JP4370957B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus that can be satisfactorily mounted on a portable electronic device or the like.

  In recent years, portable and small-sized electronic devices such as mobile phones and personal digital assistants (PDAs) have become widespread, and the use of such electronic devices as electronic money and the installation of a credit card function are also required. . In such a case, it is necessary to install a personal authentication function for identifying and authenticating the user himself / herself in such an electronic device.

  For such personal authentication, there is an image reading device that reads a fingerprint image. As the image reading device, for example, it is difficult to be damaged by static electricity charged on a subject, and the reading response speed is relatively fast. An optical image reading apparatus using a photosensor is known. However, CCDs and CMOS sensors that are frequently used as photosensors are formed on a semiconductor substrate and are opaque, and thus cannot be provided on an image display unit provided in an electronic device. It is necessary to provide an image reading device at the location. Therefore, in such a configuration, there is a problem that the size of the electronic device increases.

  Therefore, in order to reduce the size of an electronic apparatus equipped with such an image reading device for personal authentication, the image reading area of an image reading unit for reading a fingerprint image provided at a location different from the image display unit is set. Some are relatively small (see, for example, Patent Document 1). In this case, a finger is slid on a light guide plate fitted in a slit provided in the electronic device main body, and a fingerprint of the finger is read by a one-dimensional image sensor provided at a location corresponding to the light guide plate in the electronic device main body. Yes.

JP 2002-279212 A

  By the way, since the fingerprint image is read by the image reading unit as described above, the finger is slid on the light guide plate. Therefore, if the finger sliding direction and speed are not constant, the image read by the one-dimensional image sensor is used. Is distorted and reading errors are likely to occur. In addition, since the area occupied by the image reading unit for reading a fingerprint image is relatively small, an increase in the size of the electronic device can be suppressed to some extent, but the image is displayed at a location different from the image display unit. Since the reading unit is provided, and a one-dimensional image sensor, a light source for irradiating light to the light guide plate, and the like are arranged in a place different from the image display unit in the electronic device main body, the electronic device is small. There was a problem that there was a limit to the conversion.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image reading apparatus capable of reducing the size of an electronic apparatus including the image reading apparatus and preventing the occurrence of reading failure.

In order to achieve the above object, the present invention provides a display panel that displays an image based on a display signal in a display area, and a plurality of photosensors that are translucent and arranged in a matrix in the reading area. A photosensor panel that reads a subject placed in the area as an image , and the photosensor panel includes a dummy reading area having a transmittance equivalent to that of the reading area, and the reading area and the dummy reading area Are superimposed on the display panel so as to be superimposed on the display area .
In order to achieve the above object, the present invention provides a photosensor panel that has a light transmitting property and reads a subject placed in the reading area as an image by a plurality of photosensors arranged in a matrix in the reading area. And a liquid crystal display panel that displays an image based on a display signal in a display area, wherein the photosensor panel is equivalent to the reading area. It has a dummy reading area having transmittance, and the display area is provided so as to overlap the reading area and the dummy reading area.

According to the present invention, it is possible to reduce the size of an electronic apparatus including an image reading device and to prevent occurrence of reading failure.

(First embodiment)
FIG. 1 is a perspective view of a main part of an image reading apparatus as a first embodiment of the present invention. In this image reading apparatus, a backlight 11 is disposed below the liquid crystal display panel 1, and a two-dimensional photosensor panel 21 is disposed above the liquid crystal display panel 1.

  Although not shown in detail, the liquid crystal display panel 1 is an active matrix type color liquid crystal display panel, and a liquid crystal is provided between an active substrate 2 made of glass and a counter substrate 3 made of glass provided with a color filter. A polarizing plate is attached to each of the outer surfaces of the two substrates 2 and 3 and an electric field is selectively applied to the liquid crystal between the two substrates 2 and 3 according to display driving. Transmission and blocking are performed, and image display according to the display signal is emitted to the visual field side, so that image display can be performed in the display region 4 in the substantially central portion of the counter substrate 3. In this case, the lower side portion of the active substrate 2 protrudes from the counter substrate 3, and a liquid crystal driving semiconductor chip 5 is mounted on the upper surface of the protruding portion. Although not shown in detail, the backlight 11 is, for example, a planar light source type, and emits light from the upper surface.

