KR20080061052A - Calibration system and calibration method of linear light sensor - Google Patents

Abstract

It is an object of the present invention to provide an apparatus and method for calibrating a linear optical sensor that can equalize the sensitivity of all the optical sensors using the measured values of the optical sensors constituting the array.

The linear optical sensor correction system of the present invention includes a linear optical sensor formed of a plurality of arrays for outputting a predetermined incident light as a photocurrent value; A memory for storing the photocurrent value whose sensitivity is calculated using the photocurrent value and the dark current value of the linear optical sensor and the photocurrent value whose sensitivity is uniform; And a data processor for calculating the photocurrent value whose sensitivity is corrected and the photocurrent value whose sensitivity is uniform.

Description

CALIBRATION SYSTEM FOR LINEAR PHOTODIODE AND METHOD FOR THE SAME

1 is a block diagram of a linear optical sensor correction system according to the present invention,

2 is a photocurrent characteristic graph of the linear optical sensor,

3 is an optical characteristic graph of an optical sensor uniformed using a correction system according to the present invention.

* Description of the main parts of the drawings *

110: linear array optical sensor 120: data processing unit

130: memory

The present invention relates to correcting a photocurrent value output from an optical sensor, and more particularly, to a linear optical sensor for improving the uniformity of an output value output from an array optical sensor composed of an optical amplification transistor in which the photocurrent changes linearly. A calibration system and method thereof are provided.

The optical amplification type or phototransistor type high sensitivity light receiving element linear array optical sensor has higher sensitivity than the photodiode type linear array sensor. In particular, linear array sensors (single-dimensional arrays such as 256 by 1 and 512 by 1) can be used as portable high-sensitivity spectrometers. They are applied to a wide range of fields such as bio diagnostics and physicochemical analysis using weak light. . The linear array sensor is preferable to make the characteristics of all the individual elements constituting the array uniformly, but in reality, instability exists in the manufacturing process, and the yield and utilization were not high. Diode type linear array sensors using simple PN junctions have relatively good uniformity and high utilization, but transistor type linear array optical sensors in which optical amplification occurs inside devices have high unevenness between individual elements. The disadvantage is that it is difficult to use.

The cause of the uniformity problem is the sensitivity difference between the cells, dark current, changes in illumination, and the characteristics of the optical system. To compensate for this nonuniformity, the signal output from the photovoltaic cell must be corrected. The principle of correction is correcting by scanning a uniform white light to the optical sensor before setting the data of the optical sensor and setting the value as reference data.

Conventionally, a simple average value obtained by substituting an average value of all pixel rows or replacing a value in which a measured value of an optical sensor falls below a predetermined limit value is averaged.

However, since each of the optical sensors constituting the array has different output photoelectric currents and dark currents due to incident light and their sensitivity is different from each other, when a simple average value is applied, the reliability of the output sensor of the optical sensor is not high. There is a problem of deterioration.

An object of the present invention is to provide a system and method for calibrating a linear optical sensor that can equalize the sensitivity of all the optical sensors using the measured values of the optical sensors constituting the array.

The linear optical sensor correction system of the present invention includes a linear optical sensor formed of a plurality of arrays for outputting a predetermined incident light as a photocurrent value; A memory for storing the photocurrent value whose sensitivity is calculated using the photocurrent value and the dark current value of the linear optical sensor and the photocurrent value whose sensitivity is uniform; And a data processor for calculating the photocurrent value whose sensitivity is corrected and the photocurrent value whose sensitivity is uniform.

The calibration method of the linear light sensor of the present invention comprises the steps of outputting and storing the incident light as a photocurrent value using the linear light sensor; Storing a dark current value of the linear photosensor; Calculating the dark current and the photocurrent value and storing the calculated dark current and the photocurrent value as corrected photocurrent values; And storing the corrected photocurrent value as a uniform photocurrent value through the measured value of the linear optical sensor according to the incident light.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

1 is a block diagram of a linear optical sensor correction system according to the present invention.

The linear optical sensor correction system according to the present invention receives a light emitted from the outside and converts the linear light sensor 111 into a current, a data processing part (CPU: 120) and calculates the current and converts it to a numerical value It is composed of a memory 130 for storing a current value.

In the linear optical sensor according to the present invention, a floating gate and a body are connected to each other as a transistor structure.

The linear optical sensor according to the present invention may use a MOSFET type transistor formed in a silicon on insulator (SOI).

2 is a graph showing optical characteristics of a linear optical sensor.

A photo current _{K 1, K 2, ...,} K N, the flowing current of the light sensor in the absence of the light state in the case where light from a light source having a predetermined power (P) to be irradiated to the linear optical sensor 111 is When the measured dark currents are L ₁ , L ₂ ,..., L _N , the photocurrent K and the dark current L measured by each linear optical sensor 111 located in the same plurality of arrays as shown in FIG. There is a deviation. In addition, there is a difference in the photocurrent and the dark current for each of the linear optical sensors 111. Therefore, both the photocurrent and the dark current should be taken into account when calibrating the photosensor.

First, the measured dark current and photocurrent are stored in the memory. The data processor 120 outputs the photocurrent value whose sensitivity is corrected using the stored dark current, the photocurrent, and the function represented by Equation 1, and stores the photocurrent value again in the memory.

