MXPA98004344A - Proximity and ambient light monitor - Google Patents

Abstract

A proximity detector and ambient light monitor (PALM) is provided, comprising a light source for generating an optical composite signal, a light detector for providing a detected signal, a circuit for separating the ac component from the detected signal, and a switch for providing a control signal when the ac component is outside a preset range. The PALM further comprises an ambient light detector which also receives the detected signal and provides an ambient light level signal. The ambient light detection circuit rejects the signals that relate to the proximity monitoring and provides sufficient gain to overcome dayligtht filtering lens currently provided on the light detectors. The ambient light monitoring circuit provides either a continuous varying voltage proportional to the ambient light, or a simple binary signal indicating that the light is above a threshold.

Description

PROXIMITY MONITOR AND ENVIRONMENTAL LIGHT FIELD OF THE INVENTION This invention is directed to a non-proximity and ambient light monitor (PALM) and, in particular, to a PALM for a personal communication terminal.

BACKGROUND OF THE TECHNIQUE The modern personal communication terminals are designed to support a plurality of services, such as voice mail, answering services, etc. The personal communication terminals have a receiver, a transmitter, a dial pad and, in many cases, a screen. When the terminal is used in speaker or hands-free mode, the broadcasting capability allows the user to see and interact with the screen, while there is an active call, and also allows a plurality of listeners or listeners to receive the call. same communication. In the conventional receiver or receiver mode, the terminal is held against the user's ear. In general, the selection between the receiver and speaker modes is made manually by using a switch provided in the terminal. In some P1222 / 98MX cases, a terminal with a proximity detector is provided to determine the mode of use in accordance with the presence or absence of a human body or object in the vicinity of the receiver. The signal of the proximity detector is then used to switch between the speaker and handset operating modes, in accordance with the above, by increasing or decreasing the volume of the speaker, to turn on / off the screen, etc. The proximity detector / user activated switches are also used in conjunction with the automatic water supply systems. Thus, U.S. Patent No. 4,735,357 (Gregory et al., Issued April 5, 1988) presents a water tap or faucet with an automatic control system that dispenses water upon detection of a hand or object. near the exit of the peak or mouth, using infrared light .. It is also known to use an ambient light to control if the environment is sufficiently dark. to ensure the use of backlighting of the screen. U.S. Patent No. 5224,151 (Bowen et al., Granted on June 29, 1993 and assigned to AT &T Bell Laboratories) features a headset with an infrared proximity detector activated when the distance between the receiver and the user's ear is less P1222 / 98MX of a preset or specified value, in which the operation of the terminal will switch between the speaker mode and the receiver mode. The terminal disclosed in this patent comprises two infrared emission devices arranged or arranged in a spatial relationship. The light is generated by each LED in alternate periods and is then focused by an associated lens. The light emitted by the first LED is directed outward and is modulated at a rf frequency to produce a pulsed infrared output that is easily distinguishable from any incidental background light by a distance measurement circuit. The reflected light of the user is focused by another lens and is detected by a photodiode, which also receives direct light from the second LED. The second LED is used to check the operability of the handset's travel function to prevent operation of the portable communication device in the speaker mode when one of the infrared LEDs or the detector fails. However, the circuit presented in the previous US Patent is complex, requires the use of a microcomputer provided with wired microprogramming and also uses a complex light emission scheme, which requires a complicated physical placement of the IR components. This results in P1222 / 98MX a great power consumption, in inherent faults in wired microprogramming and slow decision times. There is a need to equip a personal communication terminal with a PALM to provide a fast, reliable and accurate switching activated by proximity between speaker and receiver receiver operation modes and power or energy savings by means of an intelligent Control of backlighting of the screen.