  The photo sensor panel 21 includes a glass substrate (transparent substrate) 22. A plurality of photosensors, which will be described later, are arranged in a matrix in a reading area 23 in the substantially central portion on the glass substrate 22 so that a subject (for example, a finger) is placed thereon and a subject image (for example, a fingerprint image) is read. It is configured. In this case, the reading area 23 of the photosensor panel 21 is arranged at a position corresponding to the display area 4 of the liquid crystal display panel 1, and the size of the reading area 23 is the same as the size of the display area 4 of the liquid crystal display panel 1. . On the glass substrate 22, first, second, and third drive circuit units, which will be described later, for driving a plurality of photosensors provided in the reading region 23 are adjacent to the right side, left side, and lower side of the reading region 23. 24-26 are provided. A plurality of external connection terminals 27 (see FIG. 2) are provided at the lower end portion on the glass substrate 22. The external connection terminal 27 is connected to the first to third drive circuit units 24 to 26 via a routing line described later.

  The portion of the photosensor panel 21 where the external connection terminal 27 is provided is disposed on the portion of the active substrate 2 of the liquid crystal display panel 1 where the semiconductor chip 5 is mounted. As a result, the reading area 23 of the photosensor panel 21 is superposed on the display area 4 of the liquid crystal display panel 1, and the upper edge and the lower edge of the photosensor panel 21 are on the active substrate 2 of the liquid crystal display panel 1. It arrange | positions in the position which corresponds to an upper end edge and a lower end edge.

  In FIG. 1, first and second drive circuit portions 24 and 25 are provided on the right and left sides on the photosensor panel 21, and the semiconductor chip 5 is mounted on the protruding portion of the active substrate 2 of the liquid crystal display panel 1. Therefore, the size of the photo sensor panel 21 in the left-right direction is shown to be slightly larger than the size in the same direction of the liquid crystal display panel, but the size of both panels 1 and 21 is made the same. Also good. In this case, for example, when the panels 1 and 21 are stored in the shield case, they can be easily stored.

  Next, FIG. 2 shows an equivalent circuit plan view of the photosensor panel 21 shown in FIG. In the reading region 23 on the glass substrate 22, a plurality of photoelectric conversion type thin film transistors 31 as photosensors are arranged in a matrix. The thin film transistor 31 includes a top gate electrode 32, a bottom gate electrode 33, a drain electrode 34, and a source electrode 35, whose specific structure will be described later.

  The top gate electrode 32 is connected to the first drive circuit unit (top gate driver) 24 through a top gate line 36 arranged in the row direction in the reading region 23. The bottom gate electrode 33 is connected to the second drive circuit unit (bottom gate driver) 25 via a bottom gate line 37 disposed in the row direction in the reading region 23.

  The drain electrode 34 is connected to the third drive circuit unit (drain driver) 26 via the drain line 38 arranged in the column direction in the reading region 23. The source electrode 35 is connected to a grounding external connection terminal among the external connection terminals 27 via a ground line (not shown) arranged in the reading region 23 and the like.

  Next, an example of a specific structure of part of the photosensor panel 21 shown in FIG. 2 will be described with reference to FIG. In this case, from the left side to the right side of FIG. 3, a cross-sectional view of a portion of the external connection terminal 27, a cross-sectional view of a portion of the CMOS thin film transistor that constitutes each part of the first to third drive circuit units 24 to 26, Sectional drawing of the part of the 1st-3rd interlayer contact and sectional drawing of the part of the photoelectric conversion type thin-film transistor 31 are shown.

  First, portions of the CMOS thin film transistor that constitute each part of the first to third drive circuit units 24 to 26 will be described. In the drive circuit portion formation region on the glass substrate 22, a CMOS thin film transistor including an NMOS thin film transistor 41 and a PMOS thin film transistor 42, for example, formed of a polysilicon thin film transistor is provided. Each thin film transistor 41, 42 includes semiconductor thin films 45, 46 made of polysilicon provided on the upper surfaces of the first and second base insulating films 43, 44 provided on the upper surface of the glass substrate 22, respectively. In this case, the first base insulating film 43 is made of silicon nitride, and the second base insulating film 44 is made of silicon oxide.

