Vehicular display device

Abstract

To provide a vehicular display device that can suppress occurrence of flicker.SOLUTION: A head-up display device 100 comprises: a display unit 10 that displays vehicle information; a control part 70 that controls the display unit 10; and a transforming part 72 that transforms a battery voltage Vc from an on-vehicle battery 40 and supplies the voltage as an operation power supply to the control part 70. The control part 70 comprises: a voltage detecting part 71b that detects the battery voltage Vc for every preset sampling period; and an abnormality determining part 71a that determines presence or absence of an abnormality on the basis of the battery voltage Vc detected by the voltage detecting part 71b in plural times for every sampling period, in a voltage monitoring period of time in which 500 msec or more is set. The control part 70 stops operation of the display unit 10 when the abnormality determining part 71a determines the presence of an abnormality.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a display device for a vehicle. [Background technology]

[0002] The vehicle instrument device described in Patent Document 1 comprises a display that displays vehicle information, and a control means that controls the display using a generator as its driving power source, and this control means shuts down (turns off) the display when the output potential of the generator is below a predetermined threshold value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-202634 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, when the output voltage contains a ripple voltage, which is a minute voltage fluctuation component, and the output voltage fluctuates so as to cross a threshold value, the display may repeatedly turn on and off in response in a short period of time, causing a flickering effect.

[0005] The present disclosure has been made in consideration of the above-described circumstances, and has an object to provide a vehicle display device that can suppress the occurrence of flicker. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the vehicle display device of the present disclosure comprises a display unit that displays vehicle information, a control unit that controls the display unit, and a transformation unit that transforms battery voltage from a battery and supplies it to the control unit as an operating power source, the control unit comprises a detection unit that detects the battery voltage at every predetermined sampling period, and an abnormality judgment unit that judges the presence or absence of an abnormality based on the battery voltage detected by the detection unit multiple times at every sampling period within a voltage monitoring period that is set to 500 msec or more, and the control unit stops operation of the display unit when the abnormality judgment unit judges that there is an abnormality. Effect of the Invention

[0007] According to the present disclosure, the occurrence of flicker can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a vehicle equipped with a head-up display device according to a first embodiment of the present disclosure. [Diagram 2] 1 is a schematic diagram of a head-up display device according to a first embodiment of the present disclosure. [Diagram 3] 1 is a block diagram of a head-up display device according to a first embodiment of the present disclosure. [Figure 4] 4 is a graph showing a change in a battery voltage on which a ripple voltage is superimposed and on / off of a light source according to the first embodiment of the present disclosure. [Diagram 5] 11 is a graph showing a change in a battery voltage on which a ripple voltage is superimposed and on / off of a light source according to a comparative example. [Figure 6] FIG. 11 is a block diagram of a head-up display device according to a second embodiment of the present disclosure. [Figure 7] 10 is a graph showing fluctuations in battery voltage according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (First embodiment) A vehicle display device according to a first embodiment of the present disclosure will be described with reference to the drawings. 1, the head-up display device 100 is installed in the dashboard of a vehicle 200. The head-up display device 100 emits display light L that displays an image toward a windshield 201, which is an example of a projection target member of the vehicle 200. The display light L is reflected by the windshield 201 and reaches a viewer 1 (mainly the driver of the vehicle 200). As a result, a virtual image V is displayed so as to be visible to the viewer 1.

[0010] As shown in FIG. 2, the head-up display device 100 includes a display unit 10, a plane mirror 20, a concave mirror 30, a housing 60, and a control unit .

[0011] The display unit 10 emits display light L that represents an image under the control of the control unit 70. The display unit 10 includes a display 14 and an illumination device 18.

[0012] The display 14 is a TFT (Thin Film Transistor) type liquid crystal display panel controlled by the control unit 70. Under the control of the control unit 70, the display 14 displays an image including vehicle information, and while displaying the image, receives light from the illumination device 18 and emits display light L corresponding to the image.

[0013] The lighting device 18 is located behind the display 14 and illuminates the display 14 with illumination light. The lighting device 18 includes a plurality of light sources 18a that emit light to the display 14 under the control of the control unit 70. Each light source 18a is made of an LED (Light Emitting Diode).

