JPH07175135A - Traveling body driving device - Google Patents

Abstract

PURPOSE:To provide a traveling body driving device capable of performing accurate feedback control by obtaining the accurate control signal of a linear motor. CONSTITUTION:This device is used in an image reader where either a 1st traveling body 8 or a 2nd traveling body 204 holding an optical element is directly driven as a main driving side and the other is allowed to follow by using a transmitting means such as a belt and a wire, whereby the traveling bodies are moved in a subscanning direction in the speed ratio of 2:1 and an image is read. Two linear encoders 210 and 211 are separately set in the same traveling body. Then, a feedback signal given to the linear motor is generated from the feedback signal based on an output signal from two linear encoders, a distance between at least one linear encoder and the linear motor, and a distance between two linear encoders 210 and 211.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling body drive device,
For example, the present invention relates to a traveling body driving device used in an image reading device that optically reads a document placed on a document table and obtains a document image.

[0002]

2. Description of the Related Art A first traveling body having a light source for reading an original placed on a document table and a second traveling body having a speed ratio of 1/2 of the first traveling body are the same sub-vehicle. An image reading apparatus that scans in the scanning direction to read an image described on the original document, collects the read image by a lens, and projects and forms the image on a light receiving device to obtain an original image is a factory, office, or the like. Widely used in. As a traveling body driving device for driving the first traveling body and the second traveling body in such an image reading apparatus, for example, it is proposed in Japanese Patent Laid-Open No. 23435/1993. In this traveling body drive device, wires are wound around one or both sides of the first and second traveling bodies that move in the same direction at a speed of 2 to 1, and one of the first and second traveling bodies is driven by a linear motor. However, the other traveling body is driven by the action of the wire and the moving pulley. According to this traveling body driving device, by using the linear motor, compared with the conventional method of driving the traveling body by linearly converting the power of the rotation motor by the rotation-linear conversion system including the gear and the wire system. ,
Since vibration due to the transmission / conversion system does not occur, highly accurate sub-scanning drive is possible.

In addition, in the unpublished application by the applicant, 2
In a traveling body driving device of an image reading apparatus that drives two traveling bodies at a speed of 2: 1 to read an original, a steel belt is wound around the wire instead of the wire, and the first or second
It has been proposed that either one of the running bodies is driven by a linear motor or an ultrasonic motor. According to this traveling body drive device, the precision of the sub-scanning drive can be improved. As described above, in the conventional traveling body drive device, the sub-scanning drive system is improved by using the linear motor and the ultrasonic motor.

[0004]

However, in these conventional traveling body drive devices, the encoders for sensing the speed and position, which are feedback signals, are as follows.
I haven't touched it. A commonly used method is to install a linear encoder at any one position and control the linear motor by this output signal. However, this method has a drawback that the output of the linear encoder is not an accurate feedback signal because the position of the linear encoder and the position of the linear motor are different.

Therefore, it is a first object of the present invention to provide a traveling body drive device capable of obtaining an accurate linear motor control signal and performing an accurate feedback control. It is a second object of the present invention to provide a traveling body drive device capable of always accurately controlling the traveling body even when the state changes.

[0006]

According to another aspect of the present invention, there are provided a first traveling body and a second traveling body which respectively hold an optical element.
Directly drive one of the running bodies as the main drive side,
By moving the other side by using a transmission means such as a belt or a wire, the moving body drive unit used in the image reading apparatus that moves in the sub-scanning direction at a speed ratio of 2: 1 to read an image Two linear encoders are arranged apart from each other, and a feedback signal based on the output signals of the two linear encoders, a distance between at least one linear encoder and the linear motor, and a distance between the two linear encoders are applied to the linear motor. The first object is achieved by providing a signal creating means for creating a feedback signal. According to the second aspect of the present invention, one of the first traveling body and the second traveling body, which respectively hold the optical element, is directly driven with the main drive side as the main driving side, and the other is driven by using a transmission means such as a belt or a wire. As a result, in a traveling body drive unit used in an image reading apparatus that reads an image by moving in the sub-scanning direction at a speed ratio of 2: 1, one linear encoder is arranged on the traveling body, and the linear motor outputs from the output of the linear encoder. The coefficient for obtaining the control signal at the position is determined in advance, this coefficient is multiplied by the feedback signal created from the output signal of the linear encoder to make a new feedback signal, and the linear motor is controlled based on that signal. A control means is provided to achieve the first object. According to the third aspect of the present invention, one of the first traveling body and the second traveling body, which respectively hold the optical element, is directly driven as the main drive side, and the other is driven by using a transmission means such as a belt or a wire. In a traveling body driving device used in an image reading apparatus that moves an image in a sub-scanning direction at a speed ratio of 2 to 1, two linear encoders are arranged apart from each other on the same traveling body, and At the time of scanning, one feedback signal for linear motor control is obtained from the feedback signals based on the output signals of the two linear encoders, the distance between at least one linear encoder and the linear motor, and the distance between the two linear encoders. A coefficient for determining a coefficient to be created from a feedback signal based on the output signal of the linear encoder By comprising a determining means, to achieve the second object.
According to a fourth aspect of the present invention, in the traveling body drive apparatus according to the third aspect, the coefficient determining means uses the position information from the two linear encoders as a feedback signal based on the output signals of the linear encoders, and these position informations are used. When,
From the distance between at least one linear encoder and the linear motor and the distance between the two linear encoders, a coefficient for generating a feedback signal for controlling the linear motor from the feedback signal based on the output signal of one linear encoder is determined. To do. According to a fifth aspect of the present invention, in the traveling body drive apparatus according to the third aspect, the coefficient determining means uses the speed information from the two linear encoders as a feedback signal based on the output signals of the linear encoders, and the speed information is obtained. And a coefficient for creating a feedback signal for controlling a linear motor from a feedback signal based on the output signal of a certain linear encoder from the distance between at least one linear encoder and the linear motor and the distance between the two linear encoders. To decide.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a traveling body drive apparatus of the present invention will be described in detail below with reference to FIGS. FIG. 1 shows a schematic configuration of an optical system of an image reading device in which a traveling body drive device is used. The image original 0 placed on the contact glass 1 is illuminated by a halogen lamp 2 as a light source, and the reflected light is reflected by the first mirror 3, the second mirror 4 and the third mirror 5, and is read by a lens 6, for example, a CCD. It is projected on the sensor 7. The image is read by the main scan by the CCD sensor self-scan,
In FIG. 1, the speed ratio of the first traveling body 8 on which the first mirror 3 and the halogen lamp 2 are installed and the second traveling body 204 on which the second and third mirrors are installed (not shown in FIG. 1) is 2: 1. By sub-scanning in the A direction, the entire area of the image original 0 can be read.