  The NMOS thin film transistor 41 has, for example, an LDD (Lightly Doped Drain) structure. That is, the central portion of the semiconductor thin film 45 of the NMOS thin film transistor 41 is a channel region 45a made of an intrinsic region, both sides thereof are a source / drain region 45b made of an n-type impurity low concentration region, and both sides thereof are n-type impurity high The source / drain region 45c is formed of a concentration region. On the other hand, the central portion of the semiconductor thin film 46 of the PMOS thin film transistor 42 is a channel region 46a made of an intrinsic region, and both sides thereof are a source / drain region 46b made of a p-type impurity high concentration region.

  A gate insulating film 47 made of silicon nitride is provided on the upper surface of the second base insulating film 44 including the semiconductor thin films 45 and 46. Gate electrodes 48 and 49 made of aluminum metal or the like are provided on the upper surface of the gate insulating film 47 on the channel regions 45a and 46a, respectively. A bottom gate insulating film 50, a top gate insulating film 51, and an interlayer insulating film 52 made of silicon nitride are provided on the upper surface of the gate insulating film 47 including the gate electrodes 48 and 49.

  Contact holes 53 are provided in the gate insulating film 47, the bottom gate insulating film 50, the top gate insulating film 51, and the interlayer insulating film 52 on the source / drain regions 45 c of the semiconductor thin film 45. Contact holes 54 are provided in the gate insulating film 47, the bottom gate insulating film 50, the top gate insulating film 51, and the interlayer insulating film 52 on the source / drain regions 46 b of the semiconductor thin film 46.

  Source / drain electrodes 55 and 56 made of aluminum metal or the like are provided in the contact holes 53 and 54 and on the upper surface of the interlayer insulating film 52 in the vicinity thereof. An overcoat film 57 made of silicon nitride is provided on the upper surface of the interlayer insulating film 52 including the source / drain electrodes 55 and 56.

  The NMOS thin film transistor 41 includes a semiconductor thin film 45, a gate insulating film 47, a gate electrode 48, and a source / drain electrode 55. The PMOS thin film transistor 42 includes a semiconductor thin film 46, a gate insulating film 47, a gate electrode 49, and source / drain electrodes 56. Thereby, the CMOS thin film transistor composed of the NMOS thin film transistor 41 and the PMOS thin film transistor 42, that is, the first to third drive circuit units 24 to 26 are formed on the glass substrate 22.

  Next, the photoelectric conversion type thin film transistor 31 will be described. On the upper surface of the gate insulating film 47, a bottom gate electrode 61 made of the same material as the gate electrodes 48 and 49 of the thin film transistors 41 and 42 for the drive circuit section, that is, a light shielding metal such as an aluminum-based metal is provided. A bottom gate insulating film 50 is provided on the upper surface of the gate insulating film 47 including the bottom gate electrode 61. A semiconductor thin film 62 made of intrinsic amorphous silicon is provided on the bottom gate insulating film 50 on the bottom gate electrode 61.

  A channel protective film 63 made of silicon nitride is provided at the center of the upper surface of the semiconductor thin film 62. A contact layer 64 made of n-type amorphous silicon is provided on both sides of the upper surface of the channel protective film 63 and on the upper surface of the semiconductor thin film 62 on both sides thereof. A source / drain electrode 65 made of aluminum-based metal or the like is provided on each upper surface of the contact layer 64 and on the upper surface of the bottom gate insulating film 50 in the vicinity thereof.

  A top gate insulating film 51 is provided on the top surface of the bottom gate insulating film 42 including the source / drain electrodes 65. A top gate electrode 66 made of a translucent metal such as ITO is provided on the top surface of the top gate insulating film 51 on the semiconductor thin film 62. An interlayer insulating film 52 and an overcoat film 57 are provided on the top surface of the top gate insulating film 51 including the top gate electrode 66.

  The photoelectric conversion type thin film transistor 31 includes a bottom gate type selection thin film transistor composed of a bottom gate electrode 61, a bottom gate insulating film 50, a semiconductor thin film 62, a channel protection film 63, a contact layer 64 and a source / drain electrode 65. A top gate electrode 66, a top gate insulating film 51, a semiconductor thin film 62, a channel protective film 63, a contact layer 64, and a top gate type sensor thin film transistor 65. Thereby, the photoelectric conversion type thin film transistor 31 is formed on the glass substrate 22.

