JPH09218056A - Needle type display device - Google Patents

Abstract

[PROBLEMS] To provide a needle type display device improved so as to immediately judge the pointer state when the power is turned on and to promptly indicate an actual value. SOLUTION: The pointer (11) is moved to a step motor (14).
In the needle type display device driven by, the encoder (12) that outputs the indication range indicated by the pointer and the count value corresponding to the pulse sent to the step motor are recorded to record the current position of the pointer. And a current position counter (24) for correcting the recorded value of the current position counter to a value within the pointer indicating range output by the encoder if the output value of the encoder is not 0 when the power is turned on ( 21a) and a correction prohibiting means (21b) for prohibiting the correction by the first current position correcting means when the value of the current position counter is within the pointer indicating range output from the encoder when the power is turned on.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a needle type display device in which a pointer is driven by a step motor.

[0002]

2. Description of the Related Art In a display device represented by a speedometer for displaying vehicle speed or a tachometer for displaying engine speed, a needle type display device is used in which a pointer is driven by a step motor resistant to vibration.

This step motor is a motor that rotates a pointer by a unit rotation angle when one pulse is input. Then, in the needle type display device in which the step motor is used, the difference between the instructed position to be instructed by the pointer and the current position currently instructed by the pointer is divided by the unit rotation angle, and the divided value N is obtained. Equal pulses are sent to the stepper motor for rotation, and the pointer is rotated to the indicated position.

In this case, a high resolution, that is, a small unit angle θ ₀ is required for smooth pointer movement. When an encoder that outputs an absolute value matching the resolution is used, the encoder The cost will be very high.

Therefore, in the device described in Japanese Utility Model Laid-Open No. 64-2158 (hereinafter referred to as the first conventional device), a current position counter is provided, and the count value of the current position counter is rotated in the forward direction by the step motor. +1 by sending a pulse to rotate, and-by sending a pulse to rotate in the negative direction
Then, the display position of the pointer is recorded by the count value of the present position counter. In this device, a detector that outputs a signal when the pointer indicates the 0 position is provided, and when the device starts operating, the indication value to be instructed by the pointer is 0, or the 0 signal from the detector is output. When any of the following is output, the recorded value of the current position counter is corrected so that the count value of the current position counter becomes zero.

As another conventional example, the actual fairness 6-7
As in the device described in Japanese Patent No. 29 (hereinafter referred to as the second conventional device), an encoder plate having continuous grooves on the outer edge of a disc that rotates in conjunction with the rotation of the pointer is provided, A pulse is turned on / off depending on whether or not light passes through this groove, and the current position of the pointer is output by counting the number of pulses.

In these conventional needle type display devices, when the power is turned on, in order to match the count value of the current position counter with the actual pointer pointing position, the drive system is unconditionally forcibly initialized. That is, the step motor is driven so that the pointer pointing position becomes 0 position (driving reference point),
At the same time, the current position counter is reset to 0 (setting of drive reference value).

As described above, in the conventional needle type display device, the current position indicated by the pointer is indicated by the count value of the current position counter which is counted up and down by the pulse.

In this case, the count value of the current position counter may cause a recording error due to noise or the like, or the step motor may not be driven even though a pulse is sent to the step motor. If this occurs, the recorded value recorded in the current position counter becomes a value different from the indicated position indicated by the pointer, resulting in incorrect pointer display.

Therefore, in the first conventional device, when the pointer indicates 0, the count value of the current position counter is reset to correct the error, and in the second conventional device, the count value is reset when the power is turned on. ing.

[0011]

By the way, in these conventional apparatuses, when the battery voltage is temporarily lowered by powering on other equipment during normal operation of the apparatus,
When the connector for supplying power to the device is loosened and vibration is applied to the connector, a momentary interruption may occur in which the supply of drive voltage to the device is momentarily stopped. In such a case, the apparatus starts the startup process from the beginning. At this time, the internal startup of the CPU is performed in a short time,
It takes a long time to initialize the drive system described above.