FIG. 2 shows an example of a traveling body drive device when the second traveling body is directly driven by using a linear DC motor as a direct drive, and FIG. 3 shows a second traveling body and a linear DC motor. FIG. 3 is a diagram showing the relative positional relationship between the two linear encoders as viewed from the left side of FIG. 2. In the first embodiment, the two linear encoders 210, 211 are installed separately on the same traveling body, and the two linear encoders 210, 2
11, a feedback signal based on the output signal of 11, the distance between at least one linear encoder 210 (or 211) and the linear motor, and two linear encoders 21.
A feedback signal applied to the linear motor is created from the distance between 0 and 211. This makes it possible to obtain an accurate linear motor control signal and perform accurate feedback control.

The specific structure will be described below.
The first traveling body 8 holding the light source 2 for reading the original and the reflection mirror 3 has two bearing portions 201A, 2A at one end.
01B, and one bearing portion 201C at the other end. The first traveling body 8 has two bearing portions 201.
A and 202B are fitted to the first guide shaft 202,
The bearing 201C at the other end is in contact with the second guide shaft 203. On the other hand, the second traveling body 204 has two bearings 205A, 205B and 205C, 205 at the two ends, respectively.
Equipped with D. The bearings 205A and 205B are fitted to the first guide shaft 202, and the bearings 205C and 205B
5D is in contact with the second guide shaft 203.

A drive coil 207 is attached to the lower side of the second traveling body 204 via a movable back yoke 206 for forming a magnetic circuit and a coil substrate (not shown), and the coil 207 is fixed at a position facing the drive coil 207. A magnet 208 is installed in the main body via a fixed back yoke 209 for forming a magnetic circuit so that the air gap is maintained and the SN poles on the surface alternate in the sub-scanning direction. Also,
Linear encoders 210 and 211 are installed at arbitrary two positions on the second traveling body 204. 2 and 3, the second
Movable parts 210A and 211A including a light source and a sensor are attached to the traveling body 204, and together with fixed parts 210B and 211B of a linear encoder including a linear scale fixed to the main body, so-called optical linear incremental. It forms the encoder. In addition, if it is a linear encoder, it is also possible to adopt other configurations such as a magnetic encoder.

In this configuration, when a current is applied to the coil 207 by a control system (not shown) based on the output signals of the two linear encoders 210 and 211, the second traveling body 2
04 can be driven in the sub-scan direction by direct drive in the direction A in FIG. Here, a linear DC motor is taken as an example of the direct drive, but the present invention is not limited to this as long as it is a direct drive such as a linear ultrasonic motor.

As shown in FIG. 2, a first belt 212 is hung on the outside of the first guide shaft 202 of the first traveling body 8,
A second belt 213 is hung on the outside of the second guide shaft 203 of the second traveling body 204. The first belt 212 is the same as how to hang both belts
4A and 4B are side views of the first belt 212, and the description will focus on the first belt 212. One end and the other end of the first belt 212 are fixed to different positions of the image reading apparatus main body by belt ends 300 and 300 ', respectively. The first belt 212 has two bearings 20 of the second traveling body 204.
5A, 205B (205C, 20 for the second belt 213)
5D), which is supported by a shaft (not shown) provided on the moving pulleys 214A and 214B (214C on the second belt 213,
214D) is wound around each half turn. Also,
Dynamic pulleys 214A, 214B (2 for the second belt 213
14C, 214D) the first belt 2 located in the middle part
12 (second belt 213) includes the first traveling body clamp 2
The first traveling body 8 is clamped by 15A (215B on the second belt).

In the traveling body drive device having such a structure, when the first traveling body is directly driven in the direction of arrow A in FIG. 2, the first belt 212 and the two moving pulleys 214 are provided.
The first traveling body 8 is driven from both sides at twice the speed of the second traveling body 204 by the operation of A, 214B, the second belt 213 and the two moving pulleys 214C, 214D.
As a result, the first and second traveling bodies 8 and 204 can be driven in the sub-scan at a speed ratio of 2: 1. FIG. 4A shows the sub-scanning start state, and FIG. 4B shows the sub-scanning end state. In addition, the direction of arrow A in FIG.
2 shows the same direction as the middle arrow A direction. Here, four bearings 201A fitted to the first guide shaft 202,
Each of 201B, 204A, and 204B may be, for example, a combination of a rolling bearing and a pressing member or a sliding bearing in which a round bar and a round hole are combined. Further, the first and second belts 212 and 213 are not limited to metal, rubber, or any other material as long as they are belts, and wires or the like can be used.

FIG. 5 shows the relationship between the speed measurement results by the two linear encoders in FIGS. 2 and 3 and the speed to be fed back at the position of the linear DC motor. In FIG. 5, v1 is the speed measurement result by the linear encoder (210) on the first guide shaft side,
v2 is the speed measurement result by the linear encoder (211) on the second guide shaft side. Further, vLDM is the speed to be fed back in the linear DC motor unit. now,
The distance between the two linear encoders 210 and 211 is a, and the distance between the linear encoder 210 on the first guide shaft side and the central portion of the linear DC motor is b. During the sub-scan, the traveling body can be regarded as one rigid body, so
Considering the linear encoder 210 on the guide axis side as a reference, the sub-scanning motion can be modeled as shown in FIG. Here, the direction of arrow A in FIG. 5 is the sub-scanning reading direction and is the same as the direction of arrow A in FIGS. From Fig. 5, the speed to be fed back of the linear DC motor is
It can be expressed by the following formula 1.

[0015]

## EQU1 ## vLDM = (b / a) × v2 + ((ab) /
a) × v1

Here, (b / a) and ((ab) / a)
Becomes a constant if the mechanical arrangement of the traveling body drive device is determined, and therefore this calculation can be easily realized in both digital and analog cases.

FIG. 6 is a block diagram showing the configuration of the control device according to the first embodiment. The controller is
A microcomputer 601 is provided. A microprocessor 602, a read only memory (ROM) 603, and a random access memory (RAM) 604 are connected to the microcomputer 601 via a bus line 605 such as a data bus. 606
Is a command generator that outputs a status command signal that commands the status of the linear DC motor, and generates a speed command signal and the like. The output of this command generator 606 is also the bus line 605.
Connected to. Reference numerals 607 and 608 denote state detection interface devices that process the outputs of the two linear encoders 210 and 211 and convert them into digital numerical values, and each have a counter that counts the output pulses of the linear encoders.

The control device also includes a driving interface device 609, and the microcomputer 60
The digital value of the operation result of 1 is converted into a pulse-shaped signal (control signal) for operating a power semiconductor that constitutes the driving device 610, for example, a transistor. The driving device 610 operates based on this pulse-shaped signal, and the linear DC motor 61
Control the voltage applied to 1. As a result, the sub-scanning traveling body 612 including the linear DC motor 611, that is, all the first and second traveling bodies attached to the linear DC motor.
Are driven at the desired speed. Linear DC motor 611
The speed of the (traveling body 612) is determined by the two linear encoders 210 and 211 and the interface devices 607 and 60 described above.
8 is detected and is taken into the microcomputer 601. The above description is for the case of using the discrete type microcomputer, but it is also possible to use the microcomputer in which the command generation device 606, the drive interface device 609, and the state detection interface devices 607 and 608 are integrated into one chip. Similar functionality is obtained.

