JP2018203196A - Vehicular headlight system and control method of the same - Google Patents

Abstract

To provide a technology which can avoid failure due to deterioration in response speed of a liquid crystal element due to a peripheral temperature, in a vehicular lighting fixture system using a liquid crystal element.SOLUTION: A vehicular lighting fixture system performs selective light radiation frontward of an own vehicle by using a liquid crystal element 3, and in the case where a temperature in a space where the liquid crystal element 3 is disposed is equal to or lower than a predetermined reference value, all light modulation regions of the liquid crystal element 3 are brought into a light transmission state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control technology for a vehicle headlamp for performing selective light irradiation corresponding to the position of a vehicle ahead.

  The irradiation range and non-irradiation range of light from the headlight unit of the own vehicle are set according to the position of the oncoming vehicle and the preceding vehicle (hereinafter referred to as the “front vehicle”) existing in front of the own vehicle. A vehicle headlamp system that performs selective light irradiation is known. A prior example regarding such a vehicle headlamp system is disclosed in, for example, Japanese Patent Laid-Open No. 7-108873. In this type of vehicle headlamp system, a camera is installed at a predetermined position in front of the host vehicle (for example, at the upper center of the front window), and the position of the vehicle body of the front vehicle, the taillight, or the headlight captured by the camera. Are detected by image processing. Then, light distribution control is performed so that the detected head vehicle portion is not irradiated with light from the headlamp unit of the host vehicle. It is also known to use a liquid crystal element in order to control the light irradiation range and the non-irradiation range (see, for example, JP-A-6-191346).

  By the way, generally the response speed of a liquid crystal element is not so high, and when the ambient temperature is lowered, the response speed is significantly reduced. For this reason, for example, when the ambient temperature becomes a negative temperature, the time required for each pixel of the liquid crystal element to transition to the transmissive state becomes long. For this reason, in the vehicle headlamp system as described above, for example, a relatively long time is required for the response of the liquid crystal element when an image is formed with the liquid crystal element while the light source is turned on in order to perform selective light irradiation. Therefore, the period during which the originally intended light irradiation pattern cannot be obtained becomes longer, and there is a possibility that the light distribution control cannot accurately follow the situation ahead of the own vehicle that changes every moment. .

JP-A-7-108873 JP-A-6-191346

  A specific aspect of the present invention is to provide a technique capable of avoiding a problem caused by a decrease in response speed of a liquid crystal element caused by an ambient temperature in a vehicle lamp system using the liquid crystal element.

[1] A vehicular lamp system according to an aspect of the present invention is a vehicular lamp system for selectively irradiating light in front of a host vehicle using a liquid crystal element. When the temperature of the space to be set is equal to or lower than a predetermined reference value, the vehicle lamp system makes all the light modulation regions of the liquid crystal element light transmissive.
[2] A control method for a vehicular lamp system according to an aspect of the present invention is a control method in a vehicular lamp system for selectively irradiating light in front of the host vehicle using a liquid crystal element. A vehicle lamp system control method for bringing all light modulation regions of the liquid crystal element into a light transmission state when the temperature of the space in which the liquid crystal element is arranged is equal to or lower than a predetermined reference value.

  According to the above configuration, in a vehicle lamp system that uses a liquid crystal element, if there is a possibility that the light distribution control cannot accurately follow due to a decrease in the response speed of the liquid crystal element due to the ambient temperature, Since the modulation region is in a light transmission state, it is possible to reliably irradiate light ahead of the host vehicle.

FIG. 1 is a diagram illustrating a configuration of a vehicle headlamp system according to a first embodiment. FIG. 2 is a diagram illustrating a configuration of a vehicle headlamp system according to a second embodiment. FIG. 3 is a diagram illustrating a configuration of a vehicle headlamp system according to a third embodiment.