  Next, the external connection terminal 27 will be described. The external connection terminal 27 is made of the same material as the source / drain electrodes 55 and 56 of the thin film transistors 41 and 42 for the drive circuit section, and is provided on the upper surface of the interlayer insulating film 52. In this case, the central portion of the external connection terminal 27 is exposed through a contact hole 67 provided in the overcoat film 57.

  Next, the first to third interlayer contact portions will be described. In the first interlayer contact portion, the first upper wiring 68 provided on the upper surface of the interlayer insulating film 52 is a contact hole provided in the interlayer insulating film 52, the top gate insulating film 51 and the bottom gate insulating film 50. The first lower wiring 70 provided on the upper surface of the gate insulating film 47 is connected to the first insulating film 47 via the gate insulating film 47. In this case, the first upper layer wiring 68 is formed of the same material as the source / drain electrodes 55 and 56 of the thin film transistors 41 and 42 for the drive circuit section, and the first lower layer wiring 70 is formed of the thin film transistors 41 and 42 for the drive circuit section. The gate electrodes 48 and 49 are made of the same material. An overcoat film 57 is provided on the first upper layer wiring 68.

  In the second interlayer contact portion, the second upper layer wiring 71 provided on the upper surface of the interlayer insulating film 52 is connected to the bottom via the contact hole 72 provided in the interlayer insulating film 52 and the top gate insulating film 51. It is connected to a second lower layer wiring 73 provided on the upper surface of the gate insulating film 50. In this case, the second upper layer wiring 71 is formed of the same material as the source / drain electrodes 55 and 56 of the thin film transistors 41 and 42 for the driving circuit section, and the second lower layer wiring 73 is the source of the photoelectric conversion type thin film transistor 31. -It is formed of the same material as the drain electrode 65. An overcoat film 57 is provided on the second upper layer wiring 71.

  In the third interlayer contact portion, the third upper layer wiring 74 provided on the upper surface of the top gate insulating film 51 is connected to the bottom gate insulating film 50 through the contact hole 75 provided in the top gate insulating film 51. Is connected to a third lower layer wiring 76 provided on the upper surface of the first lower wiring. In this case, the third upper layer wiring 74 is formed of the same material as the top gate electrode 66 of the photoelectric conversion type thin film transistor 31, and the third lower layer wiring 76 is the same as the source / drain electrode 65 of the photoelectric conversion type thin film transistor 31. It is made of material. An interlayer insulating film 52 and an overcoat film 57 are provided on the third upper layer wiring 74.

  Next, the electrical connection of each part shown in FIG. 3 will be described. The bottom gate electrode 61 of the photoelectric conversion type thin film transistor 31 is connected to the source / drain electrodes 55 and 56 of the thin film transistors 41 and 42 for the drive circuit section through the first lower layer wiring 70 and the first upper layer wiring 68. ing.

  The source / drain electrodes 65 of the photoelectric conversion type thin film transistor 31 are connected to the source / drain electrodes 55 and 56 of the thin film transistors 41 and 42 for the drive circuit section through the second lower layer wiring 73 and the second upper layer wiring 71. Has been. The top gate electrode 66 of the photoelectric conversion type thin film transistor 31 is connected to the thin film transistor for the driver circuit section via the third upper layer wiring 74, the third lower layer wiring 76, the second lower layer wiring 73 and the second upper layer wiring 71. 41 and 42 are connected to source / drain electrodes 55 and 56.

  The gate electrodes 48 and 49 of the thin film transistors 41 and 42 for the driving circuit section are connected to the external connection terminal 27 via the first lower layer wiring 70 and the first upper layer wiring 68 (the driving circuit section routing line). Yes. The source / drain electrodes 55 and 56 of the thin film transistors 41 and 42 for the drive circuit section are connected to the external connection terminal 27 via wiring (not shown) (leading line for the drive circuit section) provided on the upper surface of the interlayer insulating film 52. Has been.

  Next, the operation of the image reading apparatus having the above configuration will be briefly described. When this image reading apparatus is set to the display mode, the backlight 11 is turned on, and the light emitted from the upper surface of the backlight 11 is incident on the lower surface of the liquid crystal display panel 1 to drive the display of the liquid crystal display panel 1 based on the display signal. The corresponding image light is emitted from the display area 4 of the liquid crystal display panel 1 to the visual field side. The image light emitted from the display area 4 passes through the reading area 23 of the photosensor panel 21 having the same size as the display area 4 and is emitted from the reading area 23 to display an image.

