JP5078790B2 - Optical semiconductor device and mobile device - Google Patents

Description

  The present invention relates to an optical semiconductor device and a mobile device, and more particularly to an optical semiconductor device suitable for a mobile device such as a mobile phone.

  In recent years, as an optical semiconductor device, there is an illuminance sensor mounted on a mobile device with a screen typified by a mobile phone or the like to automatically adjust the brightness of the screen (for example, Japanese Patent Laid-Open No. 9-146073 (Patent Document). 1)). This is because liquid crystal panels with thin and light features are standardly used for mobile device screens, but the liquid crystal panel is designed to reduce the power consumption and keep the battery for a long time. The backlight in the back is always turned on, and the backlight is transmitted / blocked by liquid crystal. For this reason, in a dark room, even though the backlight is blocked by the liquid crystal, the leakage light cannot be ignored and the black color appears gray and the contrast ratio deteriorates. It is essential to install a sensor.

  In addition, the mobile phone has a screen with a touch panel function to improve the input human interface, but at the same time, the touch panel function detects human skin during a call, so there is a problem that the touch panel function malfunctions. Sensor to detect the skin (mainly cheeks) is needed. With such a touch panel function, an optical sensor can be realized, and an optical object detection sensor has been proposed (see, for example, Japanese Patent Laid-Open No. 62-85885 (Patent Document 2)).

  Such an object detection sensor and an illuminance sensor that measures the illuminance of ambient light are generally configured separately as shown in FIGS. 1 and 2, although they are both optical sensors.

  The object detection sensor shown in FIG. 1 includes a PD (photodiode) 101, amplifiers 102 and 103, a synchronization detection circuit 104, an oscillator 105, an LED driver unit 106, and an LED 107, and is emitted from the LED 107 and detected. The light reflected by the object 108 is received by the PD 101. The synchronization detection circuit 104 detects the presence or absence of the detected object 108 in synchronization with the light emission timing of the LED 107, and outputs the result as a detection signal.

  The illuminance sensor shown in FIG. 2 includes a PD 201, a PD 202, amplifiers 203 and 204, an operational amplifier 205, and an output circuit 206 that outputs an illuminance signal.

In a mobile device in which both the separately configured object detection sensor and illuminance sensor are mounted, the cost is high and the system configuration is complicated.
Japanese Patent Laid-Open No. 9-146073 JP-A-62-85885

  Accordingly, an object of the present invention is to provide an optical semiconductor device capable of performing object detection and ambient light illuminance measurement with a simple configuration, and to provide a mobile device capable of simplifying the system configuration by using the optical semiconductor device. It is to provide.

In order to solve the above problems, an optical semiconductor device of the present invention is
A light receiving element that converts the light reception signal into an electrical signal;
An amplifier circuit for amplifying an electric signal from the light receiving element;
An oscillator that outputs a clock signal;
A timing generation circuit that generates a timing signal based on the clock signal from the oscillator;
A light emitting element driving circuit that outputs a driving signal based on the timing signal from the timing generating circuit;
A light emitting element that emits an optical pulse based on the driving signal from the light emitting element driving circuit;
A signal processing circuit that performs signal processing on the output from the amplification circuit based on the timing signal from the timing generation circuit;
When there is a detection object in front of the light emitting element, the light pulse emitted from the light emitting element is reflected by the detection object and received by the light receiving element,
The signal processing circuit is
Based on the timing signal from the timing generation circuit and the output of the amplifier circuit, a light receiving signal synchronized with the light pulse emitted from the light emitting element is received by the light receiving element, and the light emitting element does not emit light. Sometimes when the light receiving signal is not received by the light receiving element, it is determined that the detected object is present, and a detection signal indicating the presence of the detected object is output.
The illuminance is measured based on the output from the amplifier circuit when the light emitting element does not emit light, and an illuminance signal is output.

  According to the optical semiconductor device having the above configuration, the detection of presence / absence of an object to be detected and the measurement of the illuminance of ambient light can be realized with one device with a simple configuration, and a small and inexpensive optical semiconductor device can be obtained without increasing the cost. Can be realized.

In the optical semiconductor device of one embodiment,
The timing generation circuit generates first, second, and third timing signals having different timings as the timing signal based on the clock signal from the oscillator,
The signal processing circuit is
Based on the first timing signal from the timing generation circuit and the output of the amplification circuit, the light receiving signal synchronized with the light pulse emitted from the light emitting element is received by the light receiving element, and the second , When no received signal is received by the light receiving element in the third timing signal, it is determined that the detected object is present, and a detection signal indicating the presence of the detected object is output.
The illuminance is measured based on the output from the amplifier circuit in the second and third timing signals.

