JP2008225438A - Display device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device for a vehicle capable of keeping the luminescent chromaticity and luminescent brightness of display light constant, irrespective of a temperature change. <P>SOLUTION: The display device for a vehicle irradiates a windshield 13 with the display light L so that a display image V obtained with the irradiation may be viewed by an observer 14 in the vehicle 11. The display device includes: an illuminating means 22 having a first light emitting element 23 that emits a first color light L1 and a second light emitting element 24 that emits a second color light L2, and illuminates a liquid crystal display panel 21 with illuminating light L3 including the first color light L1 and the second color light L2; a color sensor 202 that detects the light quantity of the illuminating light L3; and a control means 55 that calculates the chromaticity data and the brightness data of the illuminating light L3 in reply to the input of the light quantity data output from the color sensor 202, and also, adjusts power to be supplied to the first and second light emitting elements 23 and 24 so that the calculated chromaticity data and the calculated brightness data may become prescribed reference chromaticity data and prescribed reference brightness data, respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention irradiates display light emitted from a display (for example, a liquid crystal display panel) to a windshield of a vehicle or a dedicated reflecting member, and makes the vehicle user visually recognize a display image obtained by the irradiation. It relates to the device.

  Conventionally, various vehicle head-up displays using a liquid crystal display device having a liquid crystal display panel have been proposed, and for example, disclosed in Patent Document 1 below. Such a vehicle head-up display projects (irradiates) display light onto a transflective plate (reflecting member) called a vehicle windshield or combiner to display a virtual image. Specifically, as shown in FIG. 9, the vehicle head-up display 1 includes a liquid crystal display device 4 and a reflecting mirror 5 housed in a housing 3 having a translucent window portion 2. The display light L emitted by 4 is reflected by the reflecting mirror 5 and projected onto the vehicle windshield or combiner to display a virtual image.

Further, the liquid crystal display device 4 includes a liquid crystal display panel 6 and light emitting diodes (light emitting elements) 7 and 8 which are light sources that transmit and illuminate the liquid crystal display panel 6. The light emitting diodes 7 and 8 emit light by being supplied with a predetermined power (current value) from a light source driving circuit (not shown). The light emitting diode 7 emits green light L1 and the light emitting diode 8 emits red light L2. The liquid crystal display panel 6 is transmitted and illuminated with orange illumination light L3 in which green light L1 emitted from the light emitting diode 7 and red light L2 emitted from the light emitting diode 8 are mixed.
JP 2003-295105 A

However, due to temperature changes (including the characteristics of the light emitting diodes 7 and 8) due to the ambient environment and heat generated by the light emitting diodes 7 and 8 themselves, the light emission chromaticity and light emission luminance of the light emitting diodes 7 and 8 vary. There was a problem that. Such fluctuations in the light emission chromaticity and light emission luminance of the light emitting diodes 7 and 8 lead to fluctuations in the light emission chromaticity and light emission luminance of the illumination light L3 (that is, the display light L) that is a mixed light of the light emitting diodes 7 and 8. In particular, there is a problem in that the light emission chromaticity and light emission luminance of the display light L cannot be kept constant.
SUMMARY OF THE INVENTION In order to address the above-described problems, an object of the present invention is to provide a vehicular display device that can keep the emission chromaticity and luminance of display light constant regardless of temperature changes. .

  The present invention is a vehicle display device that irradiates a vehicle windshield or reflecting member with display light emitted from a display, and allows a user of the vehicle to visually recognize a display image obtained by the irradiation. A first light emitting element that emits colored light and a second light emitting element that emits second colored light, and illuminates the display with illumination light including the first colored light and the second colored light. The illumination means, the detection means for detecting the light quantity of the illumination light, and the light quantity data output from the detection means are input, so that the chromaticity data of the illumination light and the brightness of the illumination light are obtained by a predetermined calculation process. Data is calculated and supplied to at least one of the first and second light emitting elements so that the calculated chromaticity data and luminance data become predetermined basic chromaticity data and basic luminance data. And control means for adjusting the that power, and characterized in that it comprises a.