Then, when a momentary interruption occurs while the vehicle is running and the drive system is initialized, during that time, the indication of the pointer indicates a value that is significantly different from the actual value, and also indicates the actual value. It takes a long time to get there.

The present invention has been made in view of such circumstances, and immediately determines the pointer state when the power is turned on,
An object of the present invention is to provide an improved needle type display device for promptly indicating an actual value.

[0014]

In order to solve the above problems, a needle type display device made according to the present invention drives a pointer (11) by a step motor (14) as shown in the basic configuration diagram of FIG. In the needle type display device, the count value is increased or decreased corresponding to the pulse sent to the encoder (12) that outputs the instruction range indicated by the pointer (11) and the step motor (14). A current position counter (24) for recording the current position, and, if the output value of the encoder (12) is not 0 when the power is turned on, the current position counter (24) is set to a value within the pointer indicating range output by the encoder (12). And a value of the current position counter (24) when the power is turned on, within the pointer indicating range output by the encoder (12). If that is characterized by having a correction inhibiting means (21b) for prohibiting correction by the first current position correcting means (21a). (Claim 1)

In the structure of claim 1, when the needle type display device operates, the pointer (11) rotates, and the pointer (1) rotates.
The encoder (12) outputs a signal indicating the indication range indicated by the pointer (11) in conjunction with the rotation of (1). The count value of the current position counter (24) is
When the pulse for rotating the pointer (11) in the positive direction is sent to the step motor (14), it is incremented by +1 and when the pulse for rotating it in the negative direction is transmitted, it is decremented by -1. As a result, the current position of the pointer (11) is recorded. The first current position correction means (21a) is set to a value within the pointer instruction range output by the encoder (12) when the device is powered on and the output value of the encoder (12) is not 0. The recorded value of the position counter (25) is corrected. The correction prohibiting means (21b), when the value of the current position counter (24) is within the pointer indicating range output from the encoder (12) when the power is turned on, the first current position correcting means (2).
The correction by 1a) is prohibited.

Therefore, according to this configuration, when the power is turned on and the encoder output value is not 0, it is determined whether or not the value within the pointer indicating range output by the encoder has the value of the current position counter. If the current position counter value is outside the pointer indication range, the encoder corrects the recorded value of the current position counter to a value within the pointer indication range, and the value is within the pointer indication range. In this case, the correction is prohibited in this case, so that even if the drive voltage supplied to the device is momentarily interrupted by the effect of the other components on the power-on or the connector whose vibration is loosened while the vehicle is traveling. It is possible to give accurate pointer instructions in a short time.

Further, the first present position correcting means (21
The correction according to a) is performed by rewriting the recorded value of the current position counter (24) to a central value within the pointer indicating range output by the encoder (12). (Claim 2)

In the structure of claim 2, the first current position correcting means (21a) includes the current position counter (2).
The recorded value of the current position counter (24) is corrected by rewriting the recorded value of 4) to the central value within the pointer indicating range output by the encoder (12). Even if a difference from the indicated value occurs, the error is corrected to be small at the next timing, and the display error of the pointer can be reduced.

The pointer pointing position corresponding to the output value from the encoder (12) and the current position counter (2
If the current position recorded by 4) does not match the current position, the second current position correction means (21c) for correcting the recorded value of the current position counter (24) to a predetermined pointer indicating position defined by the encoder output. ) Is provided. (Claim 3)

In the structure of claim 3, the second current position correcting means (21c) is arranged so that the current position recorded by the current position counter (24) is not within the pointer indicating range output by the encoder (12). Is the current position counter (2
Since the recorded value of 4) is corrected at the pointer pointing position specified by the encoder output, even if there is a difference between the recorded value of the current position counter and the pointer pointing position, it is corrected to an accurate value. be able to.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of embodiments of the invention will be described below with reference to the drawings. First, the configuration of the embodiment will be described with reference to FIGS. 2 to 4. Although a speedometer is exemplified as this embodiment, the present invention is not limited to this embodiment and can be applied to other needle type display devices such as a tachometer.

