CN203433576U - CIS-based multispectral bill image capturing device - Google Patents

Abstract

The utility model provides a CIS-based multi-spectral bill image acquisition device, which at least includes an infrared sensor, a photoelectric switch sensor, a grating disc, a transmission mechanism, a multi-light source contact image sensor CIS, an FPGA control circuit, a light source control circuit, Sensor circuit, A/D conversion circuit and DC motor. The device and method use visible light, ultraviolet light, infrared light or combined light active light sources to irradiate bills to complete image shooting under multi-spectral conditions, and use computer serial ports to select light source schemes to achieve high-speed, real-time, high-quality image acquisition, display and storage. With the utility model, high-quality, multi-spectral bill image data can be quickly obtained, which can be used for bill authenticity analysis, thereby solving the high-speed and high-precision identification of bill authenticity, and improving the accuracy and stability of the bill recognition system and real-time.

Description

A CIS-based Multi-spectral Bill Image Acquisition Device

technical field

The utility model relates to the technical field of electronic circuits, in particular to the image acquisition technology of bills with anti-counterfeiting features, and provides a new image acquisition device for bill feature recognition, machine vision and other fields.

Background technique

With the development of related technologies, the production level of counterfeit bills is getting higher and higher, and the phenomenon of confusing real ones is becoming more and more rampant, affecting people's daily life and social stability. Therefore, it is imperative to improve the recognition ability of existing identification equipment.

Important bills basically have anti-counterfeiting features, and most of them can be reflected in multispectral images. The real and fake bills show different features in the multispectral image, which is convenient for equipment to distinguish and identify. Therefore, multispectral image analysis and identification technology has become an important link to improve equipment capabilities.

In order to improve the identification ability of the existing equipment, it is necessary to introduce an image link into the equipment. Existing solid-state image sensors can be classified into charge-coupled device CCD and metal-oxide-semiconductor device CMOS. Contact image sensor CIS is a new type of photoelectric coupling device based on CMOS technology. Compared with CCD, it has the advantages of small size, light weight, low power consumption, compact structure, and easy installation. It is suitable for the improvement of traditional identification equipment. .

CIS is a linear sensor with its own light source, and only one frame or line of image information can be obtained at a time of scanning. Therefore, a complete two-dimensional image must be obtained when the image is collected with a horizontal (perpendicular to the CIS direction) movement. It can be seen from this that the starting position of the CIS image acquisition and the stop position of the image acquisition have an impact on the acquired image data. If the device is still collecting images when the bill has not arrived or has passed directly under the CIS, in this case, the time for image collection of the device will be increased, and the collected images will appear redundant, which will affect the stability and quality of image collection. real-time.

The traditional method is to add an infrared sensor to the front of the device as the basis for judging the starting position of the CIS image acquisition. In order to prevent the impact of bills tilting during high-speed movement, the infrared sensor needs to be installed at the front of the CIS and ensure a certain distance requirement ( If it is installed on the same line, when the bill is tilted, the bill has passed the CIS when the infrared sensor triggers the image capture, resulting in the loss of valid image data). At this time, there are the following two processing situations.

In the first case, the edge signal of the infrared sensor is directly used as the field synchronization trigger signal of the image. Due to the distance requirement between the infrared sensor and the CIS, the collected images will be redundant.

In the second case, if the acquisition of an image is triggered after a certain distance or time delay, at this time, the acquired image is affected by mechanical properties and is unstable.

According to the above situation, this patent proposes a CIS-based multi-spectral bill image acquisition and processing method. This method uses the characteristics of FPGA parallel high-speed processing to judge the image at the front end of image acquisition, and uses the image information at the acquisition end as the entire image. The direct judgment basis for the control of the start and stop of the image does not completely depend on the mechanical properties of the system.

Utility model content

In view of the above technical problems, an object of this utility model is to provide a CIS-based multi-spectral bill image acquisition device, which ensures stable and high-quality images from the perspective of device stability and real-time performance.

