JPH0740426Y2 - Vehicle dimmer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a vehicle light control device that appropriately adjusts the emission brightness of a display image of a display device called a head-up display.

[Conventional technology]

As shown in FIG. 2, the head-up display is a projection member 2 in front of the driver's vehicle 1, for example, a windshield, so that the driver's information such as vehicle speed, mileage, remaining amount of fuel or time need not be largely moved from the forward view. The display device 6 is configured so that the display image 4 is imaged in the front view outside the windshield by projecting it on the reflecting member of the optical system 3 so as to overlap with the landscape 5 in the view.
Is.

In this head-up display, when the daytime is extremely bright, the contrast ratio between the brightness of the external light and the brightness of the display image 4 (the combined brightness of the external light and the display image 4) becomes too small, and the display image 4 is displayed. The visibility of the
If the brightness of the display image 4 is increased in order to solve this, on the contrary, the display image 4 becomes too bright and looks dazzling at night. An existing external light detecting unit 7 for detecting the brightness is provided, and the brightness adjustment signal is controlled according to the brightness of the external light detected by the external light detecting unit 7 to adjust the emission brightness of the display device 6. A dimming device having a control unit 8 using a CPU is well known. (Actual application Sho 63-113212
As shown in FIG. 5, the conventional light control device detects the brightness of external light and outputs a detection voltage 9 corresponding thereto through an A / D converter 10 to an external light detection unit 7. A control unit 8 that outputs a rectangular wave 11 according to a change in the detection voltage 9 is connected to the control unit 8.
The display device 6 is connected via the D / A converter 12 that converts a rectangular wave into an analog signal, and the emission brightness of the display device 6 is adjusted according to the brightness of external light.

Therefore, for example, if the control unit 8 uses a 4-bit CPU, A
The / D converter 10 outputs the detection voltage 9 to the CPU in correspondence with one of 16 digital signals generated from 4 bits, and changes the duty ratio of the rectangular wave 11 output from the CPU. It was adjusting by outputting 11.

FIG. 6 shows an example in which the duty ratio is changed to 2 ⁴ = 16 steps when processing is performed with the external brightness set to a range of 0 to 160 [lx] for convenience.

The brightness of external light is detected by the external light detection unit 7, and a detection voltage 9 corresponding to the brightness is output to the A / D converter 10.

In the A / D converter 10, the detection voltage 9 is divided into 16 stages of digital signals, and the duty ratio corresponding to each digital signal is output from the control unit 8.

In this example, for example, the external brightness is 40 [lx] or more and 50 [l
x], the duty ratio is 31.25%, 50 [lx]
If it is less than 60 [lx], it is set stepwise such as 37.5%.

[Problems to be solved by the device]

By the way, when the ambient light is bright,
[Lx] Even if the light emission luminance (duty ratio) is changed every time it changes, the luminance does not seem to change roughly intermittently because the change rate of the luminance is small with respect to the brightness of external light.

However, when the brightness of the outside light is dark, the emission brightness is changed by the same amount every time the outside light changes by 10 [lx] as when the outside light is bright. It is felt that the rate of change in brightness increases and that the change in brightness changes intermittently.

Also, in the case of FIG. 6, the adjustment is made with 16 different processed signals. Until then there was a drawback that it would be completely unadjustable.

Therefore, in order to perform smooth brightness adjustment, the control unit 8
It suffices to frequently change the duty ratio of No. 2 and change the duty ratio while keeping the rate of change in luminance with respect to the brightness of external light small.

This can be solved by increasing the resolution of the CPU and increasing the number of bits of the A / D converter 10, but this solution is not the best solution because the CPU itself becomes expensive.

[Means for Solving the Problems]

 The detailed description will be made with reference to the accompanying drawings.

In a vehicular display device that adjusts the light emission brightness of a display device 6 that includes a projection member 2 that projects a display image 4 in front of the driver 1, the brightness of outside light from the front of the driver 1 is detected and correspondingly detected. An external light detection unit 7 that outputs a detection signal 9 and an A / D converter 10 that digitally processes the detection signal 9 of the external light detection unit 7.
And a control unit 8 for outputting a rectangular wave 11 having a duty ratio corresponding to the digital signal, and a comparator 14 for comparing an arbitrarily set reference voltage value with a detection voltage 9 output from the external light detection unit 7. The first integrator 16 outputs to the A / D converter 10 as the detection voltage 9 which is M times the detection voltage 9 of the external light detection unit 7 by the comparison processing of the comparator 14.
And the control unit 8 in parallel with the processing of the first integrator 16.
A second integrator 16 'for outputting to the display device 6 a rectangular wave 11 having a duty ratio of 1 / M times the duty ratio output from the reference voltage set arbitrarily by the comparator 14. When the detected voltage 9 is lower than the reference voltage value by comparing the value with the detected voltage 9 from the external light detection unit 7, the first integrating unit 16 multiplies the detected voltage 9 by M, Further, the present invention relates to a vehicle light control device, characterized in that the duty ratio output from the control section 8 is multiplied by 1 / M by the second integrating section 16 '.