Here, a method of detecting the speed of the linear DC motor 611 (traveling body 612) is shown in FIG.
Two state detecting interface devices 607, 6 for processing the outputs of the two linear encoders 210, 211.
The processing method of 08 will be described. Since the functions and operations of the two condition detecting interface devices 607 and 608 are exactly the same, only one of them will be described here. The state detection interface device 607 outputs the output of the linear encoder 210 to the microprocessor 60.
It is designed to supply 2 interrupts. Also, FIG.
A counter for counting the reference clock (CLK) shown in FIG. In FIG. 7, the linear encoder 21
The state immediately before the edge 701 of the output pulse OB of 0 arrives will be described. The counter is the CL of the cycle of the OB pulse.
Based on the K signal, the given count value (eg 0FF
FFH) to perform decrement count. When the edge 701 reaches the interrupt of the microprocessor 602, the interrupt routine is started.

FIG. 8 shows the operation of this interrupt routine. When the edge 701 of the output pulse OB reaches the interrupt of the microprocessor 602, the decrement count value of the counter is latched in the internal register of the state detecting interface device 607 (step 1). Next, the latched decrement count value is stored in the RAM 604 of FIG. 6 (step 2). Then, a count initial value (0FFFFH) for counting the pulse period of Tn is given, the decrement count is started again (step 3), and the interrupt processing is ended. When the edge 702 reaches the interrupt of the microprocessor 602 again, the above steps 1 to 3 are repeated.
Each process up to is repeated. At this time, the speed v1
(I) is calculated by the following Equation 2. However, Tc
lk represents the CLK cycle, Ne represents the number of linear incremental encoder divisions per unit length, and n is CL.
The K count number represents (0FFFFH-decrement count number), and k represents a unit conversion constant to speed.

[0021]

(2) v1 (i) = k / (Tclk × Ne × N)

FIG. 9 is a block diagram showing the control system in the traveling body drive system of the first embodiment. This control system is provided with a linear DC motor 901 including a traveling body to be controlled. Linear encoder 210 (Fig. 9
Velocity v1 detected based on the output signal of
(I-1) is a block 902, which is multiplied by the constant ((ab) / a) given by the above-mentioned mathematical expression 1 to obtain the operation unit 90.
Is given to 3. Further, the velocity v2 (i-1) detected based on the output signal of the other linear encoder 211 (not shown in FIG. 9) is calculated in block 904 by the constant given by the above-mentioned formula 1. (B / a) is multiplied and given to the arithmetic unit 903. At this time, the meanings of a and b used in this constant are as shown in the above figures.

In the arithmetic unit 903, two inputs are added and the speed vLDM (i-1) of the linear DC motor unit is given to the arithmetic unit 906 via the feedback loop 905. In the calculation unit 906, the command generator 606
The control target value R (i) output from the feedback loop 905 and the difference e (i) from the feedback loop 905 are calculated. This difference e
(I) is integrated in a block 907, multiplied by a constant KI in a block 908, and given to a calculation unit 909.
At the same time, the difference e (i) is multiplied by the constant KP in the block 910 and is given to the arithmetic unit 909. The calculation unit 909 calculates the input voltage u (i) to the linear DC motor 901 by adding two inputs. Here, the control voltage value u
(I) is output to the linear DC motor, the traveling body is driven in the sub-scanning, and the above loop is repeated. Since all the control calculations including the calculation of the speed vLDM (i-1) of the linear DC motor section by the mathematical expression 1 are performed by the numerical calculations in the microcomputer 601, it can be easily realized. In addition, here, as a control method, a digital PI is used.
Although control has been described as an example, the control method may be analog, PID control, or even modern control.

As described above, in the first embodiment,
The first traveling body 8 and the second traveling body 204 each holding an optical element are directly driven with one of the first or second traveling bodies 8 and 204 as the main drive side, and the other is transmitted with a belt, a wire or the like. In the traveling body drive unit used in the image reading apparatus for reading the image by moving the sub-scanning direction at a speed ratio of 2: 1 by using the means, the two linear encoders 21 for the same traveling body are used.
0 and 211 are installed separately, a feedback signal based on the output signals of the two linear encoders, and the distance between at least one of the linear encoders and the linear motor,
Since the feedback signal applied to the linear motor is created from the distance between the two linear encoders, it is possible to obtain an accurate control signal for the linear motor and perform accurate feedback control.

Next, a second embodiment will be described. Figure 1
In the second embodiment, 0 indicates an example of the traveling body drive device when the second traveling body 204 is directly driven by using the linear DC motor as the direct drive. Further, FIG. 11 shows the relative positional relationship between the second traveling body, the linear DC motor, and one linear encoder 1001 as viewed from the left side of FIG. In addition, in FIGS. 10 and 11, the first described in FIGS.
The same parts having the same functions as those of the embodiment are given the same reference numerals, and the description thereof will be appropriately omitted.
Further, the method of following the running body by a belt such as a steel belt or a wire is also the same as that in FIG.

In the second embodiment, as shown in FIGS. 10 and 11, a linear encoder 1001 is installed at any one position on the second traveling body 204. The second traveling body 204 has a movable part 10 including a light source and a sensor.
01A is attached, and the fixed part 1001 of the linear encoder including the linear scale fixed to the main body
Together with B, a so-called optical linear incremental encoder is formed. Note that the linear encoder may have other configurations such as a magnetic encoder.

In the traveling body driving apparatus having such a structure, when a current is supplied to the coil 207 by a control system (not shown) based on the output signal of only one linear encoder 1001, the second traveling body 204 is driven. The sub-scanning drive can be performed by the direct drive in the direction A in FIG. In addition,
Here, a linear DC motor has been taken as an example of the direct drive, but various direct drives such as a linear ultrasonic motor can be used.

In the traveling body drive apparatus according to the second embodiment, it is desirable that the guide rails be perfectly parallel to the sub-scanning direction, but in reality it is almost impossible and the guide rails have a curvature. Is normal. If the guide rail has a curvature, the position of the linear encoder differs from the position of the linear DC motor. This is shown in FIG. Generally, even if the guide rail has a curvature, it is quite small. Therefore, although the motion of the traveling body is a rotational motion as shown in FIG. 12, each point on the traveling body is approximately translated. Can be considered Due to the curvature of the guide rail, the traveling body has a radius of curvature r at a point 205C on the second guide shaft of the second traveling body 204 at the center of the point O.
Let's say you are in a rotating motion. The distance between the bearing 205C and the linear encoder 1001 attached to the first guide shaft 202 side of the second traveling body 204 is c, and the distance between the central portion of the linear DC motor and the linear encoder is d. v11
Is the speed measurement result by the linear encoder 1001,
v12 is the speed at bearing 205C, and also vLDM
Represents the speed to be fed back in the linear DC motor unit. During the sub-scan, the traveling body can be regarded as one rigid body, so the velocity v12 at the bearing 205C
Can be expressed by the following expression 3, and the speed to be fed back of the linear DC motor unit can be expressed by the following expression 4 from FIG.

