JPS6249773A - Image reader - Google Patents

Abstract

PURPOSE:To shorten the reading time of first original in an operation mode of higher frequency of usage by varying the initial stopping position of an optical system in accordance with the frequencies of usage of sheet mode and book mode. CONSTITUTION:At the starting time of the operation (the time when the power supply source is turned on) of the equipment, an original illuminating unit 24 is in a position P1 that is the middle point between an original reading position P2 in the sheet mode and an optical-system scanning position P3 in the book mode. That means that the distance between the points P1 and P2 which is l12 and that l13 between P1 and P3 are in a relation: l12:l13=1:1. The equipment is used for a certain times being in this state, during which time, the times of use of the two modes are held in a memory 211 provided with a backup circuit 212. A CPU 208 derives the times of use of a mode from the memory 211. If said times are n12 for the sheet mode and n13 for the book mode, the CPU 208 sets a P'1 so that the ratio l'12:l'13 becomes equal to the ratio n13:n12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an image reading device for reading sheet originals and book originals.

More specifically, the present invention relates to an image reading apparatus that has two re-operation modes: a sheet mode in which a document is read while being conveyed by a document conveyance device, and a book mode in which the document is read by fixing the document and scanning it with an optical system. It is.

[Prior Art] Conventionally, this type of image reading device is configured such that (a) the reading position in sheet mode and the reading start position in book mode are the same position, or (b) When the reading positions in both modes are different, the reading start position in one of the modes has been regarded as the initial position.

[Problems to be Solved by the Invention] However, in the former case (a), the mechanism of the document conveying device becomes complicated, #! There were problems such as poor productivity and dead space.

In addition, in the latter case (b), the initial position is the same regardless of the presence or absence of the document transport device, so there is a problem that the difference in time required for the first document reading between the two modes becomes large. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image reading apparatus which eliminates the above-mentioned drawbacks and reduces the time required to read one image.

[Means for Solving the Problems] The present invention provides an image reading apparatus that has a sheet mode in which an image is read while conveying a document, and a book mode in which an optical system scans and reads an image. The initial stop F position of the optical system is changed depending on the frequency of use.

[Example 1 Hereinafter, the present invention will be described in detail based on Examples.

FIG. 1 is a cross-sectional configuration diagram showing an embodiment of an image reading device to which the present invention is applied, and FIG. 2 is an external view of the embodiment.

In FIG. 1, 2 is the main body of the original image reading device, and the original on the platen glass 27 is illuminated by the original illumination unit 24.
The device is configured to irradiate the document image with a lens 26 and form an original image on a CCO (charge-coupled device) 22. Also,
Reference numeral 3 denotes an automatic document feeder, which is configured to convey the document on the document placement table 31 in the direction of arrow B shown by a broken line and discharge it onto the document discharge table 32.

FIG. 3 is a block diagram showing the configuration of the COD driver 23 and control unit 21 according to this embodiment.

Next, the operation of this embodiment will be explained using FIGS. 1 and 3.

In the document reading device shown as this embodiment.

In the sheet mode, images are read while transporting unbound general paper documents using an automatic document feeder (hereinafter referred to as ADF), and in the sheet mode, documents with binding such as books are placed on the platen glass 27 and scanned by an optical system. It has two operating modes: book mode for reading images.

First, the sheet mode will be explained.

Manuscript reading device! (hereinafter referred to as a reader) is always connected to an external device (digital printer, personal computer, etc.), and the exchange of control signals between these external devices and the output of image signals to the external device are performed via the interface circuit 207. be exposed.

In this sheet mode, instructions for various modes are input from an external device while the original is placed on the original placing table 31 of the AIIF 3 (with the image facing upward).

For example, change the pixel density to 400dpi/300dpi/20
This includes determining whether to set the image signal to 0 dpi, or whether to make the image signal a binary signal or a multi-value signal. Upon receiving this instruction, the CPU 208 outputs a control signal to the timing signal generation circuit 209 and selector 206 in advance to set the pixel density and image signal.

