CN106886029B

CN106886029B - Optical sensing device

Info

Publication number: CN106886029B
Application number: CN201510929644.3A
Authority: CN
Inventors: 许哲豪; 蔡佐昇; 陈文政; 林孟勇
Original assignee: Sensorteknik Technology Corp
Current assignee: Sensorteknik Technology Corp
Priority date: 2015-12-15
Filing date: 2015-12-15
Publication date: 2020-09-08
Anticipated expiration: 2035-12-15
Also published as: CN106886029A

Abstract

The invention discloses an optical sensing device, which comprises a signal generating module, a signal receiving module and a signal processing module, wherein the signal generating module is used for generating a detection signal; the sensing module is used for receiving a reflection signal corresponding to the detection signal; and a control module, coupled to the sensing module, for correspondingly determining whether an object is close to the sensing module and a relative distance corresponding to the object according to the reflected signal; the control module further includes a matching module for matching an impedance value corresponding to the sensing module, and the matching module and the sensing module are both coupled to a ground to form a zero differential level.

Description

Optical sensing device

Technical Field

The present invention relates to an optical sensing device, and more particularly, to an optical sensing device capable of reducing a Power Supply Rejection Ratio (PSRR) accordingly.

Background

The conventional optical sensing device focuses on the improvement of the sensing efficiency, but the circuit design for internal component impedance matching has some disadvantages, which will result in the too much noise signal doping of the sensing result and affect the sensing efficiency and the accuracy of the processed signal.

Therefore, it is an important subject of the art to provide an optical sensing device capable of reducing the power supply voltage rejection ratio accordingly.

Disclosure of Invention

Therefore, it is a primary objective of the present invention to provide an optical sensing device with a reduced power supply voltage rejection ratio.

The invention discloses an optical sensing device, which comprises a signal generating module, a sensing module and a control module, wherein the signal generating module is used for generating a detection signal; the sensing module is used for receiving a reflection signal corresponding to the detection signal; and a control module, coupled to the sensing module, for correspondingly determining whether an object is close to the sensing module and a relative distance corresponding to the object according to the reflected signal; the control module further includes a matching module for matching an impedance value corresponding to the sensing module, and the matching module and the sensing module are both coupled to a ground to form a zero differential level.

Drawings

Fig. 1 and fig. 2 are schematic views illustrating an optical sensing device operating in different operating states according to an embodiment of the invention.

Fig. 3 is a schematic view of another optical sensing device according to another embodiment of the invention.

FIG. 4 is a schematic view of another optical sensing device according to another embodiment of the present invention.

Wherein the reference numerals are as follows:

1. 3, 4 optical sensing device

10 signal generating module

12 sensing module

14. 34, 44 control module

140. 340, 440 matching module

142 switching module

1420 first switching unit

1422 second switching unit

1424 third switching unit

144 calculation module

146 analog-to-digital converter

46 adjustment module

GND ground terminal

S _ D detection signal

S _ R reflected signal

S _ C1, S _ C2 and S _ C3 turn-on signals

S _ S selection signal

I_B、I_R+I_BSensing current

OB object

Detailed Description

Certain terms are used throughout the description and following claims to refer to particular components. As one of ordinary skill in the art will appreciate, manufacturers may refer to a component by different names. In the present specification and the claims to follow, differences in names are not used as means for distinguishing components, but are used as a basis for distinguishing components in terms of differences in functions. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. Furthermore, the term "coupled" is intended to encompass any direct or indirect electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections.

Referring to fig. 1 and fig. 2, fig. 1 and fig. 2 are schematic diagrams illustrating an optical sensing device 1 operating in an uninitiated state and an initialized state, respectively, according to an embodiment of the present invention. The optical sensing device 1 of the present embodiment can be used to detect whether an object OB is approaching, and includes a signal generating module 10, a sensing module 12 and a control module 14. The signal generating module 10 is configured to generate a detection signal S _ D, the sensing module 12 is configured to receive a reflection signal S _ R corresponding to the detection signal, and the control module 14 is coupled to the sensing module 12 and configured to correspondingly determine whether the object OB is close to/near the periphery of the optical sensing apparatus 1 according to the reflection signal, and the reflection signal is also configured to determine a relative distance between the object OB and the optical sensing apparatus 1.

