JPH04233589A - Display device for vehicle - Google Patents

Abstract

PURPOSE:To securely shield a driver from a television image by providing selecting means, which select and display road guidance information required for the traveling of a vehicle or television information, to the display device on which a liquid crystal filter for limiting the view angle range of a display image is mounted. CONSTITUTION:The selecting means (switch) 5 and 6 for display contents which select and output the road guidance information required for the traveling of the vehicle or the television information to the image display device. When the television information is selected by the selecting means 5 and 6, a voltage control means 7 applies a 1st voltage to the liquid crystal filter 3 and when the road guidance information is selected, a 2nd voltage which is lower than the 1st voltage is applied to the liquid crystal filter 3. The driver is therefore shielded from the television image and a person in the assistant driver's seat is given the visibility for the television image and road guidance information.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] This invention relates to a display device for a vehicle, such as a CRT display device (TV image receiving device), for displaying television information (TV or video image hereinafter referred to as “TV image”) or road guidance information (hereinafter referred to as “map display”). The present invention relates to a method for controlling a liquid crystal filter that is attached to a liquid crystal display device and that limits the viewing angle range of images displayed.

0002

2. Description of the Related Art As a conventional display device for a vehicle, there is one shown in FIG. 8, for example.

To explain the structure, a vehicle light power switch 31 is provided near the steering wheel of the vehicle, and a CRT display is provided as an image display device in the center console provided in the center of the front of the driver's seat and passenger seat of the vehicle. A device 32 is provided. Also, there is a C on the center console.
An operating switch 33 of the RT display device 32 is provided, and this switch 33 can select either a map display or a television image. Further, an adjustment dial 34 for contrast adjustment etc. is provided on the left side, and an illuminance sensor 50 for detecting the brightness and darkness of the environment in which the CRT display device 32 is installed is further provided on the right side. Further, a liquid crystal filter 35 is attached to the front of the screen of a cathode ray tube or CRT display device 32, and a liquid crystal filter control circuit 36 for controlling the operation of the liquid crystal filter according to ON/OFF signals from the operation switch 33 and vehicle control signals is attached and housed. ing. The liquid crystal filter 35 is configured so that the screen of the CRT display device 32 can be sufficiently viewed from the driver's seat side and the passenger seat side (viewing directions are indicated by 37 and 38) when no voltage is applied.

FIG. 9 shows the relationship between the installation position of the liquid crystal filter 35 and the visible position of the liquid crystal filter from the driver's seat side and the passenger seat side.

FIG. 10 shows three circuits included in the control circuit 36.
The control conditions of the liquid crystal filter 35 by the input NAND gate 39, the 2-input OR gate 40, and the 2-input AND gate 41 are shown. In this figure, if neither the television switch ON signal 45 nor the map display switch ON signal 46, which are input signals to the two-input OR gate 40, are input, the OR gate 40
Since the output of is in the Lo state, the two-input AND gate 41
The output of is also in the Lo state.

A three-input NAND gate 39 receives a vehicle speed zero km/hr signal 42, a handbrake ON signal 43, and a gear position of the vehicle's automatic transmission, for example, whether the A/T position is parked (P) or neutral (N). When the signal 44 of 2 is input, the NAND gate 39 turns OFF.
Even if either the TV switch ON signal 45 or the map display switch ON signal 46 is input to the input OR gate 40, the output of the 2-input AND gate 41 is in the Lo state and no voltage is applied to the liquid crystal filter 35. In other words, these 3
The ON signal input conditions correspond to the conditions when the vehicle is stopped. Also, if even one of these three signals 42, 43, or 44 is not input, even if other signals are input, the NA
Since the output of the ND gate 39 becomes Hi state, the TV switch ON signal 45 or the map display switch ON signal 4
6, the output of the two-input OR gate 40 goes high, so the output of the two-input AND gate 41 goes high, and a voltage is applied to the liquid crystal filter 35, causing it to operate. This condition corresponds to, for example, a state in which the vehicle is running or in the process of starting, that is, a condition that can be considered as running.

Next, the operation of this prior art will be explained.

First, when the vehicle is stopped, the three input signals 42, 43
, 44 are input (see Figure 10), so NAN
The output of the D gate 39 becomes Lo state. For this reason, the signal of the TV switch ON45 or the map display switch ON
Even when 46 signals are input, the output of the 2-input AND gate 41 is in the Lo state.