  That is, as shown in FIG. 3, in the photoelectric conversion type thin film transistor 31 portion of the photosensor panel 21, the bottom gate electrode 61 and the source / drain electrode 66 are formed of a light-shielding metal such as an aluminum-based metal. When light is incident from the lower surface side, the light is transmitted through a transmission portion other than the bottom gate electrode 61 and the source / drain electrode 66 made of a light-shielding metal, so that the upper surface side (that is, the photosensor panel 21). The light is emitted from the reading region 23) and shielded from light by the bottom gate electrode 61, and does not directly enter the semiconductor thin film 63.

  Next, a case where a finger is placed on the image reading apparatus as a subject and a fingerprint image is read will be described. When the image reading apparatus is set to the fingerprint reading mode, the backlight 11 is turned on, and light emitted from the upper surface of the backlight 11 is incident on the lower surface of the liquid crystal display panel 1. In this case, the entire display area 4 is displayed in white, for example, by display driving of the liquid crystal display panel 1. Therefore, the light incident on the lower surface of the liquid crystal display panel 1 is transmitted through the entire display area 4 and emitted from the entire display area 4. The light emitted from the entire display area 4 passes through the reading area 23 of the photosensor panel 21 having the same size as the display area 4 and is emitted from the reading area 23.

  In this state, when a finger (not shown) is placed on the upper surface of the reading area 23 of the photosensor panel 21, the light emitted from the reading area 23 of the photosensor panel 21 is irradiated to the finger, and the fingerprint protrusion ( The light is reflected at the portion corresponding to the ridge), and the light is scattered at the portion corresponding to the concave portion (downline) of the fingerprint. As a result, fingerprint image light that is optically bright and dark according to the unevenness of the fingerprint is obtained.

  The fingerprint image light passes through the top gate electrode 68, the top gate insulating film 67, and the channel protective film 64 made of a translucent metal such as ITO, and is applied to the semiconductor thin film 63. Then, electron-hole pairs corresponding to the brightness of the fingerprint image light are induced and accumulated in the semiconductor thin film 63, and a fingerprint image is read.

  As described above, in the image reading apparatus according to the present embodiment, since the photosensor panel 21 is a two-dimensional type, a subject image (fingerprint image) of a subject (finger) placed on the upper surface of the reading area 23 of the photosensor panel 21. ) Can be easily read, and the size of the reading area 23 is the same as the size of the display area 4 of the liquid crystal display panel 1, so that it has a relatively large area. It can be difficult. In addition, since the photo sensor panel 21 is arranged on the liquid crystal display panel 1, it is not necessary to provide a photo sensor panel arrangement area at a location different from the liquid crystal display panel 1, and downsizing of electronic equipment including the image reading device is reduced. Can be achieved.

  Further, in this image reading apparatus, in the photo sensor panel 21, a plurality of photoelectric conversion type thin film transistors 31 as photo sensors on the glass substrate 22 and first to third drive circuit units for driving these thin film transistors 31 are provided. Since the CMOS thin film transistors constituting 24-26 are integrally formed, the thickness of the photosensor panel 21 having the first to third drive circuit units 24-26 for driving the thin film transistor 31 is reduced. It is possible to suppress an increase in the thickness of an electronic device including the same.

  Further, in this image reading apparatus, since the CMOS thin film transistors constituting the first to third drive circuit units 24 to 26 are integrally formed on the glass substrate 22 in the photosensor panel 21, these drive circuit units are arranged as shown in FIG. Compared with the case where the semiconductor chip to be configured is mounted on the glass substrate 22, the upper surface of the photosensor panel 21 can be flattened, so that a subject such as a finger can be easily adhered to the upper surface of the photosensor panel 21. can do.

  By the way, in this image reading apparatus, in the reading mode, the display color of the active matrix type liquid crystal display panel 1 provided with a color filter is sequentially switched to red, green, and blue, and the image of the subject is read for each display color. A color image may be obtained by synthesizing the read image for each display color. In this case, a color image can be read even if the photo sensor panel 21 is a monochrome type.

