JPH01115265A - Original reader - Google Patents

Abstract

PURPOSE:To obtain video signals constant and free of irregularity in the subscanning direction even when a light source for light-transmitting original of simple constitution is used by disposing a constant density member in a manner that it can be moved in the subscanning direction. CONSTITUTION:At the time of reading a reflecting original, a white reference plate 12 is placed in the optical path, but when reading a light-transmitting original, the plate 12 is saved out of the optical path. Light from a fluorescent lamp 19 transmits through a light-transmitting original, and is formed as an image on a CCD 9 by a lens 8. At this time, since the white reference plate 12 is out of the optical path, the light beam that passed the area from which the plate 12 is saved is detected as a reference voltage by the CCD 9. An output from the main scanning is normalized corresponding to said reference voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an original reading device used in a digital copying machine and the like, and more particularly to a reading device for both transmissive and reflective originals.

[Prior Art] A digital scanner as a document reading device used in a digital copying machine etc. is as shown in FIG.
The reflected light 4 of the light irradiated from the fluorescent lamp 3 as a light source to the document on the contact glass 2 placed at the top of the digital scanner main body 1 is reflected by the first mirror 5, the second mirror 6,
It is reflected by the third mirror 7, passes through the lens 8, and enters the CCD 9 which is an image sensor.The fluorescent lamp 3 and the first mirror 5 are mounted on the first traveling body 10, and the second mirror 6 and a third mirror 7 are mounted on the second traveling body 11, and as the second traveling body 11 moves at the speed of 172 of the first traveling body 10, the optical path length from the original to the CCD 9 is kept constant. , the first traveling body 10 and the second traveling body 11 are scanned when reading the original m.

In such digital scanners, a member with a certain density is placed near the edge of the document and the reflected light from that member is
A method has been proposed in which a portion of the CD 9 is detected and the video signal voltage in the sub-scanning direction from the CCD 9 is stabilized using the detection output. That is, as shown in FIG. 10, the white reference plate 12, which is a constant temperature member, is attached to the lower surface of the contacts 1 to glass 2 so as to be located above the reset position of the first traveling body 10, and the CCD 9 is first This white reference plate 12 is read, and then the document on the contact glass 2 is read.
The output waveform of is as shown in VideoO of FIG. Note that the WB pulse is adjusted to be generated when the CCD 9 is reading the white reference plate 12. However, the first
As shown in Figure 2, the output voltage of the white reference plate 12 for the video signal output is held by the voltage control amplifier 13 using the WB pulse, and the gain of the video signal output is always set according to this value. The circuit shown in FIG. 12 can be stabilized even if the optical output changes in the sub-scanning direction. In FIG. 10, 14 indicates the effective image area of the reflective original.

Further, in FIG. 12, 13' indicates an error amplifier.

On the other hand, as shown in FIGS. 13 and 14, transparent originals are read by attaching light source devices 15a and 15b for reading transparent originals to the digital scanner shown in FIG. 9 above. . The above-mentioned light source device for reading transparent originals 1
5a has a configuration in which a linear light source 16 is used as a light source and can be illuminated approximately uniformly in the sub-scanning direction by a reflection plate 17, and the light source device 15b for reading transparent originals uses a linear light source 16 as a light source. The fluorescent lamp 18 as a light source is configured to move in accordance with the sub-scanning movement of the device 15b.

However, when reading a transparent document by attaching such a light source device 15a, 15b, etc. for reading a transparent document to a digital scanner, conventionally, by killing the circuit shown in FIG. Since reading was performed while ignoring the unevenness of the light output of the light source, it was not possible to stabilize the video signal voltage.

Therefore, in the past, attempts have been made to stabilize the video signal by stabilizing the light amount of a light source for document illumination or by uniformly illuminating a transparent document.

However, in the case of these methods, if a fluorescent lamp is used as a light source, for example, a current to be applied to the fluorescent lamp, a tube temperature control device, a precision reflector, etc. are required, which increases the cost. However, the drawback was that it could not be completely corrected.

[Objective] Therefore, the present invention aims to provide an original reading device that can obtain a stable video signal without unevenness in the sub-scanning direction even when using a light source device for reading transparent originals with a simple configuration. It is something.

[Structure] In order to achieve the above object, the present invention detects the reflected light of a constant density member provided outside the effective image area of the reflective original as a reference for the output voltage of the image sensor when reading the reflective original,
In an original reading device that normalizes the output for each main scan according to the reference voltage, the constant density member is provided so that the constant density member can be retracted out of the optical path to the image sensor when reading a transparent original. is configured to be movable in the sub-scanning direction.