(First embodiment)
FIG. 1 is a diagram illustrating a configuration of a vehicle headlamp system according to a first embodiment. The vehicle lamp system shown in FIG. 1 includes a light source 1, a parallel optical system 2, a liquid crystal element 3, a drive circuit 4, a control unit 5, a projection optical system 6, a camera 8, and a temperature sensor 9. Each component other than the camera 8 is accommodated in the housing 7, for example. This vehicle headlamp system sets a certain range including the position of the forward vehicle or the like as a non-irradiation range corresponding to the position of the forward vehicle or pedestrian existing around the own vehicle, and other ranges. Is set to the light irradiation range to perform selective light irradiation.

  The light source 1 includes, for example, a white light LED configured by combining a yellow phosphor with a light emitting element (LED) that emits blue light. In addition to the LED, the light source 1 may be a laser or a light source generally used in a vehicle lamp unit such as a light bulb or a discharge lamp. The light on / off state of the light source 1 is controlled by the control unit 5.

  The parallel optical system 2 converts the light emitted from the light source 1 into parallel light, and for example, a convex lens can be used. In this case, parallel light can be created by arranging the light source 1 near the focal point of the convex lens. As the parallel optical system 2, a lens, a reflecting mirror, or a combination of them can be used.

  The liquid crystal element 3 has, for example, a plurality of pixel regions (light modulation regions) that can be individually controlled, and each pixel region is provided in accordance with the magnitude of the voltage applied to the liquid crystal layer provided by the drive circuit 4. The transmittance is set to be variable. By transmitting light from the light source 1 to the liquid crystal element 3, an image having brightness corresponding to the above-described light irradiation region and non-irradiation region is formed. The liquid crystal element 3 of the present embodiment includes a pair of polarizing plates that are provided with a vertically aligned liquid crystal layer and arranged in crossed Nicols, and the voltage to the liquid crystal layer is not applied (or a voltage equal to or lower than a threshold value). The light transmittance is in a very low state (light-shielding state), and when a voltage is applied to the liquid crystal layer, the light transmittance is in a relatively high state (transmission state). That is, the liquid crystal element 3 of the present embodiment is a so-called normally closed type (normally black type) liquid crystal element.

  The liquid crystal element 3 includes, for example, six first electrodes extending in the vertical direction and arranged in the left-right direction when the substrate surface is viewed in plan, and 48 arranged in the vertical direction extending in the left-right direction. Second electrodes are provided. There are 288 pixel regions, each of which is a region where each first electrode and each second electrode overlap in plan view, and these pixel regions are arranged in a matrix. Each first electrode and each second electrode are connected to the drive circuit 4 and are driven in a simple matrix with, for example, 1/6 duty.

  The drive circuit 4 individually controls the alignment state of the liquid crystal layer in each pixel region of the liquid crystal element 3 by supplying a drive voltage to the liquid crystal element 3 based on a control signal supplied from the control unit 5. .

  The control unit 5 detects the position of the front vehicle or the like by performing image processing based on an image obtained by the camera 8 that captures the front of the host vehicle, and the light irradiation range according to the detected position of the front vehicle or the like. A non-irradiation range is set, and a control signal for forming an image corresponding to the light irradiation region and the non-irradiation region is generated and supplied to the drive circuit 4.

  In addition, when the temperature detected by the temperature sensor 9 is equal to or lower than a predetermined reference value, the control unit 5 sets a predetermined number (for example, all pixel regions) among the plurality of pixel regions of the liquid crystal element 3 as the transmission state. A control signal is generated and supplied to the drive circuit 4. The control unit 5 is realized by executing a predetermined operation program in a computer system having a CPU, a ROM, a RAM, and the like, for example.

  The projection optical system 6 spreads an image formed by the light transmitted through the liquid crystal element 3 (an image having light and darkness corresponding to the light irradiation region and the non-irradiation region) so as to be a light distribution for the headlight, and forward of the host vehicle. An appropriately designed lens is used. As the projection optical system 6, a lens, a reflecting mirror, or a combination of them can be used.