[0029]

## EQU00003 ## v12 = (r / (r-c)). Times.v11

[0030]

## EQU00004 ## vLDM = (((c-d) / c) + (d / c)
× (r / (r−c))) × v11 = ((r−c + d) / (r−c)) × v11

Therefore, ((r-c + d) / (r-
Since c)) is a constant determined only by the mechanical arrangement of the traveling body drive device, this calculation can be easily realized both in the digital case and the analog case.

FIG. 13 is a block diagram showing the configuration of the control device in the traveling body drive system according to the second embodiment. The parts having the same functions as those of the control device in the first embodiment shown in FIG. 6 are designated by the same reference numerals, and the description thereof will be appropriately omitted. In the second embodiment,
The output of the linear encoder 1001 fixed to the first guide shaft 202 side of the second traveling body 204 is connected to the interface device 607 for state detection. The interface device 607 for detecting the state includes a counter that counts the output pulse of the linear encoder.
The output of the state detecting interface device 607 is connected to the microcomputer 601 via the bus line 605, and feedback control is executed based on a control system block diagram described later. The method of detecting the speed, that is, the processing method of the state detection interface device 607 that processes the output of the linear encoder is the same as that described above, and thus the description thereof is omitted here.

FIG. 14 is a block diagram showing a control system in the traveling body drive system according to the second embodiment. Here, parts having the same functions as those in FIG. 9 are denoted by the same reference numerals, and the description thereof will be appropriately omitted. The speed v11 (i-1) detected by the linear encoder 1001 is multiplied by the constant ((r-c + d) / (r-c)) given by the above-mentioned formula 4 in block 1401 to obtain the speed of the linear DC motor unit. Seeking vLDM (i-1). At this time, the meanings of c, d, and r used in the constants are as shown in FIG. The obtained speed vLDM (i-1) of the linear DC motor is the feedback loop 9
It is given to the calculation unit 906 via 05. After this,
The same control calculation as in FIG. 9 is performed to obtain the control voltage u (i) for the linear DC motor. Where the control voltage u
(I) is output to the linear DC motor, the traveling body is driven in the sub-scanning, and the above loop is repeated.

As described above, all the control calculations including the calculation of the speed vLDM (i-1) of the linear DC motor section by the mathematical expression 4 are performed by the numerical calculation in the microcomputer 601, so that they can be easily realized. . Although the digital PI control has been described as an example of the control method here, the control method may be analog or P control.
It may be ID control or even modern control. Here, the case where only one linear encoder is attached has been described as an example, but if the number of linear encoders is not particularly one, it is possible to selectively use one of a plurality of attached linear encoders. You may

As described above, according to the second aspect of the invention, the first traveling body and the second traveling body which respectively hold the optical element are provided.
The traveling bodies 8 and 204 are replaced with the first or second traveling bodies 8 and 20.
By directly driving one of the four as the main driving side and driving the other by a transmission means such as a belt or a wire, the image is read by moving in the sub-scanning direction at a speed ratio of 2: 1. In the traveling body drive device used for the apparatus, a coefficient for obtaining the control signal at the position of the linear motor is previously determined from the output of the linear encoder 1001 attached to only one of the traveling bodies, and this coefficient is output from the linear encoder. The feedback signal created from the signal is used as a new feedback signal, and the linear motor is controlled based on that signal.Therefore, only one linear encoder output and simple calculation can be used to obtain an accurate linear motor control signal. Therefore, accurate feedback control can be performed.

Next, the operation when the traveling body drive device is applied to the image reading device will be described with reference to FIG. Here, the traveling body drive device is the same as that in FIGS. 2 and 3, and the block diagram of the control device is the same as that in FIG. When the image reading device starts reading with the start button or the like, it is first determined whether or not the mode is the prescan mode (step 1501). This can be easily realized, for example, by providing a button or signal for setting whether or not to perform pre-scan before reading in the image reading apparatus. If it is determined that the mode is the pre-scan mode (step 1501; Y), the traveling body drive device is driven in the sub-scan mode in the system shown in the control block diagram for pre-scan (details will be described later in FIG. 16) (step). 1052). Then, again, the curvature radius r is determined by the curvature radius determination formula, which will be described later in detail, and is written in the RAM 604 shown in the block diagram of the control device shown in FIG. 6 (step 1503), and the process returns to step 1501. , It is again determined whether or not the pre-scan mode.

When it is determined in step 1501 that the mode is not the pre-scan mode, that is, the image reading mode (step 1501; N), the traveling object is detected in the image reading control block diagram (FIG. 14). The sub-scanning drive (step 1504) is performed, the image is read (step 1505), and when all the images have been read, the flow of the image reading apparatus ends. Here, the radius of curvature r used in block 1401 in the block diagram of the control system at the time of image reading can use the radius of curvature in the state immediately before reading the image by using the value determined in step 1503 of this flowchart. As a result, accurate control can always be performed even when the state changes.

FIG. 16 is a block diagram showing the configuration of the control system for prescan. Here, the same parts as those of the control system of FIG. 9 are designated by the same reference numerals, and the description thereof will be appropriately omitted. One linear encoder (eg, Figure 2,
3 (210 or 211), the velocity v (i-
1) passes through the feedback loop 1601 and then the calculation unit 9
It is given in 06. After that, the same control calculation as in FIG. 9 is performed to obtain the control voltage u (i) for the linear DC motor. Here, the control voltage value u (i) is output to the linear DC motor, the traveling body is sub-scanning driven, and the above loop is repeated. Since all control calculations are performed by numerical calculations in the microcomputer 601, they can be easily realized. Although the digital PI control has been described as an example of the control method here, the control method is as follows.
It may be analog, PID control, or even modern control.

FIG. 17 shows the states of the sub-scanning start position and the sub-scanning end position of the traveling body controlled by the control system block diagram of FIG. α is the sub-scanning start position, and β is the sub-scanning end position. The position outputs of the two linear encoders, for example, 210 and 211 in FIGS. 2 and 3, have different values such as S1 and S2 because the traveling body is inclined by θ as shown in FIG. 17 due to the curvature of the guide shaft and the like. Show. Therefore, if the distance between the two linear encoders is c, the radius of curvature r can be easily calculated from the following Equation 5.

[0040]

## EQU00005 ## r = (S2 / (S2-S1)) * a

The position measurement by the linear incremental encoder is performed by using the microcomputer in the block diagram of the control device shown in FIG. 9 for the coefficient of the output pulse number of the linear incremental encoder which has a one-to-one relationship with the position. Easy to achieve.

