JP2830177B2 - Image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to an image reading apparatus used for a facsimile, a scanner, or the like, in which an EL light emitting element and a light receiving element are integrated.
In particular, the present invention relates to a concept for preventing a drive signal of an EL light emitting element from becoming a noise source of a light receiving element.

2. Description of the Related Art Conventionally, an image reading apparatus including a fluorescent light source, an image sensor, and an optical system that forms reflected light from a document on an image sensor is used for a facsimile, a scanner, and the like. According to this image reading apparatus, a rod lens array or the like is used as an optical system, so that it is difficult to reduce the size of the apparatus.

Therefore, the EL light emitting element as a light source and the original:
2. Description of the Related Art There has been proposed a completely close contact type ultra-compact image reading apparatus in which a close contact type image sensor having a size corresponding to 1 is integrated.

This image reading apparatus is, for example, shown in FIGS. 7, 8 and 9.
As shown in the figure, a thin-film light-receiving element array 10 using amorphous silicon is formed on a sensor substrate 1 made of glass or the like.
And an EL light emitting element 30 formed on the EL substrate 3 by a thin film process.
Are bonded via an adhesive layer 2 so as to face each other.

The light receiving element array 10 is sandwiched by sequentially laminating a plurality of individual electrodes 11 arranged in the front and back directions in FIG. 9, a photoelectric conversion layer 12 having a band shape in the front and back directions, and a common electrode 13 in a band shape on the sensor substrate 1. It is configured by arranging a plurality of photoelectric conversion elements 10 ′ composed of a type sensor. On the common electrode 13, an insulating layer
An opaque electrode 15 is deposited via 14. Opaque electrode
Reference numeral 15 denotes connection holes formed in the insulating layer 14 at regular intervals while being formed as two strips elongated in the front and back directions in FIG. 9 to define the light receiving area of the light receiving element array 10. It is electrically connected to the common electrode 13 via (not shown), and has a role of reinforcing the resistance of the common electrode 13.

The photoelectric conversion element 10 'constituting the light receiving element array 10 has 64
Alternatively, it is connected to one IC chip (not shown) for every 128 bits and driven by this IC chip. One IC
FIG. 10 shows an equivalent circuit of the light receiving element array 10 driven by the chip.

The EL light emitting element 30 has a sandwich structure in which a transparent electrode 31, an insulating layer 32, a light emitting layer 33, an insulating layer 34, and a metal electrode 35 are sequentially laminated on an EL substrate 3 made of a transparent member. As shown in FIG.
A plurality of light transmitting windows 35 correspond to the ten photoelectric conversion elements 10 '.
a is formed as an opening. Then, the metal electrode 35 and the transparent electrode 3
A drive signal is applied to the terminal 1 (terminal OO 'in FIG. 9).
Light is emitted from the light emitting layer 33 sandwiched between the two.

The light emitted from the light emitting layer 33 is the anti-EL light emitting element of the EL substrate 3.
The original 100 arranged on the 30 side is irradiated, and reflected light 50 corresponding to the density of the original enters the light receiving portion (each photoelectric conversion element 10 ') of the light receiving element array 10 from the light transmitting window 35a. Focusing on one of the photoelectric conversion element, it is temporarily stored in the capacitor C ₁ charges generated by light current is expressed equivalently wiring capacitance of the individual electrode 11 flowing to the photoelectric conversion element 10 _{'1 (Figure} 10) ,
Voltage of the input line of the voltage follower type amplifier A ₁ is changed. This voltage is extracted to sequentially open and close sequentially output line from the analog switches S ₁ Tout by the shift register R a and time-series signal. After signal detection, the input line of the voltage follower amplifier A ₁ emits a grounded residual charge by the switch K _1, performs a charge reset.

The above operation is repeated, and the analog switch
The photoelectric conversion signals are sequentially and sequentially extracted to the output line Tout by opening and closing S ₁ , S ₂ ,... Sn (n is 64 or 128), and an image signal of one line of the document is obtained.

(Problem to be Solved by the Invention) According to the structure of the image reading apparatus described above, the EL light emitting element 30
The metal electrode 35 which is a driving electrode of the light-receiving element array, the common electrode 13 and the opaque electrode 15 of the light-receiving element array 10 are close to each other with a distance of several tens μm to several hundred μm, and the driving of the EL light-emitting element 30 is shown in FIG. ± 100 ~ 250V, 50 ~ 5k with bipolar pulse like
Hz power supply is used, a high electric field is generated between the light receiving element array 10 and the EL light emitting element 30, and the common electrode 13 of the light receiving element array 10
And the power supply voltage VEE (−4 to 8) applied to the opaque electrode 15.
V) is transmitted to the light receiving element array 10 as a noise source.

