JP2016006462A - Display device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device for a vehicle that can automatically control lighting according to external light, and measure the illuminance of the external light within a wide range.SOLUTION: A display device for a vehicle includes illuminance detection means 4 for changing an output current on the basis of the illuminance of external light, a backlight 1 that illuminates display means 2 for displaying vehicle information, a conversion circuit 5 that converts a change of a current value by the illuminance detection means 4 into a plurality of voltage values and outputs the voltage values, and control means 3 including a plurality of input ports 31 and 32 that receive input of the voltage values from the conversion circuit 5 and adjusting output luminance of the backlight 1 according to the voltage values.

Description

  The present invention relates to a display device for a vehicle, and is particularly suitable for a display device for a vehicle having an automatic light control function that adjusts display luminance according to illuminance of outside light.

  For example, there is a display device using a liquid crystal display panel as disclosed in Patent Document 1. These display devices include a liquid crystal display panel that performs full-color display, a light source that transmits and illuminates the liquid crystal display panel, and a control circuit that controls the liquid crystal display panel and the light source. These liquid crystal display panels can perform desired brightness adjustment according to, for example, the illuminance of outside light, and can be realized by controlling the light intensity of a light source serving as a backlight.

JP 2006-72255 A

  According to the above-described display device, those using phototransistors as illuminance sensors are disclosed, but when the output values from these illuminance sensors change greatly, the illuminance from direct sunlight to darkness such as motorcycle meters When the range (measurement range) is large, it is difficult to read all illuminance values by a control unit including a microcomputer, and there is a problem that the illuminance of outside light cannot be measured in a wide range.

  Accordingly, an object of the present invention is to provide a vehicle display device capable of measuring the illuminance of outside light in a wide range by paying attention to the above-described problems.

The vehicle display device of the present invention includes:
Illuminance detection means for changing the output current based on the illuminance of external light;
Illumination means for illuminating a display for displaying vehicle information;
A conversion circuit that converts a current value change by the illuminance detection means into a plurality of voltage values and outputs the voltage values;
And a plurality of input ports for inputting the voltage values from the conversion circuit, and a control means for adjusting the output luminance of the illuminating means according to the voltage values.

Further, the conversion circuit is configured using a plurality of resistance elements,
The control means selects any one of the voltage values of the input ports, and determines the output luminance of the illumination means based on the voltage value.

  The present invention relates to a vehicular display device capable of automatically dimming illumination according to external light, and can measure the illuminance of external light in a wide range.

The figure which shows the example of a display of the vehicle-mounted instrument by embodiment of this invention. The figure which shows the cross section of the vehicle-mounted instrument by embodiment same as the above. The block diagram which shows the electric circuit structure by embodiment same as the above.

  Hereinafter, as an embodiment of a display device for a vehicle according to the present invention, an example applied to an in-vehicle instrument for a motorcycle will be described with reference to the drawings.

  1 and 2 show a schematic configuration of the vehicle-mounted instrument A according to the embodiment of the present invention, and FIG. 3 shows an electric circuit configuration of the vehicle-mounted instrument A.

  As shown in FIGS. 1 to 3, the vehicle-mounted instrument A functions as a composite instrument, and includes display means (display) 1, backlight (illumination means) 2, control means 3, illuminance detection means 4, and conversion circuit. 5, case 6 and the like.

  The display means 1 is a TFT-type transmissive liquid crystal panel that forms a desired image based on a control signal from the control means 3, and the display surface 11 faces the driver side of the vehicle. It is installed near the center of the handle). The display means 1 is a dot matrix type having a plurality of pixels arranged in a matrix, and realizes image display by driving each pixel. Here, each pixel of the display means 1 is composed of sub-pixels of three colors provided with red (R), green (G), and blue (B) color filters, respectively. Display is possible.

  In this case, as shown in FIG. 1, the display unit 1 displays a meter image as a pointer-type meter image composed of a plurality of pixels, and a display image composed of a plurality of pixels, such as a warning image and an indicator. The instrument image is an image for instructing and displaying the state value of the vehicle travel information to the vehicle occupant. In this case, the speed indicator that indicates the vehicle speed value using the pointer image, and the fuel remaining by bar display. It includes a quantity meter, a background image indicating the background, a numerical image such as an accumulated mileage, and a mark image for displaying a warning and an indicator. These displays can be changed to a bar graph display or the like by switching the screen.

