JPH02288190A - How to dim the light control device - Google Patents

Abstract

PURPOSE:To have dimming with enhanced grade of the dividing ability by processing ripple superposed signals at each sampling time with the period divided equally, and thereupon performing the dimming. CONSTITUTION:The duty ratio is determined in compliance with the processing signals at each sampling time with the period divided equally, wherein the ripple superposed signals 18 are set in a control (a), the signals 18 being obtained by superposing a sensor signal 1 given by an external light sensing part 2 with ripple wave signals 17 given by a ripple generating part 16. At each period, the output signal 6 corresponding to this duty ratio having undergone the averaging process for duty ratios is fed to a display device 9. This accomplishes dimming with high resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a light control method for a light control device that adjusts the luminance of a display device according to the brightness of external light.

[Conventional technology]

The conventional light control method of a light control device is to detect the brightness of external light as shown in FIG. After being amplified by step 3, the signal is input to, for example, an A/D converter 4 in the control section a, where it is digitized, and then input to the CPU 5. For example, when using a 3-bit controlled CPU5, 23-8
The sensor voltage 1 is made to correspond to the device signal formed by the standard A/D converter 4, and the CPU 5 outputs it as a 6° rectangular wave, which is converted into an analog signal via the D/A converter 7.
By inputting the light to the display device 9 through the drive circuit 8, the luminance of the display device 9 was adjusted in accordance with changes in the brightness of external light.

[Problem to be solved by the invention]

However, when using the CPU 5 with 3-bit control, for example, the control is performed using 23-8 processing signals, so as shown in FIG.
In other words, the resolution of the CPU 5 is I OO [f2 The drawback was that it could not be illuminated.

In particular, the display image 10 of the display device 9 as shown in FIG. 8 is projected by the optical system 14 onto the reflective member of the windshield in front of the driver 11, so that the display image 10 is projected within the front field of view outside the windshield rim. When used in a display device 9 called a head-up display that forms an image so that it can be seen by overlapping the scenery 15 within the field of view, it is particularly important to display a dark area where the brightness of external light is weak in order to improve visibility. I would like to adjust the brightness to 0 to lOOIJx with the resolution of CPTJ5
], the brightness remains constant and cannot be dimmed at all.

The present invention proposes a dimming method for a dimming device that solves these drawbacks.

[Means to solve the problem]

The details are as follows with reference to the accompanying drawings.

The brightness of external light is detected and a corresponding sensor signal 1 is output from the external light detection section 2, and this sensor signal 1 is converted into a processed signal to generate a 6° rectangular wave set to a predetermined duty ratio.
is set by the control unit a, and the output signal 6 corresponding to this 6° rectangular wave is output to the display device 9, thereby adjusting the light emission brightness of the display device 9 according to the brightness of external light. In the optical method, i′i? The ripple wave signal 17 output from the ripple generating section 16 is superimposed on the sensor signal l described in Section 7, and an arbitrary period T is set within the control section a.
A duty ratio is determined by making the ripple superimposed signal speed correspond to the processed signal every sampling time τ, which is obtained by equally dividing The present invention relates to a light control method of a light control device, which is characterized in that the light control device 6 outputs the correction information to the correction display device 9.

[For production]

The ripple wave signal 17 outputted from the ripple generation unit 16 is superimposed on the sensor signal 1 outputted from the external light detection unit 2, and the sampling time τ is obtained by equally dividing the period T in which the pull superimposed signal lull is set in the control unit a. The output signal 6 corresponding to the duty ratio is obtained by calculating the duty ratio corresponding to the processed signal for each cycle, and averaging the duty ratio for each cycle.
By outputting this to the display device 9, dimming with high resolution is performed.

〔Example〕

FIG. 1 is a block diagram showing one implementation of the present invention;
The figure is a waveform diagram showing the sensor voltage 1, ripple wave voltage 17, and ripple superimposed voltage voltage, and will be described in detail based on these.
Components having the same or equivalent functions as those of the conventional example are given the same reference numerals.