FIG. 18 shows another state of the sub-scanning start position and the sub-scanning end position of the traveling body. As shown in FIG. 18, a linear encoder such as that shown in FIG.
3 210, 211 speed output, or the average of some of those speed outputs, respectively v1, v2
Then, the radius of curvature r can also be expressed by the following Equation 6.

[0043]

## EQU00006 ## r = (v2 / (v2-v1)) * a

As described above, during the prescan of the image reading apparatus, the feedback signal based on the output signals of the two linear encoders, the distance between at least one linear encoder and the linear motor, and the distance between the two linear encoders. Therefore, the coefficient for creating a feedback signal for linear motor control from the feedback signal based on the output signal of a certain linear encoder is determined, so that even when the state changes, accurate control of the traveling body is always possible. I can do it. Further, the position information from the two linear encoders is used as a feedback signal based on the output signal of the linear encoder, and these position information, the distance between at least one linear encoder and the linear motor, and the distance between the two linear encoders are used. Therefore, the coefficient for creating a feedback signal for linear motor control from the feedback signal based on the output signal of a certain linear encoder is determined, so that even when the state changes, accurate control of the traveling body is always possible. I can do it. Further, the speed information from the two linear encoders is used as a feedback signal based on the output signal of the linear encoder, the speed information, the distance between at least one linear encoder and the linear motor, and the distance between the two linear encoders. Therefore, the coefficient for creating a feedback signal for linear motor control from the feedback signal based on the output signal of a certain linear encoder is determined, so that even when the state changes, accurate control of the traveling body is always possible. I can do it.

[0045]

According to the first aspect of the present invention, one of the first traveling body and the second traveling body, each of which holds the optical element, is directly driven as the main drive side, and the other is a transmission means such as a belt or a wire. In a moving body driving device used for an image reading device that reads an image by moving in the sub-scanning direction at a speed ratio of 2: 1 by using the following, two linear encoders are installed separately on the same traveling body. The feedback signal to be added to the linear motor is created from the feedback signal based on the output signals of the two linear encoders, the distance between at least one linear encoder and the linear motor, and the distance between the two linear encoders. Therefore, accurate feedback control can be performed by obtaining an accurate control signal of the linear motor. According to the second aspect of the present invention, the first traveling body and the second traveling body that respectively hold the optical element are directly driven with one of the first traveling body and the second traveling body as the main drive side, and the other is the belt and the wire. A linear encoder attached only to a traveling body in a traveling body driving device used in an image reading apparatus for reading an image by moving in the sub-scanning direction at a speed ratio of 2: 1 by using a transmission means such as The coefficient to obtain the control signal at the position of the linear motor from the output of is determined in advance, and this coefficient is multiplied by the feedback signal created from the output signal of the linear encoder to make a new feedback signal. The linear motor is controlled by a single linear encoder output and a simple calculation. Seek control signal data, can perform accurate feedback control. In the invention according to claim 3, the first traveling body and the second traveling body that respectively hold the optical element are directly driven with one of the first traveling body and the second traveling body as the main drive side, and the other is the belt and the wire. By using the transmission means such as
In a traveling body drive unit used for an image reading apparatus, which is installed in the same traveling body with two linear encoders separated from each other, the image is moved by moving in the sub-scanning direction at a speed ratio of 2: 1 and the linear scanning is performed by the image reading apparatus. At the time of pre-scan, a feedback signal for linear motor control is obtained from the feedback signals based on the output signals of the two linear encoders, the distance between at least one linear encoder and the linear motor, and the distance between the two linear encoders. Since the coefficient to be created from the feedback signal based on the output signal of the linear encoder is determined, it is possible to always accurately control the traveling body even when the state changes. According to a fourth aspect of the invention, in the traveling body drive unit of the image reading apparatus according to the third aspect,
The position information from the two linear encoders is used as a feedback signal based on the output signals of the linear encoders, and linear information is obtained from these position information, the distance between at least one linear encoder and the linear motor, and the distance between the two linear encoders. Since the coefficient for creating the feedback signal for motor control from the feedback signal based on the output signal of a certain linear encoder is determined, it is possible to always control the traveling body accurately even when the state changes. . According to the invention of claim 5, claim 3
In the traveling body driving device of the image reading device described above, 2
The speed information from the two linear encoders is used as a feedback signal based on the output signal of the linear encoder, and the speed information, the distance between at least one of the linear encoders and the linear motor, and the distance between the two linear encoders are used to determine the linear motor. Since the coefficient for creating the feedback signal for control from the feedback signal based on the output signal of one linear encoder is determined, it is possible to always control the traveling body accurately even when the state changes. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an optical system of an image reading device in which a traveling body driving device according to an embodiment of the present invention is used.

FIG. 2 is a configuration diagram of a traveling body drive device when a second traveling body is directly driven by using a linear DC motor as a direct drive of the traveling body drive device.

FIG. 3 is a left side view showing a relative positional relationship between a second traveling body of the traveling body drive device, a linear DC motor, and two linear encoders.

FIG. 4 is an explanatory diagram showing a driven method of the second traveling body in the traveling body drive device.

FIG. 5 is an explanatory diagram showing a relationship between speed measurement results by two linear encoders and speed to be fed back at the position of the linear DC motor.

FIG. 6 is a block diagram of a control device according to the first embodiment.

FIG. 7 is an explanatory diagram showing a relationship between an output (OB) pulse of a linear encoder and a clock (CLK).

FIG. 8 is a flowchart showing an operation of an interrupt routine to the microprocessor of the control device.

FIG. 9 is a block diagram of a control system in the traveling body drive apparatus according to the first embodiment.

FIG. 10 is a configuration diagram of a traveling body drive device when a second traveling body is directly driven by using a linear DC motor as a direct drive of the traveling body drive device according to the second embodiment.

FIG. 11 is a left side view showing the relative positional relationship between the second traveling body, the linear DC motor, and the two linear encoders of the traveling body drive device according to the second embodiment.

[FIG. 12] Same as above, when the guide rail has a curvature, 2
It is explanatory drawing which shows the relationship between the speed measurement result by two linear encoders, and the speed which should be fed back in the position of a linear DC motor.

FIG. 13 is a block configuration diagram of a control device in the traveling body drive system according to the second embodiment.

FIG. 14 is a block diagram of a control system in the traveling body drive system according to the second embodiment.

FIG. 15 is a flowchart showing an operation when the traveling body drive device is applied to an image reading device.

FIG. 16 is a block diagram of a control system for prescan in the traveling body drive device.

17 is an explanatory diagram showing states of a sub-scanning start position and a sub-scanning end position of the traveling body controlled by the control system block diagram of FIG.

FIG. 18 is an explanatory diagram showing another state of the sub-scanning start position and the sub-scanning end position of the traveling body.