  The camera 8 captures the front of the host vehicle and outputs an image (information) thereof, and is disposed at a predetermined position in the host vehicle (for example, the upper part inside the windshield). In addition, when the camera for other uses (for example, automatic brake system etc.) is equipped with the own vehicle, you may share the camera. Further, when such sharing is not performed, the camera 8 may be provided in the housing 7.

  The temperature sensor 9 is for detecting the temperature inside the housing 7, and is disposed, for example, in the vicinity of one liquid crystal element 3. A detection signal (a signal indicating temperature) from the temperature sensor 9 is input to the control unit 5. The position where the temperature sensor 9 is installed is sufficient if it is inside the housing 7, but it is particularly preferable that the temperature sensor 9 be located around the liquid crystal element 3 because the temperature of the liquid crystal element 3 itself can be captured more accurately.

  The vehicle lamp system of the present embodiment has the above-described configuration. Next, the liquid crystal element by the control unit 5 when the temperature in the housing 7, particularly the ambient temperature of the liquid crystal element 3 falls below the reference value. The contents of the operation control 3 will be described in detail.

  The control unit 5 acquires the temperature detected by the temperature sensor 9 and, when this temperature becomes a predetermined reference value (for example, −10 ° C.) or less, a predetermined number (a plurality of pixel regions of the liquid crystal element 3 ( As an example, a control signal for making all the pixel regions) transparent is generated and supplied to the drive circuit 4. The reference value here can be determined based on, for example, the response speed of the liquid crystal element 3 at a low temperature or the allowable value of the irradiation pattern switching speed when selective light irradiation is performed. As an example, in a general liquid crystal element, when the temperature is about −10 ° C., the response speed may be slower than 0.5 seconds. Therefore, the reference value is preferably “−10 ° C.” as described above.

  When a drive voltage is applied by the drive circuit 4 based on this control signal, the liquid crystal element 3 is in a transmissive state for a predetermined number of pixel regions. At this time, if the light source 1 is turned on under the control of the control unit 5, the light from the light source 1 passes through the liquid crystal element 3 and is irradiated forward of the host vehicle. When all the pixel regions of the liquid crystal element 3 are controlled to be in a transmissive state, light from the light source 1 is irradiated as light that irradiates the widest light distribution region without performing selective light irradiation.

  Note that the entire pixel area does not necessarily have to be, for example, even if the light distribution area corresponding to the low beam, that is, the pixel area corresponding to the lower light distribution area with respect to the vertical direction is controlled to the transmission state. Good. In this case, light is irradiated only to the light distribution region corresponding to the low beam.

(Second Embodiment)
FIG. 2 is a diagram illustrating a configuration of a vehicle headlamp system according to a second embodiment. The vehicle lamp system shown in FIG. 2 has basically the same configuration as the vehicle lamp system of the first embodiment described above, but the internal structure of the liquid crystal element is different, and a part of the crystal element is appropriately replaced. A shielding part for shielding is added. Constituent elements common to the both are denoted by the same reference numerals, detailed description thereof will be omitted, and differences will be mainly described.

  The liquid crystal element 3a has a plurality of pixel regions (light modulation regions) that can be individually controlled, and the transmittance of each pixel region according to the magnitude of the voltage applied to the liquid crystal layer given by the drive circuit 4 Is set to be variable. The difference from the first embodiment is that the liquid crystal element 3a of the present embodiment is a TN liquid crystal element in which a TFT (thin film transistor) is associated with each pixel region. The liquid crystal element 3a of the present embodiment includes a pair of polarizing plates arranged in crossed Nicols, and has a relatively high light transmittance when a voltage to the liquid crystal layer is not applied (or a voltage below a threshold value). In this state (transmission state), when a voltage is applied to the liquid crystal layer, the light transmittance is extremely low (light-shielding state). That is, the liquid crystal element 3a of the present embodiment is a so-called normally open type (normally white type) liquid crystal element. Further, the liquid crystal element 3a according to the present embodiment has 50000 pixel regions arranged in a matrix by being divided into 100 in the vertical direction and 500 in the horizontal direction in plan view. These pixel regions are connected to the drive circuit 4 and are driven in an active matrix.