  According to the above-described embodiment, based on the clock signal of the oscillator, the determination of the presence / absence of the detection object and the measurement of the illuminance of the ambient light are separately performed in a time division manner, so that the two operations do not overlap with each other. It becomes possible to output a detection signal and an illuminance signal of ambient light.

In the optical semiconductor device of one embodiment,
In the signal processing for detecting the detected object based on the first, second, and third timing signals, the signal processing circuit receives a reception signal of the light receiving element by the first timing signal, When the reception signal of the light receiving element is not received by the second and third timing signals, it is determined that the detected object is present when it is continuously repeated three times.

  According to the above embodiment, the reception signal of the light receiving element is received by the first timing signal, and the reception signal of the light receiving element is not received by the next second and third timing signals has occurred three times in succession. Sometimes, for the first time, by determining that there is an object to be detected, for example, even if fluorescent lamp noise is incident as disturbance light, it will not be erroneously detected unless the inverter frequency of the fluorescent lamp matches the frequency of the oscillator. In addition, noise resistance can be improved against spike noise that is suddenly input.

In the optical semiconductor device of one embodiment,
The light receiving element is a first light receiving element that converts a light receiving signal into an electric signal, and a second light receiving element that converts the light receiving signal into an electric signal with a spectral sensitivity characteristic different from that of the first light receiving element,
The amplifying circuit is a first amplifying circuit for amplifying an electric signal from the first light receiving element, and a second amplifying circuit for amplifying the electric signal from the second light receiving element,
The signal processing circuit is
Based on the timing signal from the timing generation circuit and the output of at least one of the first amplifier circuit or the second amplifier circuit, the presence or absence of the detection object is determined,
The illuminance is measured based on the difference between the output from the first amplifier circuit and the output from the second amplifier circuit.

  According to the above embodiment, the total spectral sensitivity is obtained by taking the difference between the outputs from the first and second amplifier circuits that amplify the electrical signals from the two first and second light receiving elements having different spectral sensitivity characteristics. Can be easily adjusted to human visibility, and illuminance corresponding to human visibility can be measured.

  In the optical semiconductor device of one embodiment, the signal processing circuit detects the distance to the detection object based on the outputs of the first and second amplifier circuits.

  According to the above embodiment, not only the presence / absence of the detection object can be determined, but also the distance to the detection object can be measured based on the received light intensity represented by the outputs of the first and second amplifier circuits, and the accuracy is higher. You can make measurements.

  In the optical semiconductor device of one embodiment, the signal processing circuit determines the presence or absence of the detection object based on a ratio of an output from the first amplifier circuit and an output from the second amplifier circuit.

  According to the above embodiment, the object to be detected is obtained by performing triangulation using the two first and second light receiving elements based on the ratio of the output from the first amplifier circuit and the output from the second amplifier circuit. The presence / absence of the detected object can be determined more accurately than the method of determining the presence / absence of the detected object based on the intensity of the reflected light from (which depends on the reflectance of the detected object).

  In the optical semiconductor device of one embodiment, the signal processing circuit measures the distance to the detection object based on the ratio of the output from the first amplifier circuit and the output from the second amplifier circuit.

  According to the above-described embodiment, the reflective object is obtained by performing triangulation using the two first and second light receiving elements based on the ratio of the output from the first amplifier circuit and the output from the second amplifier circuit. The distance to the detected object can be measured more accurately than the method of measuring the distance based on the light intensity from (which depends on the reflectance of the detected object).

  In one embodiment, the ratio of the output from the first amplifier circuit to the output from the second amplifier circuit is set based on the spectral sensitivity characteristics of the first light receiving element and the second light receiving element. to correct.

  According to the above embodiment, it is possible to perform distance measurement with high accuracy by correcting the difference in spectral sensitivity between the two first and second light receiving elements.

  In one embodiment, the light receiving element has a spectral sensitivity characteristic substantially equal to human visibility.

  According to the above embodiment, the optical system can be designed in the visible light region, and the visible light LED for illumination used in a mobile phone or the like can be shared with the light source, thereby reducing the cost. In addition, since a light-receiving element having a spectral sensitivity characteristic adapted to human visual sensitivity having no sensitivity in the infrared region can be mounted, the accuracy during illuminance measurement can be improved.