Therefore, the control circuit 3 is connected to the liquid crystal filter 35.
6 is not applied, that is, is in an OFF state, and the television image or map display displayed on the screen of the CRT display device 32 can be viewed from the driver's seat side and the passenger seat side.

Next, when driving, the three input signals 42, 43,
Since one of 44 is not input, NAND gate 3
The output of No. 9 becomes Hi state. Therefore, when either the TV switch ON signal 45 or the map display switch ON signal 46 is input, the output of the AND gate 41 becomes Hi.
In this state, a voltage is applied to the liquid crystal filter 35, and the orientation of the liquid crystal molecules in the liquid crystal filter changes, thereby blocking the passage of transmitted light toward the driver's seat side, that is, causing blackening. As a result, the liquid crystal filter is connected to the CRT display device 3 from the driver's seat side.
It acts so that the image displayed on the second screen cannot be viewed. Furthermore, the voltage applied to the liquid crystal filter is
In order to optimize light shielding and transparency, the illuminance sensor 50
The brightness and darkness of the environment in which the RT display device 32 is installed is detected and controlled by a control signal of a liquid crystal filter drive control circuit according to the detected signal. For example, when a vehicle drives at night and the front lights off switch is turned on to turn on the front lights, a high voltage is applied to the liquid crystal filter. Sometimes, the voltage applied to the liquid crystal filter is changed by a method in which a low voltage is applied (see Japanese Patent Application No. 63-74816), or by a C
A method using a liquid crystal filter drive circuit that detects the brightness and darkness of the environment in which the RT display device is installed using an illuminance sensor, and controls the liquid crystal filter drive voltage according to the output of the illuminance sensor linearly with respect to the logarithm of the illuminance. etc. are possible. When both the television and map display switches are off, no voltage is applied to the liquid crystal filter.

[0011]

However, in such conventional vehicle display devices, the voltage applied to the liquid crystal filter is controlled only by the brightness level of the external environment. Even if the map display is a detailed and static image, the displayed image may be coarse and
In addition, even if the TV image is a moving image, the voltage applied to the liquid crystal filter is constant. In addition, if such a constant voltage is set to a high voltage that reliably blocks image visibility on the driver's seat side, the transmittance of the liquid crystal filter for the displayed image will be low on the passenger seat side while the vehicle is running. Moreover, when attempting to view a detailed map display, the image becomes difficult to view. Furthermore, if such a constant voltage is set to a low voltage so that the map display is sufficiently visible on the passenger's seat side, the image will be visible from the driver's seat side (creating an eye-catching effect), for example, when the vehicle is driving at night. ) There is a fear. At this time, there is a problem in that a still image such as a map display does not attract the eye, but a moving image such as a television image does.

[0012] This invention reliably blocks the television image for the driver, and ensures the visibility of the television image and map display for the passenger seat, thereby increasing the enjoyment of viewing the television and the driver's enjoyment. It is an object of the present invention to solve the above-mentioned problems by providing a display device for a vehicle that can provide accurate instructions and assistance.

[0013]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a display device for a vehicle equipped with a liquid crystal filter that limits the viewing angle range of a displayed image. display content selection means for selecting any of the television information and outputting it to the image display device;
When the display content selected by the selection means is television information, a first voltage is applied to the liquid crystal filter, and when the display content selected by the selection means is road guidance information, the first voltage is applied to the liquid crystal filter. The liquid crystal filter is configured to include voltage control means for applying a second voltage lower than the voltage to the liquid crystal filter.

[0014]

[Operation] When displaying road guidance information (map display), the voltage applied to the liquid crystal filter is lower than when displaying TV information (TV image), so the overall transmittance of the LCD filter is lower than when displaying TV information (TV image). becomes larger, making it easier to see detailed road displays on the map from the direction of the passenger seat. On the other hand, the light shielding rate of the liquid crystal filter decreases in the direction of the driver;
In the case of road guidance information (map display), since it is a still image, there is no eye-catching effect. In addition, when viewing TV images, the transmittance of the liquid crystal filter decreases, ensuring sufficient light blocking in the driver's direction even for moving images such as TV images, while ensuring TV visibility for the passenger seat. can do.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings shown in FIGS. 1 to 7.

