JPH0965059A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader with which processing speed can be easily prevented from being decelerated. SOLUTION: The moving velocity of a carriage 11 is first accelerated to velocity v2 higher than reading velocity v1 within the approach run range from start at a home position 19 to arrival at a reading start position 18. Afterwards, the moving velocity is decelerated and becomes the reading velocity v1 in the approach run range. After the carriage moved in the remaining approach run range and an image reading range in the state of velocity v1, it returns to the home position. Thus, the moving velocity of the first carriage 11 is high in comparison with the conventional example until it arrives at the reading start position 18, at the time of repeat copy, processing speed is accelerated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device, and more particularly, to an image reading device for reading an original of a digital copying machine or an analog copying machine.

[0002]

2. Description of the Related Art Digital and analog copying machines are widely used in offices, factories and homes. This copier has been developed to increase the number of sheets that can be copied per unit time in order to efficiently perform copying work, that is,
The speed of copying is increasing. Generally, in a copier of a type in which a reading optical system is moved to read a document, it is necessary to set a carriage at a predetermined reading speed, and therefore an approach distance is set. This approach distance is determined by the image reading speed and the performance of the driving unit that moves the carriage. Then, the faster the reading speed is and the smaller the torque of the drive motor is, the longer the running distance is required. This approach distance is not determined only by the performance of the reading scanner, but in reality, products with different reading speeds commonly use the mechanism to reduce costs, and due to the reasons such as the automatic document feeder, It is not always possible to set the scanner for maximum performance. If the run-up distance is insufficient,
Since a predetermined reading speed cannot be achieved, a sufficient run-up distance is usually provided. However, since the run-up distance is set to be long, the carriage travels in a useless portion, resulting in a long processing time and a reduction in copy speed. Therefore, in the prior art, Japanese Patent Laid-Open No. 61-1
Japanese Patent No. 45540 proposes a technique for preventing a decrease in copy speed. That is, in this technique, the start position of the reading optical system (carriage) is changed according to the magnification ratio to minimize the approach distance and prevent the copy speed from decreasing.

[0003]

However, in the technique proposed in the above publication, the DC servo motor is used, but it is difficult to accurately control the position with this motor. Moreover, although the movement amount is controlled by the pulse encoder, it is difficult to accurately determine the stop position because only the speed control is originally possible. For this reason, the technique proposed in the publication cannot easily prevent a decrease in processing speed when the approach distance is long. Therefore, a first object of the present invention is to provide an image reading apparatus that can easily prevent a decrease in processing speed by another method.

Further, generally, the longer the approach distance for setting the carriage at a predetermined reading speed, the more stable the carriage becomes. The longer the distance from the start up of the image to the start of reading the image, the lower the vibration level of the carriage immediately after the start of reading and the higher the image quality, but the lower the copy speed. However, considering the case of actually making a copy,
There are cases where processing speed is required rather than image quality, and vice versa. Therefore, a second object of the present invention is to enable selection of either high image quality or high-speed processing, and to enable carriage control suitable for each case.

Further, the copying machine has a variable-magnification copying function for copying while changing the magnification. The reading speed when using this function varies depending on the scaling ratio. Compared with the case of equal magnification, the reading speed is doubled at 50% reduction, and conversely, the reading speed is halved at 200% enlargement. As described above, since the reading speed greatly changes depending on the scaling factor, it is necessary to set the running distance to the longest in accordance with the fastest reading speed. Particularly, in recent digital copying machines, the zooming range is set to a very wide range of 25% to 400%, so that the reading speed is 1/4 to 4 times as much as the normal size. Wide range.
For this reason, if the approach distance is set long according to the scaling factor that maximizes the reading speed, when reading at a slow speed such as 400% enlargement, the long approach distance is set until the reading starts. Had to move, which slowed down copy speed. Therefore, a third object of the present invention is to prevent a decrease in copy speed even in an apparatus in which the reading speed range is set wide.