  In the optical semiconductor device of one embodiment, when the illuminance measured based on the output from the amplifier circuit when the light emitting element does not emit light is equal to or higher than a preset illuminance, The presence or absence of the detected object is not determined.

  According to the above embodiment, if the illuminance of the ambient light increases, the amplification circuit may be saturated, and the accuracy of object detection cannot be maintained. It is possible to prevent malfunctions by stopping the function of discriminating.

  In one embodiment, the light receiving element is a photodiode.

  According to the above embodiment, an inexpensive and highly accurate optical semiconductor device can be provided by configuring the light receiving element with a photodiode.

In the optical semiconductor device of one embodiment,
Has an external control terminal for function stop,
A power supply control circuit is provided to reduce current consumption to substantially zero when a function stop signal is input to the external control terminal.

  According to the above embodiment, when the function stop signal is input to the external control terminal, the power supply control circuit has the function stop (shutdown) function that makes the consumption current substantially zero, so that energy saving can be achieved by the function stop.

  The mobile device according to the present invention is characterized in that any one of the above optical semiconductor devices is mounted.

  According to the mobile device having the above configuration, the system configuration can be simplified by using the optical semiconductor device capable of performing object detection and ambient light illuminance measurement with a simple configuration.

In one embodiment of the mobile device,
A foldable body,
And a discriminator for discriminating whether the main body is folded or opened.

  According to the above-described embodiment, by determining whether the main body is folded or opened by the determination unit, the object detection and the ambient light illuminance measurement are performed using the optical semiconductor device only when the main body is open. Thus, unnecessary operation of the optical semiconductor device can be prevented with the main body folded.

  In one embodiment, the signal processing circuit of the optical semiconductor device does not measure illuminance when the detected object is detected.

  According to the above-described embodiment, when the signal processing circuit of the optical semiconductor device detects the detection object, the illuminance is not measured, and thus erroneous measurement of the illuminance due to the ambient light being blocked by the detection object can be prevented.

  As is apparent from the above, according to the optical semiconductor device and mobile device of the present invention, an optical semiconductor device capable of performing object detection and ambient light illuminance measurement with a simple configuration, and a system configuration simplified using the optical semiconductor device Mobile devices that can be realized.

  Hereinafter, an optical semiconductor device of the present invention will be described in detail with reference to embodiments shown in the drawings.

[First Embodiment]
FIG. 3 is a block diagram showing a specific configuration of the optical semiconductor device according to the first embodiment of the present invention.

  As shown in FIG. 3, the optical semiconductor device according to the first embodiment includes a first PD (photodiode) 301 as an example of a first light receiving element that converts a received light signal into an electrical signal, and converts the received light signal into an electrical signal. A second PD (photodiode) 304 as an example of a second light receiving element, a first amplifier 302 and a second amplifier 303 that amplify an electric signal from the first PD 301, and a second amplifying electric signal from the second PD 304. A third amplifier 305, a fourth amplifier 306, an oscillator 309 that outputs a clock signal, a timing generation circuit 308 that generates first to third timing signals based on the clock signal from the oscillator 309, and the timing generation circuit 308. An LED driver unit 310 that outputs a drive signal based on a first timing signal from the LED driver unit 310 and the LED driver unit 310 LED (Light Emitting Diode) 311 as an example of a light emitting element that emits a light pulse based on a drive signal from the first and third amplifiers based on first to third timing signals from the timing generation circuit 308 A signal processing circuit 307 that performs signal processing on the output from 303 and the output from the fourth amplifier 306 is provided.

  Further, the cathode of the LED 311 is connected to the collector of a transistor Q301 whose output is connected to the base and whose emitter is grounded. A power source Vcc is connected to the anode of the LED 311 via a resistor R301. The LED driver section 310, the transistor Q301, and the resistor R310 constitute a light emitting element driving circuit.

  In the optical semiconductor device, the first timing signal to the third timing signal are generated by the timing generation circuit 308 based on the clock signal from the oscillator 309. The first timing signal also serves as a drive signal for LED emission, and is input to the LED driver unit 310, and the LED 311 emits light according to the first timing signal. When the detection object 312 is in front of the LED 311, the light pulse output from the LED 311 is reflected by the detection object 312 and received by the first PD 301 and the second PD 304.

  In the present invention, the best mode of the light receiving element is a photodiode. This is because it is inexpensive and enables highly accurate measurement. If there is no object to be detected, the first PD 301 and the second PD 304 output a current proportional to the ambient light. Since the outputs from the first PD 301 and the second PD 304 in this case are weak signals, the signals are amplified in the first amplifier 302, the second amplifier 303, the third amplifier 305, and the fourth amplifier 306, respectively. The first amplifier 302 and the second amplifier 303 constitute a first amplifier circuit, and the third amplifier 305 and the fourth amplifier 306 constitute a second amplifier circuit.