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a PALM that totally or partially overcomes the disadvantages of the circuits of the prior art. It is another object of the invention to provide a personal communication terminal with a PALM that automatically switches or switches the mode of operation of the terminal between the horn mode and the receiver mode in response to a movement of the terminal towards the user. Another object of the invention is to provide a PALM that uses a photodiode simultaneously in two modes, namely, in a proximity detection mode and in a detection mode. Ambient light, where the ambient light detection mode provides intelligent control of the backlighting of the screen. The P1222 / 98MX part of the circuit proximity detector is capacitively coupled to the detector and the ambient light monitor is resistively coupled to the detector. In accordance with one aspect of the invention, a proximity and ambient light monitor (PALM) is provided which comprises a light emission means for generating a composite optical signal; a light detecting means for receiving a fraction of the composite optical signal and providing a detected signal; a means for separating an ac component from the detected signal, the ac component represents a fraction of the composite optical signal; and a switching means for providing a control signal when the ac component is outside a predetermined range. In accordance with another aspect of the invention, there is provided a method for detecting the proximity and intensity of ambient light, comprising the steps of generating a composite optical signal; receiving a fraction of the composite optical signal and providing a detected signal; separating an ac component from the detected signal, the ac component represents a fraction of the composite optical signal; and providing a control signal when the ac component is outside a predetermined range. An advantage of the present invention is that it uses a simple independent design that provides the P1222 / 98MX required reliability at a low cost. The proximity detector section of the device requires only an infrared (IR) emitter, reducing complexity, failure modes, power consumption and cost. The involvement of a microcontroller is not required and, therefore, there is no development of wired microprogramming nor failures or problems inherent to wired microprogramming that lead to a safer operation. Thus, the decision of the circuit not to use CPU in real time is implemented in the hardware for a quick response and does not depend on software for decision making. A gradual audio ramping can be obtained for the transition between the two modes of operation, instead of hard or physical switching. The measurement of the integrated ambient light without an additional IR photodiode saves parts and allows integration of ambient and proximity light functions in the same circuit. With the addition of simple logic gates, a backlight for the screen can be controlled. to be activated only when the room is dimly illuminated and the user's head is not near the telephone. In a preferred embodiment of the invention, the personal communication device is a telephone headset, such as a portable wireless terminal of P1222 / 98MX a personal communication system.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing objects as well as other objects, particularities and advantages of the invention will be apparent from the following more particular description of the preferred embodiments, as illustrated in the accompanying drawings, in which: Figure IA illustrates a block diagram of the proximity light detector according to the invention; Figure IB is a block diagram of a mode of the control signal generator of Figure IA; Figure IC is a block diagram of another embodiment of the control signal generator of Figure IA; Figure 2 is a block diagram of the environmental light monitor circuit; Figure 3 is a schematic circuit of the PALM; and Figure 4 generally illustrates an earphone with the PALM according to the invention.

