JPS6035871A - Optical reader - Google Patents

Abstract

PURPOSE:To attain highly reliable, high-speed and highly accurate reading by shielding the whole thyrister array by a light shielding film. CONSTITUTION:Light is irradiated only on phototransistors out of elements arranged on an image sensor chip and an Al film 28 is adhered to the surface of the thyristor through a shielding resin film or an insulating film to prevent the surface of the thyristor from the irradiation of light. Since one thyristor has a sufficient signal holding function and a shift register can be constituted by arranging one thyristor on each stage, the number of elements of a scanning part can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical reading device that optically reads information with high precision.

(Constitution of Conventional Example and its Problems) Examples of conventional optical reading devices include a silicon picocon, a MOS tarque 9tvinocon, and the like. These processes are performed by deflecting access function laminate beams for sequential readout, so they have the advantage of being easy to perform with high resolution, but because they are not all-solid-state, they have drawbacks such as miniaturization and low power consumption.

On the other hand, examples of all-solid-state optical reading devices include CCD image sensors and MOS image sensors.

It consists of a photodiode array for light detection and a scanning circuit for sequential reading. The scanning circuit of a CCD image sensor is a CCD, and the scanning circuit of a MOS image sensor is a MOS shift register. Both of these are M
It is based on O8 integrated circuit technology and operates in 5i-
This occurs at the 8i02 interface. Since it is a light-receiving element, it needs to be packaged with a transparent material, and if the element has a large light-receiving area, the size of the guccano will also be large. It is difficult to completely encapsulate a MOS device that is sensitive to surface conditions at a low cost using the limited materials described above. In particular, it is difficult to seal a long and large reading element in a contact type reading method.

(Object of the invention) The present invention forms a sensor section and a scanning section on the same chip,
Another object of the present invention is to provide an image sensor that completely eliminates the defects of the MOS image sensor and CCD image sensor and can read with high reliability, high speed, and high accuracy.

(Structure of the Invention) The optical reading device of the present invention detects the state of a shift register and each stage of the shift register from a phototransistor array (photodiode array) for light detection and a cascade connection of thyristors, All features include a transistor array for accessing the detection phototransistor, a light-shielding film for shielding the entire thyristor array, etc. Because of the above configuration, this image sensor can be manufactured using bipolar integrated circuit technology. One thyristor has a signal holding function, and one thyristor in each stage shifts and
Since the risk can be configured, the number of elements in the scanning section can be extremely reduced. On the other hand, thyristors are sensitive to light and malfunction when triggered by irradiated light, so complete light shielding is required.

It is easy to apply an opaque film only to the thyristor region by photolithography. (Description of Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of an image sensor in one embodiment of the present invention. In FIG. 1, 11.

1□ 113. 14 is a phototransistor, S
A desired number of chips are provided on the i-chip at regular intervals.

21 122 123 +24 is a thyristor, and a coupling transistor 31 *3z + 33 + between each stage
Together with 34, it functions as a shift register. 41942p
43 #44 is a coupling transistor for detecting the conduction state of the thyristor and setting the phototransistor connected to each collector to a reading state.

Reference numeral 5 denotes an input coupling transistor that transmits the input of the start signal to the first stage thyristor. Reference numeral 6 denotes a silicon risk connected at the last stage, which, together with transistor 7, functions to facilitate the cascade connection between the image sensor chips. 81 182 $83 +84p85 is a load resistor connected to the anode of the thyristor. Resistance 91 +
92 +93 j94 +95 is resistance 101, 10□
Together with +103p1041105, the thyristor bird functions to adjust the sensitivity. The cathodes of the thyristors in the same stage, the emitters of the interstage coupling transistors, and the emitters of the coupling transistors with the phototransistor are commonly connected, and the common connection points of the odd-numbered stages and the common connection points of the even-numbered stages are connected to the shift clocks φ and 1, respectively. The collectors of the phototransistors connected to the output terminal 11 are connected in common to form an output terminal 11. 12 is an output load resistance. The operation of the image sensor of this embodiment configured as described above will be described below.