  FIG. 4 shows a timing chart of the optical semiconductor device. As shown in FIG. 4, the timing generation circuit 308 processes the clock signal from the oscillator 309. The second timing signal and the third timing signal generated by the timing generation circuit 308 are used as sample hold (SH) timing for illuminance measurement and timing for preventing malfunction of object detection.

  4 (a) shows the presence or absence of the detection object 312, FIG. 4 (b) shows the clock signal, FIG. 4 (c) shows the first timing signal, FIG. 4 (d) shows the second timing signal, and FIG. 4 (f) is a light emission waveform, FIG. 4 (g) is a reception waveform of the first PD 301, FIG. 4 (h) is a reception waveform of the second PD 304, and FIG. 4 (i) is a detection signal. Represents the first PD_SH signal, FIG. 4 (k) represents the second PD_SH signal, and FIG. 4 (m) represents the illuminance signal.

(Object detection function)
First, the object detection function of the optical semiconductor device will be described.

  The presence or absence of the detection object 312 is determined by the signal processing circuit 307 based on whether the light pulse emitted from the LED 311 is reflected by the detection object 312 and detected by the first PD 301 or detected by the second PD 304. This object detection determination may be determined from the output of only the first PD 301 or only the second PD 304. Alternatively, the logical product of the outputs of the first PD 301 and the second PD 304 may be taken.

  The waveform after amplification by the first and second amplifiers 302 and 303 is shown in FIG. 4G as the reception waveform (first PD 301), and the waveform after amplification by the third and fourth amplifiers 305 and 306 of the second PD 304. The received waveform (second PD 304) is shown in FIG. Judgment of object detection in the signal processing circuit 307 determines whether there is a reception signal synchronized with the first timing signal and whether there is a reception signal synchronized with the second timing signal and the third timing signal. . The reason why the second timing signal and the third timing signal determine whether or not there is a synchronization signal is to prevent malfunction due to disturbance light noise other than signal light.

  In addition, the optical semiconductor device detects a detection object only when the reception signal is received by the first timing signal and the reception signal is not received by the next second and third timing signals for three consecutive times. It is desirable to add a function for determining the presence or absence of 312. In this case, for example, even if fluorescent lamp noise is incident as disturbance light, no erroneous detection is made unless the inverter frequency of the fluorescent lamp matches the frequency of the oscillator 309. In addition, noise resistance can be improved against spike noise that is suddenly input.

  Since the optical semiconductor device has a function of measuring the illuminance of ambient light described later, it is better to stop the object detection function when the illuminance exceeds a certain illuminance. This is because when the illuminance is high, the outputs of the first to fourth amplifiers 302, 303, 305, and 306 are saturated and the object cannot be detected.

  FIG. 5 shows an example of the PD (photodiode) light quantity with respect to the distance of the optical semiconductor device of the first embodiment. In FIG. 5, the horizontal axis represents the distance to the detected object (arbitrary scale), and the vertical axis represents the reflected light intensity (arbitrary scale).

  Based on the characteristics shown in FIG. 5, it is also possible to determine a threshold value with a certain amount of light and output a binary digital signal that is closer or farther than the distance corresponding to the light. Furthermore, the analog signal may be output as it is, and the approximate distance to the detected object may be measured. However, since the intensity of reflected light varies depending on the reflectance of the detected object, it is limited to applications that measure the approximate distance.

  Further, although depending on the configured optical system, normally, when the distance = 0, the output is 0 and the object cannot be detected. As shown in FIG. 5, there are two detection distances for one light intensity value on the vertical axis, and there is no unique distance measurement. Therefore, it is desirable that the short distance portion where the reflected light intensity peaks from the distance = 0 is the insensitive portion of the device, and the distance from the distance to the peak light amount is measured.

(Illuminance measurement function)
Next, the procedure for measuring the illuminance of ambient light will be described with reference to the spectral sensitivity characteristics of each PD in FIG. In FIG. 6, the horizontal axis represents the wavelength (arbitrary scale), and the vertical axis represents the relative intensity (arbitrary scale).