In detail, the signal generating module 10 in this embodiment can be a light emitting diode (driven by a driving voltage Vdd), can generate a light source signal such as a non-visible light or a visible light, and can reflect the light source signal to form a reflected light source signal when the object OB approaches the optical sensing device 1, and the sensing module 12 can be a photodiode to receive the reflected light source signal. In addition, the control module 14 includes a matching module 140, which can be used as a matching capacitor for matching an impedance value (e.g., a capacitance value) corresponding to the sensing module 12. In addition, the matching module 140 and the sensing module 12 are both coupled to a ground GND, so that a zero differential level is formed between the matching module 140 and the sensing module 12. The control module 14 in this embodiment further includes a switching module 142, a calculating module 144 and an analog-to-digital converter 146, and the conducting path of the switching module 142 is switched correspondingly by a conducting signal, for example, the switching module 142 in this embodiment includes a first switching unit 1420, a second switching unit 1422 and a third switching unit 1424, and the conducting signals S _ C1, S _ C2 and S _ C3 are utilized to correspondingly switch the conducting states of the first switching unit 1420, the second switching unit 1422 and the third switching unit 1424, so as to switch different working states of the optical sensing device 1.

Specifically, as shown in fig. 1, when the signal generating module 10 is not activated (i.e. the signal generating module 10 is in an inactive state), the conducting signals S _ C1, S _ C2, S _ C3 are respectively a low level signal, a high level signal and a low level signal to switch on/off of the first switching unit 1420, the second switching unit 1422 and the third switching unit 1424 in the switching module 142, a positive input terminal of the calculating module 144 is coupled to the matching module 140, a negative input terminal of the calculating module 144 is coupled to the sensing module 12 to form a first conducting path, and the detecting signal S _ D is not generated by the signal generating module 10, and the sensing module correspondingly receives a first signal according to a background light source and correspondingly forms a sensing current I_BFor the first conduction path, reference may be made to the sensing current I shown in FIG. 1_BThe flow direction of the arrow of (1).

Further, as shown in fig. 2, when the signal generating module 10 is activated and generates the detecting signal S _ D (i.e. the signal generating module 10 is in the initialized state), the conducting signals S _ C1, S _ C2, S _ C3 are respectively a high level signal, a low level signal and a low level signal to switch on/off of the first switching unit 1420, the second switching unit 1422 and the third switching unit 1424 in the switching module 142, at this time, the positive input terminal of the calculating module 144 is coupled to the sensing module 12, the negative input terminal of the calculating module 144 is coupled to the matching module 140 to form a second conducting path, at this time, the sensing module 12 can correspondingly receive a second signal (i.e. the reflected signal S _ R) reflected by the object OB and correspondingly form another sensing current I _ R_R+I_BFor the second conduction path, the sensing current I shown in FIG. 2 can be referred to_R+I_BThe flow direction of the arrow of (1). Accordingly, after an integration operation of the calculating module 144 and the analog-to-digital converter 146 in the control module 14, the control module 14 can determine a difference between the first reflected signal and the second reflected signalTo correspond to whether the object OB is close/near to the periphery of the optical sensing device 1 while determining the relative distance of the object OB with respect to the optical sensing device 1.

Referring to fig. 3, fig. 3 is a schematic view of another optical sensing device 3 according to another embodiment of the invention. The optical sensing device 3 shown in fig. 3 is similar to the optical sensing device 1 shown in fig. 1, except that the matching module 340 of the control module 34 in the present embodiment is a light-shielded photodiode, and can completely match the impedance and capacitance values of the sensing module 12. Referring to fig. 4 again, fig. 4 is a schematic view of another optical sensing device 4 according to another embodiment of the invention. The optical sensing device 4 of fig. 4 is similar to the optical sensing device 1 of fig. 1, except that the matching module 440 of the control module 44 in this embodiment may be a tracking capacitor module, and it corresponds to a selectable capacitor array, and the control module 44 further includes an adjusting module 46 coupled between the tracking capacitor module and the adc 146, and the adjusting module 46 may correspondingly output a selection signal S _ S to the tracking capacitor module according to a calculation result after the integration operation of the control module 44, so as to control the tracking capacitor module 440 to output an adjustable capacitance value to match the impedance capacitance value of the sensing module 12, for example, the adjusting module 46 may compare whether a difference between an integrator and the adc 146 is the minimum, and further output a capacitance value of the currently used tracking capacitor module. Furthermore, when the optical sensing device 4 is not illuminated, the matching module 440 and the sensing module 12 are completely matched, and after the conducting path of the switching module 142 is switched for a plurality of times, the control module 44 can correspondingly output a zero value to adjust the adjustable capacitance value. Of course, the adjustable capacitance value output by the tracking capacitor module in the embodiment may be directly equal to the impedance value of the sensing module 12, or a closer one of the impedance values may be selected to match the impedance value of the sensing module 12, which is not intended to limit the scope of the present invention.