[Action]

The detection signal 9 corresponding to the change in the brightness of the external light output from the external light detection unit 7 is output to the comparator 14.

In the comparator 14, the value of the output detection signal 9 is compared with the arbitrarily set reference value, and if the detection signal 9 is lower, the detection signal 9 multiplied by M is digitally processed by the A / D converter 10. , Is output to the control unit 8.

When the detection signal 9 is higher than the reference value, the detection signal 9 is output to the control unit 8 via the A / D converter 10 to the control unit 8.

The control unit 8 outputs a rectangular wave 11 having a predetermined duty ratio set in the processing signal corresponding to the digital signal of the A / D converter 10 output according to the change of the detection signal 9, but the comparator 14 When the detection signal 9 is multiplied by M, the duty ratio of the rectangular wave 11 'outputted as a result is multiplied by 1 / M by the second integrator 16' and displayed on the display device 6 via the D / A converter 12. Output.

〔Example〕

FIG. 1 and FIG. 2 show an embodiment of the present invention, which will be described in detail based on this, but the elements having the same or equivalent functions as those of the conventional example are designated by the same reference numerals.

Since the head-up display shown in FIG. 2 has been described in the conventional example, its description is omitted.

FIG. 1 is a block diagram of the present invention.

The external light detector 7 is connected to the comparator 14 and the first integrator 16.

The first integrator 16 performs a predetermined process, which will be described later, on the detection voltage 9 of the external light detection unit 7 according to a command from the comparator 14.

The first integrator 16 is connected to the A / D converter 10 and converts the detection voltage 9 into a digital signal.

The A / D converter 10 is connected to the controller 8 and performs a predetermined process on the digitally converted detection voltage 9 and then converts the detection voltage 9 into a rectangular wave 11 having a duty ratio corresponding to the detection voltage 9.

The process of converting to the rectangular wave 11 is performed by the CPU 15 in the control unit 8.

The CPU 15 is connected to the A / D converter 12 via a second integrator 16 'that performs a process to be described later in parallel with the first integrator 16 according to an instruction from the comparator 14.

Next, the operation will be described.

The comparator 14 compares the internally set reference voltage value with the detection voltage 9 of the external light detection unit 7, and if the detection voltage 9 is higher than the reference voltage, outputs the detection voltage 9 as it is to the A / D converter 10. The digital signal is converted into a digital signal, and the rectangular wave 11 set to the duty ratio corresponding to the detection voltage 9 is output by the predetermined processing of the CPU 15 through the second arithmetic unit 16 ′ and the D / A converter 12, and the display device is displayed. 6 is used as the brightness adjustment signal 18.

However, when the detected voltage 9 is lower than the reference voltage value, the comparator 14 outputs the detected voltage 9 output to the first integrator 16 by M
A multiplying instruction 13 is output to the first integrator 16, and the M-folded detection voltage 9 outputs a rectangular wave 11 'set to a predetermined duty ratio by a predetermined process of the CPU 15.

Further, the comparator 14 outputs an instruction 17 for multiplying the duty ratio of the rectangular wave 11 'by 1 / M to the second integrator 16', and outputs the duty ratio multiplied by 1 / M to the D / A converter 12. It is used as the brightness adjustment signal 18 of the display device 6 via the.

Next, a specific description will be given with reference to FIGS. 3 and 4. Here, a 4-bit CPU 15 is used for the control unit 8.

Also, in order to simplify the explanation, the brightness of external light is set to 16 as in the conventional example.
The value is up to 0 [lx], and the constant M is set to 10.

The reference voltage set in the comparator 14 is output from the external light detection unit 7 when it is felt that the ratio of the change in the brightness to the change in the external light becomes large and the change in the brightness starts to change intermittently. The detection voltage 9 is set to the same value.

Here, the value is set to the value output from the external light detection unit 7 when the brightness of external light is 10 [lx].

FIG. 3 shows the processing when the detection voltage 9 of the external light detection unit 7 is higher than the reference voltage, that is, when the brightness of external light is 10 [lx] or more.

That is, unlike the conventional example shown in FIG. 6, 10 to 160 [lx]
Corresponds to 16 types of processed signals in the range of That is, the duty ratio of the rectangular wave 11 is changed with the resolution of 9.375 [lx].

In this case, the comparator 14 increases the detection voltage 9 10 times and 1/10.
The multiplying commands 13 and 17 are not output to the first and second integrators 16 and 16 ', but the output of the detection voltage 9 is directly converted into a processed signal, and the corresponding processing is performed.