As shown in FIG. 2, the illustrated speedometer comprises a display section 10, a control section 20, and a sensor section 30.

The display unit 10 includes a pointer 11 and an encoder 1.
2, index 13, step motor 14, gear group 15
It is composed of The pointer 11 has a base end 111 and a tip 112, and the base end 111 is joined to the encoder 12. In this joined state, the tip 112 is positioned at the index 13. The encoder 12 is configured as a mechanism that outputs predetermined code information according to the amount of rotation, and has the configuration shown in FIG. 3 in more detail. FIG.
As shown in the sectional view of (a), this encoder 12 is
Slit disk 121, shaft 123, and bearing 12
4, light receiving element 125, light emitting element 126, and holder 1
27.

The slit disk 121 has a circular plate-like appearance, as shown in FIG. 3 (b). The slit disk 121 is formed with a plurality of slits 122 having a predetermined pattern on concentric circles having different diameters. Further, at the center of this slit disk 121, the slit disk 121
A shaft 123 for supporting the is joined. The shaft 123 has a bearing 124, as shown in FIG.
It is rotatably attached to the holder 127 via. When attached to the holder 127, the tip of the shaft 123 projects outside the holder 127,
The base end 111 of the pointer 11 described above is joined to this tip. The slit disk 121 is arranged in the internal space of the holder 127 and rotates with the shaft 123.

The holder 127 has a slit disk 1
A plurality of light-receiving elements 125 are arranged on the upper side of 21.
A plurality of light emitting elements 126 are arranged in the lower part. The light receiving element 125 and the light emitting element 126 form a photo interrupter by forming a pair with each other.
2 are arranged at positions related to 2, that is, on concentric circles of different diameters. Therefore, when the slit disk 121 rotates and the slit 122 is positioned at the position where the light receiving element 125 and the light emitting element 126 are arranged, the light from the light emitting element 126 reaches and the light receiving element 125 outputs a voltage signal. As described above, in this encoder 12, the slit disk 121 rotates in response to the rotation of the pointer 11, and a signal corresponding to the actual pointing position of the pointer 11 is output.

The signal output from the encoder 12 is the signal shown in FIG. 3 (c). This figure is a schematic diagram showing the relationship between the speed and the encoder output in the speedometer, and the output signal of the one in which the slit 122 has five stages, that is, the one including five pairs of the light emitting element 126 and the light receiving element 125. Is illustrated. In the figure, the first indicates the output from the first light emitting / receiving element pair, and the second indicates the output from the second light emitting / receiving element pair. As described above, the first to the fifth indicate outputs of the respective light emitting / light receiving element pairs. In each of the first to fifth outputs, the first output is the first digit bit, the second output is the second digit bit, ...
・ Each corresponds to the bit of each digit,
It forms 5-bit code information. Hereinafter, this code information is referred to as Gray code.

As shown in the figure, the encoder 12 outputs a gray code "00000" when the vehicle speed is 0 km / h or more to 5 km / h. When the vehicle speed exceeds 5 km / h, the output of the first light emitting / receiving element pair changes to the on state, that is, "1", and the gray code "00001" is output. Similarly, when the vehicle speed exceeds 10 km / h, the output from the second light emitting / receiving element pair is turned on and the gray code is "000."
11 ". Below, this gray code is 5km /
The gray code corresponding to each speed range is output for each h. In this way, the encoder 12 outputs the designated range of the designated position where the pointer 11 is actually designated by the gray code.

As shown in FIG. 2, the indicator 13 is a pointer 11
Is a scale (only a part is shown in the figure) formed corresponding to the position of the tip 112 of the vehicle, and is a scale of the vehicle speed in the speedometer. The step motor 14 is composed of a main body 141 and a drive shaft 142. The drive shaft 142 is housed in the main body 141 so that its tip portion projects from the main body 141. In this housed state, the drive shaft 142 is attached to the main body 141.
In contrast, it is rotatable about the axial direction. When a drive signal from the control unit 20 is input to the main body 141, the main body 141 moves the drive shaft 14 according to the drive signal.
2 is rotated by a unit angle in the positive direction (denoted by the symbol + in the figure) or in the negative direction (denoted by the symbol −).