The details will be described with reference to the equivalent circuit in FIG. 12.
Since the photoelectric conversion element 30 and the photoelectric conversion element 10 'are arranged close to each other, they are equivalently connected via a capacitor Cc which has a large coupling capacity. Accordingly, when a high-voltage bipolar pulse is applied to the EL light emitting element 30, the potential at one end (point X) of the capacitor C (wiring capacitance) on the photoelectric conversion element 10 'side is greatly changed via the capacitor Cc (coupling capacitance). . On the other hand, on the photoelectric conversion element 10 'side, after the charge generated in the photoelectric conversion element 10' is accumulated in the capacitor C (wiring capacitance), the analog switch S for reading is closed and the charge is read as a voltage. The above-mentioned potential fluctuation has a great effect on the electric signal extracted from the photoelectric conversion element 10 ', and there is a problem that image information on the document surface cannot be read accurately.

The present invention has been made in view of the above circumstances, and an image reading apparatus in which a light receiving element is less affected by a drive signal of an EL light emitting element even when an EL light emitting element and a light receiving element are arranged in close proximity. The purpose is to provide.

(Means for Solving the Problems) In order to solve the above-mentioned problems of the conventional example, the image reading apparatus of the present invention forms a transparent electrode, an insulating layer, a light emitting layer, an insulating layer, and a metal electrode in this order on an EL substrate. EL light-emitting element, and a light-receiving element formed on a sensor substrate, the light emitted from the EL light-emitting element is reflected on the document surface disposed on the side of the EL substrate opposite to the EL light-emitting element, and the reflected light is reflected. In the image reading device configured to be guided to the light receiving element, the metal electrode is formed so as to cover the transparent electrode, and the metal electrode is electrically connected to a ground line of the light receiving element. I have.

(Operation) According to the present invention, a metal electrode is formed so as to cover the transparent electrode of the EL light emitting element, and this metal electrode is electrically connected to the ground line of the light receiving element. The generated noise is shielded by the metal electrode serving as a ground layer so as not to affect an electric signal of image information output from the light receiving element.

(Example) An example of the present invention will be described with reference to the drawings.

1 to 3 are cross-sectional explanatory views of an image reading apparatus according to the embodiment. Parts having the same configuration as those in FIGS. 7, 8, 9, and 10 are denoted by the same reference numerals. doing.

The light receiving element array 10 has a sandwich structure in which an individual electrode 11, a photoelectric conversion layer 12, and a transparent electrode 13 are sequentially stacked on a sensor substrate 1 made of ceramic or glass.

The individual electrodes 11 are formed by depositing chromium (Cr) and etching by a photolithography method to form a chromium pattern, and a plurality of individual electrodes 11 are arranged in the front and back directions in FIG. Photoelectric conversion layer 12
Is formed by depositing amorphous silicon (a-Si) by a plasma CVD method and forming a strip covering the individual electrodes 11. The transparent electrode 13 is made of indium tin oxide (IT
O) is deposited by a sputtering method, and is formed in a band shape to cover the individual electrodes 11. The photoelectric conversion layer 12 is an individual electrode
The portion sandwiched between 11 and the transparent electrode 13 constitutes each photoelectric conversion element 10 'having a sandwich structure.

The ends 11a of the individual electrodes 11 are connected to the IC chip 17 via bonding wires 16, respectively. The driving of the IC chip 17 causes the charges generated in the photoelectric conversion elements 10 'to be sequentially extracted as image signals. ing.

The EL light emitting element 30 includes a transparent electrode 31, an insulating layer 32, and a light emitting layer
3, the insulating layer 34 and the metal electrode 35 are sequentially laminated.