A multi-spectral bill image acquisition device based on CIS, the device at least includes an infrared sensor, a photoelectric switch sensor, a grating disc, a transmission mechanism, a multi-light source contact image sensor CIS, an FPGA control circuit, a light source control circuit, a sensor circuit, A/ D conversion circuit and DC motor;

Among them, the infrared sensor is fixed at the front end of the transmission mechanism, and is used to detect whether there is a bill passing through the transmission structure. If it is detected that the bill passes through the infrared sensor, the signal generated by the sensor circuit will be notified to the FPGA control circuit to start collecting an image; Otherwise, continue to detect;

The photoelectric switch sensor is fixed on one side of the grating disc, and cooperates with the grating disc to generate frame or line synchronization signals for CIS image acquisition;

The grating disk is fixed on the coaxial position of the DC motor, and cooperates with the photoelectric switch sensor to detect the transmission speed of the transmission mechanism and generate the frame or line synchronization signal for CIS image acquisition;

The transmission mechanism is driven by a DC motor according to a fixed transmission ratio. The bills pass through the infrared sensor and the multi-light source contact image sensor CIS quickly and stably through the transmission effect of the conveyor belt of the transmission mechanism;

The multi-light source contact image sensor CIS is fixed at the middle position of the transmission mechanism, perpendicular to the movement direction of the bill, controlled by the FPGA control circuit, and dynamically detects the image information of the bill;

The FPGA control circuit is used to control the selection of the multi-spectral bill image acquisition scheme, and the multi-light source contact image sensor CIS is controlled by the light source control circuit to complete the multi-spectral image acquisition task;

The light source control circuit is used to connect the FPGA control circuit and the multi-light source contact image sensor CIS to complete the light source switching operation of the CIS;

The sensor circuit is used for filtering, amplification and level conversion of the infrared sensor and the photoelectric switch sensor, and converts the sensor signal into a digital signal, which is used for FPGA to judge the starting position of an image acquisition and the starting position of a frame of image;

The A/D conversion circuit is used to convert the analog signal output by the CIS into a digital signal and transmit it to the FPGA;

The DC motor is used for the transmission of the transmission mechanism, and the bills on the transmission mechanism pass through the multi-light source contact image sensor CIS quickly and stably.

Furthermore, the multi-light source contact image sensor CIS has built-in visible light, ultraviolet light, and infrared light sources, and each light source can be individually controlled on and off.

Further, the infrared sensor is installed at the front end of the bill movement direction, and the multi-light source contact image sensor CIS is installed at the interruption position of the bill movement direction. Image sensor CIS.

Furthermore, the FPGA in the FPGA control circuit is responsible for the driving of the multi-light source contact image sensor CIS, light source control, image acquisition and storage.

Furthermore, the pulse signal generated by the infrared sensor when the bill passes is used as the field synchronization signal for the start of one image acquisition of the CIS, and the pulse signal generated by the photoelectric switch sensor in cooperation with the grating disc is used as the line synchronization signal for the start of one frame or line image acquisition of the CIS. The vertical resolution of the images is the same.

A CIS-based multi-spectral bill image acquisition method, the method comprising:

The bill is transmitted through the transmission mechanism. When the bill does not pass the infrared sensor, the image acquisition mechanism inside the FPGA is in the initial waiting state, and the CIS does not start working at this time;

When the bill passes through the transmission mechanism and touches the infrared sensor, the image acquisition mechanism inside the FPGA jumps into the delay waiting state. In this state, the external code disc signal is used as the frame or line synchronization signal to trigger the CIS image acquisition, but the image is not stored;

The FPGA uses a frame of image collected by the CIS to make a judgment. When the state jump requirements are met, that is, the FPGA judges that the ticket has been directly below the CIS at this time, and the image acquisition mechanism inside the FPGA jumps into the effective image acquisition state, and this state is turned on at the same time. CIS map acquisition and image storage;

While the image is being stored, the FPGA judges the captured frame of image. When the judgment result meets the state jump requirements, the image acquisition mechanism inside the FPGA jumps into the initial waiting state and waits for the next image to be collected.

