Matrix array image sensor chip

A method of detecting radiation incident upon an image sensor fabricated using integrated circuit technology in which the integrated circuit comprises a two dimensional matrix array of image sensing cells having a plurality of cell columns and a plurality of cell rows, each image sensing cell having a photodiode and a transistor for reading to and writing from the photodiode, horizontal scan means coupled to each cell in the array for scanning each cell row in the array, vertical scan means coupled to each cell in the array for scanning each cell column in the array, and a plurality of analogue switch means each connected between at least one of the cell columns and said horizontal scan means for receiving image data from each of said cells, each of said plurality of analogue switch means includes voltage storage means and first charge sensing amplifier means, each of said analogue switch means being also connected by a conductor to a output amplifier having its output connected to an external read-device for reading image signals from said output amplifier, said method being characterized by the steps of:

• reading a cell from an associated one of said cell columns using a selected one of the plurality of analogue switch means by generating a voltage to balance charge in the cell created in response to incident radiation,
• storing the voltage capacitively in the selected one of the plurality of analogue switch means in the form in the form of a charge corresponding to the cell charge, and
• reading out the capacitively stored information in the selected one of the plurality of analogue switch means to the output amplifier.

An integrated circuit image array sensor comprising:

• a two-dimensional matrix array of sensing cells having a plurality of cell columns and a plurality of cell rows, each of said sensing cells in said two-dimensional matrix array having a photodiode and a transistor for reading from and writing to the photodiode, each of said sensing cells in said two-dimensional matrix array generating a charge in response to radiation impinging on said cell to provide image data;
• horizontal scan means coupled to each cell in said two-dimensional matrix array for scanning each cell row of the array of sensing cells;
• vertical scan means coupled to each cell in said two-dimensional matrix array for scanning each cell column of said array of sensing cells;
• a plurality of analogue switch means each connected between at least one of said cell columns and said horizontal scan means for receiving said image data from said cells,
• each of said analogue switch means including charge sensing amplifier means for converting said charge to a voltage by integrating said charge and further including a voltage storage means for capacitively storing said voltage;
• and
• an output amplifier which is selectively connected to each of said voltage storage means.

An integrated circuit for use as an image array sensor and providing an output signal to an off-circuit read device, said integrated circuit comprising,

• a two-dimensional matrix array of sensing cells having a plurality of cell columns and a plurality of cell rows, each sensing cell having a photodiode and a transistor for reading from and writing to the photodiode,
• horizontal scan means coupled to each cell in the array for scanning each cell row of the array of sensing cells,
• vertical scan means coupled to each cell in the array for scanning each cell column of said array of sensing cells,
• a plurality of analogue switch means each connected between at least one of said cell columns and the horizontal scan means for receiving image data from said cells, each of said analogue switch means being also connected by a common conductor to a output amplifier forming the output of the integrated circuit, each of said plurality of analogue switch means includes voltage storage means and first charge sensing amplifier means which provides a preliminary detection of charge created on each cell in response to radiation impinging thereon by converting the detected charge to a voltage using a first charge integrating circuit, said first charge integrating circuit comprising an inverter means for generating a voltage to balance said charge created on each cell, and capacitively storing the voltage in said voltage storage means, in the form of a charge corresponding to the cell charge, and that said output amplifier comprises a second charge sensing amplifier means which is selectively coupled to said voltage storage means of said analogue switch means, for providing an output signal to the off-circuit read device, said output signal being a voltage proportional to the charge in said voltage storage means.