Accordingly, since the embodiments of fig. 1 to 4 of the present invention are all provided with the matching module, when the optical sensing device operates in different working environments or conditions, and since the impedance capacitance value of the sensing module (e.g. the photodiode) changes correspondingly with the process, the temperature or the bias voltage, the present embodiment can still maintain the impedance capacitance value between the sensing module (e.g. the photodiode) and the matching module (e.g. a matching capacitor, a tracking capacitor module or a shielded photodiode) to be equal or close, so that the power supply voltage rejection ratio (PSRR) of the equivalent output of the optical sensing device is optimal to combat the noise signal carried by the input voltage. Moreover, since the impedance capacitance between the sensing module and the matching module is considered to be matched in the present embodiment, and the matching module 140 and the sensing module 12 are grounded simultaneously to form the zero differential level, the load matching effect and the noise immunity of the present embodiment can be greatly improved, and compared with the prior art without the matching module, the power voltage rejection ratio provided by the present invention is improved by at least 20dB to 30 dB.

It should be noted that, those skilled in the art may correspondingly modify the number of the switching units in the switching module and the corresponding conducting signals and conducting paths in the embodiment, so that the sensing module not only maintains impedance matching between the matching module and the sensing module, but also correspondingly uses different conducting paths or conducting components to reduce noise interference transmitted from the induced current to the control module, which also falls within the scope of the present invention.

In summary, the embodiments of the present invention provide an optical sensing device, in which an internal matching module can maintain an impedance capacitance equal to or close to that of the sensing module, so that the optical sensing device can output a better power voltage rejection ratio, and meanwhile, the matching module and the sensing module are grounded together to form a zero differential level, so as to improve the load matching effect and the noise immunity of the optical sensing device.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An optical sensing device, comprising:

a signal generating module for generating a detecting signal;

the sensing module is used for receiving a reflection signal corresponding to the detection signal; and

a control module, coupled to the sensing module, for correspondingly determining whether an object is close to the sensing module and a relative distance corresponding to the object according to the reflected signal;

the control module further comprises a matching module for matching an impedance value corresponding to the sensing module, and the matching module and the sensing module are both coupled to a ground terminal to form a zero differential level;

the control module further comprises a switching module, a calculating module and an analog-digital converter, and the conducting path of the switching module is correspondingly switched according to a conducting signal;

wherein, when the signal generating module is not activated, the conducting signal switches the switching module to couple a positive input terminal of the calculating module to the matching module, and a negative input terminal of the calculating module is coupled to the sensing module to form a first conducting path, the sensing module correspondingly receives a first signal, when the signal generating module is started to generate the detection signal, the conduction signal switches the switching module, couples the positive input of the computation module to the sensing module, and coupling the negative input terminal of the calculating module to the matching module to form a second conducting path, and the sensing module correspondingly receives a second signal, and after an integration operation, the control module correspondingly judges whether the object is close to the object and the corresponding relative distance according to the first signal and the second signal.

2. The optical sensing device as claimed in claim 1, wherein the matching module is a matching capacitor, a tracking capacitor module or a light-shielded photodiode, the impedance value corresponding to the sensing module is a capacitance value, and the signal generating module is a light emitting diode for generating a light source signal and correspondingly forming a reflected light source signal to the sensing module according to the reflection of the object.

3. The optical sensing device as claimed in claim 1, wherein when the matching module is a tracking capacitor module, the control module further comprises an adjusting module coupled between the tracking capacitor module and the adc, the adjusting module outputting an adjustable capacitance value by inputting a selection signal to the tracking capacitor module according to a calculation result of the control module.

4. The optical sensing device as claimed in claim 3, wherein the matching module and the sensing module are completely matched when the optical sensing device is not illuminated, and the control module outputs a zero value to adjust the adjustable capacitance value after switching the conducting path of the switching module for a plurality of times.