JPS6255238A - Display device for vehicle - Google Patents

Abstract

PURPOSE:To prevent incorrect display on a display unit by providing a decision means to decide if the voltage of a battery is in the first case: the battery voltage is above the minimum operating voltage of a sensor, in the second case: the battery voltage changes from above to below the minimum operating voltage of the sensor, or in the third case: the battery voltage is below the minimum operating voltage of the sensor from the start of power supply, thereby making in the third case the display unit not to display. CONSTITUTION:A decision means 401 compares the battery voltage VB and the minimum operating voltage VI of a sensor 3 and decides if the condition is in the first case: the VB is above the V1, in the second case: the VB changes from above the V1 to below the V1, or in the third case: the VB is below the V1 from the start of power supply. In the first case values detected by the sensor 3 are displayed on a display unit 405, in the second case the value detected just before the battery voltage drops below the V1 is stored in a memory and displayed, and in the third case the display unit is made not to display. Accordingly incorrect display when the battery voltage has dropped can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a vehicle display device that is mounted on a vehicle such as an automobile and displays driving information.

[Conventional technology]

As a conventional technique, for example, an analog signal ff1 corresponding to a detection value detected by a detector such as a water temperature sensor or a fuel remaining amount sensor is converted into a digital quantity by an A-D converter.
There are systems in which a control circuit such as a microcomputer calculates a detected value based on this digital quantity and displays it on an electronic display (Japanese Patent Application Laid-Open Nos. 56-89012 and 1982-139017). (Refer to official bulletins, etc.)

[Problem that the invention seeks to solve]

By the way, the above-mentioned vehicle display device operates by receiving power from the vehicle battery via the ignition switch, but when the ignition switch is turned on and the starter switch is turned on to operate the starter motor,
A large current is discharged from the battery, causing the battery voltage to drop significantly (for example, a battery rated at 12V will drop to 6V).
). Therefore, if the battery voltage when it drops is higher than the minimum operating voltage of the vehicle display device, there will be no problem, but a low vignetting error will occur. In addition, as mentioned above, the vehicle display device is composed of a detector and a measurement display section that processes and displays the signal of this detector. In some cases, the minimum operating voltage of the detector (eg, 8V) is higher than the minimum operating voltage of the measurement display (eg, 5V). In this case, when the battery voltage drops, the measurement display section operates normally, but the detector does not operate normally, so the measurement display section inputs a detection signal containing an error and displays an incorrect detection value. is 1. There was a problem with this.

The present invention was made in order to solve the above-mentioned conventional problems, and an object of the present invention is to provide a display device for a vehicle that does not cause erroneous display when the battery voltage drops such as when starting an engine. do.

[Means for solving problems]

The vehicle display device according to the present invention includes a detector that detects the operating state of the vehicle, and a detector that operates even at a voltage lower than the minimum operating voltage of the detector, receives an output signal from the detector, and displays the detected value on the display. The measurement and display means compares the battery voltage and the minimum operating voltage of the detector, and determines whether the battery voltage is higher than the minimum operating voltage of the detector or not. A second case in which the state changes from a state higher than the minimum operating voltage of a discriminating means for outputting a signal to drive the driver;
The first display processing means displays the detection value of the detector on the display when the value is low, and the battery voltage is lower than the minimum operating voltage of the detector when the discrimination means is in the second case. The processing means stores the detection value of the detector immediately before the change and displays the stored value on the display.When the second table is the processing means and the third case is omitted, the display is displayed. It has a third display processing means for displaying no display.

[For production]

