General printer driving system

Abstract

The invention discloses a general printer driving system, and relates to the technical field of embedded system control, a single-chip microcomputer module of the system can read a file to be printed from a memory card, contrast enhancement and image scaling are carried out through an image processing algorithm, and character codes of a printer support protocol are packaged. The single-chip microcomputer module operates a control algorithm, drives a circuit through a communication interface, and operates a general printer according to a printing language protocol specification supported by the printer to complete file printing. The problem that a single-chip microcomputer cannot directly operate a general printer to perform printing operation is solved, and the function that an embedded system comprising the single-chip microcomputer directly drives any general printer is achieved. And meanwhile, the transmission rate, reliability and anti-interference characteristic of the printing data are also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of embedded system control, and particularly to a general printer driver system directly controlled by a single-chip microcomputer. Background Art

[0002] A printer is one of the output devices of a computer, used to print the processing results of the computer on relevant media. A printer driver refers to a software program installed in a computer for controlling and managing a printer. It acts as a bridge between the computer and the printer, converting the computer's instructions into commands that the printer can understand and execute. Printer drivers not only include basic functions such as printing, scanning, and copying, but also provide more advanced features and options such as paper size setting, print quality selection, and multi-functional layout.

[0003] Currently, general printers on the market are generally connected by a computer system such as a PC or a server through a USB interface or a parallel interface. A printer driver software is installed on the computer operating system, and then the application program on the computer calls the driver software to implement the printing operation. A single-chip microcomputer generally does not have an operating system. Even if an embedded operating system is installed on the single-chip microcomputer, almost no printer manufacturers provide corresponding driver software.

[0004] It can be seen that it is currently very difficult to directly drive a general printer to perform printing operations with a single-chip microcomputer. Only in some specific industries, there are special printers that can be driven by a single-chip microcomputer, such as cash register printers and label printers. However, these special printers often have limited single-chip microcomputers that can be matched, and generally can only print special specification papers such as thermal paper, and it is difficult to print general papers such as A4 or A3.

[0005] Therefore, how to directly operate a general printer with a single-chip microcomputer is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of the above problems, the present invention provides a general printer driver system for overcoming the above problems or at least partially solving the above problems. It solves the need of the prior art for a single-chip microcomputer system to directly operate a general printer to perform printing operations, and at the same time improves the rate, reliability, and anti-interference characteristics of print data transmission.

[0007] The present invention provides the following solutions:

[0008] A general printer driver system includes:

[0009] Embedded single-chip microcomputer module and communication interface driving circuit; the communication interface driving circuit is connected to the embedded single-chip microcomputer module, and the communication interface driving circuit is used to enumerate and initialize the communication interface of a general printer, so that the embedded single-chip microcomputer module establishes a communication connection with the general printer;

[0010] The embedded single-chip microcomputer module is used to run a printer driver algorithm; the printer driver algorithm is used to perform the following operations:

[0011] Parse the BMP picture to be printed input by the user to obtain picture information;

[0012] Convert the BMP picture to be printed into a grayscale picture according to the picture information;

[0013] Adopt the histogram equalization algorithm to enhance the contrast of the grayscale picture, and convert the grayscale picture into a 2-color picture supported by the general printer through the digital halftoning algorithm;

[0014] Adopt the bilinear interpolation algorithm to scale the 2-color picture to obtain a scaled 2-color picture;

[0015] Convert the scaled 2-color picture into the print format required by the print language supported by the general printer, and send it to the general printer.

[0016] Preferably: the parsing of the BMP picture to be printed input by the user to obtain picture information includes:

[0017] Read the first 54 bytes from the BMP picture to be printed. Among them, obtain the file header of the BMP picture to be printed from the first 14 bytes. The file header includes the type and file size information of the BMP image, and obtain the width, height, compression method and defined color information of the file header from the last 40 bytes.

[0018] Preferably: the conversion of the BMP picture to be printed into a grayscale picture according to the picture information includes:

[0019] According to the weighted average method, the RGB values of each pixel in the BMP picture to be printed are weighted and averaged according to the target weights to obtain the grayscale value corresponding to the BMP color image.

[0020] Preferably: the target weights are determined according to the survey results based on the light characteristics and the human eye's sensitivity to different colors.

[0021] Preferably: after obtaining the grayscale value, fill the corresponding data into the BMP grayscale picture in the BMP format. The weighted average of the grayscale value is shown in the following formula:

[0022] Gray = 0.299 * Red + 0.587 * Green + 0.114 * Blue

[0023] Where: 0.299 is the weight of the red channel, 0.587 is the weight of the green channel, and 0.114 is the weight of the blue channel.

