JPH036604A - Origin position correcting device for image reader - Google Patents

Abstract

PURPOSE:To prevent the omission of the image data, the fetch of the excessive image data, etc., by producing a memory address signal based on the actual position of an origin marker set on a reading sensor and fetching the image data outputted from the reading sensor into a memory at and after the picture element position of the marker. CONSTITUTION:When an image put in a setting area is read, a position where the coincidence is secured between the scanned picture element position of a reading sensor 20 and the number of mark detecting picture elements is de fined as a head address. This address is increase for each picture element clock. Then the image data given from the sensor 20 is stored in a storage place where an address is designated by the address signal outputted from a correction address generating circuit 32. That is, the actual position of an origin marker set on the sensor 20 is used as a standard for designation of the address of a line memory 33. Then the read data is stored in the memory 33. Thus it is possible to prevent the omission of the image data, the fetch of the excessive image data, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an origin position correction device in an image reading device such as an image scanner typified by an optical reader (OCR).

BACKGROUND ART FIG. 1 schematically shows a reading mechanism including an optical system of an image reading device, FIG. The figure shows a part of the reading sensor enlarged, and is used to explain the positional deviation of the origin.

1 and 2, one image reading device has a top glass 1 on which a setting area S (indicated by a chain line) is set.
0 and a reading optical system disposed below the setting area S indicates an image readable range. On the lower surface of the glass 10, a white tape 11 for initial reading operation is attached adjacent to the setting area S, and an origin marker M indicating the physical origin is drawn on this white tape 11. This origin marker M is located at a position that coincides with the side of the setting area S in the main scanning direction.

The image placed in the setting area S on the upper surface of the glass 10 or the image of the white tape 11 passes through the mirror 12, 13 and the lens system 14 and is reduced and formed onto the reading sensor 20. Mirrors 12 and 13 are used to ensure the optical path length necessary for image formation in a narrow space. In FIG. 1 mirrors 12, 13 and lenses 14 are shown schematically.

The reading sensor 20 has a large number of one-dimensionally arranged pixels 2.
1 is a one-dimensional image sensor such as a CCD. The image formed on this sensor 20 is electrically scanned (in the main scanning direction) and one line of the image is read out.
Temporarily stored in memory.

Then, by moving the reading sensor 20 relative to the setting area S in the sub-scanning direction, the two-dimensional image is finally read.

Problems to be Solved by the Invention As shown in an enlarged view in FIG. The reading circuit etc. are designed based on this. That is, the circuit is constructed so that data on the right pixel can be read (taken in) from the design starting point.

However, the mounting position of the reading sensor 20, the mirror 12,
13. Due to variations in mechanical precision of optical systems such as the lens system 14, the position on the reading sensor 20 where the origin marker M is actually imaged (this is called the physical origin) may be different from the OP.
As shown by l or OF2, it deviates from the design origin. If the physical origin shifts to the left of the design origin as indicated by OPI.

The image data between OP1 to OPD is not read (taken in) and is lost. In addition, if the physical origin shifts to the right side of the design origin as shown by OF2, D~OP2
During this period, extra image data is read and captured.
In some cases, the same amount of image data as this extra image data is read (taken) at the right end of the reading sensor 20.
is not carried out and is missing.

As the resolution of the reading sensor 20 improves, the amount of deviation of the origin position expressed by the number of pixels on one image data increases (for example, the mechanical accuracy is ±0.31 (30
0 μm) and the resolution is 120 dots/inch, one dot is 210 μm. The amount of deviation of ±300 μm is ±1.4 dots.

When the resolution of the reading sensor is 600 dots/inch, one dot is 42 μm, so the above-mentioned deviation amount is approximately ±7 dots.

Read sensors are trending toward higher resolution.

On the other hand, we cannot expect much improvement in mechanical assembly accuracy. For this reason, the origin position shift expressed in the number of pixels tends to become larger.

This invention electrically corrects the origin position deviation at the stage of capturing image data.