However, when the detected voltage 9 is lower than the reference voltage value, that is, when the brightness of outside light is 0 to 10 [lx], the duty ratio is set by performing other processing than the above processing.

The processing in this case will be described with reference to FIG.

When the brightness of the outside light is in the range of 0 to 10 [lx], the detection voltage 9 of the outside light detecting portion 7 corresponding to this range is 10 in this embodiment.
It is multiplied and output to the A / D converter 12. (The device for multiplying 19 times is the first integrator 16, and the instruction is performed by the comparator 14 as described above.) Then, when the brightness of the external light is 10 [lx] or less, the external light detection unit The voltage value detected by 7 is converted into a voltage value detected by the external light detection unit 7 when the brightness of external light is 1 to 100 [lx].

For example, if the brightness of outside light is 5 [lx] and the detection voltage 9 output corresponding to it is 5 [mV], multiply by 10 to 50.
Convert to [mV] voltage.

The voltage of 50 [mV] is digitally processed by the A / D converter 10 and output to the CPU 15.

Since the processing in the CPU 15 only converts the input digital signal to the duty ratio, refer to the graph in FIG. 3 and refer to the graph of FIG. 3, and a rectangular wave with a duty ratio of 31.25 [%] corresponding to the digital signal representing 50 [mV]. I'm trying to set 11 ',
After this, the comparator 14 causes the first accumulator 16 to detect the detected voltage 9
Since the instruction 13 that multiplies 10 is output, the second integrator 1
The duty ratio set by the CPU15 in parallel with 6 '
Outputs instruction 17 that multiplies 31.25 [%] by 1/10.

As a result, the duty ratio is converted into a rectangular wave 11 having a duty ratio of 3.125 [%] and output to the display device 6 via the D / A converter 12.

By repeating the same processing, FIG. 4 is completed.

Comparing this with the conventional example of FIG. 6, the brightness of outside light is 0
At ~ 10 [lx], it can be seen that the resolution is much higher than that of the conventional example.

That is, especially when the brightness of the external light is dark, the change in the brightness (duty ratio) with respect to the brightness of the external light is small and changes almost continuously, and the brightness should be adjusted to the optimum brightness for the external light. Is possible.

That is, the resolution could be increased without increasing the number of bits.

It should be noted that the comparator 14 directly outputs M times the detected voltage 9 times M
Outputs the doubled output voltage and detects the detected voltage 9 instead of the integrator 16.
A switch for switching and outputting the M-fold output voltage may be provided.

Further, the second integrator 16 'may be provided outside the control unit 8 and designed so that the duty ratio of the rectangular wave 11 directly output can be increased by 1 / M.

[Effect of device]

Since the present invention is configured as described above, particularly in a range in which the brightness of external light is weak and fine light emission brightness adjustment is required, good light emission brightness adjustment of a display image of a display device can be performed without increasing the processing signal of the control unit. It becomes a vehicle light control device capable of performing.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a schematic explanatory view of a head-up display, FIGS. 3 and 4 are explanatory views of an embodiment of the present invention, and FIG. 5 is a conventional example. A block diagram and FIG. 6 are explanatory views of a conventional example. 1 ... driver, 2 ... projection member, 4 ... display image, 6 ...
Display device, 7 ... External light detection unit, 8 ... Control unit, 9 ... Detection signal, detection voltage, 10 ... A / D converter, 11 ... Rectangular wave, 1
4 …… Comparator, 16 …… First integrator, 16 ′ …… Second integrator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Hisashi Kobayashi 2-32 Higashi Zao, Nagaoka City, Niigata Japan Seiki Co., Ltd. (56) References JP 62-50239 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. In a vehicular display device for adjusting the light emission brightness of a display device provided with a projection member for projecting a display image in front of a driver, the brightness of outside light from the front of the driver is detected and correspondingly detected. An external light detection unit that outputs a detection signal, an A / D converter that digitally processes the detection signal of this external light detection unit, a control unit that outputs a rectangular wave with a duty ratio corresponding to this digital signal, and optionally A comparator that compares the set reference voltage value with the detection voltage output from the external light detection unit, and the A / D conversion is performed as a detection voltage M times the detection voltage of the external light detection unit by the comparison processing of the comparator. And a rectangular wave having a duty ratio of 1 / M times the duty ratio output from the controller in parallel with the processing of the first integrator and the processing of the first integrator. From the second integrator to The reference voltage value arbitrarily set by the comparator is compared with the detection voltage from the external light detection unit, and when the detection voltage is lower than the reference voltage value, the first integration unit A vehicle light control device, wherein the detection voltage is multiplied by M, and the duty ratio output from the control unit is multiplied by 1 / M by the second integrating unit.