DESCRIPTION OF THE PREFERRED MODE P1222 / 98MX Figure 1 illustrates the block diagram of a proximity detector in accordance with an exemplary embodiment of the invention. A frequency generator 10 provides a compound pulse signal of high and low frequencies. The combination that will be used preferably is of the order of 40 kHz to 90 Hz. Also a 32 kHz and 128 Hz implementation can take advantage of frequent circuits in the specific application integrated circuit (ASIC) present in the terminal. An infrared light emitting diode (LED) 12 is reverse polarized with the anode connected to a series resistor 14 and the collector connected to ground. The composite signal is applied to the LED 12, which emits a composite optical signal corresponding to the composite electrical signal. The benefit of a composite signal of high frequency and high frequency is that the LED 12 is not transmitting continuously. With a gate frequency component of around 100 Hz and in a microsecond time, the 40 kHz burst is transmitted. rarely (approximately 10 ms), saving energy and extending the life of the LED. The composite optical signal is detected by the photodiode 16 and converted into a detected signal 17. The LED 12 and the photodiode 16 are positioned in such a way that the optical signal emitted by the LED 12 reaches the photodiode 16.

P1222 / 98MX only if it is reflected by an obstacle in the path of the light. This obstacle is, for example, the head of a telephone user when the terminal is a handset. In this way, a mode switch is obtained, which recognizes the location of the earphone close to or remote from the ear or ear of the user. A capacitor 18 separates the AC and DC components from the detected composite signal. In this way, the component AC, proportional to the fraction reflected from the composite signal generated by the generator 10, passes through the capacitor 18, while the DC component, produced mainly by the ambient light, is rejected in the path to through a monitor 2 of ambient light. The AC component is applied to a filter 20 to eliminate the signals below the low frequency, which includes the AC signal received from the electric lights. The filtered signal is amplified by a simple gain stage 22 and input to a phase switch 24. The phase switch 24 is a simple analog switch that is activated by the composite signal generated by the frequency generator 10. This eliminates the effects of random AC noise, since the noise will not be in phase with the periodic composite signal and, also, effectively rectifies the AC component. The output of the phase switch 24 is integrated P1222 / 98MX to provide a variable voltage level, which is indicative of the amount of reflected IR light. The integrator 26 can be a conventional integrator RC circuit. The voltage level 27 obtained at the output of the integrator 26 is applied to a control signal generator 28 which evaluates the magnitude of the voltage of the signal 27 and generates a control signal 29 used to control the audio level selector (not shown). The control signal 29 can be used, for example, to adjust the gain of an audio amplifier. When a significant fraction of the composite optical signal is reflected to the photodiode 16, the AC component is high and, accordingly, the audio level controller will decrease the volume of the loudspeakers. This occurs when the headset is near the ear or ear of the user. Alternatively, only when a small fraction of the composite optical signal is detected by the photodiode 16, the AC component is low, the step 28 will increase the volume of the auto speakers in the mode. hands-free (of horn). Here two options for the control signal generator 28 are disclosed and are illustrated in Figures IB and IC, respectively. Figure IB shows a window comparator 30 that emits two signals 32 and 34. The signal 32 is the result of a comparison of the voltage level 27 received from P1222 / 98MX the integrator 26 with a low voltage applied to the input 33; the signal 34 is the result of a voltage level comparison 27 with a high voltage applied to the input 35. An AND (Y) circuit 36 provides an output that effectively indicates the time at which the voltage level is greatest that the low voltage y, is less than the high voltage. This resulting condition allows the audio circuit to produce a high level of hands-free sound that would cause pain or injury if it were transmitted directly to a person's ear. As it approaches the detector it provides a larger reflected fraction and, thus, a higher level of voltage 27 at the output of the integrator 26. In this case, the voltage level becomes higher than the high voltage and ends or terminates the condition AND (Y). As indicated above, the sound level is adjusted and the hands-free operation mode is operational. A broken light emitting element or a broken detector element causes the voltage level to be less than. the low voltage, ending again with the AND (Y) condition and ending the hands-free mode of operation. The AND (Y) 36 logic function and the frequency generator 10 are generally available in most ASIC devices. Figure 1C shows another variant of the generator P1222 / 98MX 28 control signal, based on a frequency converter (V / F) 38. The output of the V / F converter 38 is a pulse current of a speed proportional to the magnitude of the voltage level obtained at the output of the integrator 26. A counter 40 evaluates the speed of the pulses that is applied to a numerical numerator 42. The numerical comparator 42 receives a low voltage at the input 26 and a high voltage at the input 35 and determines the conditions described in connection with the modality of Figure IB. The functions of the counter and the numerical comparison are circuits normally simple to implement in ASIC devices. In the presence of a microprocessor or an appropriate ASIC, the comparison can be made using software or wired thresholds. The added benefit of this approach is that a graduated signal is available at the output of the level 28 controller, to dampen the audio level in a descending or ascending manner as desired for a more pleasing change