  The shielding unit 10 is for shielding a part of the light emitting side of the liquid crystal element 3a, that is, a part of the surface facing the projection optical system 6, as necessary. The light shielding plate (movable shielding plate) and the position of the light shielding plate An actuator (for example, a motor) for controlling the motor is configured. The shielding part 10 of this embodiment changes the position of a shielding board by rotating a shielding board based on the signal given from the control part 5. FIG. Normally, the shielding plate of the shielding unit 10 is controlled to be in a position where the liquid crystal element 3a is not shielded.

  The vehicle lamp system of the present embodiment has the above-described configuration. Next, the liquid crystal element by the control unit 5 when the temperature in the housing 7, particularly the ambient temperature of the liquid crystal element 3 a is lower than the reference value. The content of the operation control of 3a and the shielding part 10 is demonstrated in detail.

  The control unit 5 acquires the temperature detected by the temperature sensor 9 and, when this temperature becomes a predetermined reference value (for example, −10 ° C.) or less, makes all the pixel regions of the liquid crystal element 3a transparent. The control signal is generated and supplied to the drive circuit 4. When a drive voltage (off voltage in this example) is applied by the drive circuit 4 based on this control signal, the liquid crystal element 3a is in a transmissive state in the entire pixel region. At this time, if the light source 1 is turned on under the control of the control unit 5, the light from the light source 1 passes through the liquid crystal element 3 a and is irradiated forward of the host vehicle.

  For example, the control unit 5 determines the irradiation pattern of either the high beam or the low beam based on the position of the vehicle in front. If the temperature detected by the temperature sensor 9 is equal to or lower than the reference value, each pixel of the liquid crystal element 3a is determined. A control signal is supplied to the drive circuit 4 so that all the pixel regions are in a transmissive state without individually controlling the regions. In addition, the control part 5 may determine the irradiation pattern in which a high beam is a low beam according to the operation state of the operation switch of the own vehicle.

  At this time, if the determined irradiation pattern is a low beam, the control unit 5 controls the shielding unit 10 so that the shielding plate overlaps a part of the liquid crystal element 3a. Thereby, the light transmitted through the pixel region corresponding to the high beam is shielded by the shielding plate and is not irradiated in front of the host vehicle, so that it is possible to avoid dazzling the front vehicle or the like. If the determined irradiation pattern is a high beam, the control unit 5 controls the shielding unit 10 so that the shielding plate does not overlap the liquid crystal element 3a. As a result, the light transmitted through the pixel region corresponding to the high beam is also irradiated in front of the host vehicle without being shielded by the shielding plate.

(Third embodiment)
FIG. 3 is a diagram illustrating a configuration of a vehicle headlamp system according to a third embodiment. The vehicular lamp system shown in FIG. 3 has basically the same configuration as the vehicular lamp system of the first embodiment described above, but the internal structure of the liquid crystal element is different and an optical for forming a low beam is provided. A system is provided separately. Constituent elements common to the both are denoted by the same reference numerals, detailed description thereof will be omitted, and differences will be mainly described.

  The liquid crystal element 3 b has a plurality of pixel regions (light modulation regions) that can be individually controlled, and the transmittance of each pixel region according to the magnitude of the voltage applied to the liquid crystal layer provided by the drive circuit 4. Is set to be variable. The liquid crystal element 3b of the present embodiment is also a so-called normally closed type (normally black type) liquid crystal element. The difference from the liquid crystal element 3 of the first embodiment is the number of pixel regions. Specifically, the liquid crystal element 3b includes, for example, four first electrodes that extend in the up-down direction and are arranged in the left-right direction when the substrate surface is viewed in plan view, and extend in the left-right direction in the up-down direction. There are 48 second electrodes arranged. There are 192 pixel regions, each of which is a region where each first electrode and each second electrode overlap in plan view, and these pixel regions are arranged in a matrix. Each first electrode and each second electrode are connected to the drive circuit 4 and are driven in a simple matrix with a 1/4 duty, for example. Further, the liquid crystal element 3b of the present embodiment is used for high beam light distribution control and is not related to low beam light distribution control.