Means for Solving the Problems An origin position correction device in an image reading device according to the present invention includes a reading sensor capable of scanning in at least one direction, which is placed at a position where an image placed in a setting area can be read through an optical system. , a controller that provides a reading start signal and a pixel clock signal to the reading sensor and controls reading timing by the reading sensor;
In the reading operation of the origin marker set at the origin position of the setting area, the scanning pixel position at which a component representing the origin marker appears in the read signal output from the reading sensor is determined from the time when the reading start signal is output to the above. An origin marker pixel number detection and holding circuit that detects by counting pixel clocks and holds it as the number of mark detection pixels, and in the reading operation of an image placed in the setting area, the scanning pixel position of the reading sensor is set to the mark detection pixel. a correction address generation circuit that generates a memory address that is incremented every pixel clock, with a position that matches the number as the first address, and a memory location that is addressed by an address signal output from the correction address generation circuit; The apparatus is characterized in that it includes a memory that stores image data provided from the reading sensor.

action at any time before use or prior to reading the image.
The reading operation of the origin marker set at the origin position of the setting area is performed at least once. The position of the origin marker is detected and the number of mark detection pixels indicating this detection position is held. During the reading operation of the image placed in the setting area, the mark detection pixel held by the scanning pixel position of the reading sensor is A memory address is generated with the position that matches the number as the first address.

The image data output from the read sensor is stored in the memory location addressed by this memory address signal. In this way, the actual position of the origin marker on the read sensor is used as a reference for addressing the memory and the read data is stored in the memory.

Embodiment FIG. 4 shows the electrical configuration of an image reading device in an embodiment of the present invention. As for the optical system on which this electrical configuration is based, those shown in FIGS. 1 to 3 can be used as they are.

A system controller 30 controls the operation of the entire image reading apparatus, and outputs a 5-pixel clock reading start signal, a marker reading signal (enable signal), a system clock, and a write signal. The pixel clock determines the read timing for each pixel of the read sensor 20. The read start signal determines the start of reading one line of data from the read sensor 20. These pixel clocks and read start signals are applied to the read sensor 20° physical origin marker pixel count detection and holding circuit 31 and correction address generation circuit 32.

The marker reading signal is outputted only when the origin marker M is to be read (this is referred to as an initial operation), and is applied to the detection and holding circuit 31. The initial operation is performed at the start of use, when the power is turned on, or when reading the image data placed in the setting area S is started.

The system clock defines the operation timing of the detection and holding circuit 31 and the correction address generation circuit 32, and has a frequency that is at least four times the frequency of one pixel clock.

The write signal provides a write command for the line memory 33.

The image signal read out from the reading sensor 20 is sent to an amplifier 34.
After being amplified by the A/D converter circuit 35, the signal is converted into a digital signal (for example, 4 bits) and sent to the data bus as read data, and transferred to the detection holding circuit 31 and line memory 33. be done.

In the initial operation, the physical origin marker pixel number detection and holding circuit 31 detects that the origin marker M is read by the optical system and detected by the sensor 2.
Position OP where the image is formed on 0 (physical origins OPI and OP2 are
(represented by P), this is expressed as the number of pixels 1 from the left end of the sensor 20, and this number of pixels 1 is held in a register or the like. This marker detection pixel number 1 is given to the correction address generation circuit 32 via the bus.

The correction address generation circuit 32 is connected to a line memory 3 that stores the read data output from the read sensor 20 during the read operation of the image placed in the setting area.
3 address signals are provided. This correction address generation circuit 32 generates a marker detection pixel number i whose scanning pixel position of the reading sensor 20 is given from the detection holding circuit 31.
A first address is generated when the first address matches the first address, and thereafter, an address that is sequentially incremented from the first address is output every two pixel clocks. This address signal is input to the line memory 33 via the address bus.

The line memory 33 receives data from the A/D conversion circuit 35.
Read image data input via the bus is stored in a storage location designated by an address signal provided from address generation circuit 32. The memory 33 stores one line of image data and transfers it to the next stage processing circuit.

FIG. 5 shows a specific configuration example of the physical origin marker pixel count detection and holding circuit 31, and a time chart showing its operation is shown in FIG. 7(A). Further, FIG. 6 shows a specific example of the correction address generation circuit 32, and shows a time chart showing its operation.
A chart is shown in FIG. 7(B).

1 pixel counter 4 with reference to Fig. 5 and Fig. 7 (^)
1 is cleared by a reading start signal inputted through the NOT circuit 42, and then nine pixel clocks are counted and a count value Q1 is output. This count value Q1 is applied to the data input terminal of the latch circuit 43.