Furthermore, the basis for the FPGA image acquisition mechanism to judge whether to enter the effective state of image acquisition is the difference between the image information of the CIS acquisition and transmission mechanism background and the image information of the bill, and the FPGA only completes the image acquisition and storage when the bill is directly below the CIS.

Furthermore, the purpose of the delay waiting state of the image acquisition mechanism inside the FPGA is to filter out the false image data generated by a certain distance between the infrared sensor (1) and the CIS installation of the multi-light source contact image sensor.

Furthermore, the effective image acquisition state of the image acquisition mechanism inside the FPGA completes the multi-spectral bill image acquisition task. When the FPGA judges that the bill has passed the CIS and jumps into the initial waiting state, the acquisition task of an image is completed.

Further, the multi-spectral image selection can notify the FPGA to select different image acquisition schemes through the PC, and complete the acquisition of different frames or line images through the light source control circuit.

With the utility model, high-quality, multi-spectral bill image data can be quickly obtained, which can be used for bill authenticity analysis, thereby solving the high-speed and high-precision identification of bill authenticity, and improving the accuracy and stability of the bill recognition system and real-time.

Description of drawings

Fig. 1 is a schematic structural diagram of a bill image acquisition device based on CIS.

Figure 2 is a block diagram of image acquisition based on SOPC technology.

Fig. 3 is a working flowchart of the bill image acquisition device based on CIS.

Figure 4 is a state transition diagram within the FPGA used to describe the entire image acquisition process.

Detailed ways

The utility model will be described in further detail below in conjunction with the embodiments and accompanying drawings, but the implementation of the utility model is not limited thereto.

Example:

The utility model selects a three-channel CIS with multiple light sources, which include visible light, ultraviolet light and infrared light, and each light source can be individually controlled on and off to facilitate the combination of different spectra. The purpose of choosing a three-channel CIS is to reduce the time for each frame or line image acquisition of the CIS and improve the real-time performance of the equipment.

Figure 1 is a schematic structural diagram of the device, which at least includes an infrared sensor 1, a photoelectric switch sensor 2, a grating disk 3), a transmission mechanism 4, a multi-light source contact image sensor CIS5, an FPGA control circuit 6, a light source control circuit 7, and a sensor circuit 8. A/D conversion circuit 9 and DC motor 10 .

The infrared sensor 1 and the photoelectric switch sensor 2 transmit the signal to the FPGA through the filter, amplification and level conversion of the sensor circuit 8, as the field synchronization signal for CIS image acquisition. The photoelectric switch sensor 2 and the grating disc 3 mounted on the DC motor 10 cooperate to generate frame or line synchronous signals for CIS image acquisition. The field synchronization signal and frame or line synchronization signal are connected to the FPGA through the sensor circuit as the basis for the entire image acquisition.

Figure 2 is a diagram of the image acquisition module based on SOPC technology, which describes the implementation of the FPGA control module. The chip can choose the FPGA of spartan series from Xilinx Company, which has high cost performance. Xilinx provides a large number of free IP cores, which can greatly shorten the user's development cycle. The PC sends instructions to the soft-core Microblaze embedded in the FPGA through the serial port, and the FPGA controls the light source control circuit to turn on or off the light source according to different schemes through command analysis. This example uses two kinds of spectral image acquisition as an example to introduce the multi-spectral bill image acquisition and processing method.

Take the 8-bit command as an example for the constraint command of communication between PC and FPGA:

The 7th and 6th bits are reserved; the 5th bit indicates that the command configures the light color of different lines, '1' means odd-numbered lines, '0' means even-numbered lines; the 4th to 0th bits represent red light and green light respectively , blue light, infrared light and ultraviolet light, '1' means to turn on the light source, '0' means to turn off the light source. As shown in Table 1 below, if the host computer sends the '00011100'B command to the FPGA, it means that the light color of the odd-numbered rows is white light (r, g, b combined light), if the host computer sends the ''00100010'B command to the FPGA When , it means that the lighting color of the even-numbered rows is infrared light.

