses is stopped (S11).

Subsequently, after waiting for a delay time Δt from the output of the next drive pulse (S12), the process ends.

The output timing of drive pulses output from the arithmetic/control device 4 equipped with the modulation/control circuit 5 operating as described above will be explained below with reference to FIG. 5 while comparing with the output timing of a conventional device. The figure shows a state where the update has been performed three times, where A is the conventional output timing, B is the output timing when only pulse modulation is performed, and C is the output timing when only pulse modulation is performed.
indicate the output timings of this embodiment.
In the same figure, each code indicating the first update is appended with the letter 1 (t ₁ , Δt _1, etc.), and each code indicating the second and third update is appended with the letter 2 or 3. I wrote it down. Furthermore, for convenience of explanation, the number of driving steps K ₁ in the first update time is assumed to be 3, and similarly K ₂ =2, K ₃ =3 will be explained.

As shown in FIG. 5A, in the conventional device, after the step motor 3 has driven a predetermined number of steps, the pointer stops during the update time T, resulting in reduced visibility. Ta.

In addition, FIG. 5B shows that S4,
The output timing is shown when S6 and S11 are excluded. In this case, the first drive pulse is output at the same time as the update starts, and thereafter a drive pulse is output at every pulse modulated period. Therefore, the drive pulse output within the update time T is averaged, and the output is smooth without any stop time. It is possible to realize a pointer drive. However, at the boundary between one update time and the next update time (for example, the boundary between the first update time and the second update time), the first period t ₁ and the second period t ₂ are large. When this is the case, the pointer is driven in stages, resulting in poor visibility.

The output timing of this embodiment shown in FIG. 5C is as follows:
There is a delay time Δt from the update start time until the first drive pulse is output by the process of S6 in FIG. 4. Furthermore, there is still a delay time Δt from when the last drive pulse is output in the process of S11 until the update time T ends. Then,
It is possible to average the time between the timing when the last drive pulse in one update time is output and the timing when the first drive pulse in the next update time is output.

That is, the last drive pulse at the first update time in FIG. 5C (indicated by arrow P ₁ in the figure)
The time between the output timing of and the output timing of the first drive pulse (indicated by arrow P ₂ in the figure) at the second update time is Δt ₁ +Δt ₂ = (t ₁ + t ₂ )/2, and the first The time is the average value of the period t ₁ in the update time of 1 and the period t ₂ in the second update time. Therefore, the pointer can be smoothly driven even when the update time is changed, and the movement of the pointer is always stable and smooth, improving visibility.

[Effect of idea]

As described above, according to the needle-type display device of the present invention, the pulse frequency of the drive pulse can be modulated in accordance with the number of drive steps, so there is no stop time during which the drive of the pointer stops within the update time, and the pointer's movement is reduced. The movement becomes smoother, and by controlling the timing at which the first drive pulse is generated, it is possible to set a delay time at the start and end of the update, which allows the pointer to move smoothly even when switching update times. Therefore, it has features such as being able to improve the visibility of the device.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the device according to the present invention, Fig. 2 is a front view of the display panel, Fig. 3 is a side view of the meter unit, and Fig. 4 explains the processing of the modulation/control circuit. FIG. 5 is a timing chart for explaining the output timing of drive pulses output from the arithmetic/control device. DESCRIPTION OF SYMBOLS 1... Device, 2... Meter display section, 3... Step motor, 4... Arithmetic/control device, 5... Modulation/control circuit, 8... Pointer, 14... Input processing circuit, 15... Support Value conversion circuit, 16...Motor drive amount calculation circuit, 18...Motor drive circuit, 19...
...Oscillation circuit.

Claims (1)

[Claims for Utility Model Registration] A step motor that drives the pointer and the number of steps of the step motor as position data, calculates the number of driving steps to the next display position based on the current position data of the pointer, and calculates the number of driving steps to the next display position. In a needle-type display device comprising calculation/control means for driving and controlling the step motor at predetermined update time units by supplying a driving pulse corresponding to the number of steps, the pulse frequency of the driving pulse is set to A needle-type display device comprising drive pulse frequency modulation/control means that modulates the frequency in accordance with the number of steps and controls the timing of generating the first drive pulse within the update time.