[0024] Preferably: Converting the grayscale image to a two-color image supported by the general printer through a digital halftoning algorithm includes:

[0025] Using dot-discrete ordered dithering with the dithering method, measuring the visual visibility of various artificial textures by performing Fourier analysis on the dot pattern under different brightness conditions to obtain an optimal ordered dithering matrix.

[0026] Preferably: The bilinear interpolation algorithm includes linearly interpolating the grayscale value f(0,0) and f(1,0) of adjacent pixels in the X direction to obtain the grayscale f(x,0) of (x,0), and linearly interpolating the grayscale value f(0,1) and f(1,1) of the other two adjacent pixels in the X direction to obtain the grayscale f(x,1) of (x,1); linearly interpolating the grayscale f(x,0) and f(x,1) in the Y direction to obtain the grayscale f(x,y) of (x,y).

[0027] Preferably: The general printer includes a printer that supports the PCL5 protocol printing language and a USB interface, and the communication interface drive circuit includes a USB drive circuit.

[0028] Preferably: The embedded single-chip microcomputer module includes a general 32-bit embedded processor with a main frequency greater than or equal to 200 MHz.

[0029] Preferably: The embedded single-chip microcomputer module communicates with the USB drive circuit through an 8-bit parallel data interface.

[0030] According to the specific embodiments provided by the present invention, the following technical effects are disclosed in the present invention:

[0031] A general printer drive system provided by an embodiment of the present application. The single-chip microcomputer module can read the file to be printed from the memory card, perform contrast enhancement and image scaling through an image processing algorithm, and encapsulate it into a character encoding supported by the printer protocol. The single-chip microcomputer module runs a control algorithm through the communication interface drive circuit and operates the general printer according to the printing language protocol specification supported by the printer to complete the printing of the file. It solves the problem that the single-chip microcomputer cannot directly operate the general printer for printing operations, and realizes the function of directly driving any general printer by an embedded system including a single-chip microcomputer. At the same time, it also improves the transmission rate, reliability, and anti-interference characteristics of the printing data.

[0032] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0034] Figure 1 is a framework diagram of a general printer driver system provided by an embodiment of the present invention;

[0035] Figure 2 is a flowchart of the operation of a general printer driver system provided by an embodiment of the present invention.

[0036] In the figure: embedded single-chip microcomputer module 1, communication interface drive circuit 2, image processing algorithm 3, control algorithm 4, general printer 5. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0038] See Figure 1 , a general printer driver system provided by an embodiment of the present invention, as Figure 1 shown, the system may include:

[0039] An embedded single-chip microcomputer module 1 and a communication interface drive circuit 2; the communication interface drive circuit 2 is connected to the embedded single-chip microcomputer module 1, and the communication interface drive circuit 2 is used to enumerate and initialize the communication interface of the general printer 5 so that the embedded single-chip microcomputer module 1 establishes a communication connection with the general printer 5;

[0040] The embedded single-chip microcomputer module 1 is used to run printer driver algorithms (image processing algorithm 3, control algorithm 4); the printer driver algorithms are used to perform the following operations:

[0041] Parse the BMP image to be printed input by the user to obtain image information; specifically, in implementation, the embodiments of the present application can provide to read the first 54 bytes from the BMP image to be printed. Among them, obtain the file header of the BMP image to be printed from the first 14 bytes, and the file header includes the type and file size information of the BMP image. Obtain the width, height, compression method, and defined color information of the file header from the last 40 bytes.

[0042] Convert the BMP image to be printed into a grayscale image according to the image information; specifically, in implementation, the embodiments of the present application can provide to perform weighted averaging on the RGB values of each pixel in the BMP image to be printed according to the target weights according to the weighted average method to obtain the grayscale value corresponding to the BMP color image.

[0043] Furthermore, the target weights are determined according to the investigation results based on the light characteristics and the sensitivity of the human eye to different colors.

[0044] After obtaining the grayscale value, fill the corresponding data into the BMP grayscale image in the BMP format. The grayscale value weighted average is shown as follows;

[0045] Gray = 0.299 * Red + 0.587 * Green + 0.114 * Blue

[0046] In the formula: 0.299 is the weight of the red channel, 0.587 is the weight of the green channel, and 0.114 is the weight of the blue channel.

