CN103024301B - The formation method of floating gate type imageing sensor - Google Patents

Abstract

The present invention proposes a kind of formation method of floating gate type imageing sensor, comprises step: resetted by each pixel cell of floating gate type imageing sensor; The primary data of reading section pixel cell; Carry out exposure image; Read data after the exposure of all pixel cells; And according to data after the primary data of partial pixel unit and the exposure of all pixel cells, carry out data operation process according to interpolation, obtain final image.It is simple that the present invention has algorithm, and operand is little, the advantage that image taking speed is fast.

Description

Imaging method of floating gate image sensor

technical field

The invention belongs to the technical field of application of floating gate image sensors, and in particular relates to an imaging method of floating gate image sensors.

Background technique

Flash memory is a common memory that is widely used in the electronic digital industry, such as smart phones and tablet computers. Flash memory realizes the storage of data through its floating gate structure, injects electrons into the floating gate through the programming operation to increase the threshold voltage of the memory cell to realize the storage of data 1, and pulls out the electrons on the floating gate through the erasing operation to reduce the The threshold voltage of the memory cell is used to realize the storage of data 0.

The floating gate image sensor is a new type of image sensor. The pixel unit of this image sensor is similar to a flash memory and adopts a floating gate structure. In a certain pressurized environment, the pixel unit of the floating gate image sensor injects the photoelectrons generated by the light signal into the floating gate through the "programming" operation to increase the threshold voltage of the pixel unit, so as to realize the recording of light intensity information, and through " The "erase" operation pulls out the electrons on the floating gate to reset the light intensity information of the pixel unit. Then through the reading circuit, the information recorded on the pixel unit can be converted into digital information, output and processed, and finally form an image.

The operation steps of the floating gate image sensor are shown in Figure 1. The "reset" operation is to restore the threshold value of the pixel unit to the initial state by means of erasing and programming; the "first data readout" operation is to use a special readout The output circuit reads out the information on the pixel unit for the first time; the "exposure imaging" operation is to expose the pixel unit, and then store the light intensity information in the pixel unit through the transformation and pressure operation; "the second data readout "The operation is to use a special readout circuit to read the information on the pixel unit for the second time; the "data operation processing" operation uses the data obtained by the second read minus the data read after reset as the final image signal . In this way, the floating gate image sensor needs to read data twice every time an image is formed. CMOS and CCD are currently the two most common image sensors, and these two image sensors only need to read data once during the imaging process. In comparison, the imaging speed of a floating gate image sensor is relatively slow.

Contents of the invention

The present invention aims at solving one of the above technical problems at least to a certain extent or at least providing a useful commercial choice. For this reason, the object of the present invention is to propose a faster solution to the data reading speed of the floating gate image sensor mentioned in the background art. The present invention proposes a faster floating gate image sensor. Imaging method.

The imaging method of a floating gate image sensor according to an embodiment of the present invention includes: A. resetting each pixel unit of the floating gate image sensor; B. reading initial data of some pixel units; C. performing exposure imaging; D. reading post-exposure data of all pixel units; and E. performing data calculation processing according to an interpolation method according to the initial data of the partial pixel units and the post-exposure data of all pixel units to obtain a final image.

In one embodiment of the present invention, the step B includes: in each row of pixel units, every k adjacent pixel units form a group, and read the initial data of the first pixel unit in the group, where K is greater than 1 and a positive integer less than the number of columns of the imaging unit in the sensor array, and the step E includes: E1. Define the value of the initial data of the unread k-1 pixel units in the group of pixel units as the value of the group The average value of the initial data of the first pixel unit and the initial data of the first pixel unit of the next group of pixel units; and E2. Subtracting the initial data of each pixel unit from the post-exposure data of each pixel unit to obtain the final image.

In the present invention, since only a part of the reset data is read, the reading time is reduced and the imaging speed is improved. At the same time, since only a part of the reset data is read, the remaining part needs to be interpolated and filled. The invention has the advantages of simple algorithm and small amount of calculation.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is the schematic diagram of the imaging method of existing floating gate type image sensor

Fig. 2 is the schematic diagram of the imaging method of the floating gate image sensor of the present invention

Figure 3 is a schematic diagram of a floating gate image sensor with an m×n pixel cell array

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Orientation or position indicated by "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. The relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, therefore It should not be construed as a limitation of the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

In the present invention, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection" and "fixation" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , or integrally connected; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the present invention, unless otherwise clearly specified and limited, a first feature being "on" or "under" a second feature may include direct contact between the first and second features, and may also include the first and second features Not in direct contact but through another characteristic contact between them. Moreover, "above", "above" and "above" the first feature on the second feature include that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. "Below", "beneath" and "under" the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.