[0014] The plane mirror 20 reflects the display light L emitted by the display unit 10 toward the concave mirror 30. The concave mirror 30 reflects the display light L reflected by the plane mirror 20 toward a windshield 201 (see FIG. 1) while magnifying it. The plane mirror 20 may be a concave mirror.

[0015] The housing 60 is made of a non-translucent resin or metal and has a hollow, substantially rectangular parallelepiped shape. Within the housing 60, each component of the head-up display device 100 is housed. The housing 60 has an opening 61 formed at a position facing the windshield 201 . The housing 60 includes a curved plate-like window portion 50 that closes the opening 61. The window portion 50 is made of a translucent resin such as acrylic, through which the display light L passes.

[0016] Next, the electrical configuration of the head-up display device 100 will be described with reference to FIG. The control unit 70 includes a microcomputer 71, a light source driver IC (Integrated Circuit) 74, a transformer 72, and a voltage divider circuit 73.

[0017] The microcomputer 71 is composed of a CPU (Central Processing Unit), a GDC (Graphic Display Controller), etc., and controls the display of images displayed on the display 14, as well as controls the lighting of each light source 18a by outputting a PWM signal to each light source 18a via a light source driver IC 74. The microcomputer 71 has an operating power supply input terminal 71i1 and a voltage detection input terminal 71i2. The microcomputer 71 has, as functional blocks, an abnormality determination unit 71a that determines whether or not there is an abnormality in the battery voltage Vc, and a voltage detection unit 71b that detects the battery voltage Vc.

[0018] The light source driver IC 74 boosts the PWM signal from the microcomputer 71 and outputs the boosted PWM signal to the multiple light sources 18a connected in parallel. The light sources 18a emit light with a luminance according to the duty ratio of the PWM signal.

[0019] The transformer 72 is a DC-DC converter that transforms the battery voltage Vc from the in-vehicle battery 40 and applies the transformed battery voltage Vc as an operating power supply to an operating power supply input terminal 71i1 of the microcomputer 71. The transformer 72 steps down the battery voltage Vc from 12V to 3.3V, for example.

[0020] The voltage dividing circuit 73 reduces the battery voltage Vc from the vehicle-mounted battery 40 to a voltage detectable by the voltage detection unit 71b (for example, 5V or less) and applies the voltage to the voltage detection input terminal 71i2 of the microcomputer 71.

[0021] The voltage detection unit 71b of the microcomputer 71 detects the battery voltage Vc based on the voltage applied to the voltage detection input terminal 71i2 for each sampling period Ts (see FIG. 4) during a display period in which display is being performed by the display unit 10. The sampling period Ts is set to, for example, 5 msec to 20 msec, and preferably 10 msec.

[0022] The abnormality determination unit 71a calculates and obtains an average voltage value Va by averaging the battery voltages Vc detected multiple times every sampling period Ts during the voltage monitoring period Td during the display period. The averaging method may be a simple average, or other known averaging methods may be used. The voltage monitoring period Td is set to 500 msec or more. For example, the voltage monitoring period Td is set to a time that allows sampling of the battery voltage Vc 40 to 60 times, for example 50 times. By setting the sampling period Ts to 10 msec and the voltage monitoring period Td to 500 msec, sampling of the battery voltage Vc is performed 50 times during the voltage monitoring period Td.

[0023] As shown in FIG. 4, in this example, the voltage monitoring periods Td are set to times that do not overlap with each other. However, the voltage monitoring periods Td may be set to times that partially overlap each other. In this case, the abnormality determination unit 71a may obtain the average voltage value Va based on the sampling results of a predetermined number of samplings (e.g., 50 samplings) from the present time every sampling period Ts.

[0024] The abnormality determination unit 71a determines whether the acquired average voltage value Va is equal to or lower than the low voltage detection threshold value ThL. If the abnormality determination unit 71a determines that the average voltage value Va is equal to or lower than the low voltage detection threshold value ThL, it determines that there is an abnormality (low voltage abnormality) in the battery voltage Vc. If this abnormality is determined, the microcomputer 71 performs a display stop process, which is a process of turning off each light source 18a and erasing the display on the display 14. This makes it possible to prevent an unstable display from being performed when there is a low voltage abnormality in the battery voltage Vc.

