Patent Publication Number: US-6667763-B1

Title: Image-Sensor emulating device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to an image-sensor emulating device. More particularly, it relates to an image-sensor emulating device capable of emulating image sensor output signals and generating image-sensor timing signals for use in debugging an image processing system or image-sensor under development. 
     2. Description of the Related Art 
     FIG. 1 schematically illustrates a circuit block diagram of a scanner  10 . In FIG. 1, a light-source driver  101  of the scanner  10  controls a light source (not shown in FIG. 1) to scan an object and obtain an image pattern  102 . The image pattern  102  is processed through the mechanism of projection and focus and then received by an image-sensor  103 , for example a CCD or CIS device. The image-sensor  103  is controlled by the timing signal (Timing) transmitted from a scanner-engine controller  106 . The image pattern  102  processed by the image-sensor  103  is amplified by an amplifier  104  and then inputted to an analog-to-digital (A/D) converter  105 , thereby converting the analog image data amplified by the amplifier  104  to digital image data. At the time of A/D conversion, the scanner-engine controller  106  outputs a reference voltage to the A/D converter  105  via a digital-to-analog (D/A) converter  110 . The converted digital image data is stored in a memory buffer  109  for further processing via the scanner-engine controller  106 . The memory buffer  109 , for example, has FIFO structure and consists of SRAM. When the image data are displayed in a host system  108 , the scanner-engine controller  106  reads and processes the digital image data from the memory buffer  109 . Then the digital image data is sent to the host system  108  for display via an interface controller  107 . 
     In addition to the devices mentioned above, a scanner further comprises an oscillator  111  for providing elementary timing signals, a power-on-reset device  112  for power management, a step-motor driver  113  monitored by the scanner-engine controller  106 , and other sensors  114  such as PIP, POP, etc. The scanner can also connect to other peripheral devices, if necessary, via the interface controller  107 . 
     During the process of developing a scanner, if the scanner output images have defects or do not meet the desired level of quality, the problem-may originate in the image-sensor  103 . For example, the characteristic of the image-sensor  103  could be poor or the image patterns  102  could be distorted by noise before being inputted to the image-sensor  103 . If the image-sensor  103  functions without problems, then the problems must occurring in the subsequent processing circuits, such as the A/D converter, etc. 
     At present, function generators can not emulate the output signals of image-sensors or the timing signals controlling the image-sensors. Engineers can not use function generators to emulate “proper” output signals of image-sensors and “proper” timing signals for triggering the image-sensors to supply to the subsequent processing circuits, thereby testing whether or not the subsequent processing circuits are functioning correctly. Therefore, the debugging process is more complicated and time consuming. 
     SUMMARY OF THE PRESENT INVENTION 
     In view of these problems, one object of the present invention is to provide an emulating device for emulating the functions of image-sensors by programmably generating the relevant image-sensor and timing signals. The timing signals also can be generated from timing signals outputted by an outside image-sensor. Therefore, the emulating device can generate predetermined image-sensor signals and timing signals such that the debugging process is simplified and the developing efficiency is also improved. Moreover, the emulating device according to the present invention can also generate a timing signal serving as a reference timing signal for emulating image-sensors. The reference timing signal can be used to compare with the actual timing signals of image-sensors. 
     In order to achieve the above objects, an image-sensor emulating device is provided for emulating the functions of the image-sensors of an image processing system in a debugging process. The image-sensor emulating device comprises: a controller establishing a link with a host system in which the image processing system displays images via the internal bus of the host system, the controller generating a reference timing signal for sensing images; at least one buffering memory device for storing reference image patterns downloaded from the host system to the controller; and at least one output converter receiving the reference image patterns read from the buffering memory device by the controller and converting the reference image patterns as output signals of the image-sensor emulating device; wherein, the controller reads the reference image patterns in response to the reference timing signal for image sensing generated by the controller itself or a timing signal generated by the image processing system. 
    
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS 
     The following detailed description, given by way of example and not intended to limit the invention solely to the embodiments described herein, will best be understood in conjunction with the accompanying drawings, in which: 
     FIG. 1 schematically illustrates a circuit block diagram of a scanner; 
     FIG. 2 illustrates an arrangement of the image-sensor emulating device applied in a debugging process of a scanner; 
     FIG. 3 illustrates a circuit block diagram of a first embodiment according to the present invention; and 
     FIG. 4 illustrates a circuit block diagram of a second embodiment according to the present invention. 
     FIG. 5 illustrates a circuit block diagram of a third embodiment according to the present invention. 
    
    
     DETAILED DESCRIPTIONS OF THE PRESENT INVENTION 
     FIG. 2 illustrates an arrangement of the image-sensor emulating device applied in the debugging process of a scanner, wherein the same devices as described in FIG. 1 are depicted with the same notations and numerals. In FIG. 2, the numeral  200  represents an image-sensor emulating device according to the present invention. 
     The image-sensor emulating device  200  establishes a link with a host system ( 108 ) via an internal bus ( 202 ) of the host system such as one of the buses ISA, EISA, PCI. The image-sensor emulating device  200  is triggered to output emulating signals in response to a timing signal (S_timing) generated by the scanner-engine controller  106 , or to a reference timing signal (R_timing) for image sensing generated by the image-sensor emulating device itself. The R_timing signal generated by the image-sensor emulating device can be compared with the S 13  timing signal generated by the scanner-engine controller  106  for carrying out the debugging process. 
     First Embodiment 
     FIG. 3 illustrates a circuit block diagram of a first embodiment according to the present invention. The image-sensor emulating device  200  according to the first embodiment is described as follows. A controller  300  establishes a link with a host system  108  via the ISA bus of the host system. The ISA bus comprises address bus (Address_bus), data bus(Data_bus), and control bus (Control_bus). A first and a second memory device ( 301   a ,  301   b ) store reference image patterns downloaded from the host system  108  to the controller  300 . A first and a second buffer ( 302   a ,  302   b ) control the transmitting directions of data flows stored in the first and second memory devices ( 301   a ,  301   b ). 
     A first output converter OPC 1  comprises a first digital-to-analog (D/A) converter  303   a  and a filtering amplifier  304   a . A second output converter OPC 2  comprises a second digital-to-analog (D/A) converter  303   b  and a filtering amplifier  304   b . These two output converters (OPC 1 , OPC 2 ) convert the digital data read from the memory devices ( 301   a ,  301   b ) into analog data and output the analog data. 
     When the image-sensor emulating device  200  is applied to a debugging process, reference image patterns or standard image patterns are first loaded into the memory devices ( 301   a ,  301   b ). Next, the scanner-engine controller  106  outputs image sensing timing signal (S-timing) for utilization by the controller  300  to emulate the functions of an image-sensor. In addition, the controller  300  can be operated in response to the reference timing signal (R-timing) generated by itself. Then, the image patterns stored in the memory devices ( 301   a ,  301   b ) are respectively outputted to the output converters (OPC 1 , OPC 2 ) by the controlling of the controller  300 . In the first embodiment, the output signals (OS, CS) of the output converters (OPC 1 , OPC 2 ) emulate the main output signal and the compensation signal of the image-sensor in a scanner respectively. The output signals (OS, CS) are amplified by the amplifier  104  and then are displayed in the host system  108 . The debugging process can be carried out by comparing the displayed image patterns with the reference image patterns. 
     In addition, the image-sensor emulating device can if necessary provide a subsystem memory device  305  consisting of ROM or RAM memory for storing the controlling programs, messages, and data, etc., utilized by the controller  300 . 
     From the above descriptions, the image-sensor emulating device is able to generate predetermined image signals (OS and CS), therefore replacing the functions of the image-sensor. By using the image-sensor emulating device to provide relevant signals generated by image-sensors, engineers can carry out the debugging process directed to the processing circuits subsequent to the image-sensors. Consequently, the efficiency and accuracy of circuit debugging is improved. Moreover, the reference timing signal (R_timing) generated by the image-sensor emulating device can also be compared with the image-sensing timing signal (S_timing) of the scanner for carrying out the debugging process. The reference timing signal (R_timing) can be programmed according to the actual application. 
     Second Embodiment 
     FIG. 4 illustrates a circuit block diagram of a second embodiment according to the present invention, wherein the same devices as described in the first embodiment are depicted with the same notations and numerals. 
     Comparing FIG. 3 with FIG. 4, the difference between the first embodiment and the second embodiment is that the second uses two dual port memory devices  400   a  and  400   b  for storing the image patterns downloaded from the host system  108 . Because the host system  108  and the controller  300  can access (read and write) the two dual port memory devices  400   a  and  400   b  at different addresses simultaneously, the efficiency of downloading the image patterns from the host system  108  to the image-sensor emulating device  200  can be improved. The first and second buffer  302   a  and  302   b  also can be eliminated. The other functions of the second embodiment are the same as the first embodiment, and thus the descriptions are omitted here. 
     Third Embodiment 
     FIG. 5 illustrates a circuit block diagram of a third embodiment according to the present invention, wherein the same devices as described in the first embodiment are depicted with the same notations and numerals. 
     Comparing FIG. 3 with FIG. 5, the difference between the first embodiment and the third embodiment is that the third embodiment does not use the first and second buffers in the first embodiment. Therefore, in the second embodiment, the image patterns stored in the memory device  301   a  and  301   b  are read by the controller  300  first and stored temporarily in the controller  300 , and then transmitted to the output converters (OPC 1 , OPC 2 ). The other functions of the second embodiment are the same as the first embodiment, and thus the descriptions are omitted here. 
     In the above embodiments, the emulating device is applied to the image systems of scanners, but it is not limited to scanners. The emulating device can be applied to any image systems with image-sensors such as CCD and CIS, etc., for improving the efficiency of the debugging process. In addition, because the emulating device establishes links with various host systems via various standard peripheral interface buses, it can connect to different host system without any problem. Therefore, the emulating device according to this invention has portability and the ability of independent off-line functions. The sizes and numbers of the memory devices used to store image patterns are determined according to the sizes of the image patterns to be downloaded. 
     From above descriptions, both the image-sensor emulating device and the scanner are linked to the same host system. However, the image-sensor emulating device and the scanner also can be linked to two different host system respectively. 
     While the invention has been described by way of examples and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.