  According to the present invention, the control means is calculated based on the luminance data of the illumination light and the chromaticity data of the illumination light, and the first current value supplied to the first light emitting element is an ideal first value. The second current value that matches the one current value, is calculated based on the luminance data of the illumination light and the chromaticity data of the illumination light, and is supplied to the second light emitting element is an ideal second value. When the current value is different, current value correction control is performed to correct the second current value to the ideal second current value.

  In the present invention, the current value correction control may increase or decrease the current value supplied to the second current value stepwise to bring the second current value closer to the ideal second current value. Features.

  ADVANTAGE OF THE INVENTION According to this invention, the initial purpose can be achieved and the display apparatus for vehicles which can maintain the light emission chromaticity and light emission luminance of display light irrespective of a temperature change can be provided.

  Hereinafter, an embodiment in which an embodiment of the present invention is applied to a head-up display for a vehicle will be described as an example with reference to the accompanying drawings.

  A head-up display 10 that is a display device for a vehicle is disposed in a dashboard 12 of the vehicle 11 (see FIG. 1). The display light L projected by the head-up display 10 is reflected by the windshield 13 toward the observer (user) 14 side. The observer 14 can visually recognize the virtual image V superimposed on the landscape. In other words, the head-up display 10 irradiates the windshield 13 with display light L emitted from a liquid crystal display panel (described later) provided in the head-up display 10, and observes a display image (virtual image) V obtained by this irradiation. It is made to be visually recognized by the person 14. Thereby, the observer 14 can observe the virtual image V superimposed on the landscape.

  The head-up display 10 includes a liquid crystal display device 20, a reflector 30 and the like housed in a housing 40 (see FIG. 2). As shown in FIG. 3, the liquid crystal display device 20 includes a liquid crystal display panel (display device) 21, an illuminator (illuminating means) 22 that illuminates the liquid crystal display panel 21, a light guide member 201, a color sensor ( Detection means) 202.

  The liquid crystal display panel 21 is composed of, for example, a TFT (thin film transistor) type liquid crystal display element in which polarizing films are provided on the front and back surfaces of a liquid crystal cell in which liquid crystal is sealed in a pair of translucent substrates. The liquid crystal display panel 21 can display a measured value of the speed of the vehicle 11 as a numerical value based on an output signal from a vehicle speed detecting means (described later) provided in the vehicle 11. The display information displayed by the liquid crystal display panel 21 is not limited to the vehicle speed, and may be arbitrary, for example, engine speed, travel distance information, navigation information, and outside air temperature information.

  On the other hand, the illuminator 22 includes a first light emitting element 23 that is a light source, a second light emitting element 24 that is a light source having a light emission color different from that of the light source, a first wiring board 25, and a second wiring board. 26, a first condenser lens 27, a second condenser lens 28, and a dichroic mirror (transmission / reflection member) 29.

  The first light-emitting element 23 is composed of a chip-type light-emitting diode that emits green light L1 that is the first colored light. In the present embodiment, eight light-emitting diodes are used, and these eight light-emitting diodes are connected in series. It shall be.

  The second light-emitting element 24 is composed of a chip-type light-emitting diode that emits red light L2, which is the second colored light. Eight light-emitting diodes are used as in the first light-emitting element 23, and these eight light-emitting elements are emitted. It is assumed that the diodes are connected in series.

  The first wiring board 25 is made of, for example, a substantially rectangular aluminum substrate having high thermal conductivity, and eight first light emitting elements 23 connected in series are mounted at a high density.

  The second wiring board 26 is made of, for example, a substantially rectangular aluminum substrate having high thermal conductivity, and eight second light emitting elements 24 connected in series are mounted at a high density. The outer shape of the second wiring board 26 is substantially the same as the outer shape of the first wiring board 25.

  The first condenser lens 27 is made of a light-transmitting synthetic resin, and has a plurality of convex spherical surfaces 27 a that protrude toward the dichroic mirror 29 corresponding to the individual first light emitting elements 23. 27 a has a function of collecting the illumination light emitted from each first light emitting element 23. The condensed illumination light (each green light L1) of each first light emitting element 23 is guided to the dichroic mirror 29 side.

