JPH01303957A - Original reader - Google Patents

Abstract

PURPOSE:To form an original reader with thin profile and high S/N by arranging a light source whose optical axis is vertical to an original and arranging a lens array whose optical axis is tilted with respect to the original. CONSTITUTION:The optical axis of an LED array 12 is aligned onto the axis of a read point 17 of an original 16 and the face of the original 16 is lighted vertically. Moreover, a lens array 13 is tilted by nearly 45 deg. and the image of a reflected light from the read point 17 on the original 16 is formed on a photodetection sensor substrate 14 placed at a position symmetrical on the optical axis of the lens array 13. Thus, all the luminance quantity radiated from the light source is contributed as the irradiating energy to obtain the picture light. The irradiating light to the original 16 is irregularly reflected and spread in every direction around the read point 17 nearly uniformly. Thus, even if the lens array is placed while its axis is tilted, the luminous quantity transfer rate of the picture light is not reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a document reading device, and more particularly to a document reading device suitable for secret reading in which the document width and the reading width correspond one to one.

[Conventional technology]

IC as a reading device for facsimile transmitters, etc.
In place of a one-dimensional array of MOS or COD called a sensor, a contact image sensor in which the width of an original corresponds to the width of a photoelectric conversion element array on a one-to-one basis has been put into practical use. This is because the optical path of the reduction optical system and its delicate adjustment are not required, and the transmitter can be made smaller and lower in price. Naturally, like an IC sensor, it is required to have stable performance and uniform sensitivity characteristics over its entire length.

As shown in FIG. 3, such a conventional contact image sensor uses a sensor device 34 in which a plurality of sensor elements are separately arranged on a substrate, an illumination light source by an LED 32, and a pair of reflected light from a document 36. A lens array 33 and a vapor guide 35 are installed in a metal housing 31 to form an erect, same-magnification image on a document 36, and the optical axis of the LED 32 is at 45 degrees and the optical axis of the lens array 33 is at 90 It is configured to be a degree.

[Problem to be solved by the invention]

Such a conventional close-contact image sensor has an LED 33
Image light illuminated by and reflected from the document 36 is guided by the lens array 33 and imaged onto the sensor device 34 . The strength is converted into an electrical signal and output, but the output signal from the sensor device 34 is usually very small, and the performance of the contact sensor is determined by how large the output signal is.

However, since the optical axis of the illumination by the LED 32 is inclined at about 45 degrees with respect to the original 36, the amount of light irradiating the original 36 is reduced to 177 lights compared to the original amount of light emitted by the LED 32. Therefore, such a configuration in which reflected light from the original 36 is received has the disadvantage that the output signal becomes small and a sufficient signal-to-noise ratio cannot be obtained. In addition, in order to compensate for this decrease, the amount of light is increased by increasing the number of chips in the LED 33 or increasing the current, but this increases the cost and generates heat, which is disadvantageous in terms of characteristics and reliability. It had become.

[Means to solve the problem]

According to the present invention, there is provided a light source that illuminates an original, an array-like light receiving sensor in which elements are arranged in a predetermined main scanning direction, and a lens array that forms an erect, same-size image of the original on the surface of the light receiving sensor. In the original reading device, the optical axis of the light source is arranged perpendicular to the original, and the optical axis of the lens array is arranged at an angle with respect to the original.

[Effect]

According to the present invention, the optical axis of the illumination such as the LED is perpendicular to the document, and the image of the document can be illuminated without attenuation of the amount of emitted light. Conventionally, the overall configuration was such that it was installed at an angle, which resulted in poor irradiation efficiency.

On the other hand, since the document can be illuminated with 100% irradiation efficiency, a large amount of reflected image light can be obtained. Since the light irradiating the original is diffusely reflected, the same amount of light can be guided onto the light receiving sensor surface even if the optical axis of the lens array is placed at an irregular angle. Therefore, even if the lens array is tilted, the amount of light does not decrease, and a high photocurrent can be obtained.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the present invention. An LED array 12 is mounted on a metal housing 11 with a length of about 250 mm. Paper guide 15. Light receiving sensor board 14° lens array 1
3 etc. are installed, and L is placed on the reading point 17 axis of the original 16.
The optical axis of the ED array 12 is aligned to illuminate the original 16 surface perpendicularly. Further, the lens array 13 is tilted at about 45 degrees, and the image reflected light from the reading point 17 of the original 16 is focused on a light receiving sensor substrate 14 installed at a symmetrical position on the optical axis of the lens array 13.