  Further, in this image reading apparatus, since light from the backlight 11 disposed on the lower side of the liquid crystal display panel 1 is used as image reading light such as a fingerprint, a light source dedicated to image reading such as a fingerprint is required. Therefore, the number of parts is reduced accordingly, and the cost can be reduced. However, since the backlight 11 is a light source for the liquid crystal display panel 1, if the sensitivity of the photosensor 31 of the photosensor panel 21 is constant, an image such as a fingerprint may not be read satisfactorily.

  For example, depending on the state of the subject (for example, the dry state of the skin on the surface of the finger) and the brightness of the surrounding environment (for example, since the finger transmits external light to some extent, the transmitted external light also becomes the fingerprint reading light) If the received light is too bright, the sensitivity of the photosensor 31 is saturated and the image cannot be read satisfactorily. On the other hand, if the received light is too dark, the image is read with sufficient contrast. Can not be.

  Therefore, the sensitivity of the photosensor 31 may be adjusted so that the image can be satisfactorily read according to the situation. In addition, instead of adjusting the sensitivity of the photosensor 31, the liquid crystal display panel 1 can change the display luminance in accordance with the display image. Therefore, if the light received by the photosensor 31 is too bright, the liquid crystal The display panel 1 may be displayed in an appropriate gray instead of white. Further, instead of adjusting the sensitivity of the photosensor 31, the brightness of the backlight 11 may be adjusted. Furthermore, the adjustment of the sensitivity of the photosensor 31 and the adjustment of the intensity of light incident on the photosensor 31 may be performed together.

  Here, when this image reading apparatus is applied to a portable electronic device such as a cellular phone, the size of the display area 4 of the liquid crystal display panel 1 is generally the minimum necessary size for reading a fingerprint (mounting). Larger than the size of the finger placed). However, in FIG. 1, the size of the reading area 23 of the photosensor panel 21 is the same as the size of the display area 4 of the liquid crystal display panel 1. Therefore, if the photosensors 31 shown in FIG. 3 are arranged in a matrix over the entire reading area 23 of the photosensor panel 21, the transmittance of the entire reading area 23 of the photosensor panel 21 becomes uniform, and this image reading apparatus is set as a display mode. When used, the display quality in the entire reading area 23 of the photosensor panel 21 can be made uniform.

(Second Embodiment)
FIG. 4 is a perspective view of a main part of an image reading apparatus as a second embodiment of the present invention. In this image reading apparatus, the difference from the case of the first embodiment shown in FIG. 1 is that a region corresponding to a part of the display region 4 of the liquid crystal display panel 1 (for example, a substantially central portion) in the photosensor panel 21. The reading area 23a has a minimum size necessary for reading the fingerprint, and the area corresponding to the remaining part of the display area 4 is a dummy reading area 23b.

  That is, photoelectric conversion type thin film transistors (photosensors) that are actually driven are arranged in a matrix in the reading area 23a, and photoelectric conversion type dummy thin film transistors (dummy photosensors) that are not driven in the dummy reading area 23b are also in the same matrix. Arranged in a shape. In this case, the photoelectric conversion type dummy thin film transistors that are not driven in the dummy reading region 23b are arranged in a matrix so that the transmittance of the dummy reading region 23b is the same as the transmittance of the reading region 23a and the transmittance is uniform. It is.

  In this image reading apparatus, the photoelectric conversion type thin film transistors that are actually driven need only be arranged in a matrix only in the reading region 23a having the minimum size necessary for fingerprint reading. In comparison, the number of photoelectric conversion type thin film transistors that are actually driven can be minimized, and as a result, the yield is improved, the cost is reduced, the drive circuit portion is reduced, the power consumption is reduced, and the like. Can be planned.

  By the way, in this image reading apparatus, in the photo sensor panel 21, the areas corresponding to the display area 4 of the liquid crystal display panel 1 are the reading area 23a and the dummy reading area 23b. Of the one display area 4, the area corresponding to the reading area 23a may be displayed in white, and the area corresponding to the dummy reading area 23b may be displayed in black, for example, to guide the finger placement area.

  Further, in the fingerprint reading mode, the area corresponding to the reading area 23a in the display area 4 of the liquid crystal display panel 1 is displayed in white, and for example, a finger is placed in the area corresponding to the dummy reading area 23b. Message display or the like can also be performed. Such a case is also possible in the case of the first embodiment.