  The second condenser lens 28 is made of a light-transmitting synthetic resin, and has a plurality of convex spherical surfaces 28a that protrude toward the dichroic mirror 29 corresponding to the individual second light emitting elements 24. 28 a has a function of condensing illumination light emitted from each second light emitting element 24. Then, the condensed illumination light (each red light L2) of each second light emitting element 24 is guided to the dichroic mirror 29 side in the same manner as each green light L1. In addition, the shape of the 2nd condensing lens 28 (each spherical surface 28a) shall be substantially the same as the shape of the 1st condensing lens 27 (each spherical surface 27a).

  The dichroic mirror 29 includes a reflective film 29a formed by vapor deposition on the front surface of the glass substrate (that is, the surface facing the back surface of the liquid crystal display panel 21). The traveling direction of each green light L1 and each red light It is inclined and arranged so as to have an inclination of approximately 45 degrees with respect to the traveling direction of L2.

  The dichroic mirror 29 transmits the green light L1 emitted from the first light emitting elements 23 and reflects the red light L2 emitted from the second light emitting elements 24. Then, each green light L1 transmitted through the dichroic mirror 29 and each red light L2 reflected through the dichroic mirror 29 are mixed by the dichroic mirror 29, and each of these mixed illumination lights (each orange light) L3 is mixed. By being led to the liquid crystal display panel 21 side, the liquid crystal display panel 21 is transmitted and illuminated. This means that the liquid crystal display panel 21 is transmitted and illuminated with each illumination light L3 including each green light L1 and each red light L2.

  In this way, the illumination light L3 transmitted through the liquid crystal display panel 21 and emitted (emitted) from the liquid crystal display panel 21 is emitted from the liquid crystal display device 20 as display light L and guided to the reflector 30 side. Become.

  The light guide member 201 is made of a light-transmitting synthetic resin such as acrylic and has a reflective surface 201a that reflects a part L4 of the illumination light L3. The light guide member 201 is arranged at a position where the illumination light L3 can be incident from the irradiation range S of the illumination light L3 and does not block the display area 21a of the liquid crystal display panel 21 (see FIG. 4).

  The color sensor 202 includes, for example, an RGB color filter (three primary colors) disposed on a surface facing the light guide member 201 (a front surface portion of the main body) and three light receiving elements disposed in the internal space of the main body. A circuit board (not shown) that detects the light quantity of a part L4 of the illumination light L3 reflected by the reflecting surface 201a of the light guide member 201 by the light receiving element. It is mounted on the wiring pattern.

  In this case, the light receiving element receives a red light receiving element that receives red light that passes through a red color filter among the RGB color filters, and green light that passes through a green color filter among the RGB color filters. A green light receiving element; and a blue light receiving element that receives blue light passing through the blue color filter among the RGB color filters.

  The RGB color filter is substantially circular and is formed in a state where the red color filter, the green color filter, and the blue color filter are evenly divided (divided into three equal parts).

  Accordingly, a part L4 of the illumination light L3 reflected by the reflecting surface 201a is emitted from the light guide member 201, passes through the RGB color filter facing the light guide member 201, and passes through the light receiving element (in this case, The red light receiving element and the green light receiving element) receive the light.

  When the color sensor 202 receives light (red light, green light) by the light receiving elements (the red light receiving element and the green light receiving element), the sensor detection current value (red color) corresponding to the intensity of each color light. Light detection current value, green light detection current value) flows on the wiring pattern.

  In this embodiment, the light quantity is detected by the color sensor 202 using the light guide member 201. However, any configuration may be adopted as long as the light quantity can be detected by the color sensor 202. Needless to say, you can.

