JP4424336B2 - Image sensor - Google Patents

Description

  The present invention relates to an image input device for reading an image such as a copying machine or a facsimile, and an image input / output device for reading an image subjected to a special medium such as a color image or banknote recognition. Related to the image sensor.

  As a line light source used for an image sensor for reading image information such as an original, a long cylindrical light source 1 is shown in FIG. 1 (see Patent Document 1) of Japanese Patent Laid-Open No. 10-79835, and an internal layer is formed on an upper layer of a reflective film 3. An illuminating device is disclosed that includes a phosphor 5 that converts ultraviolet light into visible light and an opening 2 that concentrates the emitted light.

  Further, in FIG. 3 (see Patent Document 2) of Japanese Patent Application Laid-Open No. 2003-346530, a plurality of light sources 22 are arranged at one end of the light guide 21 to form a multicolor light source, and the back surface of the light guide 21 is scattered by printing. A body pattern is disclosed.

  Further, FIG. 1 of Japanese Patent Laid-Open No. 10-173873 (refer to Patent Document 3) discloses that an original set on a contact glass is exposed from below to be exposed along the lower surface of the contact glass in order to read the original image. From the light source 3 that emits light in the visible light region and the infrared region, the visible light cut filter 13 that blocks light in the visible light region from the light source 3, and the light source 3. An image reading apparatus including an infrared cut filter 14 that blocks light in the infrared region is disclosed.

  Further, FIG. 1 (see Patent Document 4) of JP-A-9-275198 is provided with an infrared cut filter 10 in which a plurality of vapor-deposited infrared cut layers are sequentially laminated, and the predetermined arrangement on the substrate is as described above. A solid-state imaging device with an infrared cut filter for removing the infrared cut filter 10 corresponding to a sensitive portion other than the sensitive portion of the specific color among the green sensitive portion, the red sensitive portion and the blue sensitive portion forming the sensor portion; The manufacturing method is disclosed.

Japanese Patent Laid-Open No. 10-79835 (FIG. 1)

JP 2003-346530 A (FIG. 3)

Japanese Patent Laid-Open No. 10-173873 (FIG. 1)

JP-A-9-275198 (FIG. 1)

  However, the method described in Patent Document 1 does not mention measures against radiation of light having a secondary optical wavelength emitted by ultraviolet light or the like. Moreover, in the thing of patent document 2, although it is a color light source which provided the scattering pattern in the light guide, it is a light source using the LED chip of visible region, and the light source which has a special spectrum is not touched. .

  Moreover, in the thing of patent document 3, although the visible light cut filter 13 and the infrared cut filter 14 are provided in the light source vicinity with respect to the light source 3 which has a several spectrum of visible light, an area | region, and an infrared region, A specific configuration is not disclosed.

  Although the thing of patent document 4 has provided the infrared cut filter in the sensitive part, it was necessary to laminate | stack an infrared cut layer in a sensitive part, and there existed a problem that a structure became complicated.

  The present invention provides an image sensor for reading an image, which includes a filter that converts light emitted from an LED light source into a white light source and blocks the unnecessary light provided on the incident surface of the light guide. The purpose is to provide.

An image sensor according to a first aspect of the present invention includes a light source, a phosphor that emits white light by the light of the light source, and a predetermined visible light region including a part of a red light region of the light from the phosphor. A film-like optical filter that blocks light on the longer wavelength side than the wavelength of the light, and the light that has passed through the optical filter and entered the one end is propagated to the other end, and the light emitted from the side is irradiated And a sensor IC that receives light reflected from the irradiated body and converts it into an electrical signal.

The image sensor according to the invention of claim 2 is a light source, a phosphor that seals the light source and emits white light by the light of the light source, and propagates light incident on one end side to the other end side, A columnar light guide that irradiates the irradiated body with light emitted from the side surface thereof, and is installed between the one end side of the light guide and the light source. Of the light from the phosphor , A film-like optical filter that blocks light longer than the wavelength of the predetermined visible light region including a part, a lens that converges light reflected from the irradiated object, and light that has passed through this lens is received. And a sensor IC for converting into an electric signal.