[Explanation of symbols]

 0 Image original 1 Contact glass 2 Halogen lamp 3, 4, 5, First mirror, Second mirror, Third mirror 6 Lens 7 CCD sensor 8 First running body 201A, B, C, D Bearing section 202, 203 First Guide shaft, second guide shaft 204 Second traveling body 205A, B, C, D bearing 206 Movable back yoke 207 Coil 208 Magnet 209 Fixed back yoke 210, 211, 1001 Linear encoder 212, 213 First belt, Second belt 300 , 300 'Belt end 214A, 214B, 214C, 214D Dynamic pulley

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 10, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Title of Invention] Vehicle drive device

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling body drive device,
For example, the present invention relates to a traveling body driving device used in an image reading device that optically reads a document placed on a document table and obtains a document image.

[0002]

2. Description of the Related Art A first traveling body having a light source for reading an original placed on a document table and a second traveling body having a speed ratio of 1/2 of the first traveling body are the same sub-vehicle. An image reading apparatus that scans in the scanning direction to read an image described on the original document, collects the read image by a lens, and projects and forms the image on a light receiving device to obtain an original image is a factory, office, or the like. Widely used in. As a traveling body driving device for driving the first traveling body and the second traveling body in such an image reading apparatus, for example, it is proposed in Japanese Patent Laid-Open No. 23435/1993. In this traveling body drive device, wires are wound around one or both sides of the first and second traveling bodies that move in the same direction at a speed of 2 to 1, and one of the first and second traveling bodies is driven by a linear motor. However, the other traveling body is driven by the action of the wire and the moving pulley. According to this traveling body driving device, by using the linear motor, compared with the conventional method of driving the traveling body by linearly converting the power of the rotation motor by the rotation-linear conversion system including the gear and the wire system. ,
Since vibration due to the transmission / conversion system does not occur, highly accurate sub-scanning drive is possible.

In addition, in the unpublished application by the applicant, 2
In a traveling body driving device of an image reading apparatus that drives two traveling bodies at a speed of 2: 1 to read an original, a steel belt is wound around the wire instead of the wire, and the first or second
It has been proposed that either one of the running bodies is driven by a linear motor or an ultrasonic motor. According to this traveling body drive device, the precision of the sub-scanning drive can be improved. As described above, in the conventional traveling body drive device, the sub-scanning drive system is improved by using the linear motor and the ultrasonic motor.

[0004]

However, in these conventional traveling body drive devices, the encoders for sensing the speed and position, which are feedback signals, are as follows.
I haven't touched it. A commonly used method is to install a linear encoder at any one position and control the linear motor by this output signal. However, this method has a drawback that the output of the linear encoder is not an accurate feedback signal because the position of the linear encoder and the position of the linear motor are different.

Therefore, it is a first object of the present invention to provide a traveling body drive device capable of obtaining an accurate linear motor control signal and performing an accurate feedback control. It is a second object of the present invention to provide a traveling body drive device capable of always accurately controlling the traveling body even when the state changes.

[0006]

According to another aspect of the present invention, there are provided a first traveling body and a second traveling body which respectively hold an optical element.
Directly drive one of the running bodies as the main drive side,
By moving the other side by using a transmission means such as a belt or a wire, the moving body drive unit used in the image reading apparatus that moves in the sub-scanning direction at a speed ratio of 2: 1 to read an image Two linear encoders are arranged apart from each other, and a feedback signal based on the output signals of the two linear encoders, a distance between at least one linear encoder and the linear motor, and a distance between the two linear encoders are applied to the linear motor. The first object is achieved by providing a signal creating means for creating a feedback signal. According to a second aspect of the present invention, one of the first traveling body and the second traveling body , each of which holds the optical element, is directly driven as a main drive side, and the other is using transmission means such as a belt or a wire. By following
In a traveling body drive device used in an image reading device that reads an image by moving in the sub-scanning direction at a speed ratio of 2: 1,
One linear encoder is arranged on the traveling body, a coefficient for obtaining the control signal at the position of the linear motor is determined in advance from the output of this linear encoder, and this coefficient is used as a feedback signal created from the output signal of the linear encoder. And a control means for controlling the linear motor based on the signal is newly provided to achieve the first object. According to a third aspect of the invention, the first traveling body and the second traveling body that respectively hold the optical element are provided.
Directly drive one of the running bodies as the main drive side,
In the traveling body driving device used for the image reading device, the other traveling body is moved in the sub-scanning direction at a speed ratio of 2: 1 by driving the other by using a transmission means such as a belt or a wire, and the same traveling body is used. The two linear encoders are separated from each other, and when prescanning the image reading device,
Based on the feedback signals based on the output signals of the two linear encoders, the distance between at least one of the linear encoders and the linear motor, and the distance between the two linear encoders, a feedback signal for controlling the linear motor is output from one linear encoder. The second object is achieved by providing a coefficient determining means for determining a coefficient to be created from the feedback signal based on the output signal. According to a fourth aspect of the present invention, in the traveling body drive apparatus according to the third aspect, the coefficient determining means uses the position information from the two linear encoders as a feedback signal based on the output signals of the linear encoders, and these position informations are used. And a coefficient for creating a feedback signal for linear motor control from a feedback signal based on an output signal of a certain linear encoder, based on the distance between at least one linear encoder and the linear motor and the distance between the two linear encoders. To decide. According to the invention of claim 5,
4. The traveling body drive apparatus according to claim 3, wherein the coefficient determining means uses the speed information from the two linear encoders as a feedback signal based on the output signals of the linear encoders, and the speed information and at least one linear encoder. A coefficient for creating a feedback signal for controlling the linear motor from the feedback signal based on the output signal of a certain linear encoder is determined from the distance to the linear motor and the distance between the two linear encoders.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a traveling body drive apparatus of the present invention will be described in detail below with reference to FIGS. FIG. 1 shows a schematic configuration of an optical system of an image reading device in which a traveling body drive device is used. The image original 0 placed on the contact glass 1 is illuminated by a halogen lamp 2 as a light source, and the reflected light is reflected by the first mirror 3, the second mirror 4 and the third mirror 5, and is read by a lens 6, for example, a CCD. It is projected on the sensor 7. The image is read by the main scan by the CCD sensor self-scan,
In FIG. 1, the speed ratio of the first traveling body 8 on which the first mirror 3 and the halogen lamp 2 are installed and the second traveling body 204 on which the second and third mirrors are installed (not shown in FIG. 1) is 2: 1. By sub-scanning in the A direction, the entire area of the image original 0 can be read.

FIG. 2 shows an example of a traveling body drive device when the second traveling body is directly driven by using a linear DC motor as a direct drive, and FIG. 3 shows a second traveling body and a linear DC motor. FIG. 3 is a diagram showing the relative positional relationship between the two linear encoders as viewed from the left side of FIG. 2. In the first embodiment, the two linear encoders 210, 211 are installed separately on the same traveling body, and the two linear encoders 210, 2
11, a feedback signal based on the output signal of 11, the distance between at least one linear encoder 210 (or 211) and the linear motor, and two linear encoders 21.
A feedback signal applied to the linear motor is created from the distance between 0 and 211. This makes it possible to obtain an accurate linear motor control signal and perform accurate feedback control.