As shown in FIG. 6, the peak wavelengths of the spectral sensitivity characteristics of the first PD 301 and the second PD 304 are different from each other,
1st PD301-k × 2nd PD304 (where k is a constant)
Can be used to create a new spectral sensitivity characteristic different from the first PD 301 and the second PD 304 as shown by the dotted line in FIG. The illuminance can be measured by matching the sensitivity of the dotted line with the human visual sensitivity.

  Signal processing timing is signal processing synchronized with the second timing signal and the third timing signal in the timing chart of FIG. 4, and the first timing signal emitted from the LED 311 is divided in time. This is for measuring the illuminance of the ambient light with high accuracy and for avoiding interference between the self-luminous LED light and the ambient light.

  A waveform obtained by sampling and holding the received waveform (first PD 301) and the received waveform (second PD 304) of the output from the first PD 301 and the second PD 304 common to the time of object detection with the second timing signal and the third timing signal, respectively, is shown in FIG. The first PD_SH signal shown in i) and the second PD_SH signal shown in FIG. 4 (j). A signal representing the difference between the first PD_SH signal and the second PD_SH signal is an illuminance signal, which is an illuminance output suitable for human visual sensitivity.

  The illuminance signal is preferably sampled and held at the signal level obtained by the third timing signal until the next pulse of the third timing signal comes.

  According to the optical semiconductor device having the above configuration, the detection of the presence / absence of the detection object 312 and the measurement of the illuminance of the ambient light can be realized with one device with a simple configuration, and the optical semiconductor device is small and inexpensive without increasing the cost. Can be realized. Note that the light pulse emitted from the LED 311 is desirably infrared, and in this case, the first PD 301 and the second PD 304 have sensitivity characteristics in the infrared region.

  Further, by separately determining the presence / absence of the detection object 312 and measuring the illuminance of the ambient light based on the clock signal of the oscillator 309, the two operations do not overlap, and the object detection signal and An illuminance signal of ambient light can be output.

  Further, the electric signals from the two first PD 301 and the second PD 304 having different spectral sensitivity characteristics are amplified, and the spectral sensitivity is changed by the difference in output from the first and second amplifier circuits (302, 303, 305, 306). It becomes possible to easily adjust to the visibility, and the illuminance corresponding to the human visibility can be measured.

  The signal processing circuit 307 detects the light pulse emitted from the LED 311 based on the outputs of the first and second amplifier circuits (302, 303, 305, 306) representing the received light signal reflected from the detection object 312. By detecting the distance to the object 312, not only the presence / absence of the object to be detected 312 but also the object to be detected by the received light intensity represented by the outputs of the first and second amplifier circuits (302, 303, 305, 306). The distance up to 312 can be measured, and more accurate measurement can be performed.

  Further, if the illuminance of the ambient light increases, the first and second amplifier circuits (302, 303, 305, 306) may be saturated, and the accuracy of object detection cannot be maintained. In such a case, by stopping the function of determining the presence or absence of the detected object 312, it is possible to prevent malfunction.

  In the normal usage method, when detecting an object 312, it is considered that ambient light is blocked by the detection object 312, although it depends on the size of the detection object 312. It is preferable to stop the illuminance measurement function.

  In addition, when the optical semiconductor device is not used by providing a semiconductor switch between the amplifier and the power supply, between the LED driver unit and the power supply, and when the optical semiconductor device is not used, By inputting a function stop signal, it is desirable that the semiconductor switch is turned off by a power supply control circuit (not shown) to enter a standby mode in which almost no current consumption flows during function stop (shutdown).

[Second Embodiment]
FIG. 7 shows a configuration of an optical semiconductor device according to the second embodiment of the present invention.

  As shown in FIG. 7, the optical semiconductor device of the second embodiment includes an LED 311, a first PD 301, a second PD 304, a transparent resin mold part 700 that covers the LED 311, the first PD 301, and the second PD 304, and a signal processing part 703. ing. In the first PD 301 and the second PD 304, the first PD 301 is arranged at a predetermined interval in a direction substantially perpendicular to the emitting direction of the LED 311. Further, the second PD 304 is arranged outside the first PD 301. A light shielding part 702 is disposed between the LED 311 and the first PD 301.

  The transparent resin mold part 700 includes a lens part 700a that condenses the light emitted from the LED 311 and a lens that condenses the reflected light reflected by the detection object 701 on the light receiving surfaces of the first PD 301 and the second PD 304. Part 700b.

  The circuit configuration of this optical semiconductor device is the same as the circuit configuration shown in the block diagram of FIG. 3 of the first embodiment, the operation timing is as shown in FIG. 4, and FIGS. Here, a different part from 1st Embodiment is demonstrated.

