JP2552073B2 - Vehicle map display device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle map display device for displaying a road map including a vehicle position on a display device such as a CRT or a liquid crystal display to guide the vehicle.

[0002]

2. Description of the Related Art Conventionally, a user of this type of device has
The brightness of the display screen can be manually adjusted according to the ambient brightness.

[0003]

However, in such a conventional device, if the user adjusts the display screen so that the road map is easy to see in the daytime when the surroundings are bright, the display screen becomes too bright at night. On the contrary, if the display screen is adjusted to be dark so that the road map is easy to see at night when the surroundings are dark, there is a problem that the display screen becomes too dark in the daytime and the road map becomes difficult to see. It was

On the other hand, such a problem can be solved if the user frequently adjusts the brightness of the display screen.
It is very troublesome to perform the brightness adjustment frequently, and it is not performed unless the user is very careful. Therefore, in the above-mentioned conventional device, when the vehicle is driving on a dark road at night, in a tunnel, etc., the display screen is too bright, and when the driver looks at the display screen and shifts his / her eyes to the actual road, Is difficult to see, and the traveling safety of the vehicle is reduced, or conversely, the daytime display screen is too dark to provide appropriate traveling guidance to the user.

Even if the user frequently adjusts the brightness of the display screen, for example, when the vehicle enters a dim place such as a tunnel when the vehicle is running in the daytime or when the vehicle is running at night, When the brightness of the surroundings changes while the vehicle is traveling, such as when entering a bright place such as a downtown area, the brightness of the display screen cannot be adjusted, so that the problem described above occurs.

The present invention has been made in view of these problems, and provides a map display device for a vehicle in which the user can set the display screen to a brightness that is always easy to see without the user adjusting the brightness of the display screen. It is an object.

[0007]

The present invention, which has been made to achieve the above object, is provided with a display means capable of displaying a road map, and the vehicle map display for displaying the road map including the vehicle position on the display means. In the device, the detection means for detecting the brightness of the surroundings of the display means, and the brighter the surroundings, the brighter the display screen of the display means according to the brightness of the surroundings detected by the detection means. An automatic light control means for adjusting the brightness of the display screen is provided, and the automatic light control means gradually darkens the display screen when the surroundings change from a bright state to a dark state and darkens the surroundings. It is characterized in that a time constant circuit is provided for rapidly brightening the display screen when the state changes to the bright state.

[0008]

In the vehicular map display device of the present invention configured as described above, the detection means detects the brightness around the display means, and the automatic light control means responds to the detected surrounding brightness. The brightness of the display screen is adjusted so that the brighter the surroundings, the brighter the display screen of the display means. In addition, the display screen gradually darkens when the surroundings change from the bright state to the dark state due to the operation of the time constant circuit provided in the automatic light control unit, and when the surroundings change from the dark state to the bright state. Becomes bright rapidly.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 2 is a block diagram showing the overall configuration of a vehicle navigation device of an embodiment to which the present invention is applied.

As shown in FIG. 2, the navigation device of the present embodiment is a GPS antenna 2 for receiving a radio wave transmitted from an artificial satellite for a GPS (Global Positioning System).
a, the received signal is frequency-converted and demodulated to calculate latitude data, longitude data, and altitude data representing the position of the receiving point (ie, vehicle position), and to calculate the moving speed (ie, vehicle speed) of the receiving point. Well-known GPS that calculates speed data to represent
A receiver 2, an input device 4 for setting a planned traveling route of the vehicle by an external operation, an external storage device 6 made of an optical disc, a magnetic disc or the like in which map data is stored in advance, and a vehicle during traveling of the vehicle. An alarm device 12 for issuing an alarm to the driver when the vehicle deviates from the planned travel route, a display device 14 for displaying a road map including the vehicle position and various messages, a GPS receiver 2, an input device 4, CDR
The control device 20 reads various data from the OM reader 6, displays a road map on the display device 14 based on the data, and causes the alarm device 12 to issue various alarms.