On the other hand, one input terminal A of the comparator 44 is input with A/D-converted read data of the reading sensor 20, and the other input terminal B is input with a threshold value set in the setting device 45. are doing.

In the initial operation, the reading sensor 20 is reading the white tape 11, and since the image data crosses the threshold value when reading the origin marker M, the comparator 44
An output (L level) is generated from.

The output of the comparator 44 is given to a pulse width correction circuit 46.

Since the origin marker M has a constant width, the output signal of the comparator 44 also has a constant pulse width. The pulse width correction circuit 46 converts the pulse width of the output signal of the comparator 44 into a pulse width of one pixel or less using the system clock, and the output signal of this circuit 4G (referred to as a marker detection signal) is a latch signal. It is applied to the timing input terminal of circuit 43. A marker reading signal (enable signal) is also given to this pulse width correction circuit 46.
This circuit 4B operates only in the initial operation and outputs a marker detection signal only in the initial operation (only when the enable signal is applied). That is, this detection and holding circuit 31 operates only during initial operation.

The latch circuit 43 captures and holds the count value Q1 of the counter 41 at the time when the marker detection signal is applied, and outputs it as the number i of marker detection pixels.

Referring to FIG. 6 and FIG. 7(B), comparator 5
The marker detection pixel number i is input to one input terminal P of 3. The pixel counter 51 is cleared by a reading start signal input via the NOT circuit 52, and then counts one pixel clock and outputs a count value Q. This count value Q is applied to the other input terminal Q2 of the comparator 53.

The comparator 53 generates an H level output when the count value Q2 is greater than or equal to the number of marker detection pixels i. The output of the comparator 53 is corrected at its rising and falling points by a timing correction circuit 54 to which the system φ clock is input, and is applied to a clear terminal of an address counter 55.

A pixel clock is input to the clock input terminal of the address counter 55. This counter 55 counts the input pixel clock from zero from the time when the output of the comparator 53 becomes H level, and outputs the counted value as a memory address signal.

Effects of the Invention As described above, according to the present invention, a memory address signal is generated based on the actual position of the origin marker on the reading sensor. and.

The output image data from the reading sensor is taken into the memory starting from the pixel position of the origin marker. In this way, even if an error occurs in the assembly of the reading sensor, optical system, etc., the actual arrangement after one assembly is detected as the origin marker position, and the image data is stored in the memory based on this detected origin marker position. Therefore, only the image in the setting area is always accurately captured, thereby preventing the omission of one image data or the capture of extra image data.

[Brief explanation of the drawing]

Fig. 1 schematically shows the reading mechanism including the optical system of the image reading device, Fig. 2 shows the setting area viewed from below, and Fig. 3 shows an enlarged view of a part of the reading sensor. It is. FIG. 4 is a block diagram showing an embodiment of the present invention and shows the electrical configuration of an image reading device, FIG. 5 is a block diagram showing a specific example of a physical origin marker pixel number detection and holding circuit, and FIG. 6 is a correction address Block diagram showing a specific example of the generation circuit, No. 7
Figures (A) and (B) are time charts showing the operation. 20...Reading sensor 30...System controller 31...Physical origin marker pixel number detection and holding circuit 132...
- Correction address generation circuit 33...Line memory M origin marker. that's all

Claims (1)

[Scope of Claims] A reading sensor capable of scanning in at least one direction, arranged at a position where an image placed in a setting area can be read through an optical system, and providing a reading start signal and a pixel clock signal for the reading sensor. , a controller that controls reading timing by the reading sensor, a scanning pixel position where a component representing the origin marker appears in the read signal output from the reading sensor in the reading operation of the origin marker set at the origin position of the setting area; An origin marker pixel number detection and holding circuit that detects by counting the pixel clocks from the output time of the reading start signal and holds the detected mark as the number of mark detection pixels. Correction that generates a memory address that is incremented every pixel clock, with the position where the scanning pixel position of the reading sensor matches the number of mark detection pixels as the first address, in the reading operation of the image placed in the setting area. An origin position correction device for an image reading device, comprising: an address generation circuit; and a memory that stores image data given from the reading sensor in a storage location addressed by an address signal output from the correction address generation circuit.