  In the second embodiment, since triangulation is performed, the arrangement of the first PD 301 and the second PD 304 is important. FIG. 7 shows an example of this. When the detected object 701 is close, the amount of reflected light from the detected object 701 is larger in the second PD 304 than in the first PD 301. On the other hand, when the distance of the detection object 701 is far, the amount of reflected light from the detection object 701 is larger in the first PD 301 than in the second PD 304. The signal output is the ratio of the light amount of the first PD 301 to the total light amount of the first PD 301 + the second PD 304, and FIG. 8 is a plot of this by distance. 8, the horizontal axis represents the distance (arbitrary scale) to the detected object, and the vertical axis represents the first PD301 / (first PD301 + second PD304) output (arbitrary scale) (in FIG. 8, PD1 / (PD1 + PD2) output. Indicated by).

  By outputting the output of the first PD 301 / (first PD 301 + second PD 304) as an analog signal, the distance of the detected object 701 can be uniquely measured. Further, in the application for simply determining the presence or absence of the detected object 701, a desired threshold value is determined for the output of the first PD 301 / (first PD 301 + second PD 304), and it is determined whether or not there is an object near or far from that distance. it can.

  However, also in the second embodiment, since the illuminance of ambient light is measured as in the first embodiment, the spectral sensitivities of the first PD 301 and the second PD 304 are different. In the distance measurement by triangulation, the ratio of the first PD301 / (first PD301 + second PD304) becomes important, so it is important to correct the difference in spectral sensitivity between the first PD301 and the second PD304. FIG. 8 shows the output of the first PD 301 (first PD 301 + second PD 304) as a result of this correction.

  The optical semiconductor device of the second embodiment has the same effect as the optical semiconductor device of the first embodiment.

  Further, by performing triangulation using the two first PD 301 and the second PD 304 based on the ratio of the output from the first amplifier circuit (302, 303) and the output from the second amplifier circuit (305, 306). The presence / absence of the detected object 701 can be determined more accurately than the method of determining the presence / absence of the detected object 701 based on the intensity of reflected light from the detected object 701 (which depends on the reflectance of the detected object).

  Further, by performing triangulation using the two first PD 301 and the second PD 304 based on the ratio of the output from the first amplifier circuit (302, 303) and the output from the second amplifier circuit (305, 306). The distance to the detection object 701 can be measured more accurately than the method of measuring the distance based on the light intensity from the reflection object 701 (which depends on the reflectance of the detection object).

  Further, by correcting the difference in spectral sensitivity between the two first PD 301 and the second PD 304, it is possible to perform distance measurement with high accuracy.

[Third Embodiment]
FIG. 9 is a block diagram showing a specific configuration of the optical semiconductor device according to the third embodiment of the present invention.

  As shown in FIG. 9, the optical semiconductor device of the third embodiment includes a PD 901 as an example of a light receiving element that converts a received light signal into an electrical signal, an amplifier 902 and an amplifier 903 that amplify the electrical signal from the PD 901, An oscillator 906 that outputs a clock signal, a timing generation circuit 905 that generates a timing signal based on the clock signal from the oscillator 906, and an LED driver that outputs a drive signal based on the timing signal from the timing generation circuit 905 Unit 907, LED 908 as an example of a light emitting element that emits a light pulse based on a drive signal from LED driver unit 907, and an output from amplifier 903 based on a timing signal from timing generation circuit 905 And a signal processing circuit 904 for processing. The amplifier 902 and the amplifier 903 constitute an amplifier circuit.

  The cathode of the LED 908 is connected to the collector of the transistor Q901 whose output is connected to the base and whose emitter is grounded. A power source Vcc is connected to the anode of the LED 908 via a resistor R901. The LED driver portion 907, the transistor Q901, and the resistor R901 constitute a light emitting element driving circuit.

  The optical semiconductor device of the third embodiment performs the measurement of the first embodiment in the visible light region. Therefore, the spectral sensitivity of the PD 901 has a sensitivity equivalent to human visual sensitivity (dotted line in FIG. 6). The LED 908 is preferably a white LED. In the third embodiment, since the signal processing of the second PD 304 and the third timing signal in the first embodiment can be omitted, the signal processing portion can be simplified. However, a photodiode having a spectral sensitivity of visibility is usually costly because an optical filter is deposited on the photodiode or a physical material having a band gap in visibility is used.