  As shown in FIG. 2, the reflector 30 includes a concave mirror 31, a holding member 32, and a stepping motor 33. The concave mirror 31 is formed by depositing a metal (for example, aluminum) on a resin (for example, polycarbonate) to form a reflective surface 31a. The reflection surface 31a is a concave surface, and the display light L emitted from the liquid crystal display device 20 is enlarged to display the virtual image V. The concave mirror 31 is bonded to the holding member 32 with a double-sided adhesive tape. The holding member 32 is made of resin (for example, ABS), and the gear portion 34 and the shaft portion 35 are integrally formed. The shaft portion 35 of the holding member 32 is pivotally supported by the housing 40.

  A gear 36 is attached to the rotation shaft of the stepping motor 33, and the gear 36 is engaged with the gear portion 34 of the holding member 32. The concave mirror 31 is supported so as to be rotatable together with the holding member 32, and the concave mirror 31 can be rotated by the stepping motor 33 to adjust the projection direction of the display light L. The observer 14 operates a push button switch (not shown) to adjust the angle of the concave mirror 31 so that the display light L is reflected at the position of the eyes (that is, the virtual image V can be visually recognized).

  The housing 40 accommodates the liquid crystal display device 20 and the reflector 30. The housing 40 is provided with a window 41 from which the display light L is emitted. This window part 41 consists of translucent resin (for example, acrylic), and has a curved shape. Further, the housing 40 is provided with a light shielding wall 42 to prevent a phenomenon (washout) in which external light such as sunlight enters the liquid crystal display device 20 and the virtual image V becomes difficult to see. The light shielding wall 42 has a flat plate shape and is formed so as to hang obliquely from the upper part of the housing 40.

  FIG. 5 is a block diagram showing an electrical configuration of the liquid crystal display device 20. In FIG. 5, 51 is a vehicle speed detection means, 202 is a color sensor (detection means), 52 is an inverting amplifier circuit, 53 is a peak hold circuit, 54 is storage means, 55 is control means, 56 is a liquid crystal drive circuit, 57 Is a first light source driving circuit, 58 is a second light source driving circuit, 21 is a liquid crystal display panel, 23 is a first light emitting element, and 24 is a second light emitting element.

  The vehicle speed detection unit 51 includes a vehicle speed sensor for detecting the speed of the vehicle 11, detects a vehicle speed detection signal corresponding to the driving state of the vehicle 11, and outputs it to the control unit 55.

  The color sensor 202 detects the light quantity of a part L4 of the illumination light L3 reflected by the reflection surface 201a of the light guide member 201 as described above. Moreover, the said light quantity said here is defined as what contains the brightness | luminance and chromaticity of a light emitting element.

  On the wiring pattern, a first operational amplifier (not shown) as current-voltage conversion means for converting the sensor detection current value (the green light detection current value) into a first output voltage signal; And a second operational amplifier (not shown) as a current-voltage conversion means for converting the sensor detection current value (the red light detection current value) into a second output voltage signal. In the present embodiment, it is assumed that the positive power supply and the negative power supply of the first and second operational amplifiers are set to 5V and 0V, respectively.

  That is, the color sensor 202 detects the green light detection current value, and the detected green light detection current value is output from the first output voltage signal by the first operational amplifier connected to the color sensor 202 in conduction. The converted first output voltage signal is output to the inverting amplifier circuit 52 as light quantity data.

  The color sensor 202 detects the red light detection current value, and the detected red light detection current value is output from the second output voltage signal by the second operational amplifier connected to the color sensor 202 in conduction. The converted second output voltage signal is output to the inverting amplification circuit 52 together with the first output voltage signal as light quantity data.

  In the case of this embodiment, the first and second output voltage signals are output as pulse waveforms because the first and second light emitting elements 23 and 24 are PWM-controlled.

  The inverting amplifier circuit 52 receives the first output voltage signal converted into a voltage value by the first operational amplifier, thereby inverting the first output voltage signal and inverting the first output voltage signal. The output voltage signal is amplified and the amplified first output voltage signal is output to the peak hold circuit 53. Further, when the second output voltage signal converted into a voltage value by the second operational amplifier is input to the inverting amplifier circuit 52, the inverting amplifier circuit 52 inverts the second output voltage signal and inverts the second output voltage signal. 2 is amplified, and the amplified second output voltage signal is output to the peak hold circuit 53.