The image sensor according to the invention of claim 3 includes a light source, a phosphor which emits a white light by the light of the light source to seal the light source, with propagating the light incident on one end to the other end, a columnar light guide for irradiating light emitted from a side surface in the irradiated object, placed at one end of the light guide, and a holder for supporting the light source and the light guide, which is supported on the holder Film-like optics that is affixed to an end face on one end side of the light guide and blocks light from the phosphor that has a longer wavelength than the wavelength of a predetermined visible light region including a part of the red light region. A filter, a lens that converges the light reflected from the irradiated object, and a sensor IC that receives the light passing through the lens and converts it into an electrical signal are provided.

Engaging Louis Mejisensa to a fourth aspect of the present invention, light source, and a phosphor which emits a white light by the light of the light source to seal the light source, with propagating the light incident on one end to the other end A columnar light guide that irradiates the irradiated body with light emitted from the side surface, a holder disposed on one end side of the light guide, and supporting the light source and the light guide, and supported by the holder A film-like optical filter that is affixed to the light source and blocks light from the phosphor that has a longer wavelength than the wavelength of a predetermined visible light region including a part of the red light region; And a sensor IC that receives the light that has passed through the lens and converts it into an electrical signal .

  According to the image sensor of the present invention, since the film-like optical filter that blocks transmission of long-wavelength light including a part of the visible light region is installed between the light source and the light guide end, the reading region It is not necessary to install an optical filter throughout, and as a result, a common optical filter that is not restricted by the reading size of the image sensor can be used. Further, since the film-like optical filter is used as a small piece by punching or the like, stable filter performance can be obtained even if there is a manufacturing variation in filter characteristics due to a processing position that occurs during pattern formation of an organic film or the like.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1A is an exploded view showing the configuration of the image sensor according to the first embodiment. In FIG. 1A, 1 is a light source (LED substrate) on which LED chips are mounted, and 2 is a light source from the light source 1. A columnar (rod-shaped) light guide that propagates light and emits light from its side surface, 3 is an optical filter composed of a thin film organic film bonded to the end of the light guide 2, and 4 is a light guide 2 is a rod lens array (lens) that converges reflected light from a subject (illuminated body) incident from the transmissive body 4, and 6 is converged by the rod lens array 5. A sensor IC (sensor chip) that receives light, 7 is a substrate (sensor substrate) on which the sensor chip 6 is mounted, 8 is a flexible substrate that is connected to the sensor substrate 7 and supplies power for driving the light source 1, 9 Is both sides of the light guide 2 Provided, the holder for supporting the light guide 2 and the light source 1, 10 is a housing for accommodating the light guide 2 and the lens 5 disposed along the longitudinal direction of the light guide 2 and the rod lens array 5. FIG. 1B is an exploded view showing the configuration of the image sensor according to Embodiment 1, and shows the configuration when the optical filter 3 is attached to the LED chip side of the light source 1.

  FIG. 2 is a side view of the image sensor according to the first embodiment. Reference numeral 11 denotes a signal processing circuit for driving the image sensor provided on the opposite side of the sensor chip 6 on the sensor substrate 7 and driving of the light source 1. It is an electronic component such as a connector used in a circuit or the like, or an ASIC (Application Specific Integrated Circuit). The signal processing circuit and the drive circuit are referred to as a drive unit.

  FIG. 3 is a cross-sectional view of the A-A ′ portion of FIG. 2 of the image sensor according to the first embodiment. Reference numeral 12 denotes a subject such as a document or a bill. The light emitted from the light guide 2 irradiates the subject 12, and the reflected light from the subject 12 passes through the transmissive body 4, is converged by the rod lens array 5, and is received by the sensor chip 6.