in volume. Figure 2 is a block diagram of the ambient light monitor circuit illustrated in Figure IA and referred to 2. The ambient light detector requires two particularities and provides an additional feature that allows for additional modes of use. He P1222 / 98MX ambient light monitor circuit should reject signals that are related to the proximity detector and should also provide sufficient gain to overcome the daylight filtering lenses generally provided in the photodiode 16. The additional feature mentioned above is the supply or provision of the ability of the circuit to provide either a voltage of continuous variation proportional to the ambient light around the photodiode PIN or a binary signal that simply indicates that the light level is above a certain level, as selects by means of a voltage divider in the reference ground of an operational amplifier or a comparator device. The ambient light monitor 2 receives the detected signal 17, which comprises both the AC component and the DC. This signal is filtered with a simple RC filter 44 that has a cutoff frequency f = RC. The values of R and C are selected in such a way that frequencies of 50 Hz or greater are attenuated. This filter effectively eliminates the noise of the lights with AC energization and the signals that will be received by the photodiode 16 for the purposes of detecting proximity. The filtered signal is then amplified in the amplifier 46 to provide sufficient gain to provide a variable voltage signal P1222 / 98MX provide the brightness of ambient light incident on the photodiode 16 and that is not filtered by any daylight filtering or lens that may or may not be provided in the photodiode 16. A typical gain level is 30x to 50x. The gain stage 46 is preferably a simple non-inverting operational amplifier. The amplified signal is supplied to a comparator 48 together with a reference value representing the voltage that must be exceeded in order for the comparator to produce a high output. The transition from low to high at the output of comparator 48 can be used as a criterion for decision making by other circuits. For example, a liquid crystal display (LCD) with backlighting can be turned on / off using this signal. The comparator 48 can be an operational amplifier used in a comparator configuration. The reference value will then be a fixed voltage with a divider circuit. simple resistor. When the filter 44 is used to eliminate only the pulses related to the proximity detector, but which retains the rest of the light signal AC and, the reference value is selected appropriately, the level of ambient light emitted by the P1222 / 98 X comparator 48 will indicate whether the user is indoors or outdoors. The level of the ambient light can then be used with a microcomputer to further decide whether a radio-cellular connection protocol is used for a call as opposed to a wireless local-area indoor protocol, which could be less expensive if this dual mode or multi-modal phone was in use. Figure 3 is an electrical diagram of the PALM, showing the preferred embodiment of several blocks. In addition, by simply adding resistors to provide positive feedback to the appropriate amplifiers, more stable receiver and transmitter modes can be obtained. This will avoid the case in which the user holds the unit at a threshold distance where the screen is unstable and blinks or oscillates between the states. This particularity of hysteresis can be provided both in the proximity detector and in the ambient light monitor. Figure 4 illustrates a headset in general 50 representative of a portable wireless terminal of a personal communication system equipped with the PALM according to the invention. The handset in Figure 1 is only to illustrate the elements that may be present in these terminals and is not intended to limit P1222 / 98MX the scope of the invention. The handset generally includes a transmitting unit or microphone 52, a receiving unit 54 and a numeric keypad 56. Also shown are the antenna 58 and the display or display area 60, used to display or display the called numbers, messages , etc. In a preferred embodiment, the display area 60 is a backlit liquid crystal display that is activated by the PALM. It is shown that the PALM 1 is close to the receiver 54. However, the location of the PALM 1 in the earphone is not critical, while the position of the earphone within a predetermined distance of the ear or ear of the user results in the switching of the handset. terminal 50 from horn mode to receiver mode. As seen in Figure 4, the light emitting diode 12 and the infrared detector 16 are placed in the area where the ear or ear of the user is placed for use in the receiver mode. In a preferred embodiment, the infrared transmitter 12 is a GaAS light emitting diode and the infrared detector 16 is a Si photodiode. Other possible options to implement the PALM can be considered, as long as the elements satisfy certain practical considerations such as: the detector detects the proximity of the user's head and responds quickly enough to switch to the P1222 / 98MX receiver mode before the headset gets too close to the ear or ear of the user; the IR emitter and the detector in combination with the associated circuitry can be accommodated or housed within a small telephone handset; and the PALM is sufficiently economic so that it does not add significantly to the cost of the terminal. It is desirable to configure the IR emitter / detector pair to detect the presence of the user's ear or ear at approximately 25 cm. This is sufficient to provide an adjustable detection range up to 5 cm which is a reasonably safe range. It is also assumed that the emitter does not operate in a way by which the beam possesses any security threat to the skin, eyes or ear of the handset user. While the invention has been described with reference to particular exemplary embodiments, further modifications and improvements that will occur to those skilled in the art may be made within. of the scope of the appended claims without departing from the scope of the invention in its broadest aspect.