[0006]

According to a first aspect of the present invention, there is provided an image reading device for reading an image while a carriage moves on a guide rail, wherein the carriage moves from a home position to a reading start position. To
The first object is achieved by setting the moving speed of the carriage to be higher than the reading speed and then decelerating to the reading speed. According to a second aspect of the present invention, there is provided an image reading device for reading an image while the carriage moves on the guide rail, the image reading apparatus having a unit for selecting the processing speed priority mode, and the carriage is at the home position in the processing speed priority mode. The second object is achieved by setting the moving speed of the carriage to a speed higher than the reading speed while moving from the position to the reading start position and then decelerating to the reading speed. According to a third aspect of the present invention, in an image reading device that reads an image while a carriage moves on a guide rail, the carriage moves from a home position to a reading start position when a reading magnification is larger than a certain value. In the meantime, the moving speed of the carriage is set to a speed higher than the reading speed, and then the carriage is decelerated to the reading speed, thereby achieving the third object.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the image reading apparatus of the present invention will be described in detail below with reference to FIGS. FIG. 1 shows a cross section of the image reading apparatus, and FIG. 2 shows a drive system thereof. As shown in FIGS. 1 and 2, the image reading device includes a first carriage 11 and a second carriage 15.

The first carriage 11 is provided with an illumination lamp 1 for illuminating a document placed on the document surface 7 and a first mirror 12. As the illumination lamp 1, for example, a lamp such as a halogen lamp or a fluorescent lamp is used. The second carriage 15 includes a second mirror and a third mirror. The first carriage 11 and the second carriage are driven by the motor 22, the speed reducer 23, the drive pulley 21, and the wire 20, and the second carriage moves at half the speed of the first carriage 11. Then, the first carriage reciprocates within the range indicated by arrow A, and the second carriage reciprocates within the range indicated by arrow B. First and second carriages 11,
Reference numeral 15 moves while sliding on the guide rail.

The original placed on the original surface 7 is illuminated by the illumination lamp 1 which moves together with the first carriage 11, and the reflected light is reflected by the first mirror 12 and the second mirror 1.
6, reflected by the third mirror 17, passes through the lens 4 and enters the CCD 5. The image information read by the CCD 5 is input as an image signal to a computer, a printer or the like through an image processing circuit or the like.

Home positions of the first and second carriages 11 and 15 are determined by a home position sensor 19. Reading start position 1 from the home position
For the distance up to 8, the carriage 11 is at the reading start position 1
It is set to a distance sufficient to accelerate to a predetermined speed while moving up to 8. The image reading device also includes a white reference plate 2, a scale 3, an APS sensor 6, and the like.

3 and 4 show the velocity diagram of the first carriage 11, FIG. 3 shows the velocity diagram in the first embodiment, and FIG. 4 shows the conventional general velocity diagram. It was done. The conventional moving speed of the first carriage 11 is shown in FIG.
As shown in, in the approach range before reaching the reading start position 18, the image reading speed is accelerated to the image reading speed v1. Then, after moving the image reading range while moving the approaching range at the reading speed v1, the process returns to the home position. On the other hand, as shown in FIG. 3, the moving speed of the first carriage 11 in the present embodiment is first higher than the reading speed v1 within the run-up range from the home position until the reading start position 18 is reached. Fast speed v2
Accelerate to After that, the speed is decelerated to the reading speed v1 within the approach range. After that, after moving the remaining approaching range and image reading range at the reading speed v1, the process returns to the home position.

As described above, in the present embodiment, the moving speed of the first carriage 11 before reaching the reading start position 18 is faster than that of the conventional example, so that the processing speed at the time of repeat copying can be increased. In addition, the first and second
The carriages 11 and 15 return to the home position each time and are positioned by the home position sensor 19. Therefore, the position control of the motor is simplified, and even a motor that is not originally suitable for position control can be used without special control. Although the reading unit of the digital copying machine has been described in the present embodiment, the operation of the present invention can be applied to the analog copying machine.

Next, a second embodiment will be described. The image reading apparatus according to the second embodiment has an image quality priority mode and a processing speed priority mode, and can be selected by the operator by a predetermined key operation or the like.
Regarding the selection of both modes, the currently selected mode may be displayed as an image, and the display (selection) change operation may be performed only when the other mode is selected.