The specific structure will be described below.
The first traveling body 8 holding the light source 2 for reading the original and the reflection mirror 3 has two bearing portions 201A, 2A at one end.
01B, and one bearing portion 201C at the other end. The first traveling body 8 has two bearing portions 201.
A and 202B are fitted to the first guide shaft 202,
The bearing 201C at the other end is in contact with the second guide shaft 203. On the other hand, the second traveling body 204 has two bearings 205A, 205B and 205C, 205 at the two ends, respectively.
Equipped with D. The bearings 205A and 205B are fitted to the first guide shaft 202, and the bearings 205C and 205B
5D is in contact with the second guide shaft 203.

A drive coil 207 is attached to the lower side of the second traveling body 204 via a movable back yoke 206 for forming a magnetic circuit and a coil substrate (not shown), and the coil 207 is fixed at a position facing the drive coil 207. A magnet 208 is installed in the main body via a fixed back yoke 209 for forming a magnetic circuit so that the air gap is maintained and the SN poles on the surface alternate in the sub-scanning direction. Also,
Linear encoders 210 and 211 are installed at arbitrary two positions on the second traveling body 204. 2 and 3, the second
Movable parts 210A and 211A including a light source and a sensor are attached to the traveling body 204, and together with fixed parts 210B and 211B of a linear encoder including a linear scale fixed to the main body, so-called optical linear incremental. It forms the encoder. In addition, if it is a linear encoder, it is also possible to adopt other configurations such as a magnetic encoder.

In this configuration, when a current is applied to the coil 207 by a control system (not shown) based on the output signals of the two linear encoders 210 and 211, the second traveling body 2
04 can be driven in the sub-scan direction by direct drive in the direction A in FIG. Here, a linear DC motor is taken as an example of the direct drive, but the present invention is not limited to this as long as it is a direct drive such as a linear ultrasonic motor.

As shown in FIG. 2, a first belt 212 is hung on the outside of the first guide shaft 202 of the first traveling body 8,
A second belt 213 is hung on the outside of the second guide shaft 203 of the second traveling body 204. The first belt 212 is the same as how to hang both belts
4A and 4B are side views of the first belt 212, and the description will focus on the first belt 212. One end and the other end of the first belt 212 are fixed to different positions of the image reading apparatus main body by belt ends 300 and 300 ', respectively. The first belt 212 has two bearings 20 of the second traveling body 204.
5A, 205B (205C, 20 for the second belt 213)
5D), which is supported by a shaft (not shown) provided on the moving pulleys 214A and 214B (214C on the second belt 213,
214D) is wound around each half turn. Also,
Dynamic pulleys 214A, 214B (2 for the second belt 213
14C, 214D), the first traveling body 8 is provided at a predetermined position on the first belt 212 (second belt 213) in the intermediate portion.
The first traveling member clamp 215A (the second belt is 215A)
It is clamped by B) .

In the traveling body drive device having such a structure, when the first traveling body is directly driven in the direction of arrow A in FIG. 2, the first belt 212 and the two moving pulleys 214 are provided.
By the operation of A, 214B, the second belt 213 and the two moving pulleys 214C, 214D, the first traveling body 8 is driven from both sides at twice the speed of the second traveling body 204 . As a result, the first and second traveling bodies 8 and 204 can be driven in the sub-scan at a speed ratio of 2: 1. FIG. 4A shows the sub-scanning start state, and FIG. 4B shows the sub-scanning end state. In addition, the arrow A direction in FIG.
The same direction as the middle arrow A direction is shown. Here, the four bearings 201A and 2A that are fitted to the first guide shaft 202
Each of 01B, 204A, and 204B may be, for example, a combination of a rolling bearing and a pressing member, or a sliding bearing in which a round bar and a round hole are combined. Further, the first and second belts 212 and 213 are not limited to metal, rubber, or any other material as long as they are belts, and wires or the like can be used.

FIG. 5 shows the relationship between the speed measurement results by the two linear encoders in FIGS. 2 and 3 and the speed to be fed back at the position of the linear DC motor. In FIG. 5, v1 is the speed measurement result by the linear encoder (210) on the first guide shaft side,
v2 is the speed measurement result by the linear encoder (211) on the second guide shaft side. Further, vLDM is the speed to be fed back in the linear DC motor unit. now,
The distance between the two linear encoders 210 and 211 is a, and the distance between the linear encoder 210 on the first guide shaft side and the central portion of the linear DC motor is b. During the sub-scan, the traveling body can be regarded as one rigid body, so
Considering the linear encoder 210 on the guide axis side as a reference, the sub-scanning motion can be modeled as shown in FIG. Here, the direction of arrow A in FIG. 5 is the sub-scanning reading direction and is the same as the direction of arrow A in FIGS. From Fig. 5, the speed to be fed back of the linear DC motor is
It can be expressed by the following formula 1.

[0015]

[Equation 1]

Here, (b / a) and ((ab) / a)
Becomes a constant if the mechanical arrangement of the traveling body drive device is determined, and therefore this calculation can be easily realized in both digital and analog cases.

FIG. 6 is a block diagram showing the configuration of the control device according to the first embodiment. 601 is ma
Micro computer 60
2, read only memory (ROM) 603, random
The access memory (RAM) 604 is a bus 605.
Connected through. A command generator 606 outputs a status command signal that commands the status of the linear DC motor, and generates a speed command signal and the like. This command generator 6
The output of 06 is also connected to the bus line 605. 60
Reference numerals 7 and 608 denote state detection interface devices that process the outputs of the two linear encoders 210 and 211 and convert them into digital numerical values, each of which has a counter that counts the output pulses of the linear encoders.

The control device also includes a driving interface device 609, and the microcomputer 60
The digital value of the operation result of 1 is converted into a pulse-shaped signal (control signal) for operating a power semiconductor that constitutes the driving device 610, for example, a transistor. The driving device 610 operates based on this pulse-shaped signal, and the linear DC motor 61
Control the voltage applied to 1. As a result, the sub-scanning traveling body 612 including the linear DC motor 611, that is, all the first and second traveling bodies attached to the linear DC motor.
Are driven at the desired speed. Linear DC motor 611
The speed of the (traveling body 612) is determined by the two linear encoders 210 and 211 and the interface devices 607 and 60 described above.
8 is detected and is taken into the microcomputer 601. The above description is for the case of using the discrete type microcomputer, but it is also possible to use the microcomputer in which the command generation device 606, the drive interface device 609, and the state detection interface devices 607 and 608 are integrated into one chip. Similar functionality is obtained.