[0025] If the average voltage value Va exceeds the low voltage detection threshold value ThL, the abnormality determination section 71a determines that there is no abnormality (low voltage abnormality) in the battery voltage Vc and allows the display unit 10 to continue the display operation. The low voltage detection threshold ThL is set to the lower limit of the voltage at which a stable display can be performed by the display unit 10. The low voltage detection threshold ThL is set, for example, in the range of 6 V to 7 V, and as one example, is set to 6.7 V. For example, the battery voltage Vc falls below the low voltage detection threshold ThL due to the end of the life or failure of the battery 40.

[0026] The voltage detection unit 71b continues to detect the battery voltage Vc every sampling period Ts even after the display stop process. After the display stop process, the abnormality determination unit 71a determines whether the acquired average voltage value Va is equal to or greater than the low voltage release threshold ThH. If the abnormality determination unit 71a determines that the average voltage value Va is equal to or greater than the low voltage release threshold ThH, it determines that the abnormality (low voltage abnormality) in the battery voltage Vc has disappeared. In this case, the microcomputer 71 resumes the display operation by the display unit 10. The low voltage release threshold ThH is set to a voltage value higher than the low voltage detection threshold ThL to prevent display stop and restart from being repeated in a short period of time. The low voltage release threshold ThH is set in the range of 7.5V to 8.5V, for example, and is set to 8.0V as an example. The low voltage detection threshold ThL and the low voltage release threshold ThH are set within a voltage range in which a ripple voltage is likely to occur.

[0027] Similar to the low voltage detection threshold ThL and the low voltage release threshold ThH, a high voltage detection threshold and a high voltage release threshold are set for detecting a high voltage abnormality in the battery voltage Vc. The high voltage release threshold is set to a voltage lower than the high voltage detection threshold. When the average voltage value Va becomes equal to or higher than the high voltage detection threshold, the abnormality determination unit 71a determines that an abnormality (high voltage abnormality) has occurred, and the microcomputer 71 executes a display stop process. When the average voltage value Va becomes equal to or lower than the high voltage release threshold after the display stop process, the abnormality determination unit 71a determines that the abnormality (high voltage abnormality) has disappeared, and the microcomputer 71 resumes the display operation by the display unit 10.

[0028] Next, the operation and effect when a ripple voltage is superimposed on the battery voltage Vc in this embodiment will be described while comparing it with a comparative example. In the following description, as shown in Figures 4 and 5, the battery voltage Vc is superimposed with a ripple voltage, so that the battery voltage Vc forms a sine wave, with the maximum value of the battery voltage Vc exceeding the low voltage release threshold ThH and the minimum value of the battery voltage Vc falling below the low voltage detection threshold ThL. As an example, the battery voltage Vc has a frequency of 2 Hz, a period of 500 msec, an amplitude of ±1 V, and a center voltage Vb of 7.5 V. The ripple voltage is likely to occur when the ignition of the vehicle is turned on.

[0029] 5, the voltage monitoring period Te is set to 160 msec, which is less than 500 msec. That is, during the voltage monitoring period Te, the battery voltage Vc is detected 16 times in total every 10 msec sampling period Ts. During the display period during which the display unit 10 is displaying, if the voltage monitoring period Te (Te1) falls within a range that includes the minimum value of the battery voltage Vc, then at time t1 when the voltage monitoring period Te1 has elapsed, the average voltage value Va falls below the low voltage detection threshold value ThL, it is determined that there is an abnormality, and a display stop process is performed in which each light source 18a is turned off and the display on the display 14 is stopped. Thereafter, when the voltage monitoring period Te (Te2) enters a range including the maximum value of the battery voltage Vc, at time t2 when the voltage monitoring period Te2 has elapsed, the average voltage value Va becomes equal to or greater than the low voltage release threshold value ThH, it is determined that the abnormality in the battery voltage Vc has disappeared, and each light source 18a is turned on and the display 14 is resumed. Thereafter, each light source 18a is repeatedly turned on and off in the same manner, causing flicker.

