CN220290262U

CN220290262U - Image acquisition and processing module

Info

Publication number: CN220290262U
Application number: CN202320745461.6U
Authority: CN
Inventors: 唐宇恒; 唐慧明
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2023-03-31
Filing date: 2023-03-31
Publication date: 2024-01-02
Anticipated expiration: 2033-03-31

Abstract

The utility model discloses an image acquisition and processing module which is mainly used for image acquisition and real-time identification processing of a banknote counter and comprises denomination identification, image-based fake identification processing and the like. The scheme does not need a special analog-to-digital conversion (ADC), a field programmable logic device (FPGA), a high-performance processor and other independent integrated circuits, and can acquire and process analog image signals from a contact image sensor in real time by only needing a low-cost microcontroller, so that denomination identification and image-based counterfeit identification are realized, and the scheme is a low-cost solution capable of effectively improving the performance of a commercial banknote counter.

Description

Image acquisition and processing module

Technical Field

The utility model relates to the technical field of banknote counter products, in particular to a banknote image acquisition and processing module for a banknote counter.

Background

The conventional banknote image recognition scheme for a banknote counter generally requires a relatively complex circuit, and in order to collect an analog signal output from a Contact Image Sensor (CIS), as shown in fig. 1, a dedicated analog-to-digital converter (ADC), a field programmable logic device (FPGA), a high-performance processor, and other independent integrated circuits are required in a dashed frame, where the high-performance processor also requires a peripheral chip such as a DDR-SDRAM, a FLASH Memory, or an eMMC to operate. For example, the utility model patent CN211087376U discloses an automatic foreign currency note sorting system of a currency counting and detecting machine, wherein the image acquisition module comprises CIS, AD analog-to-digital conversion, a code wheel circuit, FPGA and DSP, and the DSP is a high-performance digital signal processor; the utility model patent CN113870122A discloses an image correction method, an image correction system and an image processing device for a financial machine, which comprise a CIS image sensor, an AD acquisition module, a Zynq FPGA and a DDR_SDRAM, wherein the Zynq FPGA produced by Xilinx company comprises a processing system PS and a programmable logic PL, the processing system PS is a high-performance processor based on ARMCortex-A, and the programmable logic PL is a built-in FPGA circuit and is still realized by CIS, ADC, FPGA and the high-performance processor. And the DSP and ARM Cortex-A processors all need DDR_SDRAM and other peripheral devices to work cooperatively. It can be seen that the existing scheme has high cost, is generally only used for a class-A banknote counter, sorter or banknote detector of professional financial institutions such as banks, and the low-cost banknote counter for current commercial use does not adopt banknote image recognition technology to carry out denomination recognition and counterfeit discrimination processing, only adopts a color sensor and a length sensor with lower cost, has poor performance and is often misjudged. In particular, old version dollars and banknotes in certain countries have almost the same color and length and width of banknotes with different denominations, and the color sensor and the length sensor cannot function, but only rely on magnetic judgment, and the discrimination capability is poor.

Disclosure of Invention

Aiming at the problems of the commercial low-cost banknote counter, the utility model discloses a low-cost banknote image acquisition and processing module, which can replace an independent analog-to-digital conversion (ADC), a field programmable logic array (FPGA) chip, a high-performance microprocessor and peripheral circuits thereof in a dashed line frame in FIG. 1 by adopting a low-cost Micro Controller (MCU) to acquire and further process banknote images. Therefore, the method can be used for low-cost commercial banknote counter, and the performance of the banknote counter is effectively improved.

An image acquisition and processing module of the present utility model includes:

an encoder: the paper money conveying device is arranged on the paper money conveying wheel and used for measuring the advancing speed of paper money in a paper money channel and outputting code disc signals;

contact image sensor: the paper money scanning device is arranged on one side of the paper money channel and used for scanning the passing paper money and outputting analog image signals;

and (3) a microcontroller: generating a clock signal and a line transfer signal for the contact image sensor using an on-chip timer according to the received code wheel signal output by the encoder; generating an analog-to-digital conversion clock signal by using an on-chip timer, and performing analog-to-digital conversion on an analog signal from the contact image sensor based on the built-in ADC; the microcontroller also generates a light-emitting control signal by using an on-chip timer and is used for controlling the light source driving circuit;

light source and light source driving circuit: for providing illumination light for a contact image sensor.