The external light detecting section 2 uses an optical sensor, and after amplifying the sensor voltage l outputted from the external light detecting section 2 by an amplifier 3, the sensor voltage 1 is integrated by a pulse oscillator 19 as shown in FIG. The ripple wave voltage 17 output from the pull generator 16 by connecting the circuit is superimposed by the adder 20,
This ripple superimposed voltage is calculated by the A/D converter 4, the CPU 5, and the D
The rectangular wave 6° after being inputted to the control unit a consisting of the /A converter 7 and subjected to predetermined control is converted into an analog output voltage 6 by the D/A converter 7, which is then displayed via the drive circuit 8. Output to device 9.

In addition, a CP with built-in A/D converter 4 and D/A converter 7
U5 may also be used.

Next, referring to Fig. 3.4, for convenience, 3bttcpu5 is used to generate a rectangular wave 6 by using 2''=8 processing signals.
The light control method of the light control device which changes the output of the duty ratio of 0.degree. in 8 steps will be described in more detail.

FIG. 3 shows a case where a ripple wave voltage 17 is added to the sensor voltage 1 and a pull superimposed voltage is digitized by the A/D converter 4 and input to the CPU 5.

This ripple wave signal 17 is superimposed on the sensor signal 1, and the A/D
In order to vary the processed signal from the converter 4,
An amplitude width larger than the resolution of the CPU 5, that is, the A/D converter 4 is used.

At this time, inside the CPU 5, the arbitrarily set period T (Figure 4 shows the case where it is set to the period of the pull wave signal 17) is divided into n (the figure shows the case where it is divided into four).
Let the value of the processed signal immediately after the start of the sub-ring time be the processed signal of each sampling time τ.

The CPU 5 calculates the ratio of the processed signals of each sampling time τ every period T, and sets the duty ratio of the 6° rectangular wave outputted by the CPU 5 based on this ratio.

For example, in section (A), the processed signals of each sub-ring time τ divided into four are rollJ and rl.

OJ, rloOJ, and rlooJ correspond.

This rolIJ corresponds to a duty ratio of 50[%] and rloOJ corresponds to 62.5[%], but the CP
Since U5 inputs rollJ and rloOJ at a ratio of 1:3, the result of using 1:3 average processing with duty ratio 50 [%] and duty ratio 62.51%] is 59
．． A duty ratio of 375% is set.

Similar processing is performed in section (a) and section (x) to set the duty ratio.

Rectangular wave 6 with duty ratio processed and set in this way
° is finally output from the CPU 5 for each section (every cycle T).

Therefore, in this embodiment, since the ripple superimposed signal speed is processed every sampling time τ, which is obtained by dividing the period T into four, dimming is performed with four times the resolution.If the sub-ring time τ is divided into n divisions of the period T, then The resolution will be increased to .

〔Effect of the invention〕

The present invention can perform dimming with increased resolution using an existing CPU without increasing the number of equivalent processing signals,
Good light control can be performed even in a range where the brightness of external light is weak.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a block diagram showing one implementation of the invention, FIG. 2 is a waveform diagram showing sensor voltage, ripple wave voltage, and ripple superimposed voltage, and FIG. 4
The figure is an explanatory diagram showing an example of the averaging process in the control section.
FIG. 6 is a block diagram showing a conventional method, FIG. 7 is an explanatory diagram of the conventional method, and FIG. 8 is a schematic explanatory diagram of a head-up display. . T...Period, τ...Sampling time, a...Control unit, 1...Sensor signal, 2...External light detection unit, 6.
...Output signal, 6゛...Square wave, 9...Display device,
16... Ripple generating section, 17... Ripple wave signal, Nagi... Ripple superimposed signal. 7b Anchor end [7] April 1999

Claims (1)

[Claims] Detecting the brightness of external light and outputting a corresponding sensor signal from the external light detection section, converting this sensor signal into a processed signal and setting a rectangular wave with a predetermined duty ratio by the control section, In a dimming method of a light control device that adjusts the luminance of the display device according to the brightness of external light by outputting an output signal corresponding to this rectangular wave to the display device, the ripple generating section outputs an output signal to the sensor signal. The ripple wave signal to be processed is superimposed, an arbitrary period is set in the control section, and the duty ratio is determined by making the ripple superimposed signal correspond to the processed signal at each sampling time, which is obtained by equally dividing this period, and for each period. A light control method for a light control device, characterized in that an output signal corresponding to a duty ratio obtained by averaging the duty ratios is output to the display device.