When reading a transparent document, since the agricultural member is retracted out of the optical path, the transmitted light of the retracted part is detected as a reference for the output voltage of the image sensor, and the output during main scanning is adjusted according to the reference voltage. is normalized.

Embodiments of the present invention will be described below with reference to the drawings.

In a configuration similar to the digital scanner shown in FIG. 9 in which the light source device for reading transparent originals is removable, when reading a reflective original, the white reference plate 12 is placed in the optical path as in the conventional example shown in FIG. 10. On the other hand, when reading a transparent original, the configuration is such that the white reference plate 12 is retracted out of the optical path, as shown in FIG. Note that 19 is a fluorescent lamp as a light source of a light source device for reading a transparent original, and 20 is an omnidirectional diffuser plate (or a Fresnel lens, etc.) arranged on the contact glass 2.

With this configuration, the light source device for reading transparent originals is attached to the digital scanner body 1, and the transparent original is placed in the effective image area 14 on the glass 2 to the contact 1 in the same way as when reading illegal originals. When a transparent original is read, as shown in FIG. 1, light from the fluorescent pair 19 passes through the transparent original and is imaged on the CCD 9 by the lens 8. At this time, since the white reference plate 12 is retracted out of the optical path, the light of the fluorescent pair 19 transmitted from the retracted part of the white reference plate 12 is
It is detected as a reference voltage by the CD 9, and the output during main scanning is normalized according to the reference voltage. Therefore, as shown in FIG. 11, when the main scanning of the CCD 9 starts, a white reference output corresponding to the output unevenness of the sub-scanning destination is always obtained, and the circuit shown in FIG. This makes it possible to stabilize the video signal in the sub-scanning direction.

Next, an example of a specific mechanism of the apparatus for setting the position of the white reference plate 12 is shown, for example, in FIG.
A binding member 21 that protrudes into the digital scanner body 1 when attached to the digital scanner body 1 is provided on the lower surface of the transparent document reading light source device 15a or 15b shown in FIG. , Figures 2 and 3
As shown in the figure, a mechanical switch 23 is pressed down by the coupling member 21 against the force of the spring 22.
will be established. Further, a rack 24 is carved on one side of the mechanical switch 23, and a pinion 2 that meshes with the rack 24 is formed on one side of the mechanical switch 23.
A worm 27 is provided on the shaft 26 of the worm wheel 28, and the base end of a white reference plate moving guide 30 having a tapered tip is fixed to the shaft 29 of the worm wheel 28 that meshes with the worm 27. When pressed down, the rack 24 and pinion 25, as well as the worm 27
Through the engagement of the worm wheel 28 and the worm wheel 28, the moving guide 30 can be horizontally pivoted from the position indicated by the solid line in FIG. 4 to the position indicated by the two-dot chain line. Furthermore, the movement guide 3
In order to move the white reference plate 12 along 0, the supporting portion 12a of the white reference plate 12 is engaged with the first movement guides 31 and 32 provided on the first traveling body 10 so as to be rotatable in the sub-scanning direction. ,
In addition, recesses 12b and 12 are provided at a predetermined interval on one side of the support portion 12a so that the rotational position of the white reference plate 12 can be semi-fixed at the entry position into the optical path and the retracted position from the optical path.
c, and a clip 33 that selectively fits into these recesses 12b or 12c is attached on the first traveling body 10, and when the first traveling body 10 moves from the home position 17P to the reset positions R, P. , white reference plate 1
2 can be displaced to either the solid line position or the two-dot chain line position depending on the rotational position of the moving guide 30. The force of the clip 33 is weaker than the rotational force of the moving guide 30, and is set so that the white reference plate 12 does not move even after a certain amount of photographing. Note that 34 is a slit provided in the first travel stop 10 to allow the light from the fluorescent pair 19 to pass through.

With the above configuration, the transparent original reading light source device 15
When a, 15b, etc. are mounted on the digital scanner main body 1, the coupling member 21 pushes down the mechanical switch 23, so that the rack 24 and the pinion 25 engage with each other, and the water retention
Through the engagement of the worm wheel 27 and the worm wheel 28, the moving guide 30 is rotationally displaced about the shaft 29 from the position indicated by the solid line in FIG. 4 to the position indicated by the two-dot chain line. Therefore, when the first travel stop 10 moves from the home position 1'', P to the reset position R, P when reading a transparent original, the white reference plate 12 moves along the movement guide 30 as shown by the two-dot chain line, and the optical path It is set to the evacuated state. At this time, the clip 33 fits into the four parts 12c, and the position of the white reference plate 12 is semi-fixed.