(Third embodiment)
FIG. 5 shows a perspective view of a main part of an image reading apparatus as a third embodiment of the present invention. This image reading apparatus is different from the first embodiment shown in FIG. 1 in that the counter substrate 3 of the liquid crystal display panel 1 is also used as the glass substrate (22) of the photosensor panel 21. That is, on the outer surface side of the counter substrate 3, a plurality of photoelectric conversion type thin film transistors (not shown) are arranged in a matrix, a reading region 23, first to third driving circuit units 24 to 26, and a plurality of external connections. A terminal 27 is provided.

  In this case, the liquid crystal display panel 1 is driven by a field sequential driving method as will be described later. For this reason, although not shown, the inner surface of the counter substrate 3 (the surface facing the active substrate 2) is provided with a black mask, a solid common electrode, and an alignment film, and is not provided with a color filter. . Further, the backlight 11 can emit red light, green light and blue light by switching from the upper surface thereof.

  Here, in order to mount the semiconductor chip 5 on the active substrate 2, the lower end portion of the active substrate 2 protrudes from the counter substrate 3. Further, in order to superimpose the reading area 23 of the photosensor panel 21 and the display area of the liquid crystal display panel 1, a portion of the external connection terminal 27 provided at one end portion on the outer surface side of the counter substrate 3 that also serves as the photosensor panel 21. Is protruded from the upper end portion of the active substrate 2 (the side opposite to the semiconductor chip 5 mounting side).

  Next, an example of the field sequential driving method of this image reading apparatus will be briefly described (for details, see, for example, Japanese Patent Laid-Open No. 2001-272651). One frame is divided into three first to third sub-frames, the writing state of the pixels in each row is reset at the beginning of each sub-frame, and then the display data of red, green, and blue is written to the pixels in each row Then, the backlight 11 is turned on at the end of each subframe, and any one of red light, green light, and blue light is emitted from the upper surface.

  That is, in the first subframe, red light is emitted from the upper surface of the backlight 11, and red image light corresponding to the red display data written in the pixels of each row is displayed on the display area of the liquid crystal display panel 1, that is, the photosensor panel 21. The light is emitted from the reading area 23. Next, in the second subframe, green light is emitted from the upper surface of the backlight 11, and green image light corresponding to the green display data written in the pixels of each row is displayed in the display area of the liquid crystal display panel 1, that is, the photosensor panel. 21 from the reading area 23. Next, in the third sub-frame, blue light is emitted from the upper surface of the backlight 11, and blue image light corresponding to the blue display data written in the pixels of each row is displayed in the display area of the liquid crystal display panel 1, that is, the photosensor panel. 21 from the reading area 23. Then, one color image is displayed by combining the three colors of emitted image light.

  As described above, in the image reading apparatus according to the present embodiment, since the counter substrate 3 of the liquid crystal display panel 1 also serves as the glass substrate (22) of the photosensor panel 21, the thickness of the image reading apparatus is reduced accordingly. As a result, an increase in the thickness of the electronic device including the same can be further suppressed.

(Fourth embodiment)
FIG. 6 is a perspective view of a main part of an image reading apparatus as a fourth embodiment of the present invention. In this image reading apparatus, the main difference from the case of the first embodiment shown in FIG. 1 is that a self-luminous organic EL (electroluminescence) display panel 71 is used instead of the non-self-luminous liquid crystal display panel 1. It is used and the backlight 11 is omitted.

  That is, the organic EL display panel 71 is not shown in detail, but in the case of the active matrix type and the top emission type, the display area on the upper surface of the glass substrate 72 (corresponding to the reading area 23 of the photosensor panel 21). By applying an electric field selectively to a plurality of organic EL layers arranged in a matrix in a matrix in accordance with display driving, light emission and non-light emission on the opposite side to the glass substrate 72 side are performed. Image display can be performed.

  In this case, the glass substrate 22 of the photosensor panel 21 is bonded to the upper surface side of the organic EL display panel 71 via a sealing material (not shown). The lower end portion of the organic EL display panel 71 protrudes from the photosensor panel 21, and a semiconductor chip 73 for driving the organic EL layer is mounted on the upper surface of the protruding portion. Further, the portion of the external connection terminal 27 of the photo sensor panel 21 protrudes from the upper end portion of the organic EL display panel 71.