Preferably, the microcontroller is further configured to perform recognition processing on the digital image after the analog-to-digital conversion through a preset image processing unit, and transmit a processing result to the main control module.

Preferably, the contact image sensor outputs 1 path, 2 paths or 3 paths of analog signals, each path of analog signal corresponds to a section on the contact image sensor, and each path of analog signal is collected by an ADC (analog to digital converter) built in the microcontroller.

Preferably, the on-chip analog-to-digital conversion sampling resolution of the microcontroller is less than or equal to 50DPI.

Preferably, the sampling resolution in the analog-to-digital conversion line in the microcontroller is 50DPI or 25DPI.

Preferably, the microcontroller employs an ARM Cortex-M series processor.

Preferably, the microcontroller has at least 4 on-chip timers, wherein the timer 1 generates a CIS clock signal, the timer 2 generates an ADC sampling signal, the timer 3 generates a line transfer signal and 2 light emission control signals, wherein one light emission control signal is used for controlling the light emission of the reflective light source, the other light emission control signal is used for controlling the light emission of the transmissive light source, and the timer 4 measures the period or frequency of the output signal of the encoder and is used for controlling the output frequency of the timer 3.

Preferably, the light source comprises a built-in reflection light source of the contact image sensor and a peripheral transmission light source, and the built-in reflection light source and the peripheral transmission light source comprise one or more of an infrared light source and red, green and blue LED light sources.

Preferably, the microcontroller chip further comprises a number 5 timer for generating a light control signal, and one or more of the built-in reflection light source and the peripheral transmission light source in addition to the number 3 timer control are controlled respectively.

Preferably, the light source driving circuit comprises a resistor R101 connected with a microprocessor control signal output pin, the other end of the resistor R101 is connected with a triode base electrode or a field effect tube grid electrode, a triode collector electrode or a field effect tube drain electrode is connected with a light source LED negative electrode end through a current limiting resistor R102, and a light source LED positive electrode end is connected with a 5V power supply.

Compared with the existing image acquisition and processing scheme adopting independent ADC, FPGA and high-performance microprocessor chip, the image acquisition and processing module has the advantages that the cost is greatly reduced, the image acquisition and processing module can be used for common commercial banknote counting machines, and the performance of the banknote counting machines is effectively improved while the low cost is maintained.

Drawings

Fig. 1 is a schematic block diagram of the electrical principle of a conventional banknote image acquisition and processing apparatus.

Fig. 2 is an electrical schematic block diagram of the present utility model.

Fig. 3 is an exemplary diagram of a light source driving circuit.

Detailed Description

The utility model is further described below with reference to the drawings and specific examples. The following examples are only for illustrating and explaining the present utility model and do not limit the scope of the present utility model.

As shown in FIG. 2, an electrical schematic block diagram of an image acquisition and processing module of an embodiment of the present utility model is shown, comprising an encoder, a contact image sensor, a microcontroller, a light source, and a light source drive circuit. Wherein each module is specifically described as follows:

an encoder: is mounted on the banknote transfer wheel for measuring the speed of advance of the banknote in the banknote path, outputting a code wheel signal, and outputting 1 pulse per advance by a specified distance. For example, 1 pulse is output per 1mm of advance. The encoder may be a photoelectric encoder or a hall sensor encoder. The pulse signal output by the encoder can be determined whether to reshape according to the requirement, and a comparator can be used for reshaping.

Contact Image Sensor (CIS): the paper money scanning device is arranged on one side of the paper money channel, scans the passing paper money and outputs an analog image signal. For example, if an image of the advancing direction 50DPI is required to be acquired, the Microcontroller (MCU) outputs a Clock (CLK) and a line transfer Signal (SP) according to the encoder output code wheel signal, and outputs an image signal every 1/50 inch.

Microcontroller (MCU): generating a clock signal (CLK) and a line transfer Signal (SP) for a Contact Image Sensor (CIS) using an on-chip timer according to a received signal output from the encoder; generating an analog-to-digital conversion (ADC) clock signal using an on-chip timer, performing an analog-to-digital conversion on each line of analog signals from a Contact Image Sensor (CIS); the microcontroller also generates a lighting control signal using the on-chip timer for controlling the light source driving circuit. Wherein the clock signal (CLK) and the row transfer Signal (SP) input to the touch image sensor are required to meet the timing requirements of the touch image sensor.