When completing the acquisition of a whole image, the FPGA can acquire the white light image and the infrared image only by sampling the odd and even lines. If the PC does not send commands to the FPGA, the FPGA will perform image acquisition according to the default light color parameters.

Table 1 Examples of specific light color commands

Light color selection red light green light blu ray infrared UV '00011100'B Open Open Open closure closure '00100010'B closure closure closure Open closure

The entire operation process of the device is shown in Figure 4.

Step 1: The device is powered on, the FPGA is initialized, and the PC is waiting for the multispectral parameters to be set.

Step 2: Start the motor, and if the ticket to be detected is not placed, the state of the internal image acquisition mechanism of the FPGA is the image acquisition waiting state Field_Idle. At this time, the CIS is not started and the image is not stored.

Step 3, when the bill to be detected is put in and the front end of the bill is blocked by the infrared sensor, the state of the internal image acquisition mechanism of the FPGA immediately jumps to the image acquisition delay state Field_Delay. At this time, the CIS is started but the image is not stored.

Step 4. When the FPGA judges that the ticket is directly below the CIS based on the image at the output end of the CIS, the state of the internal image acquisition mechanism of the FPGA immediately jumps to the image acquisition delay state Field_Valid, starts the CIS and stores the image.

Step 5. The state of the internal image acquisition mechanism of the FPGA is Field_Valid, and the FPGA continues to judge the relative position of the ticket and the CIS based on the image while storing the image. When the FPGA judges that all the tickets have passed directly under the CIS, the state of the internal image acquisition mechanism of the FPGA immediately jumps to Field_Idle, waiting for the next image trigger.

In order to facilitate the description of the entire image acquisition process inside the FPGA, the idea of Finite State Machine (FSM) FSM is introduced in the specific implementation. CIS is a linear sensor with its own light source, and the completion of a complete two-dimensional image acquisition requires the cooperation of field synchronization and frame or line synchronization.

The finite state machine Field_State collected as the entire image is divided into three states: Field_Idle, Field_Delay, and Field_Valid.

Field_Idle: The initial waiting state of Field_State. When the motor is not started or when the detected object passes the infrared tube sensor, Field_State is in Field_Idle; at this time, the CIS is not started; when Frame_Trig=1, that is, when the detected object passes the infrared tube sensor, Field_State will jump at this time Go to Field_Delay.

Field_Delay: The delayed waiting state of Field_State. At this time, start the CIS drive sequence, and use the external code disc signal as the line synchronization signal to trigger the image acquisition, but do not store the image; when a line of image information collected by the sampling end meets the conditions for image triggering, that is, Run_Flag=1, Field_State jumps Go to Field_Valid.

Field_Valid: Field_State is valid image acquisition state, and this state enables CIS driver and image storage at the same time. When the detected image meets the jumping condition, that is, when Stop_Flag=1, it jumps into Field_Idle and waits for the next trigger signal of the infrared pair sensor. As shown in the main state transition diagram in Figure 4.

Line_State is another finite state machine, which is used for the acquisition task of one frame image of CIS. Line_State is divided into three states: Line_Idle, Line_Delay, and Line_Valid.

When Line_State is Line_Idle, CIS is working in idle state, and no image acquisition signal is started. When the falling edge signal of the photoelectric encoder arrives, that is, Line_Trig=1, Line_State jumps into Line_Delay. The Line_Delay state is a fixed clock pulse delay, the purpose is to remove invalid pixels at the front end of the CIS; when the fixed clock pulse counter overflows, the state jumps to the valid line image acquisition state, that is, Line_Valid, to complete the acquisition of three-channel image data; After the valid pixels of the frame image are collected, the state jumps to Line_Idle, waiting for the next trigger of the line synchronization signal. As shown in Figure 4 from the state transition diagram.

