CA1320745C - Headlight management system - Google Patents
Headlight management systemInfo
- Publication number
- CA1320745C CA1320745C CA 583052 CA583052A CA1320745C CA 1320745 C CA1320745 C CA 1320745C CA 583052 CA583052 CA 583052 CA 583052 A CA583052 A CA 583052A CA 1320745 C CA1320745 C CA 1320745C
- Authority
- CA
- Canada
- Prior art keywords
- series
- producing
- pulses
- signal
- headlight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
- B60Q1/00—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor
- B60Q1/02—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to illuminate the way ahead or to illuminate other areas of way or environments
- B60Q1/04—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to illuminate the way ahead or to illuminate other areas of way or environments the devices being headlights
- B60Q1/14—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to illuminate the way ahead or to illuminate other areas of way or environments the devices being headlights having dimming means
- B60Q1/1415—Dimming circuits
- B60Q1/1423—Automatic dimming circuits, i.e. switching between high beam and low beam due to change of ambient light or light level in road traffic
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
- B60Q1/00—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor
- B60Q1/02—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to illuminate the way ahead or to illuminate other areas of way or environments
- B60Q1/04—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to illuminate the way ahead or to illuminate other areas of way or environments the devices being headlights
- B60Q1/14—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to illuminate the way ahead or to illuminate other areas of way or environments the devices being headlights having dimming means
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
- B60Q2300/00—Indexing codes for automatically adjustable headlamps or automatically dimmable headlamps
- B60Q2300/05—Special features for controlling or switching of the light beam
- B60Q2300/054—Variable non-standard intensity, i.e. emission of various beam intensities different from standard intensities, e.g. continuous or stepped transitions of intensity
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
- B60Q2300/00—Indexing codes for automatically adjustable headlamps or automatically dimmable headlamps
- B60Q2300/30—Indexing codes relating to the vehicle environment
- B60Q2300/31—Atmospheric conditions
- B60Q2300/314—Ambient light
Abstract
A B S T R A C T
An electronic device is disclosed for sensing ambient light received by the driver of an automobile and for adjusting the power to the automobile headlights into pulses whose widths are proportional to the light received The adjustment is to maintain a constant preset level of light that the driver sees.
An electronic device is disclosed for sensing ambient light received by the driver of an automobile and for adjusting the power to the automobile headlights into pulses whose widths are proportional to the light received The adjustment is to maintain a constant preset level of light that the driver sees.
Description
HEADLIGHT ~ANAGEMENT SYSTEM
1. Field of Invention This invention relates to an electronic device which automatically adjusts the automobile headlight in response to arnbient light received.
1. Field of Invention This invention relates to an electronic device which automatically adjusts the automobile headlight in response to arnbient light received.
2. Description of Prior Art There are devices which automatically switch the automobile headlights from high beam to low beam and vice versa by detecting whether light from an oncoming automobile is present. Examples are U.S. Pa-tent no. 4,577,117 (Takeda et al.), 4,599,544 (Martin), no. 4,558,260 (Masegi), and no.
4,376,909 (Tagami et al.). One defect of the prior art is that they are functionally dual state devices, and switching between high beam and low beam may cause annoying, and potentially dangerous, blinking of the headlights.
Furthermore, the prior art does really consider the fac-t that the received ambient light cornprises not only the intense light from oncoming automobiles but also light from the headlights which is reflected back from, for example, road signs, fog, snow banks and the like, and which may be diffused.
For safety, it is important to evaluate the entirety of light received by the driver and to provide a minimum level of light received by the driver. When the received light exceeds that level, it is important to decrease the intensity of the headlights so that -the received light decreases to that level; and when the received light drops below that level, to increase the intensity of the headlights to that level is again achieved.
According to the present invention, there is provided a device for automatically adjusting the intensity of an automoblle headlight in response to ambient light received in the front of the automobile. The device comprises sensing means for sens:ing said ambient light and producing a signal proportional thereto; and adjusting means, responsive to said signal, for adjusting smoothly the power to said headlight to maintain a preset constant level of said received ambient light.