The touch image sensor outputs 1 path, 2 paths or 3 paths of analog signals (Vout), each path of analog signals corresponds to one section on the touch image sensor, namely a plurality of image sensor photosensitive units, and each path of analog signals is respectively collected by an ADC (analog to digital converter) arranged in the microcontroller; the clock frequency for ADC sampling is an integer division of the CIS clock signal CLK. For example, if the CIS is operated in the 100DPI output mode, an on-chip timer is used to generate an 8MHz square wave signal as a CIS clock signal (CLK), and if a 50DPI image is acquired, the ADC acquires the image with 4MHz, that is, samples the analog signal output by the CIS at intervals; if 25DPI images are acquired, the ADC acquires the images with 2MHz, namely, the analog signals output by the CIS are sampled 1 time every 4 points. Since the CIS is required to be transferred from the line transfer Signal (SP) to the line and then output the line transfer Signal (SP) point by point after line, the MCU also generates a line transfer Signal (SP) for each line by using an on-chip timer. In order to make the CIS sensitive, the MCU also uses a timer on the chip to generate a light-emitting control signal, and the light-emitting pulse width of each row is the time length of light emission by controlling the light emission of the light source through the light source driving circuit.

As a further preferred embodiment, the Microcontroller (MCU) performs recognition processing on the digital image after the analog-digital conversion in addition to image acquisition, and the recognition processing is realized by a preset image processing software module, and the module can adopt a digital image recognition processing algorithm commonly used in the current banknote counter, including image correction, image recognition and the like. For example, geometric correction of the image is realized by extracting the boundary of paper money, and the corrected image is subjected to image processing by adopting common algorithms such as image template matching, feature matching, convolutional neural network identification and the like, so that denomination, orientation, version and currency are identified, and counterfeit identification is carried out. The above algorithms are disclosed in the related patent and non-patent literature in the field and are well known to those skilled in the art and are not the subject of the innovation of the present utility model. Meanwhile, in the scheme of the utility model, due to the reduction of the resolution of the acquired image, the common algorithms are easier to realize.

In this embodiment, a Microcontroller (MCU) generates a CIS clock signal (CLK) with an on-chip No. 1 timer, generates an ADC sample signal with an on-chip No. 2 timer, generates a line transfer Signal (SP) with an on-chip No. 3 timer, and generates 2 emission control signals, one of which is used to control the emission of the reflective light source and the other of which is used to control the emission of the transmissive light source. The reflective light source and the transmissive light source can use red, green, blue or infrared, one of the light sources can be controlled to emit light, or several light sources emit light simultaneously or in a time-sharing manner, and a No. 5 timer is adopted to generate more control signals when various light sources need to be controlled to emit light in a time-sharing manner. The present embodiment measures the period (or frequency) of the encoder output signal with a timer No. 4 for controlling the output frequencies of the timers No. 3 and No. 5. In particular, a light emission control signal for controlling the green reflected light source and the infrared transmitted light source is generated with a timer No. 3, and images of both light sources are acquired. When more images of the light sources are needed, additional light emission control signals are generated through timing No. 5, such as light emission control signals for controlling the red and blue reflection light sources, so that red, green and blue color reflection images are acquired.

Since the RAM (random access memory) built in the microcontroller is usually small, larger image data and cache data during processing cannot be stored, and the processing capacity is weak, the sampling resolution in the ADC line of the embodiment is less than or equal to 50DPI, and the implementation is realized by controlling the ADC sampling frequency. Since the resolution of commercial CIS is typically 100DPI, 200DPI, this embodiment requires image recognition using 50DPI or 25DPI sampling.

In order to reduce the cost, the microcontroller of the embodiment adopts ARM Cortex-M series processors, and particularly adopts ARM Cortex-M4 or ARM Cortex-M7 processors with higher performance. ARM Cortex-A or RISC_V processors may also be used, but at an increased cost.

