发明名称 |
Low light level photoreceptor |
摘要 |
<p>Circuitry and circuitry layout are provided to achieve a high percentage of photoreceiver area to total area and to stabilize the voltage at the base node (56) of a phototransistor (36). Voltage stabilization is achieved by a servo circuit in which a negative feedback loop from the base node to an emitter node (62) maintains a bias point, so that photocurrent is efficiently delivered to charge transfer circuitry (46). In the preferred embodiment, the base node is connected to a gate of a first transistor (50) having a drain that is connected to a source of constant current and to a gate of a second transistor (52) that functions as a source follower. The source of the second transistor is connected to the emitter node of a phototransistor. As photocurrent is generated by the reception of light, an integration capacitor (30) is charged. The relatively high percentage of photoreceiver area to total area is achieved by contributions from a number of factors, including the design of the servo circuit, use of a single transfer amplifier to service an entire row of phototransistors, and pairing the phototransistor circuits in order to permit efficient sharing of common circuit paths and circuit components. <IMAGE></p> |
申请公布号 |
EP0786897(A2) |
申请公布日期 |
1997.07.30 |
申请号 |
EP19970300190 |
申请日期 |
1997.01.14 |
申请人 |
HEWLETT-PACKARD COMPANY |
发明人 |
BAUMGARTNER, RICHARD A.;HORNAK, THOMAS;BLALOCK, TRAVIS N.;DOERNBERG, JOEY |
分类号 |
H01L27/14;H01L27/146;H01L31/10;H04N1/028;H04N1/047;H04N1/107;H04N5/335;(IPC1-7):H04N3/15 |
主分类号 |
H01L27/14 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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