The gear group 15 includes an encoder side gear 151.
And an intermediate gear 152 and a motor-side gear 153. The encoder side gear 151 is the encoder 12
Is connected to the shaft 123 of the motor side gear 15
3 is joined to the drive shaft 142 of the step motor 14. Further, the intermediate gear 152 is arranged between the encoder-side gear 151 and the motor-side gear 153 so as to mesh with both gears. Then, the gear group 15 transmits the rotation from the step motor 14 to the encoder 12.

The control unit 20 includes a CPU 21 and a ROM 22.
The RAM 23, the current position counter 24, and the non-volatile memory (NVM) 25. Regarding the control unit 20, in the present embodiment, the CPU 21, RO
M22, RAM23, present position counter 24 and NVM
Although a custom IC in which 25 are integrated is illustrated, each configuration may be individually mounted on a substrate to configure a control unit.

The CPU 21 functions as a central processing unit that operates according to an operation program stored in the ROM 22, and the ROM 22 functions as a storage unit that holds the above-mentioned operation program and other various set values. R
The AM 23 functions as a storage unit that temporarily stores necessary information when the CPU 21 is operating, or as a time counting counter for measuring time during operation. The current position counter 24 is an up / down counter that holds a current position count value corresponding to the current position of the pointer. The count value of the current position counter 24 is incremented by +1 when the drive shaft of the step motor 14 is rotated in the positive direction by a unit angle, and is decremented by -1 when the drive shaft is rotated in the negative direction by the unit angle. The NVM 25 functions as a storage unit that holds the correlation information between the gray code output from the encoder 12 and the count value of the current position counter 24.

Now, the gray code, the count value of the current position counter 24 and the contents held in the NVM 25 will be described. FIG. 4 shows the correlation between the encoder output (Gray code) and the count value of the current position counter 24, and illustrates the case where there is no error between the encoder output and the count value.

As shown in the figure, the current position counter 24
Count value of "0"("0000000") to "3"
When it is (“0000011”), the gray code is “0000
0 "is output (corresponding to a vehicle speed of 0 to 5 km / h) and the count value is" 4 "to" 7 ", the gray code is" 0000 ".
1 "is output (equivalent to a vehicle speed of 6 to 10 km / h) and the count value is" 8 "to" 11 ", the gray code is" 000 ".
11 "is output (equivalent to a vehicle speed of 11 to 15 km / h).

Then, the count value of the current position counter 24 at the point where the gray code output from the encoder 12 changes is recorded in the NVM 25 in advance.
That is, the gray code "00000" to "0000"
The count value "0000100" is recorded for the change to "1", and the gray code "00001" to "0000" is recorded.
The count value "0000011" is recorded for the change to "0". Similarly, other change points are recorded below. Further, in the NVM 25, a substantially central value in the count range of the current position counter 24 defined by the gray code is also recorded in advance. That is, the gray code "0000
The median value of the current position counter 24 is "000" for "0".
0010 ”is recorded, and the median value“ 0000110 ”is recorded for the gray code“ 00001 ”. Similarly, the median values corresponding to other Gray codes are also recorded below.

The sensor section 30 is constructed as a mechanism for obtaining information displayed by this device, and in the illustrated speedometer, as a vehicle speed sensor which outputs a pulse signal every time the vehicle travels a certain distance. It is configured. The pulse signal output from the sensor unit 30 is sent to the control unit 20 described above. Then, the vehicle speed is calculated by acquiring the pulse signal transmission interval in the control unit 20.

Next, the operation of this embodiment will be described. In the present embodiment, the target designated position calculation processing and the pointer driving processing are performed in parallel. Here, the calculation process of the target designated position will be described first.
The calculation process of the target designated position is a process performed according to the flowchart of FIG. 5, and is performed by interrupting the pointer drive process each time the pulse signal from the sensor unit 30 reaches the control unit 20.