When the image quality priority mode is selected, the conventional speed control shown in FIG. 4 is performed to increase the approach distance at the reading speed v1 and the vibration level of the carriage immediately after the reading is started. Lower to improve image quality. On the other hand, when the processing speed priority mode is selected, the speed control shown in FIG.
The processing speed is increased by increasing the moving speed of the carriage 11.

FIG. 5 is a flow chart showing the control operation of the second embodiment. First, when the operator selects a mode (step 11), it is determined whether the selected mode is the processing speed priority mode (step 12).
When the image quality mode is selected (step 12; N), the velocity diagram of FIG. 4 is selected as the rising acceleration curve of the first carriage 11 (step 13), and copying is started (step 13). Step 15). In this mode, the first carriage 11 does not exceed the reading speed v1 at the time of rising, and the reading start position 1
Since it takes a long time to move at the reading speed v1 up to 8, the carriage is stable against uneven speed, vibration, etc., and good image quality can be obtained.

On the other hand, when the processing speed priority mode is selected (step 12; Y), the first carriage 11
The speed diagram of FIG. 3 is selected as the rising acceleration curve of (step 14), and copying is started. In this mode, the first carriage 11 accelerates to a speed v2 exceeding the reading speed at the time of rising and then decelerates to the reading speed v1. Therefore, the time from the departure from the home position to the reading start position 18 is shortened.

Next, a third embodiment will be described. In the third embodiment, the speed control at the time of rising of the carriage is changed according to the scaling factor at the time of reading. When the scaling ratio is smaller than a certain value, the moving speed of the first carriage 11 is faster than when the scaling ratio is equal.
Therefore, the movement of the first carriage 11 is controlled in accordance with the velocity diagram shown in FIG. 4, and the first carriage 11 does not exceed the reading velocity v1 when rising. On the other hand, when the magnification is larger than a certain value, the moving speed of the first carriage becomes slower than when the magnification is equal. Therefore, by controlling the movement of the first carriage 11 according to the velocity diagram shown in FIG.
It becomes 2. Therefore, even when the scaling factor is large, that is, even when the enlargement is performed, the time required to move in the run-up range is short, and it is possible to prevent the processing speed from decreasing.

[0018]

According to the invention described in claim 1, it is possible to easily prevent a decrease in processing speed. According to the second aspect of the present invention, since the carriage drive control corresponding to the selection of the image quality quality priority mode and the processing speed priority mode by the operator is performed, it can be used according to the operator's request. According to the invention described in claim 3, it is possible to prevent a decrease in processing speed at the time of low-speed reading due to extension of the approach distance even when the variable power range is large.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an outline of a drive system of the image reading apparatus.

FIG. 3 is a velocity diagram of the first carriage of the image reading apparatus.

FIG. 4 is a velocity diagram of the first carriage of the conventional image reading apparatus when the image quality priority mode is selected in the second embodiment or when the scaling ratio is small in the third embodiment.

FIG. 5 is a flowchart showing a control operation in the second embodiment.

[Explanation of symbols]

 1 Illumination Lamp 2 White Reference Plate 3 Scale 4 Lens 5 CCD 6 APS Sensor 7 Original Surface 11 First Carriage 12 First Mirror 15 Second Carriage 16 Second Mirror 17 Third Mirror 18 Reading Start Position 19 Home Position Sensor 20 Wire 21 Drive pulley 22 Motor

Claims (3)

[Claims] 1. An image reading apparatus for reading an image while a carriage moves on a guide rail, wherein a moving speed of the carriage is higher than a reading speed while the carriage moves from a home position to a reading start position. An image reading apparatus characterized by increasing the speed and then decelerating to the reading speed. 2. An image reading device for reading an image while a carriage moves on a guide rail, comprising means for selecting a processing speed priority mode, wherein the carriage starts reading from a home position in the processing speed priority mode. An image reading apparatus, characterized in that a moving speed of the carriage is set to a speed higher than a reading speed while the carriage is moving to a position, and then the carriage is decelerated to the reading speed. 3. An image reading device for reading an image while a carriage moves on a guide rail, wherein when the reading magnification is larger than a certain value, the carriage moves from a home position to a reading start position. An image reading apparatus, wherein a moving speed of the carriage is set to a speed higher than a reading speed, and then the carriage is decelerated to the reading speed.