Further, the CPo 208 is an optical system document illumination unit 24.
In this embodiment, an optical position sensor (not shown) confirms whether or not the ADF 3 is at the original reading position M (22 points shown in FIG. 1).
is stopped at our office at 21 points (see Figure 1).
The ADF is activated by a document reading start command from an external device.
Move in the direction of the document reading position in step 3. When the optical position sensor (not shown) detects that 22 points have been reached, the movement of the optical system is stopped and the CPU io
8 outputs a lamp control signal to turn on the lamp 1", and also outputs a document feeding start command to the ADF 3. As a result, the document placed on the document table 31 of the ADF 3 is It is conveyed toward the path of the broken line shown in FIG. 1 (in the direction of arrow B).

Since Kisho uses a stepping motor to drive the ADF document transport and optical system scanning, by changing the frequency of the pulses used to drive the motor,
The speed of conveyance scanning can be changed freely.

As is well known, whether the leading edge of the document has reached the document illumination position of the reader 2 is detected by a document leading edge detection sensor (not shown) provided in the ADF 3. Also,
Until the original reaches the original illumination position, the image formed on the COD 22 is converted into a digital value and input to the interface circuit 207 as shown later, but since this is not the original image, the CPU 208 gives a control signal to the interface circuit 207 so as not to output the image signal.

When the document reaches the document illumination position, the CPo 208 outputs a control signal indicating that image signal output is possible to the interface circuit 207. As a result, the read image signals are sent one after another to the external device. Then, when the trailing edge of the document has finished passing the document illumination position (detected by the document leading edge detection sensor), the interface circuit 207 is again given a control signal instructing it not to output the image signal. The image signal output is stopped, and a document reading completion signal is output to an external device.

After this, if a document reading start command is not received from the external device within a certain period of time, the CPo 208 turns off the lamp, moves the document illumination unit 24 to the initial position 20, and ends the operation.

Next, the book mode will be explained. In the book mode, the document is placed on the platen glass 27 so that its right end is the leading edge of the document (see FIG. 1).

Furthermore, the original illumination unit 24 is configured to have its initial position at 13 points shown at the right end of FIG. 1, and its position is confirmed by an optical position sensor (not shown), as in the case of the sheet mode.

The pixel density and image signal settings before starting document reading are the same as in the sheet mode.

When a document reading start command is input from an external device, C
The PU 208 first illuminates the document illumination unit 24 at the PI point.
After moving to the initial position of 23 points in book mode, the lamp control signal is output and the lamp is turned on. At this point, it does not immediately start scanning for document reading, but it waits for approximately 300 seconds until the light intensity of the lamp stabilizes. Wait ~500 milliseconds.

During this time, an image signal is input to the interface circuit 207 as in the case of the sheet mode, but C:PU 2
After that, when the amount of light from the lamp becomes stable, the document illumination unit 24 immediately starts scanning in the direction of arrow A (see FIG. 1).

From the initial position of the original illumination unit 24 to the platen glass 2
There are approximately 2 to 3 ■■ to reach the leading edge position of the original at 7-hi, and during this time the scanning speed of the optical system by the motor is controlled to be stable. When the original illumination unit 24 reaches the leading edge position of the original, the CPU 208 controls the interface circuit 20.
7, a control signal indicating that image signal output is possible is output, and the read image signals are sent one after another to an external device.

Since the scanning length of the optical system is uniquely determined by the number of pulses that the CPU 208 drives the motor, CPo 20
8, it is determined that the reading of the document is completed when the necessary number of pulses is output to the motor. And CPo 20
8 turns off the lamp, instructs to disable image signal output, controls motor reversal, and outputs a document reading completion signal to an external device.

Under the motor reversal control of the CPU 208, the document illumination unit 24 moves in the opposite direction to arrow A (see FIG. 1).
It stops when an optical position sensor (not shown) detects that it has reached the initial position P3. If the next document reading start command is not received from the external device during this optical system return period, the document illumination unit 24 is moved to the initial position 21 again and the operation is completed.

Next, the circuit operation of this embodiment will be explained using the blow diagram shown in FIG.