BRIEF DESCRIPTIOM OF THE DRAWINGS
A preferred embodiment of the invention will now be described in conjunction with the drawings in which:
Figure 1 is the circuit diagram of the invention illustrating Stages 1, 2 and 3;
Figure 2 is a graph of the relationship between the output of Stage 1 and the output of Stage 2 for different calibrations;
Figure 3 are graphs of the power of Stage 3 applied to the headligh-t for several ambient light conditions.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Figure 1 is the schematic diagram for the device by which automatic adjustment of -the headlight is accomplished in three stages. S-tage 1 receives l:ight and produces a signal linearly propor-tional to -the light received. Stage 2 acts as a buffer and calibration stage.
Stage 3 is the amplifying stage powering the headlight high beam device.
In all Stages, 12 volts are provided by the automobile battery at Vcc. Specification of the components employed may be found toward the end of the disclosure and may assist to construct the circuit disclosed, but it will be apparent to those skilled in -the art that many alternative components are possible.
In Stage 1, there is a light sensor 50 which suitably mounted and orientated to sense light received by the driver. Sensor 50's outpu-t resistance varies inversely to the amount of light received. Q1 and Q2 are identical transistors which are biased identically with R1 to provide a constant current sink. The current through R1 is about 11.4 ,uA, and is identical to that through sensor 50. The resis-tance of sensor 50 ranges typically between 50KQ and lMQ.
Therefore, Vsl ranges linearly from about 0.6 volts to 11.4 volts as a function of the light received, and is input into Stage 2.
In Stage 2, amplification of Vsl by -5 to produce Vs2 is accomplished by amplifier 100 and R2 and R3. In Figure 2, the inverse relationship between Vs2 and Vsl is shown for three different adjustments of biasing resistor R4. The internal biasing oE amplifier lOU creates a minimum output of about 2 volts.
The levels identified as X, Y and Z represent the minimum level of light which the device will try to maintain, At that level, or sllghtly below it, the devlce adjusts ~he headlight according to the arnbient light received.
Biasing resistor R4 allows tuning of the circuit as ~ whole ~o accommodake component irregularlties and to adjust for light levels for a particular driving environment. The minimum level is typically set well below light levels found in c~ty driving so that extra power to ~he headlight high beam device is onl~ provided in darker rural areas.
In Stage 3, amplifier 150 and timer 200 form a pulse width modulator circuit. Timer 200 has been con~igured as a stable multivibrator. C1 is charged and discharged through R5 to produce tirner pulses Vt within the ra~e of vcc/3 and 2*Vcc/3 at a rate of 100 Hz, as seen in the top graph of Figure 3.
The effect of amplifier 150, ac-ting as a comparator comparing Vt against Vs2, is illustrated in the remaining graphs of Figure 3. If Vt > Vs2, the output of amplifier 150 will be Vcc, which shuts off Q3, Q4 and Q5, and thereby disconnects the power to headlight high beam device 250 (Vs3 = 0). If Vt < Vs2, the output will be about 2.2 volts (the minimum output due to internal biasing of ,.~, ampliEier 150), which Eorward biases power translstors Q3, Q4 and Q5 to supply ~ull-power to headlight high beam device 250 (Vs3 = Vcc). Vs3 for two intermedia-te values oE Vs2, and B, represents respectively approximatelv 65-~ and 30~
power applied to headlight high beam device 250. For the intermediate cases, the output of ampliEier 150 or Vs3 is a series of output pulses at Vs3 is applied directly to the headlight hiyh beam device 250. It will be apparent that the above method oE ~uickly pulsing the high beam device 250 mitigates heat dlssipation problems.
rl'he device described was bullt with the following components: R1, R2 and R5 - lMQ; R3 - 5MQ; R6 - lOOQ; R7 50Q;
C1 - O.l~F; Q1 and Q2 - Motorola 2N2222; Q3, Q4 and Q5 -15 Fairchild TlP42; timer 200 - Texas Instruments TLC555;
ampli~iers 100 and 150 - Motorola MC1458; light sensor -Clairex cadmiuln sulEide photocell 276-116. The names Motorola, Fairchild, Texas Instruments and Clairex are trademarks.