First, in step S110, the control unit 20 acquires the elapsed time from the previous pulse signal input time to the current pulse signal input time, that is, the pulse signal transmission interval. In the subsequent step S120, the target designated position is calculated. That is, this step S120
Then, the vehicle speed is calculated based on the pulse signal transmission interval acquired in step S110, the rotation angle of the pointer 11 on the index 13 corresponding to the calculated speed is calculated, and the process proceeds to step S130. In step S130, the rotation angle of the pointer 11 calculated in step S120, that is, the target designated angle is stored in a predetermined area (not shown) of the RAM 23. When the process of step S130 ends, the calculation process of the target designated position ends, and the process returns to the pointer driving process.

Next, the driving process of the pointer will be described.
The drive process of the pointer is performed based on the flowcharts of FIGS. 6 and 7. That is, in the drive process of the pointer, first, in step S2 in the flowchart of FIG.
At 10, power-on processing is performed. This power-on process is a process performed when the device is powered on, or when the drive voltage supplied to the device is momentarily cut off and returned to the operating voltage of the device again. This is performed according to the flowchart of FIG.

In this power-on process, first, step S3
At 10, the CPU 21 constituting the control unit 20 is initialized. Then, the process proceeds to step S320. In step S320, the output value from the encoder 12, that is, the gray code is read. Then, the read gray code is stored in a predetermined area (not shown) of the RAM 23. In step S330, the gray code acquired in step S320 is "0000."
It is determined whether it is "0".

If the gray code is "00000" in this step S330 (YES), it is determined that the vehicle is in a stopped state, the flow shifts to step S370, and the drive system is initialized. In this initialization of the drive system, the step motor is driven so that the indicated position of the pointer 11 becomes the 0 position (drive reference point), and the count value of the current position counter 24 is reset to 0 (drive reference value is set). Processing.
Then, when the process of step S370 is completed, the power-on process is completed, and the process proceeds to step S221 in the flowchart of FIG.

If the gray code is other than "0" in step S330 (NO), it is determined that the vehicle is running, and the process proceeds to step S340. In this step S340, the count value of the current position counter 24 of the RAM 23, the gray code of the encoder 12 and the count value of the current position counter 24 at the point where the gray code held in the NVM 25 changes are referred to,
It is determined whether or not the count value of the current position counter 24 is within the gray code range. If the count value of the current position counter 24 is within the gray code range in this step S340 (YES), the current position counter 2
The count value of 4 is maintained as it is. Then, the power-on process is ended, and step S2 of the flowchart of FIG.
Move to 11.

On the other hand, if the count value of the current position counter 24 is outside the range of the gray code in step S340 (NO), the process proceeds to step S350.
In this step S350, the data of the median value in the count range of the current position counter 24 corresponding to the gray code is read from the NVM 25. Then, in the following step S360, the median value data read in step S350 is written in the current position counter 24. For example, when the gray code of the encoder 12 is "00011", it is determined whether the count value of the current position counter 24 is within the range of "0001000" to "0001011".

In short, in these steps S350 and S360, it is assumed that the current position of the pointer 11 is not within the designated range of the gray code output from the encoder 12 in conjunction with the pointer 11, and the value of the current position counter 24 is The correction process is performed to the designated position (median value) defined by the Gray code.

Then, by the end of step S360,
A series of power-on processing is ended, and the process proceeds to step S211 in the flowchart of FIG.

In step S211, the RAM 2 described above is used.
A fixed time is measured by a time counter (not shown) constituted by a partial area of 3. That is, in step S211, the process waits until the count value of the clock counter becomes 0 from the specified value T. When the fixed time has passed, the process proceeds to step S220.

In step S220, the difference angle is calculated. In this processing, the count value of the current position counter 24 at the time of calculation is acquired as the current position, and the difference angle is calculated from the acquired count value and the above-described target designated position. In step S221, the step motor 1
The drive pulse number N to be sent to 4 is calculated. That is, in this step S221, the above-mentioned step S220
The number of drive pulses N to be sent to the step motor 14 is calculated by dividing the difference angle calculated in step 1 by the unit rotation angle of the step motor 14.