FIG. 1 is a diagram showing an embodiment of the present invention. First, to explain the configuration, there is a CRT display device connected to a television receiver (not shown) and a video device (map information reproducing device) not shown in the center console provided in the center of the front of the driver's and passenger seats of the vehicle. 1 and a liquid crystal filter 3 attached to the front of a cathode ray tube, that is, a CRT screen 2. Furthermore, CRT
An illuminance sensor 4 that detects the degree of brightness, that is, the illuminance, of the place where the display device 1 and the liquid crystal filter 3 are installed.
is located. 7 is a signal 5 for turning on the television switch as means for selecting display contents of the CRT display device 1;
This is a circuit that switches the set voltage when either the map display switch ON signal 6 or the map display switch ON signal 6 is selected and input, that is, the set voltage switching circuit (current control means), and this is the main component of this embodiment. 11 is a signal 8 when the vehicle is stopped, that is, when the vehicle speed is 0 km/hr, as in the conventional case.
, ON signal 9 when the hand brake or side brake is in operation, and the automatic driving gear position of the vehicle, that is, the A/T position is parked (P) or neutral (
When receiving any of the signals 10 (N), the liquid crystal filter 3 is not activated, and is activated while driving.
This is a liquid crystal filter drive control circuit that controls the operation of the liquid crystal filter 3. 12 is the viewing direction of the liquid crystal filter 3 from the driver's seat side, and 13 is the viewing direction of the liquid crystal filter 3 from the passenger seat side. FIG. 2 shows a processing circuit (incorporated in the liquid crystal filter drive control circuit 11) when the photodiode 16 is used as the illuminance sensor 4. This circuit includes an operational amplifier 14, an amplifying operational amplifier 15, a photodiode 16,
resistance thermistor 17, voltage variable device 18, current source 19,
It is composed of a fixed resistor 20.

The role of the electric circuit shown in FIG. 2 is as follows. That is, when the amount of light input to the photodiode 16 is small, such as at night, the voltage corresponding to the amount of light is compared with the reference voltage determined by the voltage variable device 18 using the operational amplifier 14, and the output is sent to the resistor thermistor. At step 17, the temperature-compensated amplification operational amplifier 15 amplifies the output to a large output, and applies this output to the liquid crystal filter 3 as a large voltage.On the other hand, during the daytime when the illuminance is high, the voltage applied to the liquid crystal filter 3 is reduced to approximately , as shown in FIG. 3 (characteristics of the output portion of the operational amplifier 14). Here, the voltage variable device 18 in FIG. 2 adjusts the degree of balance of the voltage of the current source 19, and the photodiode 16 adjusts the slope of the straight line in FIG.

The voltage applied to the liquid crystal filter 3 is controlled by the illuminance sensor 4 (photodiode 16), and as shown in FIG. 1, when the map display switch ON signal 6 is input, the set voltage is switched. The circuit 7 is configured to be able to switch to a circuit that makes the voltage V smaller than that for normal television images.

Next, the operation of the above embodiment will be explained. In FIG. 1, a 6-inch in-vehicle CRT display device 1, which has a liquid crystal filter 3 attached to the front of a CRT screen 2 that displays either a television image or a map display, is installed in a direction 12 toward the driver's seat and in a direction 12 toward the passenger seat. It is installed in the center console where it can be seen from 13.

(a) When stopped In this case, all three signals 8, 9 and 10 are input to the liquid crystal filter drive control circuit 11, so either the TV switch ON signal 5 or the map display switch ON signal 6 is input. Even if the voltage is input, the liquid crystal filter control circuit 11 does not output an output and no voltage is applied to the liquid crystal filter 3, as in the conventional case. Therefore, both the driver and the passenger can view the television image or map display selected by operating the switch.

(b) When driving In this case, at least one of the three signals 8, 9 and 10 is not input to the liquid crystal filter drive control circuit 11, so the control circuit 11 outputs it to the liquid crystal filter 3. . The degree of this output, that is, the applied voltage varies depending on the selection of the display screen.

■ When selecting a television image, the television switch ON signal 5 is input to the set voltage switching circuit 7, and the output of the set voltage V large (same voltage as before) is input to the control circuit 11. 11 outputs the voltage to be applied to the liquid crystal filter 3. As a result, the liquid crystal filter 3 becomes black in the maximum contrast direction of the liquid crystal, that is, in the viewing direction 12 from the driver's seat side, so that the television image cannot be viewed. That is, it is possible to prevent the television image from attracting the driver's attention. However, since the liquid crystal filter 3 has a narrow viewing angle band, blackening does not occur in the viewing direction 13 from the passenger seat side, so the passenger seat person can view and enjoy the television image.