[0030] On the other hand, in this embodiment, as shown in Fig. 4, the voltage monitoring period Td is set to a time of at least one cycle of the battery voltage Vc, that is, at least 500 msec. As a result, the average voltage value Va is equal to or close to the center voltage Vb of the battery voltage Vc. Therefore, the average voltage value Va is kept above the low voltage detection threshold value ThL, and each light source 18a is kept on and the display 14 continues to display. This makes it possible to suppress the occurrence of flicker.

[0031] (effect) According to the first embodiment described above, the following effects are achieved. A head-up display device 100, which is an example of a display device for a vehicle, includes a display unit 10 that displays vehicle information, a control unit 70 that controls the display unit 10, and a transformer unit 72 that transforms a battery voltage Vc from an in-vehicle battery 40 and supplies the battery voltage Vc to the control unit 70 as an operating power source. The control unit 70 includes a voltage detector 71b that detects the battery voltage Vc at every preset sampling period Ts, and an abnormality determination unit 71a that determines the presence or absence of an abnormality based on the battery voltage Vc detected by the voltage detector 71b multiple times at every sampling period Ts within a voltage monitoring period Td that is set to 500 msec or more. The control unit 70 stops the operation of the display unit 10 when the abnormality determination unit 71a determines that there is an abnormality. Stopping the operation of the display unit 10 includes turning off the light source 18a. This configuration prevents the display unit 10 from repeatedly stopping and restarting its operation even when a ripple voltage (voltage fluctuation) of about 2 Hz (500 msec period) occurs, which often occurs in the in-vehicle battery 40. This makes it possible to prevent flicker from occurring.

[0032] Second embodiment A vehicle display device according to a second embodiment of the present disclosure will be described with reference to the drawings. In this embodiment, when the battery voltage is outside the ripple generating voltage range, the voltage monitoring period is set to a shorter time in order to improve the responsiveness of the abnormality determination compared to when the battery voltage is within the ripple generating voltage range. The following mainly describes the differences from the first embodiment. 6, the control unit 70A includes a voltage detection circuit 75 that detects whether or not the battery voltage Vc is within the ripple generation voltage range Ar, in addition to the above-mentioned microcomputer 71, light source driver IC 74, transformer unit 72, and voltage divider circuit 73. The ripple generation voltage range Ar is set to a battery voltage range in which a ripple voltage is likely to occur, and is set within a range of, for example, 6V to 9V, and more preferably, 6.5V to 8.5V. The voltage detection circuit 75 includes a comparator 76 and a level shift unit 77. The comparator 76 receives the battery voltage Vc and outputs a detection signal indicating whether the battery voltage Vc is within the ripple generation voltage range Ar to the level shift unit 77. The level shift unit 77 transforms the detection signal into a voltage readable by the microcomputer 71 and outputs it to the microcomputer 71.

[0033] The abnormality determination unit 71a receives a detection signal from the voltage detection circuit 75 and determines whether or not the battery voltage Vc is within the ripple generating voltage range Ar. 7, during a period Tb during which the battery voltage Vc is determined to be within the ripple generation voltage range Ar, the abnormality determination unit 71a obtains an average voltage value Va based on the detection results of the battery voltage Vc a predetermined number of times (e.g., 50 times) within a voltage monitoring period Td set to 500 msec or more, as in the first embodiment. Thereafter, the presence or absence of an abnormality is determined based on the obtained average voltage value Va, as in the first embodiment.

[0034] Meanwhile, during the period Ta or Tc during which the battery voltage Vc is determined to be outside the ripple generating voltage range Ar, the abnormality determination unit 71a obtains an average voltage value Va based on the detection results of the battery voltage Vc a predetermined number of times (e.g., 16 times) within the voltage monitoring period Te set to less than 500 msec. Thereafter, similarly to the first embodiment, the presence or absence of an abnormality is determined based on the obtained average voltage value Va. Since the voltage monitoring period Te is shorter than the voltage monitoring period Td, it is possible to quickly determine whether the battery voltage Vc is abnormal outside the ripple generating voltage range Ar. As described above, in the period Ta when the battery voltage Vc exceeds the ripple generation voltage range Ar, or in the period Tc when the battery voltage Vc is below the ripple generation voltage range Ar, the number of samplings required to obtain the average voltage value Va is reduced by making the voltage monitoring period shorter than in the period Tb when the battery voltage Vc is within the ripple generation voltage range Ar.