[Equation 1]

(Y _N : Photocurrent function whose sensitivity of the photo sensor located in the Nth array is corrected, K _N : Photocurrent measured by the photo sensor located in the N th array, the amount of light emitted from the light source with a predetermined power P, L _N : Dark current of optical sensor located in Nth array)

The actual sensitivity of the optical sensor is the output photocurrent (K) relative to the power (P) input to the optical sensor, which means the slope as the coefficient of X. However, in the absence of light, there is a dark current flowing inside the optical sensor. Therefore, the current flowing through the actual optical sensor should subtract the dark current from the output photocurrent. Therefore, by using the value obtained by subtracting the dark current (L) value from the photocurrent (K) value output from the optical sensor provided for each array, calculates the relative current of the photosensitive value of the optical sensor formed for each array and stores it in the memory. . In the case of a specific optical sensor, since the deviation between the photocurrent and the dark current is small, the value may be at the level of the dark current value. Therefore, a predetermined dark current L value is added for data reliability.

 When the photocurrent whose sensitivity is corrected for each optical sensor of each array is expressed by Equation 1, it is represented by a graph having various inclinations (sensitivity). Although the sensitivity of the optical sensor has been corrected to some extent, it is still necessary to equalize the slope, that is, to make the sensitivity uniform, so that the optical current characteristics of all the optical sensors are uniform since the difference in the slope is still shown. The uniformity of the sensitivity is calculated by the data processor 120 using the measured value stored in the memory 130, but by using a function as shown in Equation 2 below, the sensitivity of the optical sensor is equalized.

[Equation 2]

(H (Y _N ): uniform photocurrent function of the photo sensor located in the Nth array, A _H : maximum photocurrent value, A _L : minimum photocurrent value, Y _N : photocurrent with corrected sensitivity of the photo sensor located in the Nth array Function, K _N : Light current measured by the light sensor located in the Nth array, and L _N : Dark current of the light sensor located in the Nth array.

3 is an optical characteristic graph of an optical sensor uniformed using the correction system according to the present invention, and shows an optical sensor characteristic graph of the Nth array whose sensitivity is corrected by Equation 1. FIG. Sensitivity-corrected graphs exist as many as the number of photosensors, but only one is shown as an example. All the graphs whose sensitivity is corrected are moved to the graph uniformed by the equation 2, whereby the sensitivity of all the optical sensors is equalized as shown in FIG. That is, the final output data is normalized with the dark current and the photocurrent geometry.

Although the present invention has been shown and described with reference to the preferred embodiments as described above, it is not limited to the above embodiments and those skilled in the art without departing from the spirit of the present invention. Various changes and modifications will be possible.

The linear optical sensor calibration system and method of the present invention have the effect of equalizing different photocurrent characteristics between optical sensors that may occur due to manufacturing process problems through a program, thereby greatly improving the yield of a product.

Claims (6)

A linear optical sensor formed of a plurality of arrays for outputting predetermined incident light as a photocurrent value; A memory for storing the photocurrent value whose sensitivity is calculated using the photocurrent value and the dark current value of the linear optical sensor and the photocurrent value whose sensitivity is uniform; And A data processor for calculating the photocurrent value at which the sensitivity is corrected and the photocurrent value at which the sensitivity is uniform Compensation system for a linear optical sensor comprising a. The method of claim 1, wherein the function for calculating the photocurrent value whose sensitivity is corrected is:

(Y _N : Photocurrent function whose sensitivity of the photo sensor located in the Nth array is corrected, K _N : Photocurrent measured by the photo sensor located in the N th array, the amount of light emitted from the light source with a predetermined power P, L _N : Dark current of optical sensor located in Nth array) The method of claim 1, wherein the function for calculating a tube current value with uniform sensitivity is:

System of linear light sensor. (H (Y _N ): uniform photocurrent function of the photo sensor located in the Nth array, A _H : maximum photocurrent value, A _L : minimum photocurrent value, Y _N : photocurrent with corrected sensitivity of the photo sensor located in the Nth array Function, K _N : Light current measured by the light sensor located in the Nth array, and L _N : Dark current of the light sensor located in the Nth array. Storing a dark current value and a photo current value of the linear optical sensor; Calculating the dark current and the photocurrent value and storing the dark current and the photocurrent value as the photocurrent value whose sensitivity is corrected; And Storing a photocurrent value having a uniform sensitivity by using the photocurrent value whose sensitivity is corrected Correction method of the linear optical sensor comprising a. The method of claim 4, wherein the function for calculating the photocurrent value whose sensitivity is corrected is

Method of linear light sensor. (Y _N : the corrected photocurrent function of the optical sensor located in the Nth array, K _N : the dark current of the optical sensor located in the Nth array, L _N : the amount of light irradiated from the light source with a predetermined power P) Photocurrent measured by an optical sensor located at The method of claim 4, wherein the function for calculating the photocurrent value with uniform sensitivity is

Method of linear light sensor. (H (Y _N ): uniform photocurrent function of the photo sensor located in the Nth array, A _H : maximum photocurrent value, A _L : minimum photocurrent value, Y _N : photocurrent with corrected sensitivity of the photo sensor located in the Nth array Function, K _N : Light current measured by the light sensor located in the Nth array, and L _N : Dark current of the light sensor located in the Nth array.

Images