The silica is of the N-gate type and is truncated by applying a negative voltage to the gate electrode compared to the anode. First, when the H level i4(6) pulse is input to the S terminal, the collector current of the transistor 5 flows, the gate electrode of the thyristor 21 goes to the L level (active), and in this state, the cathode of the thyristor When the thyristor reaches the L level, the thyristor becomes conductive, and the conductive state is maintained even after the gate voltage becomes the H level (inactive). In this state, the transistor 41 for coupling with the phototransistor is also not conductive due to the common connection between the pace and the emitter, and the phototransistor 11
A current is caused to flow through the terminal, and the photoelectric conversion signal is outputted to the output terminal 11. Similarly, the coupling transistor 3I with the next stage is also in a conductive state, and the second stage thyristor is at the L level, but the cathode (connected to ■) of the second stage thyristor 22 is at the H level, so the thyristor 22 is in a non-conductive state. Maintain continuity. In the next clock state (φ-H, ?;=L), thyristor 2
Since dart No. 2 is at the L level, when the cathode voltage of the thyristor 22 transitions to the L level (d=L), the second stage thyristor becomes conductive. As a result, the photoelectric conversion signal of the phototransistor 12 is read as described above. Also, in this clock state, the state of the first stage thyristor changes from conductive to non-conductive. In this way, the conduction states of the thyristors are sequentially shifted from left to right. Along with this, the photoelectric conversion signal of the run risk is outputted from the left phototransistor to the output line in order from the left phototransistor to the right in FIG. In the circuit of Figure 1, the signal is V. C (for example, 5V) is the ffi zero point, and its polarity is negative. If it is difficult to use a signal with the zero point at Vcc', the image sensor power source may be a negative voltage source. Although the polarity is negative, a signal whose zero point is 0 voltage can be obtained.

FIG. 2 is a timing diagram of various driving IP pulses and reading output signals of the present image sensor.

The period of the start signal is the integration time of the phototransistor in the charge accumulation mode.

This image sensor uses a standard bipolar IC process (
It can be easily manufactured using the ebitaxial solena method. A single thyristor can constitute one stage of a shift register, and furthermore, a coupling transistor between stages can be formed in the same isolation region as the thyristor. Therefore, the scanning circuit for reading can be formed on an extremely small area, and the light receiving area of the phototransistor can be increased to the limit determined by the resolution. Furthermore, since the collectors of all phototransistors are connected in common, they can be formed in the same isolation region, and the drawbacks associated with element isolation of bipolar ICs can be minimized.

FIG. 3 is a circuit diagram of an image sensor according to a second embodiment of the present invention. In Figure 3, 131+132,
133 and 1134 are phototransistors, and a desired number of phototransistors are provided at regular intervals on the Si chip. 141 1
142 +143 e144 is a thyristor, and a coupling transistor 151 between each stage.

It functions as a shift register together with 15□ and 153 and 154. Load resistor 161 on each anode of each thyristor
．． 162. 163 y164 and PNP for switch
) Run risk 171 p 172 + 17s *1
74 all connected. This switching transistor (9) has its collector connected to the phototransistor, and has the effect of placing the phototransistor in the full reading state or in the integrating state depending on the conduction or non-conduction state of the thyristor. 18
is an input coupling transistor that transmits the input of the start signal to the first-stage thyristors 14- and 9-. 19 is a thyristor connected to the final stage, and transistor 20
It also functions to facilitate cascade connections between image sensor chips. Resistor 211 #212 *21s 121
4 1215 is resistance 221 1222 +223 12
Together with 24 1225, it functions to adjust the trigger sensitivity of the thyristor. The cathodes of the thyristors in the same stage and the emitters of the interstage coupling transistors are connected in common, and the common connection point of the odd-numbered stages and the common connection point of the even-numbered stages are connected to the shift clocks φ and 2, respectively. The emitters of each phototransistor are commonly connected to form an output terminal 23. 24 is an output load resistance.

Since the operation of this embodiment is basically the same as that of the first embodiment, a detailed explanation of the operation will be omitted.

New setting of conducting or non-conducting state of thyristor (10
) 7'cPNP) It is detected by the run risk, and when it is in a conductive state, it puts the phototransistor in a reading state, and when it is in a non-conducting state, it puts it in an integrating state. In this way, by providing a buffer switch with a PNP run risk, a large amplitude output signal can be obtained. Another feature of this embodiment is that a signal based on the ground level can be obtained.

