CN106295487A - Fingerprint detection method of capacitive fingerprint sensor - Google Patents

Abstract

A fingerprint detection method of a capacitance type fingerprint sensor is characterized in that a plurality of first sensing units are arranged in a large sensing area of the capacitance type fingerprint sensor, a plurality of second sensing units with the quantity less than that of the first sensing units are arranged in a plurality of small sensing areas in the large sensing area, the second sensing units are enabled to have a periodically alternate enabling state and a closing state, and only when the enabling state detects that an object approaches to a generated sensing value and then exceeds a set threshold value, the capacitance type fingerprint sensor enables the first sensing units and the second sensing units to carry out fingerprint scanning operation, so that the capacitance type fingerprint sensor can achieve the effects of energy saving and automatic starting.

Description

Fingerprint detection method of capacitive fingerprint sensor

technical field

The invention relates to a capacitive fingerprint sensor, in particular to a fingerprint detection method for saving power of the capacitive fingerprint sensor.

Background technique

Personal unique biological characteristics, such as fingerprints, voiceprints, and eye irises, are used as a way to confirm personal identity. With the development of technology, it has gradually become popular. Especially the technology of fingerprint recognition has been widely used today. Electronic devices that require personal identification.

For example, in China Taiwan Patent Publication No. 200713084, an embedded fingerprint encryption mobile phone is disclosed. The embedded fingerprint encryption mobile phone includes a fingerprint capture unit, a parallel port and a comparison unit. The fingerprint capture unit is for a user to place a finger to capture a simulated fingerprint image of the finger, convert the simulated fingerprint image into a digital fingerprint image and output it. The parallel port is for receiving and temporarily storing the digital fingerprint image, and outputting a fingerprint comparison signal. The comparison unit receives the fingerprint comparison signal, reads the digital fingerprint image through the parallel port, and uses a minutiae matching algorithm to compare the digital fingerprint image with a built-in fingerprint image and output A comparison result, and then determine whether the user can use the mobile phone according to the comparison result, so as to increase the security of the mobile phone and the data inside it.

However, for a portable electronic device, limited by the design of the electronic device for the convenience of portability, the allowable volume is limited, so that the capacity of the battery installed in the electronic device generally cannot be too large. The power consumed by each component is negligible. Therefore, how to save the operating power of a fingerprint scanning component and combine the convenience of use has become the goal of various businesses.

Contents of the invention

The main purpose of the present invention is to solve the problem of high power consumption of the existing fingerprint scanning element if it is normally turned on for detection.

In order to achieve the above object, the present invention provides a fingerprint detection method of a capacitive fingerprint sensor, which is applied to a capacitive fingerprint sensor. The capacitive fingerprint sensor includes a capacitive sensing array, and the capacitive sensing array Comprising a plurality of first sensing units and a plurality of second sensing units less in number than the first sensing units, the fingerprint detection method includes the following steps:

Step 1: The capacitive fingerprint sensor makes the second sensing unit have an enabled state and an off state alternately periodically, the second sensing unit starts a proximity detection mode in the enabled state, and activates a proximity detection mode in the off state state start-sleep mode;

Step 2: The capacitive fingerprint sensor makes the second sensing unit enter the enable state and activate the proximity detection mode, and the second sensing unit generates a sensing value for an approaching object in the proximity detection mode ;

Step 3: the capacitive fingerprint sensor accumulates the sensing value generated when the second sensing unit executes the approach detection mode in the enabled state and detects that the object is approaching; and

Step 4: The capacitive fingerprint sensor determines whether the sensed value accumulated in the enabled state reaches a threshold;

Wherein, when it is judged that the accumulated sensing value reaches the threshold value, the capacitive fingerprint sensor enables the first sensing unit and the second sensing unit to activate a fingerprint detection mode to perform a fingerprint scanning operation;

Wherein, when judging that the accumulated sensing value does not reach the threshold value, the capacitive fingerprint sensor clears the sensing value and makes the second sensing unit enter the off state to activate the sleep mode.

In this way, in the capacitive fingerprint sensor of the present invention, a small number of the second sensing units have the enabled state and the off state alternately periodically, reducing the time when the capacitive fingerprint sensor is not in operation. The power consumption during fingerprint scanning, and when the accumulated sensing value of detecting the proximity of the object reaches the threshold value, the fingerprint scanning operation can be automatically executed, not only does not need an additional start switch, it is convenient to use, and can avoid general The situation where the fingerprint scanning operation is activated by mistake due to a short approach without fingerprint scanning.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

Fig. 1 is a schematic flow chart of the steps of an embodiment of the present invention;

FIG. 2 is a schematic diagram of a block configuration according to an embodiment of the present invention.

detailed description

Relating to the detailed description and technical content of the present invention, it is now described as follows in conjunction with the accompanying drawings:

Please refer to FIG. 1 and FIG. 2 together. FIG. 1 is a schematic diagram of the steps of an embodiment of the present invention. FIG. 2 is a schematic diagram of a block configuration of an embodiment of the present invention. As shown in the figure, the present invention is a capacitive The fingerprint detection method of the fingerprint sensor is applied to a capacitive fingerprint sensor, and the capacitive fingerprint sensor can be installed in various electronic devices that require fingerprint recognition for identity authentication, such as common mobile electronic devices, Such as smartphones, tablets, laptops, etc. The capacitive fingerprint sensor includes a capacitive sensing array 10, a large sensing area 11, and a plurality of small sensing areas 12 dispersed in the large sensing area 11. The capacitive sensing array 10 includes a plurality of The first sensing unit 111 and a plurality of second sensing units 121, the first sensing unit 111 is arranged in the large sensing area 11 and arranged in an array, the number of the second sensing unit 121 is less than that of the first sensing unit 121 The sensing unit 111 is arranged in the small sensing area 12 and arranged in an array. In this embodiment, at least one of the small sensing areas 12 can be located in the center of the large sensing area 11. The fingerprint detection method includes The following steps:

Step 1: The capacitive fingerprint sensor makes the second sensing unit 121 have an enabled state and an off state alternately periodically, and the second sensing unit 121 starts a proximity detection mode in the enabled state, and then The off state initiates a sleep mode. In this embodiment, the second sensing unit 121 is in the enabled state for a duration of 40ms to 60ms, and can activate the approach detection mode to detect whether an object is approaching, and in the off state for a time, is It lasts between 150ms and 250ms, and the sleep mode can be activated to stop the operation. The above-mentioned duration is only an example, and it is not limited. The duration can be set according to actual use requirements. The duration of the sleep state is sufficient.

Step 2: The capacitive fingerprint sensor makes the second sensing unit 121 enter the enable state and activate the approach detection mode, and the second sensing unit 121 generates a sense for the approaching object in the approach detection mode measured value. In the approach detection mode, the second sensing unit 121 located in the small sensing area 12 generates the corresponding sensing value for the approach of the object, and the sensing value can be, for example, a capacitance change value. And the second sensing unit 121 is arranged in the small sensing area 12 at the central position of the large sensing area 11, which helps to improve the time when the object approaches the capacitive sensing array 10 in the proximity detection mode. , the detection accuracy.

Step 3: The capacitive fingerprint sensor accumulates the sensing value generated when the second sensing unit 121 executes the approach detection mode in the enabled state and detects the approach of the object. In this embodiment, the capacitive fingerprint sensor further includes an accumulator 40, a multiplexer 20, and an analog-to-digital converter 30, the accumulator 40 is electrically connected to the second sensing unit 121, the The multiplexer 20 is electrically connected between the second sensing unit 121 and the multiplexer 20 , and the analog-to-digital converter 30 is electrically connected between the multiplexer 20 and the accumulator 40 . In the approach detection mode, since the approach of the object is weak for each of the second sensing units 121 compared to the sensing value that can be generated by the general contact detection, it is necessary to use the multiplexer The sensor 20 is electrically connected with each of the second sensing units 121, sequentially selects and receives the sensing values generated by each of the second sensing units 121, and then passes the analog-to-digital converter 30 to convert the sensing values It is converted from an analog form to a digital form, and is accumulated by the accumulator 40 to obtain a sum value for judging the approach of the object.

Step 4: The capacitive fingerprint sensor determines whether the sensed value accumulated in the enabled state reaches a threshold. The capacitive fingerprint sensor compares the sum value obtained by accumulating the sensing values in step 3 with a set threshold value to determine whether the approaching object is a finger for fingerprint scanning, The threshold value can be set with reference to the actual value required for one finger approaching.

When the sum value reaches the threshold value, the capacitive fingerprint sensor judges that the accumulated sensing value reaches the threshold value, indicating that the object may be a finger, and the capacitive fingerprint sensor enables the The first sensing unit 111, and enabling both the first sensing unit 111 and the second sensing unit 121 to activate a fingerprint detection mode, so as to perform a fingerprint scanning operation.

And when the sum value does not reach the threshold value, the capacitive fingerprint sensor judges that the accumulated sensing value does not reach the threshold value, which means that the distance between the object and the capacitive fingerprint sensor is not enough or the object is not close to the capacitive fingerprint sensor for a long enough time, so it is determined that the object should not be the finger that intends to perform the fingerprint scanning operation, and the capacitive fingerprint sensor clears the sensed value, And make the second sensing unit 121 enter the off state to activate the sleep mode, and still disable the first sensing unit 111, so as to save power consumption.

In addition, it should be noted that, in the present invention, step 5 may also be included after step 4.