The invention proposes a new imaging method of the floating grid image sensor, which can help the floating grid image sensor to achieve faster imaging speed.

As shown in Figure 2, the imaging method of the present invention comprises the following steps:

A. Reset the pixel unit, and restore the threshold value of the pixel unit to the initial state by means of erasing and programming.

B. Perform data reading after reset. In this step, for a photosensitive array with m×n pixel units (as shown in Figure 3), in each row of pixels, read data every k pixels (wherein, k<n), the specific operation is : Each k pixel is a group, and the first one of this group of data is taken out of the value of each group (for example, P _m-1,1 , P _m-1,2 , P _m-1,3 , P _m-1,4. ,...,P _m-1,k-1 , P _m-1,k are a group of k pixels, and the group of pixels can only read after reset out the value of P _m-1,1 ). In this way, the number of data reads after reset will be reduced to the original 1/k, and the read time will also be reduced to the original 1/k. Among them, the value of k can be adjusted within a certain range according to the needs of imaging accuracy. The smaller the value of k, the higher the imaging accuracy but the slower the imaging speed. Conversely, the larger the value of k, the lower the imaging accuracy but the faster the imaging speed. When k is 1, the data after reset is completely read. At this time, the speed is the slowest but the precision is the highest.

C. Carry out exposure imaging, and save the image information on the image sensor.

D. Read out all the data on the pixel after exposure and imaging.

E. Process the data after exposure and imaging with the data read out in the second step to obtain the final image. In the "data operation and processing" link, the interpolation method is used to approximately restore the k-1 data that has not been read out of every k data in the second step. The specific implementation method of the interpolation method is: in each group of data, the values of the k-1 pixels that have not been read out are taken from the value read out of the group they are in and the value read out in the next group. The average value of values (for example, P _m-1,2 , P _m-1,3 , P _m-1,4 .,...,P _m-1,k of row m-1 in Fig. 3 The value of -1 pixel is the average value of this group of readout values P _m-1,1 and the next group of readout values P _m-1,k+1 , and the next group of unread k-1 in this row pixels P _m-1,k+2 , P _m-1,k+3 , P _m-1,k+4 ,...,P _m-1,2k , will take P _m-1,k+1 and P _{m-1, the average value of 2k+1} , and so on), because the reset operation can uniformly restore the pixels to the initial threshold, so the method of partially reading the reset data can ensure the accuracy of the data.

In the present invention, since only a part of the reset data is read, the reading time is reduced and the imaging speed is improved. At the same time, since only a part of the reset data is read, the remaining part needs to be interpolated and filled. The invention has the advantages of simple algorithm and small amount of calculation.

Any process or method descriptions in flowcharts or otherwise described herein may be understood to represent modules, segments or portions of code comprising one or more executable instructions for implementing specific logical functions or steps of the process , and the scope of preferred embodiments of the invention includes alternative implementations in which functions may be performed out of the order shown or discussed, including substantially concurrently or in reverse order depending on the functions involved, which shall It is understood by those skilled in the art to which the embodiments of the present invention pertain.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limitations to the present invention. Variations, modifications, substitutions, and modifications to the above-described embodiments are possible within the scope of the present invention.

Claims (1)

1. An imaging method of a floating gate type image sensor, characterized in that, comprising: A. Resetting each pixel unit of the floating gate image sensor; B. Read the initial data of some pixel units, specifically including: in each row of pixel units, each adjacent k pixel units form a group, and read the initial data of the first pixel unit of the group, wherein k is greater than 1 and a positive integer less than the number of columns of imaging elements in the sensor array; C. Perform exposure imaging; D. Reading the post-exposure data of all pixel units; and E. According to the initial data of the part of the pixel units and the exposed data of all the pixel units, perform data calculation processing according to the interpolation method to obtain the final image, specifically including: E1. Define the value of the initial data of the unread k-1 pixel units in the group of pixel units as the initial data of the first pixel unit in the group and the initial data of the first pixel unit in the next group of pixel units the mean of the data; E2. Subtracting the initial data of each pixel unit from the post-exposure data of each pixel unit to obtain a final image.