The CCD 22 included in the CCD driver 23 is connected to the timing signal generation circuit 209 included in the control unit 21.
Various timing signals φ1゜φ2. φR1
In response to φSH (see FIG. 4), the CCD drive circuit 20
3. The image analog signal output from this CCD 22 is amplified by an amplifier 201 and input to an A/D converter 202. In the A/D converter 202, the image signal is converted from an analog signal to a 6-bit digital signal according to the timing signal ΦAn generated by the timing signal generation circuit 209.
It is output to the control unit 21.

The control unit 21 converts this digital image signal into the two modes mentioned above (i.e. binary mode).

(multi-value mode) and output to an external device. Which of these two modes the signal is outputted according to is determined by a command from an external device, and the C
Po 208 will output a control signal to selector 206.

In the multi-value mode, the 6-bit image signal is input to the interface circuit 207 via the selector 206 in order to convert it to 4-bit. In the case of multi-value mode, the interface circuit 207 backs up the 4-bit signal for two pixels into an 8-bit signal and outputs it to an external device.

Furthermore, in the binary mode, a 6-bit image signal is converted into 1-bit by the binary conversion circuit 205 according to the slice level output from the CPo 20B, and is input to the selector 206. This slice level has two values.

One of them is a level specified by an external device, and in this case, the CPU '208 outputs the slice level specified by the external device to the binarization circuit 205 as is. The other is 0, which is the slice level based on background density detection.
In the background density detection method performed in this embodiment, the background density detection circuit 204 detects the maximum density value (brightest value) for each l line in the main scanning direction of the image, and this is detected by the CPU 208.
The averaged result of several lines is output to the binarization circuit 205 as a slice level.

The image signal binarized by the above method is sent to the selector 2.
It is input to the interface circuit 207 via 0B. In the case of the binary mode, the interface circuit 207 backs up 8 pixels to form an 8-bit signal and outputs it to an external device.

Next, a method of pixel density conversion performed in this embodiment will be described.

5(A) to (C) show the enable signals in the sub-scanning direction (VE multiplied signal and system clock (Ll: LK multiplied signal knee enlarged).
In the case of pi, one period of the VE signal corresponds to one line of the optical system scanning motor. Also, the period of the CLK signal is φ1. It has the same period as the timing signal such as φ2.

Figure 5 (B) shows the case of 200 dpi (that is, 1/2 pixel density compared to Figure 5 (A)), and both the VE times signal and the CLK signal have a period of 1/2 of that in Figure 5 (A). ing. The VE multiplication signal is controlled by the CPU 208, and the motor rotates as in the case of FIG.

Although image signals are obtained at the same cycle, they are output to an external device only when the VE multiplied signal is active.

Further, the CPU 208 controls the timing signal generation circuit 20
9, the background density detection circuit 204.2
Value conversion circuit 205. In order to output the CLK signal shown in FIG. 5B to the interface circuit 207, an image signal is output to the interface circuit 207 once every two pixels. Therefore, the pixel density is 1/2 in both main scanning and sub-scanning.

Similarly, in the case shown in FIG. 5(C), the pixel density is 1/4 of that shown in FIG. 5(A).

I will explain how to set the offshore Lj + volume lji i5su to a distance of about 1m l.

As shown in FIG. 6(A), at the start of use of the water device (when the power is turned on), the document illumination unit 24 is located at the midpoint between the document reading position P in the sheet mode and the optical system scanning position P3 in the book mode. It is located in That is, the distance intersection between Pl and P, 11 and P, and the distance between 23, 3 is intersection I2: intersection day = 1: l ・
...(1) is set at the position Pl. This position is set when it is determined that the frequency of use of sheet mode and book mode is unknown at the initial stage of use.

Now, after it has been used a number of times in this state, a sequence for changing the setting of P8 is entered. The number of times the two modes have been used so far is held in a memory 211 equipped with a backup circuit 212 (see Figure 3).
Kote, CP[I 208 t*) MoIJ 21
The number of uses in each mode is extracted from 1, and for example, if the number of uses in sheet mode is 1112 and the number of uses in book mode is J3, the ratio of ``4'' to ``cross'' is C12: CB = nG : n12 −(
2) Set P'F'' so that Accumulate the total amount (2) depending on the time.
) P′1 position is changed so as to satisfy the equation.