  Since this image reading apparatus does not include a backlight as compared with the case of the third embodiment illustrated in FIG. 5, the image reading apparatus can be significantly reduced in thickness, and an electronic apparatus including the backlight can be reduced in thickness. Can do. In addition, an anode electrode, an organic EL layer, and a cathode electrode are laminated in this order in the display region on the upper surface of the glass substrate 72 of the organic EL display panel 71. However, non-light emission is caused by the intrusion of impurities such as moisture from the outside. Although a dark spot which is an area is easily generated and grows, a sealing material is disposed around the display area on the organic EL display panel 71, and the glass substrate of the organic EL display panel 71 and the photosensor panel 21 is interposed through the sealing material. 22 can be prevented from intruding impurities such as moisture into the display area on the organic EL display panel 71, and the generation and growth of dark spots can be suppressed to improve reliability. Can do.

  The organic EL display panel 71 may be a bottom emission type, that is, an anode electrode, an organic EL layer, a cathode electrode, and a protective film are laminated in this order on the display region on the lower surface of the glass substrate 72, and glass An image may be displayed by light emission toward the substrate 72 side. In this case, the problem of generation and growth of dark spots does not occur due to the difference in constituent materials. Further, it is not necessary to attach the bottom emission type organic EL display panel 71 and the glass substrate 22 of the photo sensor panel 21 to each other via a sealing material.

(Other embodiments)
In the above embodiment, the case where a photoelectric conversion type thin film transistor is used as a photosensor has been described. However, the present invention is not limited to this, and a photo die auto may be used. Further, in the above-described embodiment, the case where the drive circuit unit is configured by a CMOS thin film transistor including a polysilicon thin film transistor has been described. However, the present invention is not limited thereto, and may be configured by only an NMOS thin film transistor. You may make it comprise with a combination with an amorphous silicon thin-film transistor.

1 is a perspective view of a main part of an image reading apparatus as a first embodiment of the present invention. The equivalent circuit top view of the photosensor panel shown in FIG. Sectional drawing shown in order to demonstrate the specific structure of a part of photosensor panel shown in FIG. The perspective view of the principal part of the image reading apparatus as 2nd Embodiment of this invention. The perspective view of the principal part of the image reading apparatus as 3rd Embodiment of this invention. The perspective view of the principal part of the image reading apparatus as 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 4 Display area 11 Backlight 21 Photo sensor panel 22 Glass substrate 23 Reading area 24-26 Drive circuit part 31 Photoelectric conversion type thin-film transistor (photo sensor)

Claims (8)

A display panel for displaying an image based on the display signal in a display area ;
A photosensor panel having translucency and reading a subject placed in the reading area as an image by a plurality of photosensors arranged in a matrix in the reading area ;
The photo sensor panel has a dummy reading area having a transmittance equivalent to that of the reading area, and the reading area and the dummy reading area are superimposed on the display panel so as to overlap the display area. An image reading apparatus. The dummy reading area is provided so as to surround the reading area,
The image reading apparatus according to claim 1, wherein the photo sensor panel is overlapped with the display panel so that the reading area is within the range of the display area. The image reading apparatus according to claim 1, wherein the reading area is formed to have a smaller area than the display area. 4. The image reading according to claim 1, wherein a driving circuit for driving the photosensor is formed integrally with the photosensor outside the reading area. 5. apparatus. The image reading apparatus according to claim 4, wherein dummy photosensors having a structure equivalent to the photosensor and not driven by the drive circuit are arranged in a matrix in the dummy reading area. 6. The image reading apparatus according to claim 1, further comprising: a display that guides reading of the subject image in an area of the display area that overlaps the dummy reading area. The image reading apparatus according to claim 1, wherein the photosensor includes a thin film transistor in which gate electrodes are provided on an upper layer side and a lower layer side of a semiconductor thin film. A photosensor panel having translucency and reading a subject placed in the reading area as an image by a plurality of photosensors arranged in a matrix in the reading area;
The photosensor panel is one of a pair of substrates, and a liquid crystal display panel that displays an image based on a display signal in a display region,
The photo sensor panel has a dummy reading area having the same transmittance as the reading area,
The image reading apparatus, wherein the display area is provided so as to overlap the reading area and the dummy reading area.

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