[0047] Adopt the histogram equalization algorithm to enhance the contrast of the grayscale image, and convert the grayscale image into a 2-color image supported by the general printer through the digital halftone algorithm; specifically, in implementation, the embodiments of the present application can provide to use the dot discrete state ordered dithering of the dithering method, and measure the visual visibility of various artificial textures by performing Fourier analysis on the dot pattern under different brightness conditions to obtain the optimal ordered dithering matrix, so that the screened image retains the most detailed information compared with the processing result of using the dot aggregation state ordered dithering.

[0048] Adopt the bilinear interpolation algorithm to scale the 2-color image to obtain the scaled 2-color image; specifically, in implementation, the embodiments of the present application can provide that the bilinear interpolation algorithm includes linearly interpolating the grayscale values f(0,0) and f(1,0) of adjacent pixels in the X direction to obtain the grayscale f(x,0) of (x,0), and linearly interpolating the grayscale values f(0,1) and f(1,1) of two other adjacent pixels in the X direction to obtain the grayscale f(x,1) of (x,1); linearly interpolating in the Y direction by f(x,0) and f(x,1) to obtain the grayscale f(x,y) of (x,y).

[0049] Convert the scaled 2-color image into the print format required by the print language supported by the general printer, and send it to the general printer.

[0050] The system provided by the embodiments of the present application can be applied to a variety of different printers. When in use, it only needs to be adjusted according to the connection interface and print language of the printer. For example, in one implementation, the embodiments of the present application can provide that the general printer includes a printer with a print language supporting the PCL5 protocol and a USB interface, and the communication interface driver circuit includes a USB driver circuit.

[0051] Furthermore, the embedded single-chip microcomputer module 1 includes a general 32-bit embedded processor with a main frequency greater than or equal to 200 MHz. The embedded single-chip microcomputer module communicates with the USB driver circuit through an 8-bit parallel data interface.

[0052] The general printer driver system provided by the present application realizes direct operation of a general printer by a single-chip microcomputer; runs image processing algorithms and control algorithms on the embedded single-chip microcomputer module; and is connected to the general printer through a communication driver circuit, realizing direct control and data transmission of the general printer.

[0053] Taking a general printer with a USB communication interface and a PCL5 print language as an example, the general printer driver system provided by the present application will be introduced in detail below.

[0054] The embodiments of the present application can provide a driver system for a general printer directly operated by a single-chip microcomputer. The system can include: an embedded single-chip microcomputer module 1 and a USB driver circuit 2. The embedded single-chip microcomputer module is used to run a printer driver algorithm, and the printer driver algorithm can include an image processing algorithm 3 and a control algorithm 4; the embedded single-chip microcomputer module can be communicatively connected to a general printer 5 through the USB driver circuit.

[0055] The embedded single-chip microcomputer module is a 32-bit processor with a main frequency above 200 MHz, and runs image processing algorithms and control algorithms internally; the USB driver circuit constructs a USB bus driver circuit with a domestic CH376S bus conversion chip as the core; the embedded single-chip microcomputer module communicates with the USB driver circuit through an 8-bit parallel data interface; the USB driver circuit is connected to the general printer through a USB bus.

[0056] The embedded single-chip microcomputer module is based on a general 32-bit embedded processor and can be used as long as the main frequency is greater than or equal to 200 MHz; the general printer is an ordinary printer supporting the PCL5 protocol and a USB interface.

[0057] It is also possible to effectively suppress high-frequency interference to 8-bit parallel data transmission during the operation of the embedded single-chip microcomputer module and the general printer through anti-interference design of the data bus, avoiding data loss or control instruction errors.

[0058] Among them, the USB drive circuit 2 is used to perform USB enumeration and initialization on the general printer 5. The single-chip microcomputer module 1 reads and writes the memory card through the SDIO protocol to implement the FATFS file management system. The image processing algorithm 3 running on the single-chip microcomputer module 1 realizes the parsing of BMP pictures, obtains picture information, converts the color picture into a grayscale picture, enhances the picture contrast through the histogram equalization algorithm, and converts the grayscale picture into a 2-color picture supported by the black and white laser printer through the digital halftone algorithm; changes the size of the printed picture through the bilinear interpolation algorithm. The control algorithm 4 running on the single-chip microcomputer module 1 converts the 2-color picture data into the print format required by the PCL5 print language and encapsulates and optimizes various functions.

[0059] When specifically implemented, the image processing algorithm 3 mainly parses the format of the BMP picture. Its processing process is as follows: read the first 54 bytes from the BMP image file. Among them, obtain the BMP file header from the first 14 bytes, including information such as the type and file size of the BMP image, and obtain the width, height, compression method, and color definition information of the BMP image from the last 40 bytes, and convert these key information into a format data stream for subsequent algorithms to use.

[0060] Since the general printer 5 involved in the embodiment of the present application only supports black and white, it is necessary to convert the BMP image into a grayscale image. According to the weighted average method, the RGB values of each pixel in the color image are weighted and averaged according to a certain weight to obtain the grayscale value corresponding to the BMP color image. The weights usually used are determined based on the results of investigations on the characteristics of light and the sensitivity of the human eye to different colors. Because the human eye has the highest sensitivity to green, followed by red, and the lowest to blue, the usual weight settings are: red channel weight: 0.299, green channel weight: 0.587, blue channel weight: 0.114. The specific formula is shown in Formula 1. After obtaining the grayscale value, fill the corresponding data into the BMP grayscale image according to the BMP format. The grayscale value weighted average is set as follows:

[0061] Gray = 0.299 * Red + 0.587 * Green + 0.114 * Blue

[0062] To improve the difficulty of the human eye in obtaining image details, the embodiment of the present application uses histogram equalization to increase the local contrast of the image, enhance the contrast of pictures that are too bright or too dark, but does not affect the overall contrast. The histogram equalization algorithm is shown as follows:

[0063]

[0064] To adapt to the printing of images of different sizes, the system provided by this application uses the bilinear interpolation algorithm to scale BMP images, avoiding the problem of image quality degradation caused by discontinuous pixel values. The basic principle of the bilinear interpolation algorithm is to calculate the linear interpolation based on the gray values of the four pixel points around the original pixel point. The image scaling and contrast enhancement algorithms based on the bilinear interpolation theory convert the original file to be printed into a lightweight data stream suitable for processing by an embedded system, improving the data transmission speed between the USB driver circuit and the printer.

[0065] The basic process is that the gray value f(x,0) of (x,0) is linearly interpolated in the X direction from the gray values f(0,0) and f(1,0) of adjacent pixels, and the gray value f(x,1) of (x,1) can be obtained by linearly interpolating f(0,1) and f(1,1) of the other two adjacent pixels in the X direction. Finally, the gray value f(x,y) of (x,y) can be obtained by linearly interpolating f(x,0) and f(x,1) in the Y direction. Therefore, the calculation formula of the bilinear interpolation algorithm is: f(i+u,j+v)

[0066] =(1 - u)(1 - v)f(i,j)+u(1 - v)f(i + 1,j)+(1 - u)vf(i,j + 1)

[0067] +uvf(i + 1,j + 1)

[0068] This application uses halftone technology to make an image with rich tones be presented as close as possible to the original image on a binary device. The core of halftone technology lies in taking advantage of the visual characteristics of the human eye. By treating several or more points as a whole in space and taking the average value, the color of the original image is quantified, so that when observing the halftone-processed image, a continuous effect can be formed as a whole, making the converted image visually similar to the original image within a certain distance.

[0069] This application mainly uses the dot discrete state ordered dither of the dithering method. By performing Fourier analysis on the dot pattern under different brightness conditions, the visual visibility of various artificial textures is measured, and the optimal ordered dither matrix is designed. The screened image obtained can retain more detailed information than the processing result using the dot aggregation state ordered dither, and has a better visual effect.

[0070] The system provided by this application integrates and encapsulates PCL5 printer language commands, converting them into a convenient function form. By calling the corresponding functions, precise control and efficient instruction transmission to the PCL5 printer can be achieved. For example, the instruction to set the number of copies to be printed by the printer is: Esc&l#X

[15] . However, since the printer only recognizes ASCII codes, the instruction needs to be converted to ASCII codes first and then sent to the printer according to the PCL5 printing format. It can be seen that the single-chip microcomputer printing language instructions compliant with the PCL5 protocol are provided, the data transmission and control instructions based on the USB bus are realized, and the basic function of directly operating a general printer by the embedded single-chip microcomputer module to perform a printing operation is completed.

[0071] The system operation process provided by this application is as Figure 2 shown.

[0072] After the system is powered on, the hardware is first initialized, including the clock initialization of the single-chip microcomputer module 1, the LED initialization, the initialization of the control pins of the USB drive circuit 2, and the SD initialization. After the initialization is completed, the SD card is detected. If an SD card is inserted and the SD card does not load the file system management, then the file management system of the SD card is initialized. After completion, the printer USB is enumerated. If the enumeration fails, a reset is performed and then it is executed again. If the enumeration is successful, the photo is read from the SD card, then the color picture is converted into a grayscale picture, and then the histogram equalization is performed on the grayscale picture. After completion, bilinear interpolation is performed on the picture to obtain a scaled picture. Then, the halftone algorithm conversion is performed on the picture to obtain image data composed only of 0 and 1. Then, the data is converted into the PCL5 format and sent to the printer. After receiving the data, the printer starts printing.

[0073] In summary, for the general printer driver system provided by this application, the single-chip microcomputer module can read the file to be printed from the memory card, perform contrast enhancement and image scaling through image processing algorithms, and encapsulate them into character encodings supported by the printer protocol. The single-chip microcomputer module runs the control algorithm through the communication interface drive circuit and operates the general printer according to the printing language protocol specifications supported by the printer to complete the printing of the file. It solves the problem that the single-chip microcomputer cannot directly operate the general printer to perform a printing operation, and realizes the function of directly driving any general printer by the embedded system containing the single-chip microcomputer. At the same time, it also improves the transmission rate, reliability and anti-interference characteristics of the printing data.

[0074] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0075] From the description of the above embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of this application, in essence, or the part that makes a contribution to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disc, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0076] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the key point of each embodiment is to illustrate the differences from other embodiments. In particular, for a system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The systems and system embodiments described above are only illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A universal printer driver system, characterized in that: It includes an embedded single-chip microcomputer module and a communication interface driving circuit; the communication interface driving circuit is connected to the embedded single-chip microcomputer module, and the communication interface driving circuit is used to enumerate and initialize the communication interface of the universal printer so that the embedded single-chip microcomputer module establishes a communication connection with the universal printer; The embedded single-chip microcomputer module is used to run the printer driver algorithm; the printer driver algorithm is used to perform the following operations: Parse the BMP image to be printed input by the user to obtain image information; Converting the to-be-printed BMP image into a grayscale image according to the image information; A histogram equalization algorithm is used to enhance the contrast of the grayscale image, and a digital halftone algorithm is used to convert the grayscale image into a two-color image supported by the universal printer; Scaling the two-color image using a bilinear difference algorithm to obtain a scaled two-color image; The scaled two-color image is converted into a printing format required by a printing language supported by the universal printer, and sent to the universal printer.

2. The universal printer driving system according to claim 1, characterized in that: The step of parsing the BMP picture to be printed input by the user to obtain picture information includes: The first 54 bytes are read from the BMP image to be printed, wherein the file header of the BMP image to be printed is obtained from the first 14 bytes, the file header including the type and file size information of the BMP image, and the width, height, compression method and color definition information of the file header are obtained from the last 40 bytes.

3. The universal printer driving system according to claim 1, characterized in that: The converting the to-be-printed BMP picture into a grayscale picture according to the picture information comprises: According to the weighted average method, the RGB value of each pixel in the BMP image to be printed is weighted averaged according to the target weight to obtain the gray value corresponding to the BMP color image.

4. The universal printer driving system according to claim 3, characterized in that: The target weights are determined based on findings based on light characteristics and the sensitivity of the human eye to different colors.

5. The universal printer driving system according to claim 4, characterized in that: After obtaining the grayscale value, fill the corresponding data into the BMP grayscale image in BMP format. The weighted average of the grayscale value is shown as follows: Gray=0.299*Red+0.587*Green+0.114*Blue Where: 0.299 is the red channel weight, 0.587 is the green channel weight, and 0.114 is the blue channel weight.

6. The universal printer driving system according to claim 1, characterized in that: The grayscale image is converted into a two-color image supported by the universal printer by a digital halftone algorithm, comprising: The point discrete state orderly dithering of the dithering method is used. The visual visibility of various artificial textures is measured by Fourier analysis of the point pattern under different brightness conditions to obtain the optimal orderly dithering matrix.

7. The universal printer driving system according to claim 1, characterized in that: The bilinear interpolation algorithm includes linearly interpolating the grayscale values ​​of adjacent pixels f(0,0) and f(1,0) in the X direction to obtain the grayscale f(x,0) of (x,0), and linearly interpolating the grayscale f(x,1) of (x,1) in the X direction from the other two adjacent pixels f(0,1) and f(1,1); and linearly interpolating f(x,0) and f(x,1) in the Y direction to obtain the grayscale f(x,y) of (x,y).

8. The universal printer driving system according to claim 1, characterized in that: The universal printer includes a printer supporting the printing language of the PCL5 protocol and a USB interface, and the communication interface driving circuit includes a USB driving circuit.

9. The universal printer driving system according to claim 8, characterized in that: The embedded single-chip microcomputer module includes a general 32-bit embedded processor with a main frequency greater than or equal to 200 MHz.

10. The universal printer driving system according to claim 9, characterized in that: The embedded single-chip microcomputer module communicates with the USB drive circuit via an 8-bit parallel data interface.

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