Light source and light source driving circuit: for providing illumination light for a Contact Image Sensor (CIS). The CIS is generally internally provided with a reflective light source, and may have four LED light sources of red (R), green (G), blue (B) and Infrared (IR), and may control each light source driving circuit according to an emission control signal generated by the MCU according to an image processing requirement, so as to control one or more of the LED light sources to emit light. An LED transmission light source may be provided to collect transmission images, such as an Infrared (IR) transmission light source, and red (R), green (G), and blue (B) LED transmission light sources.

Fig. 3 is an exemplary diagram of a light source driving circuit, which is used for controlling one LED light source, the control signal cis_led_b from the MCU is connected to the base electrode or the gate electrode of the Q100A transistor through a resistor R101 (which may be omitted), the collector electrode or the drain electrode of the Q100A transistor is connected to the negative terminal of the light source LED through a current limiting resistor R102, and the positive terminal of the light source LED is connected to the 5V power supply. If a current limiting resistor is built into the light source, R102 may be omitted.

The system also comprises a main control module in fig. 2, which is used for setting the working mode and the function of the microcontroller, receiving the image recognition processing result from the microcontroller, monitoring the position of paper money in the paper money channel, controlling each motor of the paper money counter and realizing a man-machine interface. The main control module controls the working mode of the paper money image acquisition and processing module through a man-machine interface. The main control module is a necessary module of the banknote counter, and can share one microcontroller chip with the image acquisition and processing module when the resources in the Microcontroller (MCU) are enough, and can also be independently realized by another microcontroller chip.

After the image acquisition and processing module of the scheme is adopted, each timer, an on-chip ADC (analog to digital converter) and the like are initialized when the machine is started, then the encoder can trigger each timer to output as long as paper money enters a paper money channel, collect digital image signals, realize the function of image acquisition, further realize image processing through a microcontroller, and further realize the identification and fake identification of the currency type and the denomination of the paper money. Compared with the traditional image recognition scheme based on the FPGA and the high-performance processor, the cost is greatly reduced.

The description of the specific embodiments presented above is only useful for aiding in the understanding of the aspects of the present utility model and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the utility model can be made without departing from the principles of the utility model and these modifications and adaptations are intended to be within the scope of the utility model as defined in the following claims.

Claims

1. An image acquisition and processing module, comprising:

2. The image acquisition and processing module according to claim 1, wherein the contact image sensor outputs 1, 2 or 3 analog signals, each corresponding to a segment on the contact image sensor, each analog signal being acquired by an ADC built into the microcontroller.

3. The image acquisition and processing module of claim 1, wherein the on-chip analog-to-digital conversion sampling resolution of the microcontroller is less than or equal to 50DPI.

4. The image acquisition and processing module of claim 3, wherein the intra-analog-to-digital conversion line sampling resolution in the microcontroller is 50DPI or 25DPI.

5. The image acquisition and processing module of any one of claims 1-4, wherein the microcontroller employs an ARM Cortex-M series processor.

6. The image acquisition and processing module of claim 5, wherein the microcontroller has at least 4 on-chip timers, wherein timer No. 1 generates a CIS clock signal, timer No. 2 generates an ADC sample signal, timer No. 3 generates a row transfer signal and 2 light emission control signals, wherein one light emission control signal is used to control the light emission of the reflective light source, the other light emission control signal is used to control the light emission of the transmissive light source, and timer No. 4 measures the period or frequency of the encoder output signal and is used to control the output frequency of timer No. 3.

7. The image acquisition and processing module of claim 5, wherein the light source comprises a built-in reflective light source of the contact image sensor and a peripheral transmissive light source, the built-in reflective light source and the peripheral transmissive light source comprising one or more of an infrared light source and red, green, and blue LED light sources.

8. The image acquisition and processing module of claim 7, wherein the microcontroller chip further includes a number 5 timer for generating light control signals for controlling one or more of the red, green, and blue LED light sources of the built-in reflective light source and the peripheral transmissive light source, respectively, except for the number 3 timer control.

9. The image acquisition and processing module according to claim 1, wherein the light source driving circuit comprises a resistor R101 connected with a control signal output pin of the microprocessor, the other end of the resistor R is connected with a base electrode or a gate electrode of the triode, a collector electrode or a drain electrode of the triode is connected with a negative electrode terminal of the light source LED through a current limiting resistor R102, and a positive electrode terminal of the light source LED is connected with a 5V power supply.