  Further, since the PD 901 has a spectral sensitivity characteristic equal to human visual sensitivity, the optical system can be designed in the visible light region, and the visible light LED for illumination used in a mobile phone or the like can be shared with the light source, thereby reducing the cost. Can be achieved. In addition, since a light-receiving element having a spectral sensitivity characteristic adapted to human visual sensitivity having no sensitivity in the infrared region can be mounted, the accuracy during illuminance measurement can be improved.

[Fourth Embodiment]
The optical semiconductor device of the present invention is preferably mounted on a mobile phone.

  FIG. 10 is a diagram showing a mobile phone 1 as an example of a mobile device in which the optical semiconductor device 2 of the present invention is mounted, and FIG. 11 is a schematic block diagram showing the configuration of the mobile phone 1.

  10 and 11 includes an optical semiconductor device 2 and a control device 3 that receives the illuminance signal and the detection signal (proximity information) from the optical semiconductor device 2 and controls the main body of the mobile phone 1. ing.

  By mounting the optical semiconductor device 2 on the mobile phone 1, the brightness of the screen of the mobile phone 1 can be automatically adjusted by the illuminance of ambient light. Further, when the operator is on a call, sensing the operator's skin (cheek, ear, etc.) as a detected object can stop the touch panel function of the screen and turn off the backlight of the screen.

  In recent years, foldable mobile phones have circulated as mobile phones, but by using the optical semiconductor device of the present invention, the mobile phone can be folded by proximity information or distance information and illuminance information of a detected object. It can be determined whether it is folded or not folded. For example, when the detected object is detected and the illuminance is 10 lux or less, it can be determined that the mobile phone is folded. With the optical semiconductor device of the present invention, it is possible to determine whether or not a foldable mobile phone is folded, thereby reducing the number of discriminators currently used with mechanical switches, reducing the number of parts, and realizing an inexpensive mobile phone I can do it.

  In addition, in a mobile phone provided with a determination unit that determines whether the main body is folded or opened, the optical semiconductor device of the present invention is used to perform object detection and ambient light illuminance measurement only when the main body is open. This makes it possible to prevent unnecessary operation of the optical semiconductor device when the main body is folded.

  In the first to fourth embodiments, the photodiode is used as the light receiving element. However, the present invention is not limited to this, and a phototransistor or another light receiving element may be used.

  Although specific embodiments of the present invention have been described, the present invention is not limited to the first to fourth embodiments, and various modifications can be made within the scope of the present invention.

FIG. 1 is a block diagram schematically showing a conventional object detection sensor. FIG. 2 is a block diagram schematically showing a conventional illuminance sensor. FIG. 3 is a block diagram showing the optical semiconductor device according to the first embodiment of the present invention. FIG. 4 is a diagram showing signal processing timing of the optical semiconductor device. FIG. 5 is a diagram showing the distance characteristics of the light amount of the light receiving element of the optical semiconductor device. FIG. 6 is a diagram showing the spectral sensitivity of the light receiving element of the optical semiconductor device. FIG. 7 is a block diagram showing an optical semiconductor device according to the second embodiment of the present invention. FIG. 8 is a view showing an output form of the optical semiconductor device. FIG. 9 is a block diagram showing an optical semiconductor device according to the third embodiment of the present invention. FIG. 10 is a diagram showing a mobile phone on which the optical semiconductor device according to the fourth embodiment of the present invention is mounted. FIG. 11 is a schematic block diagram showing the configuration of the mobile phone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mobile phone 2 ... Optical semiconductor device 3 ... Control apparatus 301 ... 1st PD
302 ... 1st amplifier 303 ... 2nd amplifier 304 ... 2nd PD
305 ... 3rd amplifier 306 ... 4th amplifier 307 ... signal processing circuit 308 ... timing generation circuit 309 ... oscillator 310 ... LED driver part 311 ... LED
312 ... Detection object 700 ... Transparent resin mold part 701 ... Detection object 702 ... Light shielding part 703 ... Signal processing part 901 ... PD
902 ... Amplifier 903 ... Amplifier 904 ... Signal processing circuit 905 ... Timing generation circuit 906 ... Oscillator 907 ... LED driver unit 908 ... LED

Claims (15)