In step S230, the step motor 1
The drive pulse is sent to the signal No. 4. Then, in the subsequent step S231, the count value of the current position counter 24 is increased or decreased. That is, this step S2
At 31, when the step motor 14 is rotated in the positive direction, the count value of the current position counter 24 is incremented by 1, and when it is rotated in the negative direction, the count value is decremented by -1. The positive / negative direction determination is performed by setting a flag in a predetermined area (not shown) in the RAM 23.

In step S240, it is determined whether the output value of the encoder 12 has changed from the output value in the previous operation cycle. And if there is a change (YES)
To step S241, and if there is no change (NO), to step S250. Step S
At 241, the value of the pointer pointing position corresponding to the change point is read from the NVM 25. Then, the following step S242
Then, it is determined whether or not the pointer pointing position read in step S241 and the count value of the current position counter 24 match.

If it is determined in step S242 that they do not match (NO), step 243 is executed.
In step S26, the pointer indicating position read in step S241 is written in the current position counter 24.
Move to 0. That is, the gray code which is the output value from the encoder 12 is changed from "0000" to "0000".
When it changes to “1”, the value “0000100” read from the NVM 25 is written as the count value of the current position counter 24. Also, in this step S242,
If it is determined that they match (YES), step S24.
2 is skipped and the process proceeds to step S260.

On the other hand, when there is no change in the output value of the encoder 12 in step S240 and the process proceeds to step S250, the count value of the current position counter 24 is within the instruction range output by the encoder 12 in step S250. Or not. Then, when the count value of the current position counter 24 is outside the range specified by the encoder 12 (NO), the process proceeds to step S251.
In this step S251, the median value data recorded in advance in the NVM 25 is read out, and the subsequent step S252
Then, this median value is written in the current position counter 24.

For example, when the gray code of the encoder 12 is "00000", the corresponding median value "000001".
0 "is read, and when the gray code is" 00001 ", the corresponding median value" 0000110 "is read and written as the count value of the current position counter 24 to perform correction. Then, when the process of step S252 ends, the process proceeds to step S260.

In step S260, step S221
It is determined whether or not a number of pulses equal to the driving pulse number N calculated in step S14 have been sent to the step motor 14, and if not sent (NO), the process proceeds to step S230 and the processes of steps S230 to S260. Is repeatedly executed.
If N driving pulses have been transmitted (YES), the process proceeds to step S211, and the processes of step S211 and subsequent steps are executed again.

The steps S211 to S211 described above are performed.
The series of processes of 260 is continuously performed until the supply of the drive voltage to the device is stopped. That is, until the ignition switch is turned off by the operation of an ignition switch (not shown), or the drive voltage is momentarily interrupted due to the power-on of another device or the loosening of the coupling part of the connector that supplies power to the device. Will continue until. When this series of processes is completed due to the ignition switch being turned off or the drive voltage being momentarily cut off, the ignition switch is turned on or the drive voltage being momentarily cut off is restored, and the process proceeds to step S210 described above. The subsequent processing is executed again.

As described above, in this embodiment, when the power is turned on (S210), the output value of the encoder 12 is 0 (the gray code is "0000").
0 ”) (YES in S330), the pointer 11 defined by the Gray code output from the encoder 12
It is determined whether or not the value of the current position counter 24 is in the value within the instructed range (S340). When the value of the current position counter 24 is out of the pointer instructed range (NO in S340), the encoder 12 The recorded value (count value) of the current position counter 24 is corrected to a value within the pointer indicating range to be output (S3
50, S360), if the value is within the pointer indication range (S
Since the correction is prohibited to YES in 340), a momentary interruption of the drive voltage supplied to the device occurs due to the fact that the power of other components is turned on or the vibration of the other components acts on the connector where the vibration is relaxed. However, it is possible to give accurate pointer instructions in a short time.