(2) When selecting the map display, the map display switch ON signal 6 is input to the switching circuit 7. At this time, since the set voltage V of the switching circuit 7 becomes small, the control circuit 11 outputs an output to apply a lower voltage to the liquid crystal filter 3. This lower voltage setting will lead to a reduction in the light blocking performance on the driver's seat side, but since a still image with low contrast, such as a map display, is less eye-catching than a TV image, the reduction in light blocking performance will be less. there is no problem. As this voltage is lowered, the transmittance on the passenger seat side increases and the display becomes brighter, making the image display easier to see even when displaying a detailed map.

Furthermore, when the illuminance of the outside world (environment) changes during day and night while driving, the output voltage of the operational amplifier 15 is changed by the circuit shown in FIG. 15 and output. As a result, the voltage applied to the liquid crystal filter 3 is automatically adjusted by the output of the liquid crystal filter drive control circuit 11 according to the environmental illuminance of the CRT screen 2 and the liquid crystal filter 3. Here, as shown in FIG. 3, the vertical axis represents the output voltage in volts (V), and the horizontal axis represents the logarithmic illuminance in lux, the relationship between the illuminance of the illuminance sensor 4 and the output voltage. is a linear relationship that slopes downward to the right. The output voltage from this illuminance sensor 4 is applied to the liquid crystal filter drive control circuit 1.
1 as described above according to the illuminance, and is applied to the liquid crystal filter 3. In FIG. 4, the vertical axis shows the liquid crystal applied voltage in volts (V), and the horizontal axis shows the logarithmic illuminance in lux, the illuminance unit.

In FIG. 4, line 21 indicates a higher set voltage for television images, line 22 indicates a lower set voltage for map display, and line 22 indicates a lower set voltage for map display. It is set so that it goes below. However, these lines 21 and 22 are lower than the minimum line 24 of the voltage necessary for shading the TV image on the driver's seat side, and below this line 24, and also below the minimum voltage line 25 necessary for shading the map display. Since the voltage is set upward, that is, at a high voltage, the above-mentioned effect can be achieved well. moreover,
FIG. 5 shows the relationship between the transmittance characteristics of the liquid crystal filter 3 and the image viewing angles from the driver's seat side and the passenger seat side. In this figure, the vertical axis is the transmittance of the liquid crystal filter 3 in percentage (%), and the horizontal axis is the viewing angle with the origin at the midpoint between the driver's seat and the passenger's seat, the left side being the passenger side, and the right side being the driver's seat side. Area and frequency (deg)
Indicated by

In FIG. 5, 26 indicates a TV image at an illuminance of 10,000 l.
ux, transmittance when driven at voltage 3.0V, 27
shows the performance curve of transmittance when the map display is similarly driven at a voltage of 2.8V. As a result, since the transmittance is generally low on the driver's seat side (to the right of 0), the eye-attracting effect of the television image is reduced, but on the passenger seat side, the transmittance increases and the map display becomes brighter and easier to see.

FIG. 6 shows a flowchart of the image display device. Turn on the TV switch in STEP-1 or press S
Depending on whether the map display switch is turned on in TEP-9, the display image of the image display device is selected as a television image or a map display. In STEP-2, the television image selected in STEP-1 is displayed. STEP-9 in STEP-10
The selected map will be displayed. STEP-3~S
At TEP-5, signals indicating the running state of the vehicle are sequentially input. That is, the vehicle speed is 0 km/hr 8, the handbrake ON signal 9, and the A/T position P or N signal 10.
When the liquid crystal filter drive control circuit 11 inputs this, it is determined that the vehicle is stopped, and the process proceeds to STEP-7, where no voltage is applied to the liquid crystal filter 3, that is, the liquid crystal filter 3 becomes in an OFF state. STEP-3
~ If any of STEP-5 is NO, proceed to STEP-6, and when selecting the TV switch ON, proceed to STEP-1.
1, the driving voltage of the liquid crystal filter 3 is driven by the high setting voltage 21 by the setting voltage switching circuit 23. On the other hand, if NO in STEP-6, that is, the map display switch is
In the case of N, proceed to STEP-12 and change the driving voltage of the liquid crystal filter 3 to the low setting voltage 22 by the setting voltage switching circuit 7.
It will be driven by

[0028] Furthermore, in STEP-1, turn on the TV switch.
When both of the map display switches ON and STEP-9 are OFF, the process advances to STEP-8 and the liquid crystal filter drive is turned OFF.