FIG. 4 is a schematic diagram of the arrangement of elements on the image sensor chip. 25 is a phototransistor array, 26 is an array having thyristors and coupling transistors as units, and 27 is an interchip connection pad.

Further, 28 is a film for light shielding. Thyristors are sensitive to irradiated light, and in order to prevent malfunctions associated with this, it is important to irradiate only the phototransistor with light and not irradiate the thyristor with light. For this purpose, an At film is attached on the thyristor via a light-shielding resin film or an insulating film. This step can be easily accomplished by photolithography.

Although a phototransistor was used as the light detection sensor in the above embodiment, any element that receives light and generates a current can be used for this purpose. For example, a photodiode, a photoconductive film, etc. can also be used.

(Effects of the Invention) As is clear from the above description, the present invention provides a sensor array for photodetection, a thyristor array for sequentially accessing the sensor array, a coupling transistor for imparting a shift function to the thyristor array, and a conduction state of each thyristor. It consists of a coupling transistor that transmits light to a phototransistor (photodiode) and a shielding film that prevents light from irradiating the thyristor.The number of elements required for the scanning section can be significantly reduced, allowing for high density despite being a bipolar process. , it becomes possible to manufacture multi-bit image sensors. Also, since it is a bipolar process, MOS or CC using the surface area
It is characterized by higher reliability than the D image sensor.

The power supply also operates with a single power supply, and only the one bit that is being read is in a conductive state among all the thyristors, and only this thyristor consumes power, while the other thyristors that are in the off state do not consume power, so the power consumption is extremely low. It has the characteristic of being small.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an image sensor according to an embodiment of the present invention, FIG. 2 is a timing diagram of various drive/+)less and read output signals, and FIG. 3 is a circuit diagram of an image sensor according to a second embodiment of the present invention. The circuit diagram of the image sensor, FIG. 4, is a schematic diagram of the arrangement of elements on the image sensor chip. 11 112 913 114 e13t *13z
#133 + 134...Phototransistor, 21
. 2□ * 2a * 24. 14t p 142 +
143 +144...thyristor, 3t +32
t3a +34 +41. 42 +43 14.11
51 1152 +153.154...Coupling transistor, 5,18...Input coupling transistor, 6.19
...Thyristor at the final stage, 7.20...Coupling transistor at the final stage, 81982 $83 +84 e8s
+161 m162 j163p164...Load resistance, 9! , 9□ , 93. 94 *9S 1101 m102 5lOa 110
4 1 (13) 1 05 e 21t + 212 + 213 #
214 m215 *22+ 1222 1223.
224 1225...Dirt resistance, 11.23...
Video signal output terminal, 12.24... Output load resistance, 1
71. 172 *17a 1174 ... PNP for switch
) run risk, 25... phototransistor array, 26... thyristor and coupled transistor play,
27...Grad for inter-chip connection, 28...Light shielding film (14)

Claims (3)

[Claims] (1) A scanning section consisting of a shift register configured by cascading a phototransistor or photodiode for light detection and a thyristor with a coupling transistor, and detecting the state of each stage of the thyristor to detect a phototransistor or photodiode for detection. An optical reading device comprising a driving transistor array to be accessed and having the entire thyristor array shielded from light by a light shielding film. (2) Connect a pace electrode and an emitter electrode to the P-type gate electrode and cathode electrode of each thyristor, respectively, and connect the collector electrode to the N-type dart electrode of the next-stage thyristor to form a coupling NPN run risk; A driving NPN run risk is formed by connecting a pace electrode and an emitter electrode to the pace electrode and emitter electrode of the coupling transistor, respectively, and connecting the collector electrode to the emitter of the phototransistor or the cathode of the photodiode. An optical reading device according to claim (1) (3) Connect the pace electrode and emitter electrode to the P-type gate electrode and cathode electrode of each thyristor, respectively, and connect the collector electrode to the N-type r-) electrode of the next stage thyristor to create a coupling NPN (run risk) , connect a load resistor between the thyristor anode electrode and the positive power supply,
The emitter electrode is connected to the positive power supply, the pace electrode is connected to the anode electrode, and the collector electrode is connected to the collector of the phototransistor or the anode of the photodiode.
NP) The optical reading device according to claim 1, characterized in that it has a run risk.