Further, the recorded value of the current position counter 24 is corrected by rewriting the recorded value of the current position counter 24 to the central value within the pointer pointing range defined by the output of the encoder 12 (S350, S360). Even if a difference occurs between the recorded value of the current position counter 24 and the indicated value of the pointer 11, the error is corrected to be small at the next timing, and the display error of the pointer 11 can be reduced.

If the current position recorded by the current position counter 24 is not within the pointer indicating range output by the encoder 12 at the point where the output from the encoder 12 has changed (YES in S240) (NO in S242). ), The recorded value of the current position counter 24 is corrected at the pointer pointing position corresponding to the change point of the output of the encoder 12 (S2).
Since it is done in step 43), even if there is a difference between the recorded value of the current position counter 24 and the indicated position of the pointer 11, it can be corrected to an accurate value.

As is clear from the above description, the basic configuration of the present invention and the flowchart of this embodiment have the following correspondence. First in the basic configuration of the present invention
The current position correcting means (21a) corresponds to steps S350 and S360 in the flowchart, and the correction inhibiting means (21b) corresponds to step S340. In addition, the second current position correction means (21c), step S2
40 to S243.

[0058]

As described above, according to the present invention,
The following effects are obtained. That is, when the power is turned on and the encoder output value is not 0, it is determined whether or not the value within the pointer indicating range output by the encoder has the value of the current position counter, and the current position counter When the value is outside the pointer indication range, correct the recorded value of the current position counter to a value within the pointer indication range output by the encoder,
Since the correction is prohibited when the value is within the pointer indication range, the drive voltage supplied to the device by turning on the power of other component equipment or acting on the connector whose vibration is relaxed while the vehicle is running. Even if a momentary interruption occurs, it is possible to give an accurate pointer instruction in a short time.

Further, since the means for correcting the recorded value of the current position counter by rewriting the recorded value of the current position counter to the central value within the pointer indicating range output from the encoder is provided, Even if a difference occurs between the recorded value and the indicated value of the pointer, the error is corrected to be small at the next timing, and the display error of the pointer can be reduced.

If the current position recorded by the current position counter is not within the pointer indicating range output by the encoder, the recorded value of the current position counter is corrected at a predetermined pointer indicating position defined by the encoder output. Since the correction means is provided, even if there is a difference between the recorded value of the current position counter and the pointer pointing position, it can be corrected to an accurate value.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a basic configuration of the present invention.

FIG. 2 is a diagram illustrating a configuration of an embodiment.

FIG. 3 is a diagram illustrating a configuration of an encoder 12 and an encoder output (Gray code).

FIG. 4 is a diagram showing a correlation between an encoder output and a count value of a current position counter 24.

FIG. 5 is a flowchart illustrating a process of calculating a designated position in the embodiment.

FIG. 6 is a flowchart illustrating a pointer driving process according to the embodiment.

FIG. 7 is a flowchart illustrating a power-on process performed during a pointer driving process in the embodiment.

[Explanation of symbols]

 10 display unit 11 pointer 12 encoder 14 step motor 20 control unit 21 CPU 22 ROM 23 RAM 24 current position counter 25 NVM (nonvolatile memory) 30 sensor unit

Claims (3)

[Claims] 1. A needle-type display device in which a pointer is driven by a step motor, an encoder for outputting a designated range designated by the pointer, and a count value up and down corresponding to a pulse sent to the step motor. A current position counter for recording the current position of the pointer, and a first current position for correcting the recorded value of the current position counter to a value within the pointer indicating range output by the encoder if the output value of the encoder is not 0 when the power is turned on. It has a correction means and a correction prohibition means for prohibiting the correction by the first current position correction means when the value of the current position counter is within the pointer indicating range output from the encoder when the power is turned on. Needle type display device. 2. The correction by the first current position correction means is performed by rewriting a recorded value of the current position counter to a central value within a pointer indicating range output from the encoder. Needle type display device. 3. The recorded value of the current position counter is defined by the encoder output when the pointer indicating position corresponding to the output value from the encoder does not match the current position recorded by the current position counter. The needle type display device according to claim 1 or 2, further comprising a second current position correction means for correcting the pointer pointing position.