FIG. 7 shows a flowchart of another embodiment. In this embodiment, the set voltage is switched between a television image display, a map display (rough map display), and a detailed map display (fine map display). In STEP-1, it is determined whether the television switch is ON or not. If YES, the process advances to STEP-2 and the television image is displayed. If NO, proceed to STEP-9 and determine whether to display a map; if YES, proceed to STEP-11 to display a map. If NO in SETP-9, STE
Proceed to P-10, determine whether to display a detailed map, and press Y.
If ES, proceed to STEP-12 to display a detailed map; if NO, proceed to STEP-8 to turn off the liquid crystal filter drive. STEP-2, STEP-11 and ST
After displaying any of EP-12, STEP-3~S
The process sequentially proceeds to TEP-5, and it is determined whether a signal indicating the running state of the vehicle has been input. STEP-3~5 is YES
When S, proceed to STEP-7, and the liquid crystal filter 3 has
No voltage is applied, that is, the state is OFF. STEP3～
If any of 5 is NO, proceed to STEP-6 and determine YES or NO for detailed map display.If NO, that is, when displaying the TV image and map, set the driving voltage of the liquid crystal filter 3. It is driven by the high setting voltage 21 by the voltage switching circuit 23. On the other hand, YES in STEP-6
S, that is, when displaying a detailed map, proceed to STEP-14 and set the drive voltage of the liquid crystal filter 3 by setting the voltage switching circuit 2.
3, it is driven at a low set voltage 22. As described above, in this embodiment, the map display, that is, the rough map display, is regarded in the same way as a television image, and by distinguishing it from a detailed map, it is possible to prevent the effect of attracting attention to the driver's seat side during driving.

Note that the present invention can be similarly applied to the case where a video image is used instead of a television image. Furthermore, the same effect can be obtained by changing the brightness of the CRT display by applying a voltage.

[0031]

[Effects of the Invention] As explained above, according to the present invention, it is possible to prevent the eye-attracting effect of TV images on the driver, and to make it easier for the passenger to see the TV image or the map display, thereby making driving more enjoyable and enjoyable. This has the effect of providing accurate instructions and assistance to the driver.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of an embodiment of a vehicle display device based on the present invention.

FIG. 2 is an electrical drive circuit diagram using an illuminance sensor.

FIG. 3 is a performance chart showing the relationship between the received light illuminance and the output voltage of the illuminance sensor.

FIG. 4 is a performance diagram showing the relationship between the received light illuminance of the illuminance sensor, the liquid crystal applied voltage, and the control voltage.

FIG. 5 is a performance chart showing the relationship between the transmittance of a liquid crystal filter and the viewing angle.

FIG. 6 is a flowchart of an embodiment of a vehicle display device according to the present invention.

FIG. 7 is a flowchart of another embodiment of the vehicle display device according to the present invention.

FIG. 8 is a basic configuration diagram of a conventional vehicle display device.

FIG. 9 is a diagram showing a planar positional relationship between a liquid crystal filter and a viewing position.

FIG. 10 is a block diagram showing operating conditions of a liquid crystal filter.

[Explanation of symbols]

1 CRT display device 2 CRT screen 3 Liquid crystal filter 4 Illuminance sensor 5 TV switch ON signal (selection means) 6 Map display switch ON signal (selection means) 7 Set voltage switching circuit (voltage control means) 8 Vehicle speed zero km/
hr signal 9 Handbrake ON signal 10 A/T position P or N signal 11 Liquid crystal filter drive control circuit 12 Viewing direction from the driver's seat side 14 Operational amplifier 15 Amplification operational amplifier 16 Photodiode 17 Resistance thermistor 18 Voltage variable device 19 Current Source 20 Fixed resistance 21 High setting voltage 22 Low setting voltage

Claims (1)

[Claims] Claim 1: In a vehicle display device equipped with a liquid crystal filter that limits the viewing angle range of a displayed image, a display that selects either road guidance information or television information necessary for driving the vehicle and outputs it to the image display device. content selection means, and if the display content selected by the selection means is television information, applying a first voltage to the liquid crystal filter;
A display device for a vehicle, comprising voltage control means for applying a second voltage lower than the first voltage to the liquid crystal filter when the display content selected by the selection means is road guidance information.