  The backlight 2 can be a light emitting diode that illuminates the display means 1 via the light guide 21. The backlight 2 is a chip component for surface mounting, and is mounted on the circuit board 7 on the back side of the display means 1. The backlight 2 is electrically connected to the control means 3, and emits illumination light by being driven based on a control signal given from the control means 3. In this case, the control means 3 can be controlled to emit and output from the backlight 2 at a desired luminance by pulse width modulation control.

  The light guide 21 is formed in a flat plate shape with a light-transmitting synthetic resin such as acrylic, and is arranged in parallel with the display unit 1 on the back side of the display unit 1. The light guide 21 reflects and diffuses the incident light from the adjacent backlight 2 and emits the light from the exit surface on the display means 1 side, so that the emission luminance on the exit surface is spread over the entire area. Make it almost uniform. As described above, the backlight 2 illuminates and transmits the entire display unit 1 from behind by the light from the emission surface.

  The display unit 1, the backlight 2, and the light guide 21 constitute a display unit B that can be illuminated and displayed so that the user can see it even in a dark environment such as at night. In addition, although what comprised the display panel B by the display means 1 which consists of a liquid crystal panel, and the illumination means which consists of the backlight 2 was shown, it can replace with self-luminous type panels, such as an organic electroluminescent panel. In this case, the control means 1 can perform optimal display output by adjusting the display brightness of the panel.

  The control means 3 includes a CPU and a memory, and is composed of a known microcomputer that controls the backlight 2 and the display means 1 by transmitting a control signal by calculating a predetermined program. 7 is implemented. The control means 3 is connected to the backlight 2, the conversion circuit 5, etc., and is electrically connected (communication connection) so that vehicle speed and the like can be input as vehicle information. Here, the vehicle information includes vehicle travel information including the gear position and direction instruction operation, the state of the vehicle, and an abnormal signal from each device.

  The control means 3 includes a drawing processing circuit, and the drawing processing circuit performs drawing arithmetic processing such as generating an image to be displayed on the display means 1 using image data stored in a storage unit stored in advance. The storage unit for storing image data is preferably a nonvolatile memory such as a flash memory. For example, the drawing processing circuit can display a display image 12 on the display surface 11 by outputting a control signal for driving each constituent pixel of the display unit 1.

  The illuminance detection means 4 can be a phototransistor and is provided so that external light can be received from the detection unit. The illuminance detection means 4 detects illuminance such as sunlight that illuminates the vehicle-mounted instrument A, and controls the detection signal (illuminance information). Output to. In this case, the illuminance detection means 4 can output a current value that changes according to the illuminance as a detection signal.

  The illuminance detection means 4 is connected to a power supply circuit 8 composed of a regulator that steps down a power supply of about 12 V connected to an on-vehicle battery or a power generation unit to make a constant voltage of 5 V. From the power supply circuit 8 The supplied power is changed in current and used as a detection signal. The power supply circuit 8 is mounted on the circuit board 7 and is also used as a drive power supply for the control means 3 and the like.

  The conversion circuit 5 changes the current value changed by the illuminance detection means 4 into a voltage value corresponding to the current change, in this case, a plurality of voltage values, so that the control means 3 can read the current value. Output to a plurality of voltage value detection ports (first port 31 and second port 32), and a plurality of resistance elements (first resistance element 51 and second resistance element 52) are connected in series. It is configured to connect and ground. The control means 3 has a function of converting a voltage signal (analog signal) input via the first port 31 and the second port 32 into a digital value.

  The resistance values of the first resistance element 51 and the second resistance element 52 are the first resistance element 51 for setting a current range corresponding to the voltage range (0 to 5 V) input by the first port 31 and Considering the combined resistance value of the second resistance element 52 and the resistance value of the second resistance element 52 for setting the current range corresponding to the voltage range (0 to 5 V) input to the second port 32 You can choose. In this case, a resistance value of 100 ohms is applied to the first resistance element 51, and a resistance value of 72 ohms is applied to the second resistance element 52.

  The case 6 is formed by fitting a plurality of molded products made of synthetic resin to form a space for housing the above-described components such as the circuit board 7 and the display unit 1. The case 6 faces the display surface 11 of the display unit 1 and has an illuminance. The detection unit 4 includes a light transmission part that can receive light and a light shielding part that holds each component at a predetermined position. Further, the case 6 houses the illuminance detection means 4 and at least a partition wall for preventing exposure light or the like from the backlight 2 on the display unit B side from being exposed to the illuminance detection means 4 side. 4 and the display means 1, and in this case, an illuminance detection unit comprising a predetermined space is formed by surrounding the illuminance detection means 4.