Also, instead of the mechanical white reference plate positioning device mentioned above,
For example, when the light source devices 15a and 15b for reading transparent originals are mounted on the digital scanner main body 1, this can be detected electrically and the white reference plate 12 can be moved by a motor or the like, or, as shown in FIG. As shown, the white reference plate 12
The white reference plate 12 may be directly moved by providing a rack 12d on the support portion 12a and rotating the pinion 34 that meshes with the rack 12d by driving the motor 35.

FIG. 6 shows the operating sequence when these white reference plate position setting devices are used. That is, in the mechanical case, when the transparent original reading light source device 15a or 15b is installed,
First, the moving guide 30 is rotationally displaced to a predetermined position, and then the first traveling body 10 is once moved from the home positions H, P to the reset positions R, P, and this operation causes the white substrate 4 (plate 12 to move along the optical path). After that, the first traveling body 10 returns to the home positions H and P and enters a standby state in which it waits for a signal such as a scan start signal to be sent.On the other hand, in the electrical case, The white reference plate 12 is moved to the set position by the drive of the motor without performing the movement of the first travel pause 10 and enters a standby state.

FIG. 7 shows an example of application of the present invention, in which the contact glass 2 is positioned above the optical path entrance position of the white reference plate 12.
A cover 36 of a predetermined width is movably disposed on the top, and when reading a reflective original, the cover 36 can hide the white reference plate 12 and indicate the effective image area 14, as shown in (1'). Sometimes, as shown in 2), the above-mentioned bar 36 is moved out of the optical path.

When the cover 36 is provided, the operation of the embodiment described above is not hindered in any way, but the white reference plate 12 is further eliminated.

However, by making the back surface (lower surface) of the cover 36 white, the cover 36 can be used as the white reference plate 12.

FIG. 8 shows another embodiment of the present invention, in which a transparent original effective image area 37 is converted into a reflective original effective image area 1 when a transparent original is read.
4, and the difference area VJ of the image area 37°14,
38 is configured to take a white reference level when reading a transparent original. Further, for this purpose, two diffusion plates (or transparent plates) 39a and 39b are arranged on the contact glass 2 so that the transparent original is not placed in the difference area 38, and these two diffusion plates 39a, 39b, the difference area 38
Now, paste it together to make it a part where the manuscript cannot enter, and make it a transparent manuscript image area 37.
In this case, the transparent original can be opened and closed without pasting, and the transparent original can be set only in the transparent original effective image area 37. Thereby, it is possible to prevent mistakes in setting the document on the knee 11-.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[Effects] As described above, according to the document reading device of the present invention, the constant density member for determining the reference voltage from the output voltage of reflected light when reading a reflective document is retracted from the optical path of the image sensor when reading a transparent document. As a result, a stable video signal with no unevenness in the sub-scanning method can be obtained even when using a light source device for reading transparent originals with a simple configuration that does not use a precise light amount stabilizing device or a reflector. It has an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a document reading device of the present invention, FIG. 2 is a schematic front view showing an example of a white reference plate position setting device, FIG. 3 is a plan view of FIG. 2, and FIG. 4 is a white reference plate FIG. 5 is a perspective view showing another example of the white reference plate position setting device; FIG. 6 is an explanatory diagram of the sequence by the device of the present invention; FIG. 7 (( ) and (f) are diagrams of applied examples of the present invention, FIG. 8 is an explanatory diagram of another embodiment of the present invention, FIG. 9 is a schematic diagram of a digital scanner showing an example of a document reading device, and FIG. 10 is an explanatory diagram of the conventional video signal stabilization method, Fig. 11 is an explanatory diagram of the COD output waveform, Fig. 12 is a circuit diagram for stabilizing the video signal, and Figs. 13 and 14 are both transparent. It is a schematic diagram of a light source device for document reading. 1... Digital scanner main body, 3... Fluorescent pair, 9.
... COD, 12... White reference plate, 13... Voltage control amplifier, 30... White reference plate movement guide.

Claims (1)

[Claims] 1) When reading a reflective original, the reflected light from a constant density member provided outside the effective image area of the reflective original is detected as a reference for the output voltage of the image sensor, and the output for each main scan is normalized according to the reference voltage. In the document reading device that is
A document reading device characterized in that the constant density member is configured to be movable in the sub-scanning direction so that the constant density member can be moved out of the optical path to the image sensor when reading a transparent document.