  The low beam unit 11 is, for example, a projection-type lamp, and is used to form a low beam in a space in front of the host vehicle. The on / off state of the low beam unit 11 is controlled by the control unit 5.

  In the vehicle headlamp system according to the present embodiment, a high beam unit is configured including the light source 1, the liquid crystal element 3b, and the like, and depending on the position of a normal high beam or the position of a preceding vehicle or the like by the high beam unit. Selective light irradiation is performed. Further, the low beam is irradiated by the low beam unit 11. The high beam and the low beam are added together to form the entire light distribution pattern.

  The vehicle lamp system of the present embodiment has the above-described configuration. Next, the liquid crystal element by the control unit 5 when the temperature in the housing 7, particularly the ambient temperature of the liquid crystal element 3 a is lower than the reference value. The contents of the operation control 3b will be described in detail.

  The control unit 5 acquires the temperature detected by the temperature sensor 9 and, when this temperature falls below a predetermined reference value (for example, −10 ° C.), makes the entire pixel region of the liquid crystal element 3b transparent. The control signal is generated and supplied to the drive circuit 4. When a drive voltage (on-voltage in this example) is applied by the drive circuit 4 based on this control signal, the entire liquid crystal element 3b is in a transmissive state. At this time, if the light source 1 is turned on under the control of the control unit 5, the light from the light source 1 passes through the liquid crystal element 3b and is irradiated forward of the host vehicle to form a high beam.

  For example, the control unit 5 determines the irradiation pattern of either the high beam or the low beam based on the position of the vehicle ahead. If the temperature detected by the temperature sensor 9 is equal to or lower than the reference value, each pixel of the liquid crystal element 3b is determined. A control signal is supplied to the drive circuit 4 so that all the pixel regions are in a transmissive state without individually controlling the regions. In addition, the control part 5 may determine the irradiation pattern in which a high beam is a low beam according to the operation state of the operation switch of the own vehicle.

  At this time, if the determined irradiation pattern is a high beam, the control unit 5 turns on the light source 1 and turns on the low beam unit 11 as well. As a result, the light transmitted through the pixel region corresponding to the high beam is irradiated to the front of the host vehicle to form a high beam, and the light emitted from the low beam unit 11 is irradiated to the front of the host vehicle to form the low beam. The If the determined irradiation pattern is a low beam, the control unit 5 turns off the light source 1 and turns on only the low beam unit 11. As a result, there is no light transmitted through the pixel region corresponding to the high beam, so a high beam is not formed in front of the host vehicle, and only a low beam is formed.

  Even when the low beam irradiation pattern is selected, if the temperature detected by the temperature sensor 9 is equal to or lower than the reference value, the control unit 5 controls all the pixel regions of the liquid crystal element 3b to remain in the transmissive state. Thereby, even when the irradiation pattern is switched to the high beam thereafter, the high beam can be quickly formed by controlling the light source 1 to the lighting state.

  According to each embodiment as described above, in a vehicle lamp system using a liquid crystal element, when there is a possibility that the light distribution control cannot be accurately followed due to a decrease in the response speed of the liquid crystal element due to the ambient temperature, Since the all-light modulation region of the liquid crystal device is in a light transmission state, it is possible to reliably irradiate light ahead of the host vehicle.

  Note that the present invention is not limited to the contents of the above-described embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, in each of the embodiments described above, a vertical alignment type or a TN type liquid crystal element is shown as an example of the configuration of the liquid crystal element. it can.