A light receiving element that converts the light reception signal into an electrical signal;
An amplifier circuit for amplifying an electric signal from the light receiving element;
An oscillator that outputs a clock signal;
A timing generation circuit that generates a timing signal based on the clock signal from the oscillator;
A light emitting element driving circuit that outputs a driving signal based on the timing signal from the timing generating circuit;
A light emitting element that emits an optical pulse based on the driving signal from the light emitting element driving circuit;
A signal processing circuit that performs signal processing on the output from the amplification circuit based on the timing signal from the timing generation circuit;
When there is a detection object in front of the light emitting element, the light pulse emitted from the light emitting element is reflected by the detection object and received by the light receiving element,
The signal processing circuit is
Based on the timing signal from the timing generation circuit and the output of the amplifier circuit, a light receiving signal synchronized with the light pulse emitted from the light emitting element is received by the light receiving element, and the light emitting element does not emit light. Sometimes when the light receiving signal is not received by the light receiving element, it is determined that the detected object is present, and a detection signal indicating the presence of the detected object is output.
An optical semiconductor device that measures illuminance and outputs an illuminance signal based on an output from the amplifier circuit when the light emitting element does not emit light. The optical semiconductor device according to claim 1,
The timing generation circuit generates first, second, and third timing signals having different timings as the timing signal based on the clock signal from the oscillator,
The signal processing circuit is
Based on the first timing signal from the timing generation circuit and the output of the amplification circuit, the light receiving signal synchronized with the light pulse emitted from the light emitting element is received by the light receiving element, and the second , When no received signal is received by the light receiving element in the third timing signal, it is determined that the detected object is present, and a detection signal indicating the presence of the detected object is output.
An optical semiconductor device, wherein the illuminance is measured based on outputs from the amplifier circuit in the second and third timing signals. The optical semiconductor device according to claim 1 or 2,
In the signal processing for detecting the detected object based on the first, second, and third timing signals, the signal processing circuit receives a reception signal of the light receiving element by the first timing signal, An optical semiconductor device characterized in that it is determined that the detected object is present when the reception signal of the light receiving element is not received by the second and third timing signals when it is continuously repeated three times. In the optical semiconductor device according to any one of claims 1 to 3,
The light receiving element is a first light receiving element that converts a light receiving signal into an electric signal, and a second light receiving element that converts the light receiving signal into an electric signal with a spectral sensitivity characteristic different from that of the first light receiving element,
The amplifying circuit is a first amplifying circuit for amplifying an electric signal from the first light receiving element, and a second amplifying circuit for amplifying the electric signal from the second light receiving element,
The signal processing circuit is
Based on the timing signal from the timing generation circuit and the output of at least one of the first amplifier circuit or the second amplifier circuit, the presence or absence of the detection object is determined,
An optical semiconductor device, wherein the illuminance is measured based on a difference between an output from the first amplifier circuit and an output from the second amplifier circuit. The optical semiconductor device according to claim 4,
The signal processing circuit detects a distance to the detection object based on outputs of the first and second amplifier circuits. The optical semiconductor device according to claim 4 or 5,
The optical semiconductor device, wherein the signal processing circuit determines the presence or absence of the detection object based on a ratio of an output from the first amplifier circuit and an output from the second amplifier circuit. In the optical semiconductor device according to any one of claims 4 to 6,
The optical signal semiconductor device according to claim 1, wherein the signal processing circuit measures a distance to the detection object based on a ratio of an output from the first amplifier circuit and an output from the second amplifier circuit. The optical semiconductor device according to claim 7,
An optical semiconductor device, wherein a ratio between an output from the first amplifier circuit and an output from the second amplifier circuit is corrected based on spectral sensitivity characteristics of the first light receiving element and the second light receiving element. In the optical semiconductor device according to any one of claims 1 to 3,
The optical semiconductor device, wherein the light receiving element has a spectral sensitivity characteristic substantially equal to human visibility. The optical semiconductor device according to any one of claims 1 to 9,
The signal processing circuit does not determine the presence or absence of the detected object when the illuminance measured based on the output from the amplifier circuit when the light emitting element does not emit light is equal to or higher than a preset illuminance. An optical semiconductor device. In the optical semiconductor device according to any one of claims 1 to 10,
An optical semiconductor device, wherein the light receiving element is a photodiode. In the optical semiconductor device according to any one of claims 1 to 11,
Has an external control terminal for function stop,
An optical semiconductor device comprising: a power supply control circuit for reducing current consumption to substantially zero when a function stop signal is input to the external control terminal.   A mobile device comprising the optical semiconductor device according to any one of claims 1 to 12. The mobile device according to claim 13.
A foldable body,
A mobile device comprising: a determination unit that determines whether the main body is folded or opened. The mobile device according to claim 13 or 14,
The mobile device, wherein the signal processing circuit of the optical semiconductor device does not measure illuminance when the detected object is detected.

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