  FIG. 4 is a cross-sectional view showing the internal structure of the light guide 2. Reference numeral 2 a denotes a pattern formed with white paint so that light is uniformly emitted from the side surface of the light guide 2 over the longitudinal direction of the light guide 2. Light scattering pattern. 1 to 4, the same reference numerals indicate the same or corresponding parts.

  Next, the operation will be described. The illumination system of the light source 1, the light guide 2, and the optical filter 3 will be described with reference to FIG. In FIG. 5A, 1a is a blue LED and 1b is a yellow fluorescent resin (phosphor) sealed with resin so as to surround the blue LED 1a. In the drawing, blue light emitted from a blue LED 1 a mounted on the LED substrate 1 is converted into white light by a yellow phosphor 1 b having a complementary color relationship with blue, and is incident on an end portion of the light guide 2. An optical filter 3 patterned with an organic film having a thickness of about 0.1 mm is provided on the end of the light guide 2 on the light guide 2 side. Moreover, in FIG.5 (b), the optical filter 3 is installed in the LED board 1 side.

  This optical filter 3 blocks the transmission of light on the long wavelength side such as near infrared including part of visible light, and exhibits spectral characteristics as shown in FIG. In FIG. 6, the transmission of light is blocked for wavelengths greater than 650 nm. Light incident on the inside of the light guide 2 that does not include the spectrum of light on the long wavelength side propagates in the longitudinal direction of the light guide 2, but part of the light is scattered and reflected by the light scattering pattern 2 a to guide the light. Radiated from the side of the body 2 to the outside. The light scattering pattern 2a is formed as a slit pattern and a continuous pattern, and is designed to emit a uniform amount of light from the side surface of the light guide 2 facing the light scattering pattern 2a in the longitudinal direction of the light guide 2. The

  Next, the light receiving system of the sensor chip 6 mounted on the sensor of the image sensor will be described with reference to FIG. FIG. 7 is a plan view showing the sensor chip 6 mounted on the sensor substrate 7. 60 is a pixel (light receiving portion), and 6R is a red filter composed of a red gelatin material by dividing the pixel 60 into three equal parts. (R filter), 6G is a green filter (G filter) made of a green gelatin material, and 6B is a blue filter (B filter) made of a blue gelatin material. Each filter 60R, 60G, 60B absorbs light corresponding to each color and performs photoelectric conversion. Reference numeral 70 denotes a wire bonding pad for transferring an input / output signal for driving the sensor chip 6.

  Usually, a plurality of sensor chips 6 are mounted and driven by connecting SI (start) signal and SO signal. The signal output of each pixel photoelectrically converted by the light receiving unit 60 is sequentially opened / closed by an analog switch group with an opening / closing signal from a shift register, and is sent to the outside as an output signal as an image signal. In the case of color reading on the subject 12, the respective outputs filtered by the filters 60R, 60G, and 60R are sequentially or simultaneously sent to the signal processing circuit as analog signals based on the color read signal synchronized with the CLK (clock) signal. Send it out.

  Next, a case where a color image is read will be described. FIG. 8 is a diagram for explaining the spectral characteristics of the filters 60R, 60G, and 60B provided in the sensor chip 6. In the first embodiment, the blue spectrum (475 nm), the green spectrum (525 nm), and the red spectrum (640 nm). ) Is used as a predetermined reading color, so a filter having spectral characteristics of each color corresponding to those spectra is provided.

  By the way, although each filter 60R, 60G, 60B provided in the sensor chip 6 selectively receives each color, it does not maintain a filtering characteristic for a long-wavelength side spectrum such as a near infrared ray, and in red reading. Is close to the near-infrared wavelength, so the presence of a long-wavelength spectrum appears as noise during reading. That is, in the black absorption image of the subject 12, the light emitted from the light source 1 is absorbed by the subject 12, and the dark output (dark signal output when the LED is lit) is preferably zero, but it depends on the spectrum on the long wavelength side. There is an increase in the dark output, and the dark output varies depending on each reading color. Further, the spectrum output on the long wavelength side which is not necessary for reading the image in the red spectrum region affects the adjacent pixel 60, and as a result, an output different from the original image is generated.