  In addition, the case 6 is provided with a turn-back portion 62 that divides the display area of the display unit 11 and covers an unnecessary part other than the display area of the display unit 1 and the light reception of the illuminance detection unit 4. The light transmitting portion of the case 6 may be a transparent synthetic resin material such as acrylic, or a member with adjusted transmittance can be used. In the latter case, the external light illuminance considering the transmittance can be used. Illumination output to the measurement and display means 1 is made.

  With the configuration described above, the control unit 3 can determine the illuminance based on the voltage values at the first and second input ports 31 and 32 and adjust the output luminance of the backlight 2 based on the illuminance. The optimum display output according to the brightness of the can be automatically performed.

  The control means 3 has a predetermined switching threshold value set in the voltage value between the lower limit (0V) and the upper limit (5V) in the first input port 31 or the second input port 32, respectively. When one input port 31, 32 exceeds the switching threshold, the illuminance is calculated based on the voltage value input by the other input port 31, 32. Therefore, since a wide range can be read with respect to the detection signal from the illuminance detection means 4, even if the difference in brightness is large, illumination output corresponding to the usage environment of the in-vehicle instrument A can be performed. Further, by inputting signals using the plurality of input ports 31 and 32, the recognizable resolution can be increased, and illuminance measurement with higher accuracy can be achieved. The switching threshold described above can provide stable display output by providing a hysteresis when deciding which voltage value to select between the first and second input ports 31 and 32.

  Such an in-vehicle instrument has a plurality of illuminance detection means 4 for changing the output current based on the illuminance of outside light, a backlight 1 for illuminating the display means 2 for displaying vehicle information, and a plurality of current value changes by the illuminance detection means 4. And a plurality of input ports 31 and 32 for inputting the voltage value from the conversion circuit 5, and adjusting the output luminance of the backlight 1 according to the voltage value And a control means 3 for performing.

  Further, the conversion circuit 5 is configured by using a plurality of resistance elements (first and second resistance elements 51 and 52), and the control means 3 has a voltage value of one of the plurality of input ports 31 and 32. And the output luminance of the backlight 1 is determined based on this voltage value.

  Therefore, even if the illuminance detection means 4 causes a large current value change based on a wide illuminance range, the display device for a vehicle can accurately measure the illuminance.

  Although the embodiments of the present invention have been described above, the present invention is not construed as being limited to the above-described embodiments, and can be applied to various embodiments without departing from the scope of the present invention. . For example, the illuminance detection means 4 has a temperature characteristic in which the deviation of the output value with respect to the predetermined temperature increases as the temperature difference from room temperature increases due to high temperature or low temperature. It is also possible to perform correction in consideration of temperature characteristics, and to detect more accurate illuminance.

  The present invention relates to a display device for a vehicle, and is suitable, for example, as an instrument for a vehicle mounted on a moving body including an automobile, a motorcycle, an agricultural machine, or a construction machine.

1 Display means (display)
11 Display surface 12 Display image 2 Backlight (illumination means)
21 Light guide 3 Control means 31 1st input port 32 2nd input port 4 Illuminance detection means 5 Conversion circuit 51 1st resistance element 52 2nd resistance element 6 Case 61 Partition wall (wall part)
62 Light-shielding part 63 Vent hole 64 Porous membrane 7 Circuit board 8 Power supply circuit A Vehicle-mounted instrument (vehicle display device)
B Display unit C Illuminance detector

Claims (2)

Illuminance detection means for changing the output current based on the illuminance of external light;
Illumination means for illuminating a display for displaying vehicle information;
A conversion circuit that converts a current value change by the illuminance detection means into a plurality of voltage values and outputs the voltage values;
A vehicle display device comprising: a plurality of input ports for inputting the voltage values from the conversion circuit; and control means for adjusting output luminance of the illumination means according to the voltage values. The conversion circuit is configured using a plurality of resistance elements,
2. The vehicle display device according to claim 1, wherein the control unit selects a voltage value of one of the input ports and determines an output luminance of the lighting unit based on the voltage value. 3. .

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