  Here, an example of the inverting amplification process of the first output voltage signal in the inverting amplifier circuit 52 will be described. FIG. 6A illustrates an output waveform (pulse waveform) in a state where the first output voltage signal corresponding to the first current value supplied to the first light emitting element 23 is input to the inverting amplifier circuit 52. ) Is an example. That is, in FIG. 6A, the output voltage signal (the first output voltage signal) is 5 V from the time T1 to the time T2, which is a predetermined time (for example, 5 μs). Since the output voltage signal is 3V from time T2 to time T3, which is the light emission state, the first light emitting element 23 is in light emission state from time T3 to time T4, which is the predetermined time. Since the output voltage signal is 5 V, the first light emitting element 23 is in a non-light emitting state.

  FIG. 6B shows a state in which the waveform of the first output voltage signal shown in FIG. That is, in FIG. 6B, the output voltage signal becomes 0V by inverting the signal from time T1 to time T2, and the output voltage signal becomes 2V by inverting the signal from time T2 to time T3. From time T3 to time T4, the output voltage signal becomes 0V by inverting the signal.

  FIG. 6C shows a waveform obtained by amplifying the waveform of the first output voltage signal shown in FIG. That is, in FIG. 6C, from time T2 to time T3, the output voltage signal is changed from 2V to 5V, for example, by amplifying the signal. Note that, from time T1 to time T2 and from time T3 to time T4, the output voltage signal in the state before being amplified is 0V, so that the output voltage signal after amplification remains of 0V. The inversion amplification processing of the first output voltage signal has been described above, but the same processing is performed for the inversion amplification processing of the second output voltage signal.

  When the first and second output voltage signals, which are amplified signals output from the inverting amplifier circuit 52, are input to the peak hold circuit 53, the peak level (peak level) of the first and second output voltage signals is input. Value) and the peak level of the first and second output voltage signals (for example, in FIG. 6C, the peak level of the first output voltage signal is the output voltage signal from time T2 to time T3). Is output to the control means 55.

  The storage means 54 includes first correction data that is an initial setting current value based on the luminous flux rank and chromaticity rank of the first light emitting element 23, and an initial setting current based on the luminous flux rank and chromaticity rank of the second light emitting element 24. The second correction data which is a value is stored.

  FIG. 7 is a diagram showing the first correction data to be supplied to the first light emitting element 23 based on the luminous flux rank and chromaticity rank of the first light emitting element 23. In the case of the present embodiment, the first correction data is shown in FIG. Both the luminous flux rank and chromaticity rank of the light emitting element 23 are set in three stages. In the following description, only the first light emitting element 23 will be described, and detailed description of the second light emitting element 24 will be omitted. In FIG. 7, the luminous flux rank is set in three stages of A, B, and C, and the chromaticity rank is set in three stages of 1, 2, and 3. Therefore, the first correction data that is the initial set current value is 9 There are street data values.

  That is, in FIG. 7, if the luminous flux rank is A and the chromaticity rank is 1, the current value A1 that is the first correction data value is the initial setting current value that should be supplied to the first light emitting element 23 first. If the luminous flux rank is A and the chromaticity rank is 2, it is assumed that the current value A2 is an initial setting current value to be supplied to the first light emitting element 23 first. If the luminous flux rank is A and the chromaticity rank is 3, It is assumed that the current value A3 is an initial setting current value to be supplied to the first light emitting element 23 first. Similarly, when the luminous flux ranks are B and C, similarly, the current values B1 to B3 and C1 to C3 are the initial setting current values to be supplied to the first light emitting element 23 according to the chromaticity rank. To do.

  The control means 55 comprises a microcomputer having a ROM storing processing operation programs, a RAM temporarily storing calculation values, and a CPU for executing the programs.

  The control means 55 receives the peak level of the first and second output voltage signals (the light amount data) output from the peak hold circuit 53 as an input signal, so that the illumination light L3 is obtained by a predetermined calculation process. Chromaticity data and luminance data are calculated.