P1222 / 98MX

Claims (20)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. A proximity and ambient light monitor comprising: a light emitting medium to generate a composite optical signal; a light detecting means for receiving a fraction of the composite optical signal and providing a detected signal; means for separating an ac component from the detected signal; and a switching means for providing a control signal when the ac component is outside a predetermined range.
2. 2. A proximity and ambient light monitor according to claim 1, further comprising a detector. of ambient light to receive the detected signal and provide a level signal of ambient light.
3. 3. A proximity and ambient light monitor according to claim 1, wherein the light emitting means comprises: a frequency generator for generating a signal P1222 / 98MX composite; and a light emitting diode (LED) to receive the composite signal and produce the composite optical signal.
4. 4. A proximity and ambient light monitor according to claim 3, wherein the composite signal comprises a high frequency pulse signal modulated with a low frequency pulse signal.
5. 5. A proximity and ambient light monitor according to claim 1, wherein the light detecting means comprises a photodiode.
6. 6. A proximity and ambient light monitor according to claim 5, wherein the photodiode is connected to the anode to receive the composite signal through a resistor to ground and with the cathode toward a positive bias voltage.
7. 7. A proximity and ambient light monitor according to claim 1, wherein the means for separation comprises: a capacitor connected to the detector means of. light to pass through to the ac component; and a filter connected in series with the capacitor to block the harmonic of the ac component having a frequency lower than the low frequency to provide a filtered ac signal.
8. 8. A proximity and ambient light monitor P1222 / 98 X according to claim 9, wherein the switching means comprises: an ac / dc converter to obtain a voltage level representative of the intensity of the fraction of the composite optical signal; and a generator of the control signal for comparing the voltage level with the predetermined interval and generating the control signal.
9. 9. A proximity and ambient light monitor according to claim 8, wherein the ac / dc converter comprises: a phase switch for receiving the filtered ac signal and the composite signal, which rectifies the filtered ac signal and provides a rectified signal; an integrator to integrate the rectified voltage to produce at the voltage level.
10. A proximity and ambient light monitor according to claim 8, wherein the control signal generator comprises: an advantage comparator for receiving the voltage level and the predetermined range consisting of a minimum threshold and a maximum threshold, which compares the voltage level with the minimum threshold and with the maximum threshold and, in accordance with the above, provides a low and a high level; P1222 / 98MX a logical AND (Y) means to receive the low level and the high level and provide the control signal.
11. 11. A proximity and ambient light monitor according to claim 8, wherein the generator of the control signal comprises: a voltage converter at a frequency to receive the voltage level and provide a pulse signal of a frequency proportional to the level of voltage; a counter to receive the impulse signal and provide an impulse count; and a numerical comparator for receiving the pulse count and the predetermined interval consisting of a minimum threshold and a maximum threshold, which compares the pulse tip with the minimum threshold and with the maximum threshold and generates the control signal.
12. 12. A proximity and ambient light monitor according to claim 8, wherein the control signal generator comprises: a voltage / frequency converter for receiving the voltage level and providing a pulse signal of a frequency proportional to the level of voltage; a counter for providing an impulse count for the impulse signal; and a means to process the impulse count and generate the control signal, the control signal has a P1222 / 98MX ramp variation.
13. 13. A proximity and ambient light monitor according to claim 2, wherein the ambient light detector comprises: a filter for receiving the detected signal and passing through a filtered signal comprising the harmonic having a lower frequency than the low frequency; an amplifier to amplify the filtered signal; and a comparator to receive the filtered signal after the amplification and a reference value and, provide the signal of the ambient light level.
14. 14. A PALM according to claim 1, in combination with an earphone terminal, comprises means for providing the control signal to an audio level selector of the headset terminal and, accordingly, operating the level selector. audio in a receiver mode characterized by a low volume audio signal and a horn mode characterized by a. high volume audio signal.
15. 15. A proximity and ambient light monitor according to claim 14, wherein the light emitting means and the light detecting means are placed in the headset terminal, such that the fraction of the composite optical signal reaches the medium light detector every time P1222 / 98MX that an opaque obstacle to light gets in the way of the composite optical signal.
16. 16. A proximity and ambient light monitor according to claim 2, in combination with an earphone terminal comprising means for * providing the control signal to an audio level selector ALS) of the handset terminal and, In accordance with this, operate the audio level selector in the receiver mode, characterized by a low volume audio signal, and one in a horn mode, characterized by a high volume audio signal and, a means for receiving to signal the ambient light level and operate the back light of the handset terminal.
17. 17. A method for detecting the proximity and intensity of ambient light, comprising the steps of: generating a composite optical signal; provide a fraction of the composite optical signal; provide a fraction of the optical signal. composed of a light detector means, each time an obstacle opaque to light intervenes in the path of the composite optical signal; converting the fraction of the composite optical signal into a detected signal; separating an ac component from the detected signal; Y P1222 / 98MX provide a control signal when the ac component is outside a predetermined interval.
18. 18. A method according to claim 17, further comprising the step of processing the detected signal and providing a signal of the ambient light level.
19. 19. A method according to claim 17, further comprising the step of maintaining the control signal during a substantially small reduction of the detected signal.
20. 20. A method according to claim 18, further comprising the step of maintaining the signal of the ambient light level constant during the substantially small reduction of the detected signal. P1222 / 98MX