The transparent electrode 31 is formed by depositing ITO, In ₂ O ₃ , SnO ₂ or the like to a thickness of 0.1 μm and forming a strip in the front and back direction in FIG. The insulating layer 32 is formed in a strip shape so as to cover the transparent electrode 31 by depositing SiNx, SiO ₂ or the like by sputtering or CVD. The light emitting layer 33 is formed by coating ZnS: Mn, ZnS: TbF ₃ or the like on the insulating layer 32.
It is formed in a belt shape by deposition using a B vapor deposition or sputtering method, and its area is smaller than that of the insulating layer 32. Insulation layer 34
, Like the insulating layer 32, SiNx, sputtering SiO ₂ or the like or C
A film is formed by a VD method, and is formed in a band shape so as to cover the light emitting layer 33 and the insulating layer 32. The metal electrode 35 is formed by depositing an opaque metal such as aluminum by sputtering or vapor deposition to form a strip wider than the transparent electrode 31 (the width of the light receiving element array 10 in the sub-scanning direction is longer). 34 so as to cover the insulating layer 3
The configuration is such that the transparent electrodes 31 are not connected to each other due to the presence of 2,34. The light receiving element is arranged on the metal electrode 35 such that the light emitted from the light emitting layer 33 is reflected by the original 100 disposed on the side opposite to the EL light emitting element 30 of the EL substrate 3 and the reflected light is incident on the light receiving element array 10. On each light receiving portion (photoelectric conversion element 10 ') of the array 10, a rectangular light transmitting window 35a is formed. The light-transmitting window 35a is formed by stacking an opaque metal electrode 35 made of a metal such as aluminum, and then etching the metal electrode 35 by a photolithography method.

The terminal O of the transparent electrode 31 is connected to the EL drive power supply 41, and the terminal O 'of the metal electrode is connected to the ground line 42 of the light receiving element array 10.
(FIG. 2).

The light receiving element array 10 and the EL light emitting element 30 are joined via the insulating adhesive layer 2 so that each light receiving portion of the light receiving element array 10 and the light transmitting window 35a of the EL light emitting element 30 are aligned. . The adhesive layer 2 is mixed with a spherical transparent spacer having a diameter of several tens of μm, so that the bonding between the sensor substrate 1 and the EL substrate 3 can be made constant.

When a bipolar pulse of ± 200 V is applied between the transparent electrode 31 and the metal electrode 35 (between the terminal O and the terminal O ') to light the EL light emitting element 30, the transparent electrode 31 and the metal electrode 35 are sandwiched. Light is emitted from the light emitting layer 33, and the anti-EL light emitting element of the EL substrate 3
It irradiates 100 surfaces of the original document arranged on the 30 side. Then, the reflected light passes through the light transmitting window 35a and is guided to the light receiving element array 10, where photoelectric conversion is performed and an image is read. At this time, since the metal electrode 35 is formed so as to cover the transparent electrode 31, and the metal electrode 35 is connected to the ground line 42 of the light receiving element array 10, the metal electrode 35 becomes a ground layer, and noise is reduced. It acts so as to shield the transparent electrode 31 that is the source, and can shield noise without leakage. As a result, noise is not superimposed on the image reading output obtained by the light receiving element array 10, and stable image reading without noise is performed.

Since the transparent electrode 31 located immediately above the light-transmitting window 35a is not shielded from the light receiving element array 10 due to the presence of the light-transmitting window 35a, noise may leak from the light-transmitting window 35a. However, the light transmitting window 35 occupies the entire EL light emitting element 30.
Since the area of a is small, it does not significantly affect the image reading output.

Also, as shown in FIGS. 4 and 5, if the opening 31a is formed in the transparent electrode 31 located directly above the light transmitting window 35a, the transparent electrode 31 does not exist directly above the light transmitting window 35a and noise is generated. Since it does not become a source, it is possible to prevent noise from leaking from the light transmitting window 35a as described above. Such an opening 31a can be formed by photolithographic etching after the deposition of the transparent electrode 31. In FIGS. 4 and 5, parts having the same configuration as those in FIGS. 1 and 3 are denoted by the same reference numerals.

Further, according to the above embodiment, since the light emitting layer 33 is configured to be covered and hidden by the metal electrode 35, the light emitted from the light emitting layer 32 is not included in the EL light emitting element except for the light emitted from the light transmitting window 35a. No leakage out of 30. Therefore, it is possible to prevent the light 60 (see FIG. 9) emitted from the side surface of the EL light emitting element 30 from being reflected on the interface of the adhesive layer 2 and entering the light receiving element array 10.

FIG. 6 shows another embodiment of the present invention, in which parts having the same configuration as in FIG. 5 are denoted by the same reference numerals.

In this embodiment, the transparent conductive layer is formed so as to cover the insulating layer 34.
Form 36. The transparent conductive layer 36 is formed by depositing a light-transmitting conductive member, for example, indium tin oxide (ITO). Then, a transparent window 35a is formed on the transparent conductive layer 36.
A metal electrode 35 having a transparent conductive layer
36 and the same potential. With the configuration described above, since it is not necessary to provide an opening in the transparent conductive layer 36, the transparent electrode 31 can be entirely covered with the transparent conductive layer 36, and the noise generation source can be completely shielded. In this embodiment, the transparent conductive layer
Since it is formed so as to cover the transparent electrode 31 with 36, if the purpose is only to shield the noise source,
The metal electrode 35 formed on the transparent conductive layer 36 may have the same size as the transparent electrode 31, that is, an area smaller than the transparent conductive layer 36. However, in order to prevent the emission of light from the side surface of the EL light emitting element 30, it is preferable that the transparent conductive layer 36 be entirely covered with the metal electrode 35 as shown in FIG. In the case of the present embodiment, since the transparent conductive layer 36 is formed so as to completely cover the transparent electrode 31, the light emitting layer 33 immediately above the light transmitting window 35a is provided.
It is necessary to provide the opening 31a in the transparent electrode 31 so as not to emit light.

According to the above-described embodiment, the metal electrode of the EL light emitting element serves as a ground layer with respect to the transparent electrode.
It is possible to prevent the potential of the point (FIG. 12) from fluctuating. As a result, the electric signal of the image information output from the light receiving element can be prevented from being affected by noise generated from the driving signal of the EL light emitting element.

Also, since the metal electrode of the EL light emitting element is configured to be a ground layer, the ground layer can be formed during the manufacturing process of the EL light emitting element, and can be easily manufactured without going through a special step. .

(Effects of the Invention) According to the present invention, the metal electrode is formed so as to cover the transparent electrode of the EL light emitting element, and this metal electrode is electrically connected to the ground line of the light receiving element. The noise generated from the signal is blocked by the metal electrode serving as the ground layer, and EL
The driving power supply of the light emitting element does not give noise to the electric signal extracted from the light receiving element, an electric signal for accurately reading image information can be obtained, and the S / N ratio can be improved.

[Brief description of the drawings]

1 is an explanatory sectional view showing an embodiment of the present invention, FIG. 2 is a simplified equivalent circuit diagram corresponding to one IC chip of the embodiment of FIG. 1, and FIG. 3 is an embodiment of FIG. FIG. 4 is an explanatory plan view of an EL light emitting element portion, FIG. 4 is an explanatory plan view showing another embodiment of an EL light emitting element portion, FIG. 5 is an explanatory sectional view taken along line VV ′ of FIG. 4, and FIG. Sectional explanatory view showing another embodiment of an EL light emitting element portion,
FIG. 7 is an explanatory plan view of an image reading apparatus in which a conventional light receiving element and an EL light emitting element are integrated, and FIG. 8 is a view VIII-VII of FIG.
FIG. 9 is a cross-sectional view taken along the line I ′, FIG. 9 is a cross-sectional view taken along the line IX-IX ′ in FIG. 7, FIG. 10 is a simplified equivalent circuit diagram of a part of the light-receiving element array, and FIG. Waveform diagram shown, twelfth
The figure is a simplified equivalent circuit diagram of an image reading device integrated with an EL light emitting element for one photoelectric conversion element. DESCRIPTION OF SYMBOLS 1 ... Sensor board 2 ... Adhesive layer 3 ... EL substrate 10 ... Light receiving element array 30 ... EL light emitting element 31 ... Transparent electrode 32 ... Insulating layer 33 ... Light emitting layer 34 ... Insulating layer 35 ... ... Metal electrode 35a ... Transparent window 41 ... EL drive power supply 42 ... Ground line 100 ... Document

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-15459 (JP, A) JP-A-1-184964 (JP, A) JP-A-2-106980 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H01L 27/14-27/148 H01L 29/762-29/768 H04N 1/028-1/031

Claims (1)

(57) [Claims] 1. An EL light emitting device comprising: an EL light emitting element formed on a EL substrate in the order of a transparent electrode, an insulating layer, a light emitting layer, an insulating layer, and a metal electrode; and a light receiving element formed on a sensor substrate. In an image reading device in which light emitted from the element is reflected by a document surface arranged on the side opposite to the EL light emitting element of the EL substrate, and the reflected light is guided to the light receiving element, the transparent electrode is covered. An image reading apparatus, wherein the metal electrode is formed and the metal electrode is electrically connected to a ground line of the light receiving element.