  Specifically, the luminance data of the illumination light L3 includes the peak level value of the first output voltage signal and the peak level of the first output voltage signal in a single pulse waveform of the first output voltage signal. The luminance data of the green light L1 calculated from the time when the value is output, the peak level value of the second output voltage signal in the single pulse waveform of the second output voltage signal, and the second It is calculated by a predetermined calculation process using the luminance data of the red light L2 calculated from the time when the peak level value of the output voltage signal is output. The luminance data of the illumination light L3 means the brightness of the display image (virtual image) V.

  Further, the chromaticity data of the illumination light L3 is calculated by using predetermined luminance data of the green light L1, the luminance data of the red light L2, and the peak level values of the first and second output voltage signals. Calculated by processing. Then, the luminance data and the chromaticity data of the illumination light L3 calculated in this way are used to supply the first and second light emitting elements 23 and 24, respectively, by a predetermined calculation process. First and second current values are calculated.

  Here, ideal current values to be supplied to the first and second light emitting elements 23 and 24 are basic luminance data (target luminance data) and basic chromaticity data (target chromaticity data) of the illumination light L3. Based on this, it can be calculated by a predetermined calculation process. In this case, the basic chromaticity data (the target chromaticity data) is a desirable (target) wavelength (chromaticity) region (range) of the illumination light L3 in the known CIE chromaticity diagram. Point to. The basic luminance data (the target luminance data) indicates a state in which the brightness of the display image (virtual image) V is a desired (target) predetermined brightness.

  The control means 55 includes the first and second current values (calculated values) calculated based on the luminance data and chromaticity data of the illumination light L3, the target luminance data of the illumination light L3, and the target chromaticity. The ideal (target) first and second current values (target values) calculated based on the data are compared, and the calculated first value and the ideal first current value are compared. Are different from each other, the current value correction control for correcting (adjusting) the calculated value to the ideal first current value is performed, and the second current value that is the calculated value and the ideal second value are performed. When the current value is different, current value correction control is performed to correct (adjust) the calculated value to the ideal second current value. At this time, for example, when the first current value that is the calculated value matches the ideal first current value, only the second current value that is the calculated value is used as the ideal current value. What is necessary is just to correct | amend to a 2nd electric current value.

  Therefore, the above-described current value correction control is performed so that the calculated luminance data and chromaticity data of the illumination light L3 become the predetermined basic luminance data and basic chromaticity data of the illumination light L3. This has substantially the same meaning as adjusting the current (power) supplied to at least one of the first and second light emitting elements 23 and 24.

  Incidentally, FIG. 8 shows the second current value supplied to the second light emitting element 24 when the calculated second current value and the ideal second current value are different. An example of current value correction control for correcting to an ideal second current value is shown. Hereinafter, the current value correction control for the second light emitting element 24 will be described with reference to FIG.

  For example, in FIG. 8, before reaching a certain time t1, the second current value (that is, the current value supplied to the second light emitting element 24) that is the calculated value is 200 mA. It is assumed that the second current value is 300 mA.

  In this case, first, the control means 55 calculates the difference between the ideal second current value (300 mA) and the calculated second current value (200 mA). This difference is calculated as 300-200 = 100 mA. Then, the control unit 55 calculates a division value (first adjustment value) obtained by dividing this difference by a positive integer N (in this embodiment, N is 5) stored in the storage unit 54. For example, when N = 5, the first adjustment value is calculated as 100 mA / 5 = 20 mA.

  Next, when reaching the time t1, the control means 55 adds the first adjustment value (20 mA) to the second current value (200 mA) that is the calculated value, and the first adjustment is 220 mA. A current value is set as the second current value. The first adjustment current value is maintained until a time t2 after 100 ms elapses from the time t1.

  Next, before the time t2 is reached, the control means 55 is the first adjusted current which is the ideal second current value (300 mA) and the second current value that is maintained until the time t2 is reached. The difference from the value (220 mA) is calculated. This difference is calculated as 300−220 = 80 mA. Then, the control means 55 calculates a division value (second adjustment value) obtained by dividing the difference by the integer N. The second adjustment value is calculated as 80 mA / 5 = 16 mA.