FIG. 7 shows an embodiment in which the initial position of the optical system is different in the sheet mode and the book mode, thereby eliminating the difference in the time required for first document reading between the modes. In this figure, components that perform the same functions as those in the embodiment shown in FIG. 1 are given the same numbers.

FIG. 8 is a detailed circuit diagram of the CCD driver and control unit of the embodiment shown in FIG. They have the same number. However, in this figure, unlike FIG. 3, the memory 211 and the backup circuit 212 are not included.

Since the operation of the embodiment shown in FIGS. 7 and 8 is almost the same as that of the embodiment shown in FIGS. 1 to 3, detailed explanation of the operation will be omitted.

Next, we will explain how to set the initial position of the optical system according to this embodiment. In this embodiment, as shown in FIG. be. In this case, a platen cover 4 is attached instead of the ADF 3.

When the power of this device is turned on, the CPU 208
The F control signal detects whether or not the ADF is installed. If the ADF 3 is not installed as shown in FIG. The optical system drive motor is controlled to stop at the optical system initial position P in the optical system mode.

Whether the document illumination unit 24 has reached the P7 position or is originally located at the P1 position is detected using the optical position sensor described above. Particularly in the book mode, the 21st position is always the initial position and the document reading operation described above is performed.

As shown in FIG. 9(B), when the ADF 3 is installed, the document illumination unit 24
is set to the optical system initial position P2 in sheet mode.

Then, with the state F stopped at the P2 position, the A
The document is transported using DF3.

When the AIIF 3 is attached in this way to perform a document reading operation, P2 is the initial position, but it can also be used in book mode. Therefore, when this device enters a communication state for mode setting such as pixel density with an external device, if no document is loaded in the ADF 3, the device controls the document illumination unit 24 to immediately start moving to the PL position. do.

[Effects of the Invention] As described above, according to the present invention, the initial position of the optical system can be changed depending on the frequency of use of the sheet mode and the book mode. The time required to read the original can be reduced. In other words, by adopting a configuration in which the initial positions of the optical system are different in the sheet mode and the book mode, the present invention has the special effect that the time required for the first document reading can be set to differ depending on the frequency of use of both modes. can be obtained.

Further, according to another embodiment to which the present invention is applied, the initial position of the optical system when the power is turned on can be set depending on whether or not the A11F is attached. There will be no difference in time. Furthermore, even when the ADF is installed, the optical system can be moved from the ADF reading position to the book mode initial position immediately after deciding to use book mode, so there is no difference in the time required for the first document reading between the two modes. It disappears.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram showing an embodiment of an image reading device to which the present invention is applied, and FIG. 2 is an external view of the embodiment. FIG. 3 is a block diagram showing the configuration of the CCD driver and control unit according to the same embodiment, FIGS. 4 and 5 (A) to (C) are timing diagrams showing the operation of the same embodiment, and FIG. 6 ( A) and (B) are cross-sectional configuration diagrams explaining the operation of the same embodiment, FIG. 7 is a cross-sectional configuration diagram showing another embodiment of the present invention, and FIG. 8 is a CCD driver and control unit according to the same embodiment. FIGS. 9A and 9B are cross-sectional configuration diagrams illustrating the operation of the same embodiment. 2... Original reading device, 21... Control unit. 22... CCD, 23... CCU driver, 24... Original illumination unit, 25... Reflection mirror, 26... Lens, 27... Platen glass, 3... Automatic document feeder ( ADF), 31...Original loading table. 32... Original discharge table. Figure 2. 8 "l-,, No, river! 1\8
'6.8! '211b One: l>”> (A) Figure 6

Claims (1)

[Claims] 1) In an image reading device that has a sheet mode in which an image is read while conveying a document and a book mode in which an image is read by scanning an optical system, initial stop of the optical system is performed depending on the frequency of use of the sheet mode and the book mode. An image reading device characterized in that its position can be changed.