A device has been described which adjus-tment o~
the headlights is made automatically without the driver becoming aware of that adjustment because the device maintains a cons-tant level oE light incoming into the driver. It should be understood that while a preferred embodiment oE the present invention has been illustrated, many variations may be devised by those skilled in the art within the scope of -the following claims.
4,376,909 (Tagami et al.). One defect of the prior art is that they are functionally dual state devices, and switching between high beam and low beam may cause annoying, and potentially dangerous, blinking of the headlights.
Furthermore, the prior art does really consider the fac-t that the received ambient light cornprises not only the intense light from oncoming automobiles but also light from the headlights which is reflected back from, for example, road signs, fog, snow banks and the like, and which may be diffused.
For safety, it is important to evaluate the entirety of light received by the driver and to provide a minimum level of light received by the driver. When the received light exceeds that level, it is important to decrease the intensity of the headlights so that -the received light decreases to that level; and when the received light drops below that level, to increase the intensity of the headlights to that level is again achieved.
According to the present invention, there is provided a device for automatically adjusting the intensity of an automoblle headlight in response to ambient light received in the front of the automobile. The device comprises sensing means for sens:ing said ambient light and producing a signal proportional thereto; and adjusting means, responsive to said signal, for adjusting smoothly the power to said headlight to maintain a preset constant level of said received ambient light.
BRIEF DESCRIPTIOM OF THE DRAWINGS
A preferred embodiment of the invention will now be described in conjunction with the drawings in which:
Figure 1 is the circuit diagram of the invention illustrating Stages 1, 2 and 3;
Figure 2 is a graph of the relationship between the output of Stage 1 and the output of Stage 2 for different calibrations;
Figure 3 are graphs of the power of Stage 3 applied to the headligh-t for several ambient light conditions.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Figure 1 is the schematic diagram for the device by which automatic adjustment of -the headlight is accomplished in three stages. S-tage 1 receives l:ight and produces a signal linearly propor-tional to -the light received. Stage 2 acts as a buffer and calibration stage.
Stage 3 is the amplifying stage powering the headlight high beam device.
In all Stages, 12 volts are provided by the automobile battery at Vcc. Specification of the components employed may be found toward the end of the disclosure and may assist to construct the circuit disclosed, but it will be apparent to those skilled in -the art that many alternative components are possible.
In Stage 1, there is a light sensor 50 which suitably mounted and orientated to sense light received by the driver. Sensor 50's outpu-t resistance varies inversely to the amount of light received. Q1 and Q2 are identical transistors which are biased identically with R1 to provide a constant current sink. The current through R1 is about 11.4 ,uA, and is identical to that through sensor 50. The resis-tance of sensor 50 ranges typically between 50KQ and lMQ.
Therefore, Vsl ranges linearly from about 0.6 volts to 11.4 volts as a function of the light received, and is input into Stage 2.
In Stage 2, amplification of Vsl by -5 to produce Vs2 is accomplished by amplifier 100 and R2 and R3. In Figure 2, the inverse relationship between Vs2 and Vsl is shown for three different adjustments of biasing resistor R4. The internal biasing oE amplifier lOU creates a minimum output of about 2 volts.
The levels identified as X, Y and Z represent the minimum level of light which the device will try to maintain, At that level, or sllghtly below it, the devlce adjusts ~he headlight according to the arnbient light received.
Biasing resistor R4 allows tuning of the circuit as ~ whole ~o accommodake component irregularlties and to adjust for light levels for a particular driving environment. The minimum level is typically set well below light levels found in c~ty driving so that extra power to ~he headlight high beam device is onl~ provided in darker rural areas.
In Stage 3, amplifier 150 and timer 200 form a pulse width modulator circuit. Timer 200 has been con~igured as a stable multivibrator. C1 is charged and discharged through R5 to produce tirner pulses Vt within the ra~e of vcc/3 and 2*Vcc/3 at a rate of 100 Hz, as seen in the top graph of Figure 3.