  Next, when the time t2 is reached, the control means 55 is 236 mA obtained by adding the second adjustment value (16 mA) to the first adjustment current value (220 mA) maintained until the time t2 is reached. A second adjustment current value is set as the second current value. The second adjustment current value is maintained until a time t3 after 100 ms elapses from the time t2, for example.

  Next, the control means 55, before reaching the time t3, the second adjustment current, which is the ideal second current value (300 mA) and the second current value that is maintained until the time t3 is reached. The difference from the value (236 mA) is calculated. This difference is calculated as 300−236 = 64 mA. Then, the control means 55 calculates a division value (third adjustment value) obtained by dividing this difference by the integer N. The third adjustment value is calculated as 64 mA / 5 = 12.8 mA.

  Next, when the time t3 is reached, the control means 55 adds the third adjustment value (12.8 mA) to the second adjustment current value (236 mA) maintained until the time t3 is reached. A third adjustment current value of 248.8 mA is set as the second current value. The third adjustment current value is maintained until a time t4 after 100 ms elapses from the time t3, for example.

  Hereinafter, although detailed explanation is omitted, the current value correction control exactly as described above is performed by the control means 55 at times t4, t5, t6. That is, this is calculated as the calculated value as shown in FIG. 8 when the current value correction control is different from the calculated second current value and the ideal second current value. The current value supplied to the second current value is increased stepwise every predetermined time, and the second current value, which is the calculated value, is made to approach the ideal second current value as much as possible. It means that

  That is, the value of the second current value after the current value adjustment at time t6 is about 273.8 mA, but the current value correction at the time t6 is repeated several times after the time t6. The adjusted second current value of 273.8 mA is closer to the ideal second current value (300 mA). The above is an example of the current value correction control for the second light emitting element 24.

  In the present embodiment, the current value correction control is an example in which the second current value, which is the calculated value, is increased in a stepwise manner so as to approach the ideal second current value. As described above, for example, when the second current value that is the calculated value is larger than the ideal second current value, the current value correction control is the second value that is the calculated value. Needless to say, control is performed so that the current value is decreased stepwise to approach the ideal second current value.

  Then, the control means 55 performs control to output a drive control signal to the first light source drive circuit 57 so as to drive the first light emitting element 23 to light through the first light source drive circuit 57. That is, the control means 55 outputs a drive control signal to the first light source drive circuit 57 so as to supply the ideal (optimum) first current value to the first light emitting element 23. Further, the control means 55 performs control such that a drive control signal is output to the second light source drive circuit 58 so as to drive the second light emitting element 24 to light through the second light source drive circuit 58. That is, the control unit 55 outputs a drive control signal to the second light source drive circuit 58 so as to supply the ideal (optimum) second current value to the second light emitting element 24.

  Accordingly, the first and second light emitting elements 23 and 24 are supplied with the ideal first and second current values, respectively, so that the first light emitting element 23 has a green color so that it has a desired light amount. The second light emitting element 24 emits red light so as to have a desired light amount. Then, the green light L 1 and the red light L 2 are again mixed by the dichroic mirror 29, and a part L 4 of the mixed illumination light L 3 is detected by the color sensor 202. Thereafter, as shown in FIG. 5, the signals (first and second output voltage signals) are transmitted from the color sensor 202 to the inverting amplifier circuit 52, the peak hold circuit 53, and the control means 55, and the ideal first A process is performed in which the current value is constantly supplied to the first light emitting element 23 and the ideal second current value is constantly supplied to the second light emitting element 24.

  According to this embodiment, it is possible to suppress fluctuations in the light emission luminance and light emission chromaticity of each light emitting element 23, 24 due to temperature changes caused by the ambient environment, heat generated by each light emitting element 23, 24 itself, and the like. The ideal first current value is always supplied to the light emitting element 23 regardless of the temperature change, and the ideal second current value is always supplied to the second light emitting element 24 regardless of the temperature change. Therefore, the light emission luminance and light emission chromaticity of the illumination light L3 (that is, the display light L), which is a mixed light of the light emitted from the light emitting elements 23 and 24, can be kept constant regardless of the temperature change. It becomes possible.