  Further, in each of the above-described embodiments, when all the pixel regions of the liquid crystal element are controlled to be in a transmissive state according to the temperature, selective light irradiation is not performed on the front side of the host vehicle. You may make it notify to the passenger of the own vehicle. Specifically, it may be notified by image display using an image display device provided in the own vehicle, or may be notified by voice output using a speaker provided in the own vehicle. Accordingly, the driver can grasp that the high light and the low beam can be switched using the operation switch, but the selective light irradiation is not performed.

1: Light source 2: Parallel optical system 3, 3a, 3b: Liquid crystal element 4: Drive circuit 5: Control unit 6: Projection optical system 7: Housing 8: Camera 9: Temperature sensor 10: Shielding unit 11: Low beam unit

Claims (11)

A vehicle lamp system for selectively irradiating the front of the vehicle with a liquid crystal element,
When the temperature of the space in which the liquid crystal element is arranged is equal to or lower than a predetermined reference value, all the light modulation regions of the liquid crystal element are in a light transmission state.
Vehicle lamp system. A vehicle lamp system for selectively illuminating the front of the host vehicle,
A light source;
A liquid crystal element having a plurality of light modulation regions and forming an image using light from the light source;
A drive circuit for driving the liquid crystal element;
A temperature sensor for detecting a temperature of a space in which the liquid crystal element is disposed;
A controller that controls the drive circuit to perform the selective light irradiation;
Including
When the temperature detected by the temperature sensor is equal to or lower than a predetermined reference value, the control unit is configured so that all of the plurality of light modulation regions of the liquid crystal element are in a light transmission state. To control the
Vehicle headlamp system. A shielding part having a movable shielding plate capable of shielding a part of the liquid crystal element;
The control unit controls the shielding unit to shield a part of the liquid crystal element by the movable shielding plate when the temperature detected by the temperature sensor is equal to or lower than a predetermined reference value.
The vehicular lamp system according to claim 2. The control unit selects whether to block a part of the liquid crystal element by the shielding unit according to an operation state of an operation switch provided in the host vehicle.
The vehicular lamp system according to claim 3. A low beam unit for irradiating light to a relatively lower region in the vertical direction in front of the vehicle;
The image formed by the light source and the liquid crystal element is irradiated to a relatively upper region in the vertical direction in front of the host vehicle.
The vehicular lamp system according to claim 2. The control unit turns on the low beam unit or turns on the low beam unit and the light source according to an operation state of an operation switch provided in the host vehicle.
The vehicular lamp system according to claim 5. A control method in a vehicle lamp system for performing selective light irradiation on the front side of a host vehicle using a liquid crystal element,
When the temperature of the space in which the liquid crystal element is arranged is equal to or lower than a predetermined reference value, all the light modulation regions of the liquid crystal element are in a light transmission state.
A control method for a vehicular lamp system. The vehicle lamp system includes a shielding unit having a movable shielding plate capable of shielding a part of the liquid crystal element,
When the temperature is equal to or lower than a predetermined reference value, a part of the liquid crystal element is shielded by the movable shielding plate of the shielding part.
The control method of the vehicle lamp system of Claim 7. Selecting whether or not to block a part of the liquid crystal element by the shielding unit according to the operation state of the operation switch provided in the host vehicle;
The method for controlling the vehicular lamp system according to claim 8. The vehicular lamp system further includes a low beam unit for irradiating light to a relatively lower region in the vertical direction in front of the host vehicle.
The image by the light transmitted through the liquid crystal element is irradiated to a relatively upper region in the vertical direction in front of the host vehicle.
The control method of the vehicle lamp system of Claim 7. According to the operation state of the operation switch provided in the host vehicle, the low beam unit is turned on, or the low beam unit and the light source are turned on.
The method for controlling the vehicular lamp system according to claim 10.

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