The effect of amplifier 150, ac-ting as a comparator comparing Vt against Vs2, is illustrated in the remaining graphs of Figure 3. If Vt > Vs2, the output of amplifier 150 will be Vcc, which shuts off Q3, Q4 and Q5, and thereby disconnects the power to headlight high beam device 250 (Vs3 = 0). If Vt < Vs2, the output will be about 2.2 volts (the minimum output due to internal biasing of ,.~, ampliEier 150), which Eorward biases power translstors Q3, Q4 and Q5 to supply ~ull-power to headlight high beam device 250 (Vs3 = Vcc). Vs3 for two intermedia-te values oE Vs2, and B, represents respectively approximatelv 65-~ and 30~
power applied to headlight high beam device 250. For the intermediate cases, the output of ampliEier 150 or Vs3 is a series of output pulses at Vs3 is applied directly to the headlight hiyh beam device 250. It will be apparent that the above method oE ~uickly pulsing the high beam device 250 mitigates heat dlssipation problems.
rl'he device described was bullt with the following components: R1, R2 and R5 - lMQ; R3 - 5MQ; R6 - lOOQ; R7 50Q;
C1 - O.l~F; Q1 and Q2 - Motorola 2N2222; Q3, Q4 and Q5 -15 Fairchild TlP42; timer 200 - Texas Instruments TLC555;
ampli~iers 100 and 150 - Motorola MC1458; light sensor -Clairex cadmiuln sulEide photocell 276-116. The names Motorola, Fairchild, Texas Instruments and Clairex are trademarks.
A device has been described which adjus-tment o~
the headlights is made automatically without the driver becoming aware of that adjustment because the device maintains a cons-tant level oE light incoming into the driver. It should be understood that while a preferred embodiment oE the present invention has been illustrated, many variations may be devised by those skilled in the art within the scope of -the following claims.
Claims (7)
1. A device for automatically adjusting the intensity of an automobile headlight in response to ambient light received by the driver, comprising:
(a) sensing means for sensing said ambient light and producing a signal proportional thereto;
(b) adjusting means, responsive to said signal, for smoothly adjusting the power to said headlight to maintain a preset constant level of said received ambient light.
(a) sensing means for sensing said ambient light and producing a signal proportional thereto;
(b) adjusting means, responsive to said signal, for smoothly adjusting the power to said headlight to maintain a preset constant level of said received ambient light.
2. A device according to claim 1, wherein said adjusting means has power varying means for varying the power to said headlight into a first series of pulses whose widths are proportional to said signal.
3. A device according to claims 1 or 2 having linearization means for producing said signal to be linearly proportional to said received ambient light.
4. A device according to claim 2, wherein said power varying means includes:
(a) a timer for producing a second series of equi-timed pulses; and (b) a comparator, responsive to said second series of pulses and said signal, for producing said first series of pulses.
(a) a timer for producing a second series of equi-timed pulses; and (b) a comparator, responsive to said second series of pulses and said signal, for producing said first series of pulses.
5. A device according to claim 2, having linearization means for producing said signal to be linearly proportional to said received ambient light, and wherein said power varying means includes:
(a) a timer for producing a second series of equi-timed pulses; and (b) a comparator, responsive to said second series of pulses and said signal, for producing said first series of pulses.
(a) a timer for producing a second series of equi-timed pulses; and (b) a comparator, responsive to said second series of pulses and said signal, for producing said first series of pulses.
6. A device according to claim 1, wherein said adjusting means includes:
(a) a timer for producing a series of equi-timed timer pulses; and (b) a comparator, responsive to said series of timer pulses and said signal, for producing a series of output pulses.
(a) a timer for producing a series of equi-timed timer pulses; and (b) a comparator, responsive to said series of timer pulses and said signal, for producing a series of output pulses.
7. A device according to claim 6, having linearization means for producing said signal to be linearly proportional to said received ambient light.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 583052 CA1320745C (en) | 1988-11-14 | 1988-11-14 | Headlight management system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 583052 CA1320745C (en) | 1988-11-14 | 1988-11-14 | Headlight management system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1320745C true CA1320745C (en) | 1993-07-27 |
Family
ID=4139094
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 583052 Expired - Fee Related CA1320745C (en) | 1988-11-14 | 1988-11-14 | Headlight management system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1320745C (en) |
-
1988
- 1988-11-14 CA CA 583052 patent/CA1320745C/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |