Patent Application
20220214227
This application claims the benefit of priority from Japanese Patent Application No. 2021-001717 filed on Jan. 7, 2021, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a temperature detection device, a temperature detection system, a display device, and a head-up display.
What-is-called head-up displays (HUD) that project an image onto a member having a light-transmitting property, such as glass, have been known.
The technique above describes that sunlight may be incident on a display device through an optical system. When the display device is exposed to the sunlight condensed by the optical system, the temperature of a place thereof exposed to the sunlight becomes high and the display device may be adversely affected. A temperature information acquisition method in which a temperature is specified on the basis of change in an electric resistance value of an electrode provided as a temperature detection element has been known.
When a temperature detection function is added to the display device simply, a circuit corresponding to a display output function and a circuit corresponding to the temperature detection function are separately provided and wiring is coupled to each of the circuits. A signal transmission path is also required between the circuit corresponding to the display output function and the circuit corresponding to the temperature detection function in order to control display in response to increase in temperature. Accordingly, the above-mentioned display device causes complication due to increase in the number of circuits and wiring lines and causes increase in cost of a wiring substrate.
The present disclosure has been made in view of the above-mentioned problem, and an object thereof is to provide a temperature detection device, a temperature detection system, a display device, and a head-up display capable of preventing increase in cost due to provision of a temperature detection function.
A temperature detection device according to an embodiment of the present disclosure includes a plurality of temperature sensors each including a temperature detection resistor element provided in a temperature detection region, and a storage unit configured to store therein unique information for each of a plurality of the temperature detection resistor elements. The temperature detection resistor element is provided for each of a plurality of partial temperature detection regions in the temperature detection region, and an externally provided control device reads out the unique information stored in the storage unit and detects a temperature for each of the partial temperature detection regions in the temperature detection region based on the unique information and an output potential that is output from the temperature sensor.
A temperature detection system according to an embodiment of the present disclosure includes a temperature detection device including a plurality of temperature sensors each including a temperature detection resistor element provided in a temperature detection region, and a storage unit configured to store therein unique information for each of a plurality of the temperature detection resistor elements, the temperature detection resistor element being provided in each of a plurality of partial temperature detection regions in the temperature detection region, and a control circuit configured to read out the unique information stored in the storage unit and detect a temperature for each of the partial temperature detection regions in the temperature detection region based on the unique information and an output potential that is output from the temperature sensor.
A display device according to an embodiment of the present disclosure includes a display panel configured to display an image, and the temperature detection device above. The temperature detection device is arranged so as to overlap with the display panel.
A head-up display according to an embodiment of the present disclosure includes a display panel configured to display an image, and a temperature detection device arranged so as to overlap with a display surface of the display panel. The temperature detection device includes a plurality of temperature sensors each including a temperature detection resistor element provided in a temperature detection region, and a storage unit configured to store therein unique information for each of a plurality of the temperature detection resistor elements, the temperature detection resistor element is provided for each of a plurality of partial temperature detection regions in the temperature detection region, and an externally provided control device reads out the unique information stored in the storage unit and detects a temperature for each of the partial temperature detection regions in the temperature detection region based on the unique information and an output potential that is output from the temperature sensor.
Modes for carrying out the present disclosure (embodiments) will be described in detail with reference to the drawings. Contents described in the following embodiments do not limit the present disclosure. Components described below include those that can be easily assumed by those skilled in the art and substantially the same components. Furthermore, the components described below can be appropriately combined. What is disclosed herein is merely an example, and it is needless to say that appropriate modifications within the gist of the disclosure at which those skilled in the art can easily arrive are encompassed in the scope of the present disclosure. In the drawings, widths, thicknesses, shapes, and the like of the components can be schematically illustrated in comparison with actual modes for more clear explanation. They are however merely examples and do not limit interpretation of the present disclosure. In the present specification and the drawings, the same reference numerals denote components similar to those described before with reference to the drawing that has been already referred, and detail explanation thereof can be appropriately omitted.
A housing 4 accommodates therein the light source unit 6 functioning as a light source device, the display panel 2 configured to output the image using light L from the light source unit 6 as a light source, the diffusion plate 9 provided between the display panel 2 and the light source unit 6, the optical system RM, and a temperature detection device 10.
The light L emitted from the light source unit 6 is diffused by the diffusion plate 9 and reaches the display panel 2, so that a part or all of the light L passes through the display panel 2 to be light of the image. In the HUD device 1 in the first embodiment, the optical system RM including a mirror member RM1 and a mirror member RM2 guides the light L after passing through the display panel 2 to the projection plate WS. The mirror member RM1 is a plane mirror, and the mirror member RM2 is a concave mirror. The mirror member RM1 may be a concave mirror. The mirror member RM2 may be a plane mirror. The optical system RM is not limited thereto, and the optical system RM may include one mirror member or equal to or more than three mirror members.
Light of the image that has passed through the optical system RM is reflected by the projection plate WS and reaches a user H to be recognized as an image VI in a visual field of the user H. That is to say, the HUD device 1 in the first embodiment functions as a display system configured to project the image onto the projection plate WS. It is sufficient that the projection plate WS is a member having a light-transmitting property and located on the visual line of the user H. The projection plate WS is, for example, a windscreen, a windshield, or a light-transmitting plate member called a combiner of a vehicle, the combiner being provided as a separate member from the windscreen.
As illustrated in
In response to the desire, the temperature detection device 10 is provided on the mirror member RM1 side with respect to the display panel 2 in the first embodiment. As illustrated in
The temperature detection device 10 may be separated from the display panel 2 or abut against or adhere to the display panel 2. The temperature detection device 10 may be provided integrally with the display panel 2.
The sensor base member 20 has a temperature detection region SA and a peripheral region GA. The temperature detection region SA includes a plurality of partial temperature detection regions PA. The partial temperature detection regions PA are regions in which a plurality of temperature detection resistor elements ER included in the sensor unit 40 are respectively provided.
The first direction Dx is one direction in a plane parallel with the sensor base member 20. The second direction Dy is one direction in the plane parallel with the sensor base member 20 and is a direction orthogonal to the first direction Dx. The second direction Dy may non-orthogonally intersect the first direction Dx. A third direction Dz is a direction orthogonal to the first direction Dx and the second direction Dy, and is a direction normal to the sensor base member 20.
Each temperature detection resistor element ER is an electric resistor using compound (metal compound) containing an alloy or metal, or metal as a material. The resistor element ER may be a multilayered body formed by stacking a plurality of types of materials falling under at least one of the metal, alloy, and metal compound. An expression “alloy or the like” in explanation of the first embodiment indicates a material capable of being employed as a composition of the resistor element ER. In the example illustrated in
The peripheral region GA is a region between the outer periphery of the temperature detection region SA and end portions of the sensor base member 20 and is a region in which no temperature detection resistor element ER is provided. A plurality of reference resistor elements 41 and the storage unit 50 are provided in the peripheral region GA. The temperature detection resistor elements ER provided in the respective partial temperature detection regions PA and the reference resistor elements 41 provided in the peripheral region GA configure a temperature sensor, which will be described later.
The storage unit 50 is a rewritable non-volatile memory such as a flash memory. The storage unit 50 stores therein pieces of unique information for the respective temperature detection resistor elements ER provided in the partial temperature detection regions PA. The pieces of unique information that are stored in the storage unit 50 are, to be specific, unique values indicating electric characteristics differing for the respective temperature detection resistor elements ER. Resistance values of the temperature detection resistor elements ER under a constant temperature environment may be different due to variations, and change rates of the resistance values thereof for temperature change may be different. Accordingly, when the temperature detection device 10 of the present disclosure detects the temperatures of the partial temperature detection regions PA in the temperature detection region SA, it needs to compensate for variations of the electric characteristics differing for the respective temperature detection resistor elements ER.
The control device 100 supplies control signals to the sensor unit 40 and the storage unit 50 to control detection operations of the temperature detection device 10. The control device 100 may have a mode that supplies control signals to the display panel 2 and the light source unit 6 to control the display operations in the display panel 2 and lighting or non-lighting of the light source unit 6.
As illustrated in
In the temperature sensor SENS(m), a current generated on the basis of the input potential Vin tries to flow to the reference potential GND. The flow of the current to the reference potential GND is however inhibited depending on the volume resistivity of the temperature detection resistor element ER(m), so that a current toward the control device 100 is generated. The current flowing toward the control device 100 generates the output potential Vout(m). That is to say, as the volume resistivity of the temperature detection resistor element ER(m) is higher, the output potential Vout(m) is increased.
Where a resistance value of the reference resistor element 41 is Rref and a resistance value of the temperature detection resistor element ER(m) is Re(m), the output potential Vout(m) of the temperature sensor SENS(m) is expressed by the following equation (1).
Vout(m)=[Re(m)/{Re(m)+Rref}]×Vin (1)
In this case, a temperature TPA(m) detected by the temperature sensor SENS(m) is expressed by the following equation (2).
TPA(m)=[Rref/{Vin/Vout(m))−1)}]×a(m)+b(m) (2)
In the above-mentioned equation (2), a first coefficient a(m) and a second coefficient b(m) are unique values for compensating for variations of the electric characteristics of the temperature detection resistor element ER(m) and are different for each temperature detection resistor element ER(m). Accordingly, when the control device 100 calculates the temperatures of the respective partial temperature detection regions PA that are detected by the corresponding temperature sensors SENS(m), it needs to apply the first coefficients a(m) and the second coefficients b(m) differing for the respective temperature detection resistor elements ER(m) of the temperature sensors SENS(m), in other words, for the respective output potentials Vout(m) that are output from the partial temperature detection regions PA.
In the present disclosure, the storage unit 50 stores therein the first coefficients a(m) and the second coefficients b(m) corresponding to the output potentials Vout(m) that are output from the respective temperature sensors SENS(m) as the pieces of unique information for the respective temperature detection resistor elements ER(m) provided in the corresponding partial temperature detection regions PA. The control device 100 accesses the storage unit 50 to read out the first coefficients a(m) and the second coefficients b(m) corresponding to the output potentials Vout(m) that are output from the respective temperature sensors SENS(m), and calculates the temperatures of the respective partial temperature detection regions PA in the temperature detection region SA. Hereinafter, the configuration for performing processing of calculating the temperatures of the respective partial temperature detection regions PA in the temperature detection region SA and the temperature calculation processing will be described.
The control circuit 110 is configured by a temperature detection control IC packaged as a what-is-called one-chip integrated circuit (IC), for example. The control circuit 110 may have a mode that is configured by a plurality of ICs, for example.
The control circuit 110 includes a temperature detection circuit 80, a central processing unit (CPU) 84, a bus 85, a read only memory (ROM) 86, an electrically erasable programmable read only memory (EEPROM) 87, a random access memory (RAM) 88, and a general purpose input output (GPIO) 89. The temperature detection circuit 80 includes a filter 81, an amplification circuit 82, and an A/D conversion circuit 83.
The filter 81 is a filter circuit configured to remove noise from the output potentials Vout(m) that are output from the partial temperature detection regions PA of the temperature detection device 10. The amplification circuit 82 amplifies the output potentials provided by noise processing by the filter 81. The A/D conversion circuit 83 converts analog output potentials provided by amplification by the amplification circuit 82 into digital signals.
The CPU 84 of the control circuit 110 performs various pieces of arithmetic processing such as processing based on the digital signals generated by the A/D conversion circuit 83.
The bus 85 functions as a transmission path of various digital signals in the control circuit 110, and for example, it transmits the digital signals that are output from the A/D conversion circuit 83 to the CPU 84. The A/D conversion circuit 83, the CPU 84, the bus 85, the ROM 86, the EEPROM 87, the RAM 88, and the GPIO 89 are coupled to the bus 85.
The ROM 86 stores therein a computer program and the like in a non-rewritable manner. The computer program and the like indicate a software computer program that is read out in processing by the CPU 84 and data that is referred in execution of the software computer program. The EEPROM 87 stores therein the computer program and the like in a rewritable manner. The RAM 88 temporarily stores therein various pieces of date and parameters that are generated with execution processing of the computer program and the like by the CPU 84.
The GPIO 89 transmits signals to the outside in response to output from the CPU 84 and the like through the bus 85.
The power supply circuit 120 is a circuit configured to supply the input potential Vin to the sensor unit 40 of the temperature detection device 10. Potential difference between the input potential Vin and the reference potential GND is thereby applied to the temperature sensor SENS(m) illustrated in
In the above-mentioned configuration, the control circuit 110 performs communication with the storage unit 50 of the temperature detection device 10 and an external high-order control device 200. The present disclosure is not limited by a protocol, an interface, and the like of communication that is performed with the storage unit 50 of the temperature detection device 10 and the external high-order control device 200.
Hereinafter, the temperature detection processing in the control device 100 using the temperature detection device 10 according to the first embodiment will be described.
The storage unit 50 of the temperature detection device 10 stores therein the pieces of unique information illustrated in
First, the control device 100 determines whether the temperature detection processing is started (step S101). When the temperature detection processing is not started (No at step S101), the control device 100 repeats the processing at step S101 until the temperature detection processing is started (Yes at step S101). The start of the temperature detection processing may be in a mode in which a temperature detection start instruction is input from the high-order control device 200 or in a mode in which the control device 100 includes a trigger (for example, a timer) of starting the temperature detection processing, for example. The temperature detection processing illustrated in
When the temperature detection processing is started (Yes at step S101), the pieces of unique information illustrated in
The power supply circuit 120 of the control device 100 supplies the input potential Vin to the sensor unit 40 of the temperature detection device 10 (step S103).
The control device 100 detects the output potential Vout(m) output from the sensor unit 40 of the temperature detection device 10 (step S104), calculates the temperature TPA(m) detected by the temperature sensor SENS(m) with the above-mentioned equation (2) using the pieces of unique information acquired from the storage unit 50 of the temperature detection device 10 for the output potential Vout(m) (step S105), and temporarily stores the calculated temperature TPA(m) in the RAM 88 of the control circuit 110, for example (step S106).
The control device 100 determines whether the temperatures TPA(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored (step S107). When the temperatures TPA(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are not stored (No at step S107), the control device 100 repeats the pieces of processing at step S104 to step S107 until the temperatures TPA(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored (Yes at step S107).
When the temperatures TPA(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored (Yes at step S107), the control device 100 performs predetermined control on the display panel 2 and the light source unit 6 using the temperatures TPA(m) corresponding to the partial temperature detection regions PA (step S108) and returns to the processing at step S101. As the predetermined control on the display panel 2, a mode in which any of a plurality of display control patterns is applied depending on the temperatures TPA(m) corresponding to the respective partial temperature detection regions PA may be employed. As the predetermined control on the light source unit 6, a mode in which any of a plurality of light source control patterns is applied depending on the temperatures TPA(m) corresponding to the respective partial temperature detection regions PA may be employed. The present disclosure is not limited by the modes of the control on the display panel 2 and the light source unit 6 depending on the temperatures TPA(m) corresponding to the partial temperature detection regions PA.
Next, a method of deriving the pieces of unique information for the respective temperature detection resistor elements ER(m) provided in the corresponding partial temperature detection regions PA, which are illustrated in
A setting tool device is coupled to the temperature detection device 10 according to the first embodiment as a precondition of the processing of deriving the first coefficients a(m) and the second coefficients b(m) for the respective temperature detection resistor elements ER(m) as the pieces of unique information, which is illustrated in
The processing of deriving the pieces of unique information, which is illustrated in
TPA1(m)=[Rref/{(Vin/Vout1(m))−1}]×a(m)+b(m) (3)
TPA2(m)=[Rref/{(Vin/Vout2(m))−1)}]×a(m)+b(m) (4)
First, the control device 100 starts processing of detecting the output potentials Vout1(m) that are output from the respective partial temperature detection regions PA of the temperature detection device 10 under the first temperature TPA1 environment (step S1).
The power supply circuit 120 of the control device 100 supplies the input potential Vin to the sensor unit 40 of the temperature detection device 10 (step S201).
The control device 100 detects the output potential Vout1(m) output from the sensor unit 40 of the temperature detection device 10 (step 5202) and temporarily stores the output potential Vout1(m) in the RAM 88 of the control circuit 110, for example (step S203).
The control device 100 determines whether the output potentials Vout1(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored (step S204). When the output potentials Vout1(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are not stored (No at step S204), the control device 100 repeats the pieces of processing at step S202 to step S204 until the output potentials Vout1(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored (Yes at step S204).
When the output potentials Vout1(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored, the control device 100 subsequently starts processing of detecting the output potentials Vout2(m) that are output from the respective partial temperature detection regions PA of the temperature detection device 10 under the second temperature TPA2 environment (step S2).
The power supply circuit 120 of the control device 100 supplies the input potential Vin to the sensor unit 40 of the temperature detection device 10 (step S301).
The control device 100 detects the output potential Vout2(m) output from the sensor unit 40 of the temperature detection device 10 (step S302) and temporarily stores the output potential Vout2(m) in the RAM 88 of the control circuit 110, for example (step S303).
The control device 100 determines whether the output potentials Vout2(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored (step S304). When the output potentials Vout2(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are not stored (No at step S304), the control device 100 repeats the pieces of processing at step S302 to step S304 until the output potentials Vout2(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored (Yes at step S304).
When the output potentials Vout2(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored, the control device 100 subsequently starts processing of calculating the first coefficients a(m) and the second coefficients b(m) corresponding to the respective temperature detection resistor elements ER(m) (step S3).
The control device 100 reads out the output potential Vout1(m) and the output potential Vout2(m) (step S401), calculates the first coefficient a(m) and the second coefficient b(m) corresponding to the temperature detection resistor element ER(m) using the above-mentioned equation (3) and the above-mentioned equation (4) (step S402), and temporarily stores the first coefficient a(m) and the second coefficient b(m) in the RAM 88 of the control circuit 110, for example (step S403).
The control device 100 determines whether the first coefficients a(m) and the second coefficients b(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored (step S404). When the first coefficients a(m) and the second coefficients b(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are not stored (No at step S404), the control device 100 repeats the pieces of processing at step S401 to step S404 until the first coefficients a(m) and the second coefficients b(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored (Yes at step S404).
When the first coefficients a(m) and the second coefficients b(m) corresponding to all of the partial temperature detection regions PA in the temperature detection region SA are stored, the control device 100 stores, in the storage unit 50 of the temperature detection device 10, the first coefficients a(m) and the second coefficients b(m) corresponding to the respective temperature detection regions PA as the pieces of unique information illustrated in
Subsequently, the control device 100 starts processing of checking consistency of the pieces of unique information (step S4).
The control device 100 reads out the pieces of unique information stored in the storage unit 50 (step S501) and determines whether the pieces of read unique information are normal (step S502). When the pieces of read unique information are normal (Yes at step S502), the processing of deriving the pieces of unique information is ended. When the pieces of read unique information are not normal (No at step S502), the control device 100 returns to step S1 and repeats the above-mentioned processing of deriving the pieces of unique information. In the processing of checking the consistency of the pieces of unique information from step S4, a mode in which whether pieces of data of the first coefficients a(m) and the second coefficients b(m) temporarily stored in the RAM 88 of the control circuit 110 and pieces of data of the first coefficients a(m) and the second coefficients b(m) as the pieces of unique information stored in the storage unit 50 match with each other is determined may be employed. The present disclosure is not limited by the method of checking the consistency of the pieces of unique information stored in the storage unit 50.
As described above, in the present disclosure, the temperature detection device 10 according to the first embodiment includes the storage unit 50 configured to store therein the first coefficients a(m) and the second coefficients b(m) corresponding to the output potentials Vout(m) that are output from the respective temperature sensors SENS(m) as the pieces of unique information for the respective temperature detection resistor elements ER(m) provided in the corresponding partial temperature detection regions PA, and the external control device 100 reads out the pieces of unique information stored in the storage unit 50 to perform the temperature detection processing for the respective partial temperature detection regions PA in the temperature detection region SA in the temperature detection device 10. Increase in cost due to provision of the temperature detection function in the HUD device 1 can thereby be prevented.
The temperature detection device 10 according to the first embodiment can appropriately change and update the pieces of unique information stored in the storage unit 50 because the storage unit 50 configured by, for example, the non-volatile memory can be rewritten. Flexible approach such as rewriting of the pieces of unique information by the control device 100 can therefore be performed as described above when the pieces of unique information need to be changed or updated after shipping of the temperature detection device 10.
It is sufficient that the temperature detection device 10 according to the first embodiment supplies power supply to the input potential Vin, the non-volatile memory configuring the storage unit 50, and the like from the control device 100 when the temperature detection processing is performed. Power consumption can thus be reduced in comparison with that when a circuit corresponding to the control circuit 110 is mounted on a temperature detection device. The control circuit 110 can enhance accuracy of the necessary output potentials Vout(m) in the temperature detection processing by understanding the input potential Vin that is supplied from the power supply circuit 120.
The temperature detection device 10 according to the first embodiment includes no circuit corresponding to the control circuit 110 that performs the temperature detection processing. Accordingly, the temperature detection device 10 is not necessarily required when a temperature detection processing computer program is changed or updated, and the temperature detection processing computer program can be changed or updated only by the control device 100.
The temperature detection device 10 does not have to be provided in the HUD device 1. For example, the temperature detection device 10 may be provided so as to overlap with a display device in another mode, the temperature detection device 10 may be combined with a device other than the display device, or the temperature detection device 10 may be provided alone.
In a temperature detection device 10a according to the second embodiment illustrated in
The multiplexer 42 is a switch circuit configured to couple any one of the temperature detection resistor elements ER(m) and the control device 100. The multiplexer 42 selects the temperature detection resistor element ER(m) that is electrically coupled to the control device 100 among the temperature detection resistor elements ER(m). In the present embodiment, the multiplexer 42 is configured by a logic IC provided in the peripheral region GA of a sensor base member 20a. The multiplexer 42 selects the temperature detection resistor element ER(m) to be coupled to the control device 100 with a control signal that is output from the GPIO 89 of the control circuit 110 provided in the control device 100, for example. The temperature sensor SENS(m) illustrated in
Modification
The components in the above-mentioned embodiments can be appropriately combined. Other action effects provided by the modes described in the present embodiments that are obvious from description of the present specification or at which those skilled in the art can appropriately arrive should be interpreted to be provided by the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-001717 | Jan 2021 | JP | national |