[0035] (effect) According to the second embodiment described above, the following effects are achieved. (1) When the battery voltage Vc detected by the voltage detection unit 71b is within a ripple generation voltage range Ar in which ripple voltage is likely to occur, the abnormality determination unit 71a determines the presence or absence of an abnormality based on the battery voltage Vc detected by the voltage detection unit 71b a plurality of times for each sampling period Ts within a voltage monitoring period Td which is an example of a first voltage monitoring period set to 500 msec or more, and when the battery voltage Vc detected by the voltage detection unit 71b is outside the ripple generation voltage range Ar, the abnormality determination unit 71a determines the presence or absence of an abnormality based on the battery voltage Vc detected by the voltage detection unit 71b a plurality of times for each sampling period Ts within a voltage monitoring period Te which is an example of a second voltage monitoring period set to less than 500 msec. According to this configuration, the occurrence of an abnormality can be quickly detected in the high voltage and low voltage ranges where ripple voltages are relatively unlikely to occur, and the operation of the display unit 10 can be quickly stopped when an abnormality occurs.

[0036] (2) The voltage detection circuit 75 includes a comparator 76 that receives the battery voltage Vc and outputs a detection signal indicating whether or not the battery voltage Vc is within the ripple generating voltage range Ar. According to this configuration, by using the comparator 76, it becomes possible to quickly detect whether the battery voltage Vc is within the ripple generating voltage range Ar, and the responsiveness of the abnormality determination is improved.

[0037] The present disclosure is not limited to the above-described embodiments and drawings. Modifications (including deletion of components) can be made as appropriate within the scope of the present disclosure. An example of a modification will be described below.

[0038] (Modification) In each of the above-described embodiments, the vehicle display device is the head-up display device 100 having the display unit 10. However, the vehicle display device may be a vehicle instrument device having the display unit 10. In each of the above embodiments, the low voltage detection threshold ThL and the low voltage release threshold ThH may be set to the same value. In the second embodiment, the voltage detection circuit 75 may be built into the microcomputer 71 as a function of the microcomputer 71. [Explanation of symbols]

[0039] 1. Viewer 10 Display unit 14 Display 18 Lighting Equipment 18a light source 20 plane mirror 30 concave mirror 40 Vehicle Battery 50 Window 60 Case 61 Opening 70,70A Control section 71 Microcomputer 71a Abnormality determination section 71b Voltage detection section 71i1 Operating power input terminal 71i2 Voltage detection input terminal 72 Transformer section 73 Pressure Circuit 74 Light source driver IC 75 Voltage detection circuit 76 Comparator 77 Level shift section 100 Head-up display device 200 vehicles 201 Windshield L display light V Virtual Image t1,t2 time Ar Ripple generation voltage range Ta,Tb,Tc period Va Average voltage value Td, Te, Te1, Te2 Voltage monitoring period Vb Center voltage Vc Battery voltage Ts Sampling period ThH Low voltage release threshold ThL Low voltage detection threshold

Claims

1. A display unit for displaying vehicle information; A control unit that controls the display unit; a transformer unit that transforms a battery voltage from a battery and supplies the transformed battery voltage to the control unit as an operating power source; The control unit is a detection unit that detects the battery voltage at each preset sampling period; an abnormality determination unit that determines the presence or absence of an abnormality based on the battery voltage detected by the detection unit a plurality of times for each sampling period during a voltage monitoring period that is set to 500 msec or more, The control unit stops the operation of the display unit when the abnormality determination unit determines that an abnormality exists. Vehicle display device.

2. The abnormality determination unit is when the battery voltage detected by the detection unit is within a voltage range in which a ripple voltage is likely to occur, during a first voltage monitoring period, which is the voltage monitoring period set to 500 msec or more, the presence or absence of an abnormality is determined based on the battery voltage detected by the detection unit a plurality of times for each sampling period; when the battery voltage detected by the detection unit is outside the voltage range, during a second voltage monitoring period set to less than 500 msec, the presence or absence of an abnormality is determined based on the battery voltage detected by the detection unit a plurality of times for each sampling period. The display device for a vehicle according to claim 1 .

Images