The control unit 20 includes a CPU 21, a ROM
22, a RAM 23, an input / output port 24, and a well-known microcomputer provided with a bus line 25 connecting these parts, and the alarm device 12 and the display device 14 are connected via an alarm drive device 26 and a display drive device 27. Drive each.

Then, when the vehicle driver inputs a guidance command for the traveling route via the input device 4, the control device 20 responds to the command to display a predetermined area including the vehicle position detected by the GPS receiver 2. The map data is read from the external storage device 6, a road map is displayed on the display device 14 based on the read map data, and the vehicle position is highlighted on the displayed map. At this time, if the vehicle driver has already set the planned traveling route of the vehicle, the road that is the set planned traveling route is highlighted on the display map.

Next, as shown in FIG. 1A, the display device 14 is provided with a terminal 30 for adjusting color density, color tone, and brightness.
A liquid crystal display device (hereinafter, referred to as an LCD unit) 30 as a display unit including a, 30b, and 30c, and an LCD
A variable resistor 32 connected to the color depth adjustment terminal 30a of the unit 30, a variable resistor 34 also connected to the color tone adjustment terminal 30b, and a brightness adjustment terminal 3
0c connected to the automatic dimming circuit 36.

Both ends of each of the variable resistors 32 and 34 are connected to the power supply line (+ 5V) and the ground line (GND) of the LCD unit 30, and the voltage between them is divided according to the position of the sliding contact. As a result, the control voltages VA and VB for adjusting the color density and hue are generated, and the generated control voltages VA and VB are set to L
By inputting respectively to the color density adjusting terminal 30a and the color tone adjusting terminal 30b of the CD unit 30, the LCD
It is well known to adjust the color density and color tone of the display screen of the unit 30.

On the other hand, the automatic light control circuit 36, as shown in FIG. 3, is the brightness (illuminance: lux) around the LCD unit 30.
Accordingly, the brightness (display surface illuminance) of the display screen is automatically adjusted within a range of about 42 lux to about 130 lux so that the display screen becomes brighter as the surroundings become brighter.

That is, the automatic light control circuit 36 of the present embodiment.
As shown in FIG. 1 (b), Cd is a detection means, and the resistance value changes according to the brightness around the LCD unit 30.
An optical sensor 40 made of S (cadmium sulfide) or the like is provided,
One end of this optical sensor 40 is connected to the LCD via the resistor R1.
It is connected to the power supply line (+ 5V) of the unit 30 and the other end of the optical sensor 40 is connected to L via the variable resistor VR1.
The voltage generated at the sliding contact of the variable resistor VR1 is connected to the ground line (GND) of the CD unit 30 and transformed into the control voltage VC via the buffer circuit 44 including the resistors R2 and R3 and the operational amplifier OP1. By inputting to the brightness adjustment terminal 30c of the LCD unit 30, the brightness of the LCD unit 30 is automatically adjusted according to the resistance value of the optical sensor 40 (that is, the ambient brightness). .

In the automatic light control circuit 36, a capacitor C1 having a predetermined capacity (for example, 47 μF) is connected in parallel to the optical sensor 40, and a connection point between the optical sensor 40 and the variable resistor VR1 is further connected. An upper and lower limit voltage setting circuit 46 for setting the upper limit voltage of the control voltage VC to about 1.35V and the lower limit voltage to about 0.45V is connected. The upper and lower limit voltage setting circuit 46 is connected between the power supply line (+ 5V) of the LCD unit and the ground line (GND), and divides the voltage between the lines to obtain the reference voltage VUP for setting the upper limit voltage. A pair of voltage dividing resistors R to generate
4, R5 and a pair of voltage dividing resistors R that similarly divide the voltage between the lines to generate the reference voltage VDW for setting the lower limit voltage.
6, R7, an anode is connected to the connection point between the optical sensor 40 and the variable resistor VR1, and a cathode is connected to the voltage division point of the voltage dividing resistors R4 and R5.
1 and a lower limit voltage setting diode D2 whose anode is connected to the voltage dividing points of the voltage dividing resistors R6 and R7 and whose cathode is connected to the connecting point between the optical sensor 40 and the variable resistor VR1. .