  Further, the spectral sensitivity of the light receiving portion of the C-MOS sensor chip 6 using a silicon semiconductor tends to be higher in the longer wavelength side such as infrared rays as shown in FIG. In other words, compared to other photoconductive image sensors equipped with amorphous silicon (a-si), etc., the sensitivity of receiving light in the infrared region is high and even weak infrared light affects the image quality during color reproduction. give.

  FIG. 9 is a diagram showing the light intensity when the optical filter (IRCF) 3 is not installed on the end portion of the light guide 2 or the LED substrate 1, and unnecessary light exists on the long wavelength side. On the other hand, FIG. 10 is a diagram showing the light intensity when the optical filter (IRCF) 3 is installed on the end of the light guide 2 or the LED substrate 1, and it can be seen that a wavelength longer than about 650 nm is cut. .

  From the above, a film-like optical filter that blocks transmission of long-wavelength light including a part of the visible light region is installed between the light source and the light guide end, so that unnecessary light such as infrared light is received. Therefore, the dark output level can be stabilized and the red image or the like can be faithfully read by each reading color.

  In the first embodiment, color image reading has been mainly described. However, the filters 60R, 60G, and 60B are not necessary for reading a monochrome image using a white light source including a red spectrum. Further, in an image sensor equipped with the filters 60R, 60G, and 60B, a monochrome image can be read by using, for example, an output signal of the filter 60G having an intermediate wavelength. Further, although the filters 60R, 60G, and 60B have been described using optical wavelength band filters, even if a dropout color filter or a low-frequency cut filter for each color is used, there is a corresponding effect on color reading.

Embodiment 2. FIG.
A second embodiment of the present invention will be described with reference to FIG. FIG. 11 is an explanatory diagram of an illumination system incorporating a light source, a light guide, and an optical filter. Fig.11 (a) is the figure which looked at the illumination system from the longitudinal direction, and FIG.11 (b) is the principal part side view of an illumination system. 11A and 11B, 100 is an LED substrate (light source), 100a is a blue LED, 100b is a yellow phosphor that is resin-sealed so as to surround the blue LED 100a, and 100c is a lead that drives the light source 100. An electrode, 200 is a light guide having a pentagonal cross section obtained by cutting a part of a quadrangular prism, and 200a is a white plastic material that covers the outer periphery of the light guide 200 and efficiently propagates light inside the light guide 200 in the longitudinal direction. 200b is a light scatterer provided on the surface of the light guide 200, and 200c is a light emitting part provided in a substantially opposite position of the light scatterer 200b and provided in a region not covered by the cover 200a. is there. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

  Next, the operation will be described. In FIG. 11, blue light emitted from the blue LED 100 a mounted on the LED substrate 100 is converted into white light by a yellow phosphor 100 b having a complementary color relationship with blue, and is incident on the end of the light guide 200. Since the optical filter 3 patterned with an organic film having a thickness of about 0.1 mm is disposed between the LED substrate 100 and the light guide 200 at the end of the light guide 200, the optical filter 3 As a result, the wavelength in the infrared region is cut, and only predetermined visible light can enter the light guide 100.

  For example, when adjusting the output level of blue light with strong light intensity emitted from the light source 1 as shown in FIG. 9 or FIG. 10 described in the first embodiment, the optical filter 3 is blue. By providing a low-frequency cut filter that reduces the light transmittance, the output level of not only infrared light but also blue light is lowered, and a stable image sensor that is free from noise even if secondary spectrum is generated in the ultraviolet light region. Can be read.