  The control means 55 performs a predetermined program (calculation) process based on the vehicle speed detection signal input from the vehicle speed detection means 51 and operates the liquid crystal display panel 21 to operate the liquid crystal display panel 21 via the liquid crystal drive circuit 56. Control is performed so as to output a drive control signal to the circuit 56. Thereby, the vehicle speed of the vehicle 11 is displayed on the liquid crystal display panel 21.

  In the present embodiment, the example in which the display light L emitted from the liquid crystal display panel 21 is applied to the windshield 13 of the vehicle 11 has been described. For example, the display light L is favorably applied to the windshield 13 in the direction of the viewer 14. A combiner film to be reflected may be provided, or the display light L may be irradiated to a dedicated reflecting member different from the windshield 13.

  In the present embodiment, two types of light emitting elements 23 and 24 having different emission colors are used. However, for example, three types of light emitting elements having different emission colors may be used.

1 is a schematic view of a head-up display showing an embodiment of the present invention. Sectional drawing of the display apparatus for vehicles which shows embodiment same as the above. The side view of the liquid crystal display device which shows embodiment same as the above. Explanatory drawing of the display area of the liquid crystal display panel which shows embodiment same as the above. The block diagram of the liquid crystal display device which shows embodiment same as the above. (A) is a figure which shows the waveform in the state where the output voltage signal was input into the inverting amplifier circuit. FIG. 7B is a diagram illustrating a state in which the waveform of the output voltage signal in FIG. (C) is a figure which shows the state which amplified the waveform of the output voltage signal of FIG.6 (b). The figure which shows the relationship between the luminous flux rank of a light emitting element, chromaticity rank, and the optimal electric current value which should be supplied to a light emitting element. FIG. 10 is a current value adjustment characteristic diagram for correcting a second current value supplied to the second light emitting element to an ideal second current value. Sectional drawing of the display apparatus for vehicles which shows a prior art example.

Explanation of symbols

11 Vehicle 13 Windshield 14 Observer (User)
21 Liquid crystal display panel (display)
22 Illuminator (illumination means)
23 1st light emitting element 24 2nd light emitting element 29 Dichroic mirror (transmission reflection member)
54 storage means 55 control means 202 color sensor (detection means)
L Display light L1 Green light (first colored light)
L2 Red light (second colored light)
L3 Orange light (illumination light)
V Display image (virtual image)

Claims (3)

A display device for a vehicle that irradiates a vehicle windshield or a reflecting member with display light emitted from a display device, and causes a user of the vehicle to visually recognize a display image obtained by the irradiation,
A first light emitting element that emits first colored light and a second light emitting element that emits second colored light are provided, and the display device is illuminated with illumination light including the first colored light and the second colored light. Illumination means for illuminating;
Detection means for detecting the amount of illumination light;
By inputting the light amount data output from the detection means, the chromaticity data of the illumination light and the luminance data of the illumination light are calculated by a predetermined calculation process, and the calculated chromaticity data, And control means for adjusting electric power supplied to at least one of the first and second light emitting elements so that the luminance data becomes predetermined basic chromaticity data and basic luminance data. Display device for a vehicle. The control means includes
Calculated based on the luminance data of the illumination light and the chromaticity data of the illumination light, and the first current value supplied to the first light emitting element matches the ideal first current value, and
When the second current value calculated based on the luminance data of the illumination light and the chromaticity data of the illumination light and supplied to the second light emitting element is different from the ideal second current value,
The vehicle display device according to claim 1, wherein current value correction control is performed to correct the second current value to the ideal second current value. The current value correction control is characterized in that a current value supplied to the second current value is increased or decreased stepwise to bring the second current value closer to the ideal second current value. 3. The vehicle display device according to 2.

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