That is, the LCD unit 30 of this embodiment
Is equipped with a backlight that emits light from the back side of the display surface. By adjusting the voltage applied to the liquid crystal to adjust the polarization angle of the liquid crystal, the amount of light transmitted from the backlight, and thus the display Since the brightness of the screen can be adjusted and the brightness of the display screen is set to change with respect to the control voltage VC as shown in FIG. 4, the automatic light control circuit 36 In order to adjust the brightness of the display screen in the range of about 42 lux to about 130 lux as described above, the lower limit of the control voltage VC is set to about 0.45 V and the upper limit is set to about 1.35 V, and within that range. Therefore, the control voltage VC is generated.

In the automatic light control circuit 36 of the present embodiment having such a configuration, when the surroundings are bright, the resistance value of the optical sensor 40 becomes small, so that the connection point between the optical sensor 40 and the variable resistor VR1 is reduced. The voltage VCO, and consequently the control voltage VC, increase, and conversely, when the surroundings are dark,
Since the resistance value of the optical sensor 40 increases, the optical sensor 40
The voltage VCO at the connection point between the variable resistor VR1 and the variable resistor VR1, and consequently the control voltage VC, decreases. Therefore, the display screen of the LCD unit 30 is controlled by the control voltage VC so that the brighter the surrounding area, the brighter it becomes in accordance with the surrounding brightness.

Further, in the automatic light control circuit 36 of the present embodiment, since the capacitor C1 is connected in parallel to the photosensor 40, the charge corresponding to the voltage across the photosensor 40 is accumulated in this capacitor C1. It When the surroundings change from a dark state to a bright state, the optical sensor 4
When the ambient voltage changes from a bright state to a dark state, the voltage across the capacitor C1 is discharged due to the decrease in the voltage across the voltage due to the decrease in the resistance value of 0. On the contrary, the voltage across the voltage increases as the resistance of the photosensor 40 increases. Thus, the capacitor C1 is charged.

The charging / discharging time of the capacitor C1 corresponds to a time constant determined by the resistance value of the optical sensor 40 and the capacitance of the capacitor C1. However, when the surrounding becomes bright, the resistance of the optical sensor 40 is reduced. Since the value decreases, the time constant at the time of charging the capacitor C1 becomes small, and conversely, when the surrounding becomes dark, the resistance value of the optical sensor 40 increases, so the time constant at the time of discharging the capacitor C1 becomes large.

Therefore, for example, as shown in FIG. 5 (a), if the vehicle enters the tunnel from the outside at time t1 while the vehicle is running in the daytime, the display screen has a brightness corresponding to the brightness of the outside ( For example, it slowly changes over a period of time (for example, 15 seconds) from time 125 (lux) to time t10 when the brightness corresponds to the brightness in the tunnel (for example, 80 lux). If the user goes out of the room, the display screen changes in a short time (for example, 1.3 seconds) from the brightness corresponding to the brightness inside the tunnel to the brightness t20 corresponding to the brightness outside.

That is, in this embodiment, the capacitor C1 is connected in parallel to the optical sensor 40 so that the display screen is gradually darkened in the automatic light control circuit 36 when the surroundings are suddenly darkened. When the surroundings suddenly become bright, a time constant circuit is formed to make the display screen brighter rapidly.This makes it possible to change the brightness of the display screen according to human visual characteristics with respect to changes in ambient brightness. Is there.

Further, as shown in FIG. 5 (b), for example, at night, when the vehicle travels on a road with a street light,
In the case where the ambient brightness does not change significantly but changes periodically, unless the capacitor C1 is connected in parallel to the optical sensor 40, the brightness of the display screen is a sawtooth wave according to the ambient brightness change. However, in the present embodiment, since the time constant circuit is formed in the automatic light control circuit 36 as described above, the brightness of the display screen does not change in a sawtooth shape, and the display screen is It can be kept at a constant brightness.