In the present invention, if the battery voltage is higher than the minimum operating voltage of the detector, the detected value of the detector is displayed on the display, and if the battery voltage changes from higher than the minimum operating voltage of the detector to the following state, the following is shown. The detected value of the detector immediately before the state is entered is memorized and this memorized value is displayed on the display.If the batch lj iff pressure is below the minimum operating voltage of the detector from the time when power supply from the battery starts, the display will be displayed. By not displaying the display, erroneous display when the battery voltage is low is prevented.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is an in-vehicle battery, 2 is an ignition switch, 31t is a detector, 4 is a measurement display means, and the detector 3 and measurement display means 4 are connected to a vehicle display device
Both of them are supplied with power from a battery 1 via an ignition switch 2. The detector 3 has a built-in constant voltage power supply circuit (not shown), and its minimum operating voltage is set to v1. Further, the minimum operating voltage of the measurement display means 4 is assumed to be V2. Furthermore, in the measurement display means 4, the determination means 401
The battery voltage vB and the minimum operating voltage Vl of the detector 3 are
・The first case in which the battery voltage Vn is higher than the voltage V1, the second case in which the battery voltage Vn changes from the state of 71 or higher to the following state, and the power supply from the battery 1 by turning on the ignition switch 20. Distinguish between the third case in which the battery voltage Vn is less than or equal to ■1 from the starting point,
The determining means 401Fi outputs a signal indicating each case, and one of the first to third display processing means 402 to 404 is activated by this signal. In the first case, the first display processing means 402 displays the detection value of the detector 3 as it is on the display 405, and in the second case, the twentieth surface water treatment means 403 changes the battery voltage Ve to the voltage. The detected value of the detector 3 immediately before the value changes to v1 or less is stored, and this memorized value is displayed on the display 405. In the third case, the display 405 is turned off by the third display processing means 404. 3.

FIG. 2 shows the detailed configuration of the civil engineering embodiment, where 5 is a starter switch and 6 is a starter motor circuit.

Further, in the indicator 11 display means 4, 406 is the input circuit 4.
06a, microcomputer consisting of CPU 406b, memory 406c and 101 outputs 406d, 407° 408i, J: Ignition switch 2
409 is a resistor that divides the battery voltage VnTh which is inputted at [7], and inputs the output signal VP of a detector 3 such as a boost sensor that detects the intake pressure of the engine, for example. And digitally? f
Input circuit 406a of microcomputer 406
This is an A-D converter that sends data to 410t is a drive circuit that receives a display signal from the output path 406d of the microcomputer 406 and drives the display 405. Display device 40
Reference numeral 5 is composed of, for example, a liquid crystal display panel, and the detection value of the detector 3 is divided into eight stages, and a segment pattern 405a corresponding to each stage is lit.
05b indicates a scale pattern. 411th is a power supply circuit that forms a power supply voltage VC suitable for digital circuits such as 5V from the battery voltage, and this power supply is used by the microcomputer 4.
06, A-I) is supplied to the converter 409 and the drive circuit 410.

Next, the operation of the configuration shown in FIG. 2 will be explained using the flowchart of the program stored in the memory 406C of the microcomputer 406 shown in FIG. 3 and FIGS.
) will be explained with reference to the time chart shown in FIG. first,
When the ignition switch 2 is turned on at time t in Figure 4), a power-on reset circuit (not shown) is activated, and the microcomputer 406 starts execution at time t2. If we compare this with acid 2 using the flowchart in Figure 3, we get
First, the process starts, initialization is performed in step S1, and rLle is set to flag F, which will be described later. Next, Stetsu 7″
In step S2, the divided voltage value VBD of the battery Vn and the output voltage Vp of the detector 3 are input, and in step S3, the battery voltage VB is calculated from the divided voltage value van. Battery voltage Vn is detected by detector 3
It is determined in step S4 that the voltage is higher than the lowest operating voltage V1, and step fss is executed.In step S5, the detected value fn of the detector 3 is obtained from the input voltage Vp,
In S6, a display signal for lighting the segment of the display 405 corresponding to this detector P is output to the drive circuit 410. Based on the display signal from the drive circuit 410t, the fifth
The display 405 is driven to display as shown in FIG.

Next, in step S7, the detected value P' is stored in the memory M,
In step 88, the flag F indicating that Stella 7p S5 to S7 has been executed is set to r I J,,,,', and the process returns to Step 7°S2. As shown in Figure 4, time t2-t
Since the battery voltage vB is higher than voltage 71 during 4,
Steps 82 to S8 are repeatedly executed, and the detection (MP) of the detector 3 is displayed as is on the display 405.

Next, in Fig. 4, when the starter switch 5 is turned on at time t3, the starter circuit 6 is activated (7, so a large current flows and the battery voltage VB decreases at time t1-1).
4 is lower than the minimum operating voltage V1 of the detector 3 (but 1-7, higher than the minimum operating voltage V2 of the 10th measurement display stage 4), after execution of steps 82 and 83, it is determined in step S4 and the step fS9Th Execute. In step S9,
By determining whether or not steps 85 to S7 have been executed based on the 7 lag F, the battery voltage VB is set to 71.
It is determined that the above state has changed to the lower state.