FIG. 1 is an exploded view showing a configuration of an image sensor according to Embodiment 1 of the present invention. FIG. 1A shows an optical lens attached to a light guide, and FIG. 1B attached an optical lens to a light source. Indicates the case. It is a side view of the image sensor by Embodiment 1 of this invention. It is sectional drawing of the image sensor by Embodiment 1 of this invention. It is sectional drawing of the light guide of the image sensor by Embodiment 1 of this invention. It is explanatory drawing of the illumination system of the image sensor by Embodiment 1 of this invention, Fig.5 (a) attaches an optical lens to a light guide, FIG.5 (b) attaches an optical lens to a light source. Indicates the case. It is a figure explaining the spectral characteristic of the optical filter of the image sensor by Embodiment 1 of this invention. It is a top view explaining the structure of the sensor chip of the image sensor by Embodiment 1 of this invention. It is a figure explaining the spectral characteristic of the sensor chip of the image sensor by Embodiment 1 of this invention. It is a figure explaining the output characteristic of the image sensor when not mounting the optical filter of the image sensor by Embodiment 1 of this invention. It is a figure explaining the output characteristic of the image sensor at the time of carrying the optical filter of the image sensor by Embodiment 1 of this invention. It is explanatory drawing of the illumination system of the image sensor by Embodiment 2 of this invention, Fig.11 (a) is explanatory drawing which looked at the illumination system from the longitudinal direction, FIG.11 (b) is the principal part side view of an illumination system. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source (LED board), 1a LED chip, 1b Fluorescent substance, 2 Light guide, 2a Light scattering pattern (light scatterer), 3 Optical filter, 4 Transmitter, 5 Lens (rod lens array), 6 Sensor IC ( Sensor chip), 7 sensor substrate (substrate), 8 flexible substrate, 9 holder, 10 housing, 11 electronic component, 12 irradiated body (irradiated body), 60 light receiving unit (pixel), 60R red filter, 60G green filter 60B Blue filter. 70 pad (wire bonding pad), 100 light source (LED substrate), 100a LED, 100b phosphor, 100c lead electrode, 200 light guide, 200a cover, 200b light scatterer, 200c light emitting part.

Claims (4)

A light source, a phosphor that emits white light by the light of the light source, and light from the phosphor that is longer than the wavelength of a predetermined visible light region including a part of the red light region is blocked. A film-shaped optical filter, a columnar light guide that propagates light incident on one end through the optical filter to the other end, and irradiates the irradiated object with light emitted from the side surface; An image sensor comprising: a sensor IC that receives light reflected from an irradiation body and converts the light into an electrical signal. A light source, a phosphor that seals the light source and emits white light by the light of the light source, and propagates light incident on one end side to the other end side, and transmits light emitted from the side surface to the irradiated body A wavelength of a predetermined visible light region including a columnar light guide to be irradiated and a part of the red light region of the light from the phosphor that is installed between the one end side of the light guide and the light source. A film-like optical filter that blocks light on the longer wavelength side, a lens that converges the light reflected from the irradiated object, and a sensor IC that receives the light passing through the lens and converts it into an electrical signal Image sensor. A light source, and a phosphor which emits a white light by the light of the light source to seal the light source, with propagating the light incident on one end to the other end, the light emitted from the side surface in the irradiated object A columnar light guide to be irradiated, disposed on one end of the light guide, a holder for supporting the light source and the light guide, and an end face on one end of the light guide supported by the holder is the out of light from the phosphor, the film-shaped optical filter for blocking light of a longer wavelength side than the wavelength of a predetermined visible light region including a portion of the red light region, the light reflected from the irradiated object An image sensor comprising a lens that converges the light and a sensor IC that receives light passing through the lens and converts it into an electrical signal . A light source, a phosphor that seals the light source and emits white light by the light of the light source, and propagates light incident on one end side to the other end side, and transmits light emitted from the side surface to the irradiated body A columnar light guide to be irradiated, disposed at one end of the light guide, a holder for supporting the light source and the light guide, and affixed to the light source supported by the holder, from the phosphor Of the light, a film-like optical filter that blocks light on the longer wavelength side than the wavelength of the predetermined visible light region including a part of the red light region, a lens that converges the light reflected from the irradiated object, An image sensor comprising a sensor IC that receives light passing through a lens and converts it into an electrical signal .

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