Therefore, according to the vehicular navigation system of this embodiment, the road map can be always displayed in an easy-to-see manner without making the user feel dazzling or dark, and the driving safety of the vehicle is deteriorated. Therefore, it becomes possible to always provide appropriate travel guidance.

In the above embodiment, the automatic light control circuit 36
However, when the automatic dimming circuit 36 is operated by the power supply circuit in the LCD unit 30, the LCD unit 30 operates normally due to insufficient capacity of the power supply circuit. In such a case, the automatic dimming circuit 36 may be provided with a separate power supply circuit so that only the control voltage VC is input to the LCD unit 30.

Further, in the above embodiment, the device for displaying the road map by the LCD unit 30 which is a liquid crystal display device has been described. However, the present invention can be applied to a device using a CRT as a display device. Needless to say. Furthermore, in the above-described embodiment, as the detection means for detecting the ambient brightness, the resistance value C changes according to the ambient brightness.
Although the optical sensor 40 made of dS or the like is used, any photoelectric conversion element, such as a photodiode or a phototransistor, whose electric characteristics change according to the ambient brightness can be used as the detecting means.

Further, in the above embodiment, the automatic light control circuit 36 including a resistor, a diode, an operational amplifier and the like is used as the automatic light control means, but the automatic light control means constitutes, for example, the control device 20. It can also be realized as one process of a microcomputer.

[0029]

As described above, in the vehicle map display device of the present invention, the screen of the display device for displaying the road map is bright when the surroundings are bright, such as outdoors during the day.
On the contrary, it automatically adjusts the light so that it becomes dark when the surroundings are dark, such as at night or in a tunnel. Also, for example, if the surrounding area suddenly gets dark, such as when the vehicle enters a dim place such as a tunnel during the day, the display screen is gradually darkened, and during the day, the vehicle is outdoors from a dim place such as a tunnel. When the surrounding area suddenly becomes bright, such as when the user escapes to, the display screen is rapidly brightened.

Therefore, according to the present invention, the road map is
It can be displayed with the optimal brightness according to the surrounding brightness, and the brightness of the display screen can be changed according to the human visual characteristics in response to the surrounding brightness change.
The road map can be always displayed in an easy-to-see manner without causing the user to feel dazzling or dark, and it is possible to always provide appropriate traveling guidance without lowering the traveling safety of the vehicle.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a configuration of a display device and an automatic light control circuit provided in the display device according to an embodiment.

FIG. 2 is a block diagram showing the overall configuration of the vehicle navigation device of the embodiment.

FIG. 3 is a graph showing a brightness adjustment characteristic of a display screen by an automatic light adjustment circuit.

FIG. 4 is a graph showing the relationship between the control voltage output from the automatic light control circuit and the brightness of the display screen.

FIG. 5 is a time chart exemplifying a change in the brightness of the display screen as the vehicle travels.

[Explanation of symbols]

2 ... GPS receiver 4 ... Input device 6 ... External storage device 14 ... Display device 20 ... Control device 27 ... Display drive device 30 ... LC
D unit 36 ... Automatic light control circuit 40 ... Optical sensor 44 ... Buffer circuit 46 ... Upper / lower limit voltage setting circuit C1 ... Capacitor

Claims (1)

(57) [Claims] 1. A display means capable of displaying a road map,
In a vehicle map display device for displaying a road map including a vehicle position on the display means, a detection means for detecting the ambient brightness of the display means, and a detection means for detecting the ambient brightness according to the ambient brightness detected by the detection means. , So that the display screen of the display means becomes brighter as the surroundings become brighter, and an automatic light control means for adjusting the brightness of the display screen is provided, and the automatic light control means further changes the surroundings from a bright state to a dark state. A map display for a vehicle, which is provided with a time constant circuit that gradually darkens the display screen when there is a change and rapidly brightens the display screen when the surroundings change from a dark state to a bright state apparatus.