Step 5: Return to Step 2 after finishing the fingerprint scanning operation or the closed state. In this way, when the first sensing unit 111 and the second sensing unit 121 finish performing the fingerprint scanning operation, the capacitive fingerprint sensor makes the first sensing unit 111 return to the disabled state, the The second sensing unit 121 enters the enabled state again, and then activates the proximity detection mode to perform detection, and returns to step 2 . And when the second sensing unit 121 finishes executing the sleep mode, the capacitive fingerprint sensor makes the second sensing unit 121 enter the enabled state again, and then starts the proximity detection mode to perform detection, and returns to Step 2, in this way, if the object that has not reached the threshold value approaches, the second sensing unit 121 will cycle periodically between the enabled state and the closed state according to steps 2 to 4. A sensing unit 111 is disabled to save power.

In summary, due to the present invention in the capacitive fingerprint sensor, only a small number of the second sensing units have the enabled state and the disabled state alternately periodically, and the duration of the enabled state The time can also be shorter than the duration of the dormant state, greatly reducing the power consumption of the capacitive fingerprint sensor when no fingerprint scanning is performed. Furthermore, once the sensing value accumulated when detecting the approach of the object reaches the threshold value, the first sensing unit and the second sensing unit can be automatically enabled to perform the fingerprint scanning operation, not only without additional The start switch is easy to use, and it can avoid the problem of falsely starting the fingerprint scanning operation caused by the short-term approach of the non-fingerprint scanning object or the short distance from the capacitive fingerprint sensor. It has both power saving and use The advantage of convenience.

Of course, the present invention can also have other various embodiments, and those skilled in the art can make various corresponding changes and deformations according to the present invention without departing from the spirit and essence of the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (10)

1. a fingerprint detection method for capacitance type fingerprint sensor, is applied to a capacitance type fingerprint sensor, This capacitance type fingerprint sensor includes a capacitance sensing array, and this capacitance sensing array comprises multiple first sense Survey unit and multiple quantity the second sensing unit less than this first sensing unit, it is characterised in that this refers to Marks detection method comprises the steps of

Step 1: this capacitance type fingerprint sensor makes this second sensing unit have an enable the most alternately State and a closed mode, this second sensing unit starts one near detection pattern in this enabled status, in This closed mode starts a park mode；

Step 2: this capacitance type fingerprint sensor makes this second sensing unit enter this enabled status and startup should Near detection pattern, this second sensing unit produces a sensing near detection pattern to a close object in this Value；

Step 3: this capacitance type fingerprint sensor adds up this second sensing unit and performs this in this enabled status and lean on This sensing value that nearly detection pattern this object detected is close and produces；And

Step 4: this capacitance type fingerprint sensor judges whether this sensing value in this enabled status is accumulative arrives One threshold value；

Wherein, in judging that this accumulative sensing value arrives this threshold value, this capacitance type fingerprint sensor make this One sensing unit and this second sensing unit starting one fingerprint detection pattern, to carry out a fingerprint scan operation；

Wherein, in judging that this accumulative sensing value is not up to this threshold value, this capacitance type fingerprint sensor is the most clear Except this sensing value and make this second sensing unit enter this closed mode and start this park mode.

The fingerprint detection method of capacitance type fingerprint sensor the most according to claim 1, its feature exists In, in step 1, this enabled status continues between 40ms to 60ms.

The fingerprint detection method of capacitance type fingerprint sensor the most according to claim 1, its feature exists In, in step 1, this closedown shape continues between 150ms to 250ms.

The fingerprint detection method of capacitance type fingerprint sensor the most according to claim 1, its feature exists In, in step 1, this second sensing unit decommissions in this park mode.

The fingerprint detection method of capacitance type fingerprint sensor the most according to claim 1, its feature exists One is comprised for arranging the big sensing region of this first sensing unit and multiple in, this capacitance type fingerprint sensor It is scattered in the little sensing region of this big sensing region, at least one this little sense for arranging this second sensing unit Survey region and be positioned at the central authorities of this big sensing region.

The fingerprint detection method of capacitance type fingerprint sensor the most according to claim 1, its feature exists In, in step 3, it is tired with what this second sensing unit was electrically connected with that this capacitance type fingerprint sensor further includes one Adding device, this capacitance type fingerprint sensor utilizes this accumulator to add up this sensing value.

The fingerprint detection method of capacitance type fingerprint sensor the most according to claim 6, its feature exists Add up this sensing value of each this second sensing unit in, this accumulator.

The fingerprint detection method of capacitance type fingerprint sensor the most according to claim 6, its feature exists In, in step 3, this capacitance type fingerprint sensor further includes one and is electrically connected at this second sensing unit and is somebody's turn to do The simulation numeral that multiplexer and between accumulator is electrically connected between this multiplexer and this accumulator Transducer, this multiplexer receives this sensing value of this second sensing unit, and is sent to this Analog-digital Converter Device is changed, then is added up this sensing value by this accumulator.

The fingerprint detection method of capacitance type fingerprint sensor the most according to claim 1, its feature exists In, further include step 5, after terminating this finger scan operation or this closed mode, then return to step 2.

The fingerprint detection method of capacitance type fingerprint sensor the most according to claim 1, its feature exists In, this sensing value is the changing value of an electric capacity.