Therefore, step 810 is executed 17, and a signal indicating the contents of the memo 'JM detected and stored immediately before time t4 is output. As a result, steps 82 to 84, 89, and 810 are repeatedly executed between times t4 and t6, and the display 4
05, the contents of memory M are always displayed. At time t5, the engine (not shown) starts, and when the dynamo (not shown) starts charging the battery, the battery voltage vB rises to its charge voltage (approximately 13.5V) at t. do. Therefore, after time t6, steps 82 to S
8 is repeated and the momentary detector P is displayed.

Next, as shown in FIG.
The state of 3 or more and Vt or less continues at time t141. In this way, the battery voltage Vn changes to the voltage V! immediately after the start of power supply to the measurement display means 4. If it is less than or equal to the time tl in FIG. 4(B)! After starting with Steps 81 to S4, execute Steps S without executing Steps 85 to S8.
9 is executed, and since it is F-0, step 811 is executed. This Stella fS11 outputs a signal that makes the display 405 non-display, and an example of the display at this time is shown in FIG.
Shown in H). Although the scale pattern 405b is displayed,
It doesn't have to be displayed. When the engine starts at time t1m () in Fig. 4, and when the battery voltage Vn exceeds the voltage Vrt'' at time t14, the execution of Stella 7''82 to S8 is repeated, and the detected value P is displayed every moment. Ru. in this way,
When the battery voltage vB is lower than the lowest operating voltage V1 of the detector 3, the previous detected value is held and displayed on the display 405 according to the state of the battery voltage before it became low,
If the detection operation has not been performed before a certain time, the display 405 is turned off to prevent erroneous display.

In the above embodiment, a constant voltage power supply circuit (
(not shown) and is configured to be supplied with power from the battery 1 via the ignition switch 2. However, it is not necessary to incorporate this constant voltage power supply circuit into the main body of the detector 3; for example, it may be provided in the measurement display means 4. good. Further, the output signal of the detector 3 does not need to be an analog voltage, and may be an alternating current signal having a frequency according to the detected value, such as in a capacitance type fuel remaining amount detector.

〔Effect of the invention〕

As described above, according to the present invention, when the battery voltage is higher than the minimum operating voltage of the detector, the detection value of the detector is displayed on the display, and the battery voltage is lower than or equal to the lowest operating voltage of the detector. When the state changes to the following state, the detection value of the detector immediately before the following state occurs is memorized, this memorized value is displayed on the display, and the battery voltage is the minimum of the detector from the time when power supply from the battery starts. When the battery voltage is lower than the operating voltage, the display is not displayed, and it is possible to prevent erroneous display when the battery voltage is low.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of the device of the present invention, FIG. 2 is a detailed configuration diagram of the device of the present invention, and FIG. 3 is a diagram showing the operation of the device of the present invention.
(B) is a time chart showing the operation of the apparatus of the present invention, and (B) is a time chart showing the operation of the apparatus of the present invention. DESCRIPTION OF SYMBOLS 1... Vehicle battery, 3... Detector, 4... Measurement display means, 401... Discrimination means, 402-404...
-Display processing means, 405...Display device. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa Figure 4 (A) Figure 4 (B) Figure 5

Claims (1)

[Claims] (1) A detector that detects the driving condition of the vehicle and is powered by the on-board battery and operates even at a voltage lower than the minimum operating voltage of the detector, receives the output signal of this detector and displays the detected value on the display. The measurement display means compares the battery voltage with the minimum operating voltage of the detector, and determines whether the battery voltage is higher than the minimum operating voltage of the detector or the battery voltage is higher than the minimum operating voltage of the detector. A second case in which the battery voltage changes from a state higher than the minimum operating voltage of the detector to a state below, and a third case in which the battery voltage is lower than the minimum operating voltage of the detector from the time when power supply from the on-board battery starts are determined. a first display processing means which receives the output of the discrimination means and causes the detection value of the detector to be displayed on the display in the first case; a second display processing means for storing the detection value of the detector immediately before the battery voltage changes to below the minimum operating voltage of the detector and displaying this stored value on a display; A display device for a vehicle, characterized in that it has a third display processing means that makes the display display no display in the third case.