The above-mentioned implementation description is a preferred implementation mode of the present utility model, but the implementation mode of the present utility model is not limited by the above-mentioned implementation description, and any other changes, modifications and substitutions made without departing from the spirit and principle of the present utility model , combination, and simplification, all should be equivalent replacement methods, and are all included in the protection scope of the present utility model.

Claims (5)

1. the multispectral bill image collecting device based on CIS, it is characterized in that, this device at least comprises infrared sensor (1), optoelectronic switch sensor (2), grating disc (3), connecting gear (4), multi-light source contact type image sensor CIS(5), FPGA control circuit (6), control circuit for light source (7), sensor circuit (8), A/D change-over circuit (9) and direct current generator (10);

Wherein, infrared sensor (1) is fixed on the front position of connecting gear (4), for detection of whether having bill to pass through on transfer structure (3), while if bill being detected by infrared sensor (1), by sensor circuit (7), the signal notice FPGA control circuit (6) producing is started to gather piece image; Otherwise, continue to detect;

Optoelectronic switch sensor (2) is fixed on a side of grating disc (3), coordinates the frame or the line synchronizing signal that produce for CIS image acquisition with grating disc (3);

Grating disc (3) is fixed on direct current generator (10) coaxial position, coordinates, for detection of the transmission speed of connecting gear (4) and frame or the line synchronizing signal that produces CIS image acquisition with optoelectronic switch sensor (2);

Connecting gear (4) by direct current generator (9) according to fixing transmission than transmission, bill is by the travelling belt gearing of connecting gear (4), fast and stable pass through infrared sensor (1) and multi-light source contact type image sensor CIS(5);

Multi-light source contact type image sensor CIS(5) be fixed on the middle end position of connecting gear (4), perpendicular to the direction of motion of bill, by FPGA control circuit (6), control the image information of detection of dynamic bill;

FPGA control circuit (6) is for controlling multispectral bill image acquisition Scheme Choice, by control circuit for light source (7), controls multi-light source contact type image sensor CIS(5) complete multi-optical spectrum image collecting task;

Control circuit for light source (7) is for connecting FPGA control circuit (6) and multi-light source contact type image sensor CIS(5), complete the light source switch operation of CIS;

Sensor circuit (8) is for filtering, amplification and the level conversion of infrared sensor (1) and optoelectronic switch sensor (2), sensor signal is converted to digital signal, the reference position gathering for judgement one sub-picture of FPGA and the enable position of a two field picture;

A/D change-over circuit (9) is for being converted to the simulating signal of CIS output digital signal and being transferred to FPGA inside;

Direct current generator (10) is for connecting gear (4) transmission, and bill on connecting gear (4) is quick, stable passes through multi-light source contact type image sensor CIS(5).

2. according to a kind of multispectral bill image collecting device based on CIS described in claims 1, it is characterized in that multi-light source contact type image sensor CIS(5) built-in visible ray, ultraviolet light, infrared light light source, and each road light source gauge tap separately.

3. according to a kind of multispectral bill image collecting device based on CIS described in claims 1, it is characterized in that, infrared sensor (1) is installed on the front position of bill direction of motion, multi-light source contact type image sensor CIS(5) be installed on the interruption position of bill direction of motion, be that bill is when the upper motion of connecting gear (4), first by infrared sensor (1), afterwards by multi-light source contact type image sensor CIS(5).

4. according to a kind of multispectral bill image collecting device based on CIS described in claims 1, it is characterized in that, FPGA has been responsible for multi-light source contact type image sensor CIS(5 in FPGA control circuit (6)) driving and light source control, image acquisition and storage.

5. according to a kind of multispectral bill image collecting device based on CIS described in claims 1, it is characterized in that, infrared sensor (1) bill by time the pulse signal field sync signal that collection starts as CIS piece image that produces, the line synchronizing signal that the pulse signal that optoelectronic switch sensor (2) coordinates grating disc (3) to produce starts as CIS mono-image frame grabber.

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