In the document reading device having such a structure, since the optical axis of the illumination light source of the LED array 13 is not inclined with respect to the surface of the document 16, the entire amount of light emitted by the light source is contributed as irradiation energy for obtaining image light. It turns out. Manuscript 16
The illumination light irradiated on the reading point 17 is diffusely reflected and dispersed almost uniformly in all directions around the reading point 17. Therefore, even if the lens array axis is tilted and installed, the light intensity transmission rate of the image light will not be reduced. Light receiving sensor board 14
The photocurrent of the sensor element increases by a corresponding amount when the optical axis of the light source is made vertical, and a high optical signal can be obtained. Further, the height of the reading device can be reduced because the lens array 13 is used at an angle, and a thinner image sensor can be realized.

FIG. 2 is a schematic cross-sectional view showing another embodiment of the present invention.

Light receiving sensor board 14. Lens array 13° paper guide 15. The relative positional relationship of the light sources and the like installed in the metal housing 11 is the same as in the first embodiment. Here, a fluorescent tube 28 is used as the illumination light source. Since the fluorescent tube 28 has uneven light intensity in the length direction, the paper guide 15 and the fluorescent tube 28
A shading correction plate 27 is installed between the two.

Just by installing the shading correction plate 27, the uniformity of the amount of light in the main scanning direction can be well reproduced. The document reading device having such a configuration can obtain the effects shown in the first embodiment, as well as
Since the amount of light is further increased due to the illumination by the fluorescent tube 28, a large photocurrent can be obtained. Further, unlike an LED array, sensitivity correction is not required for each element, and there is an advantage that the structure can be advantageously constructed in terms of cost.

〔Effect of the invention〕

As described above, the present invention is configured such that the illumination light source is arranged perpendicularly to the surface of the document to maximize the light reflected from the document. Therefore, since the optical signal also increases accordingly, it is possible to obtain a high-performance, thin document reading device with a high S/N ratio.

If this is used, for example, in a facsimile reading device, it will have the effect of realizing high-quality information transmission using an image signal that is faithful to the original. In addition, in the present invention, the light source is an LED.
Although arrayed fluorescent tubes are used, other elongated light sources such as halogen lamps and xenon lamps may be used. Furthermore, the angle of inclination of the lens array with respect to the document is not limited to 45 degrees, but may be other than 45 degrees depending on the relative structural relationship between the lens array and the light source, and the arrangement may be such that they do not interfere with each other's optical axes. Good. Furthermore, since the irradiation efficiency of the light source is improved, it becomes possible to reduce the number of LED chips and suppress heat generation, resulting in higher reliability and lower costs.

[Brief explanation of the drawing]

1 and 2 are schematic cross-sectional views showing respective embodiments of the present invention, and FIG. 3 is a schematic cross-sectional view of a conventional document reading device. 11.31...Metal casing, 12,32...
...LED array, 13.33...Lens array, 14°34...Sensor device board, 1
5.35... Paper guide, 16.36...
...Manuscript, 17...Reading point, 27...
. . . shading correction plate, 28 . . . fluorescent tube. Agent Patent Attorney Shinsuke Uchihara Shi length su ζ 柁え/, 3: He-hano f゛id A〈 原■高/7: Magazine Tsuno p92;, a/ = lbi * ¥ = #. 3Z: 1ED 33 Lens Ai Blade Serana Device Praise Bar Guide 5th: Hara (Taka)

Claims (1)

[Claims] It includes at least a light source that illuminates the original, a light receiving sensor in the form of an array in which elements are arranged in a predetermined main scanning direction, and a lens array that forms an erect same-size image of the original on the surface of the light receiving sensor. An original document reading device comprising: an optical axis of the light source is arranged perpendicular to the original document, and an optical axis of the lens array is arranged at an angle with respect to the original document. reading device.