Here, a method of detecting the speed of the linear DC motor 611 (traveling body 612) is shown in FIG.
Two state detecting interface devices 607, 6 for processing the outputs of the two linear encoders 210, 211.
The processing method of 08 will be described. Since the functions and operations of the two condition detecting interface devices 607 and 608 are exactly the same, only one of them will be described here. The state detection interface device 607 outputs the output of the linear encoder 210 to the microprocessor 60.
It is designed to supply 2 interrupts. Also, FIG.
A counter for counting the reference clock (CLK) shown in FIG. In FIG. 7, the linear encoder 21
The state immediately before the edge 701 of the output pulse OB of 0 arrives will be described. The counter is the CL of the cycle of the OB pulse.
Based on the K signal, the given count value (eg 0FF
FFH) to perform decrement count. When the edge 701 reaches the interrupt of the microprocessor 602, the interrupt routine is started.

FIG. 8 shows the operation of this interrupt routine. When the edge 701 of the output pulse OB reaches the interrupt of the microprocessor 602, the decrement count value of the counter is latched in the internal register of the state detecting interface device 607 (step 1). Next, the latched decrement count value is stored in the RAM 604 of FIG. 6 (step 2). Then, a count initial value (0FFFFH) for counting the pulse period of Tn is given, the decrement count is started again (step 3), and the interrupt processing is ended. When the edge 702 reaches the interrupt of the microprocessor 602 again, the above steps 1 to 3 are repeated.
Each process up to is repeated. At this time, the speed v1
(I) is calculated by the following Equation 2. However, Tc
lk represents the CLK cycle, Ne represents the number of linear incremental encoder divisions per unit length, and n is CL.
The K count number represents (0FFFFH-decrement count number), and k represents a unit conversion constant to speed.

[0021]

[Equation 2]

FIG. 9 is a block diagram showing the control system in the traveling body drive system of the first embodiment. This control system is provided with a linear DC motor 901 including a traveling body to be controlled. Linear encoder 210 (Fig. 9
Velocity v1 detected based on the output signal of
(I-1) is a block 902, which is multiplied by the constant ((ab) / a) given by the above-mentioned mathematical expression 1 to obtain the operation unit 90.
Is given to 3. Further, the velocity v2 (i-1) detected based on the output signal of the other linear encoder 211 (not shown in FIG. 9) is calculated in block 904 by the constant given by the above-mentioned formula 1. (B / a) is multiplied and given to the arithmetic unit 903. At this time, the meanings of a and b used in this constant are as shown in the above figures.

In the arithmetic unit 903, two inputs are added.
Then, the speed vLDM (i-1) of the linear DC motor is calculated.
ing. The speed vL of the obtained linear DC motor section
DM (i-1) goes through a feedback loop 905,
It is given to the calculation unit 906. In the calculation unit 906, the control target value R output from the command generator 606 is output.
(I) and the difference e (i) from the feedback loop 905
Is calculated. This difference e (i) is integrated in block 907, multiplied by a constant KI in block 908, and the calculation unit 9
09 is given. At the same time, the difference e (i) is multiplied by the constant KP in the block 910 and is given to the arithmetic unit 909. The calculation unit 909 calculates the input voltage u (i) to the linear DC motor 901 by adding two inputs. Here, the control voltage value u (i) is output to the linear DC motor, the traveling body is sub-scanning driven, and the above loop is repeated. The speed vLD of the linear DC motor section according to Formula 1
Since all the control operations including the calculation of M (i-1) are performed by the numerical operation in the microcomputer 601, it can be easily realized. Although the digital PI control has been described as an example of the control method here,
The control method may be analog, PID control, or even modern control.

As described above, in the first embodiment,
The first traveling body 8 and the second traveling body 204 each holding an optical element are directly driven with one of the first or second traveling bodies 8 and 204 as the main drive side, and the other is transmitted with a belt, a wire or the like. In the traveling body drive unit used in the image reading apparatus for reading the image by moving the sub-scanning direction at a speed ratio of 2: 1 by using the means, the two linear encoders 21 for the same traveling body are used.
0 and 211 are installed separately, a feedback signal based on the output signals of the two linear encoders, and the distance between at least one of the linear encoders and the linear motor,
Since the feedback signal applied to the linear motor is created from the distance between the two linear encoders, it is possible to obtain an accurate control signal for the linear motor and perform accurate feedback control.

Next, a second embodiment will be described. Figure 1
FIG. 0 shows an example of the traveling body drive device in the second embodiment in which the second traveling body 204 is directly driven by using the linear DC motor as the direct drive. Further, FIG. 11 shows the relative positional relationship between the second traveling body, the linear DC motor, and one linear encoder 1001 as viewed from the left side of FIG. In addition, in FIGS. 10 and 11, the first described in FIGS.
The same parts having the same functions as those of the embodiment are given the same reference numerals, and the description thereof will be appropriately omitted.
Further, the method of following the running body by a belt such as a steel belt or a wire is also the same as that in FIG.

In the second embodiment, as shown in FIGS. 10 and 11, a linear encoder 1001 is installed at any one position on the second traveling body 204. The second traveling body 204 has a movable part 10 including a light source and a sensor.
01A is attached, and the fixed part 1001 of the linear encoder including the linear scale fixed to the main body
Together with B, a so-called optical linear incremental encoder is formed. Note that the linear encoder may have other configurations such as a magnetic encoder.

In the traveling suspension drive system thus constructed, when a current is passed through the coil 207 by a control system (not shown) based on the output signal of only one linear encoder 1001, the second traveling body 204 is driven. The sub-scanning drive can be performed by the direct drive in the direction A in FIG. In addition,
Here, a linear DC motor has been taken as an example of the direct drive, but various direct drives such as a linear ultrasonic motor can be used.

In the traveling body drive apparatus according to the second embodiment, it is desirable that the guide rails be perfectly parallel to the sub-scanning direction, but in reality it is almost impossible and the guide rails have a curvature. Is normal. If the guide rail has a curvature, the position of the linear encoder differs from the position of the linear DC motor. This is shown in FIG. Generally, even if the guide rail has a curvature, it is quite small. Therefore, although the motion of the traveling body is a rotational motion as shown in FIG. 12, each point on the traveling body is approximately translated. Can be considered Due to the curvature of the guide rail, the traveling body has a radius of curvature r at a point 205C on the second guide shaft of the second traveling body 204 at the center of the point O.
Let's say you are in a rotating motion. The distance between the bearing 205C and the linear encoder 1001 attached to the first guide shaft 202 side of the second traveling body 204 is c, and the distance between the central portion of the linear DC motor and the linear encoder is d. v11
Is the speed measurement result by the linear encoder 1001,
v12 is the speed at bearing 205C, and also vLDM
Represents the speed to be fed back in the linear DC motor unit. During the sub-scan, the traveling body can be regarded as one rigid body, so the velocity v12 at the bearing 205C
Can be expressed by the following expression 3, and the speed to be fed back of the linear DC motor unit can be expressed by the following expression 4 from FIG.

[0029]

[Equation 3]

[0030]

[Equation 4]

Since ( (r−c + d) / (r−c)) is a constant determined only by the mechanical arrangement of the traveling body drive device, this calculation is easy in both digital and analog cases. Can be realized.

FIG. 13 is a block diagram showing the configuration of the control device in the traveling body drive system of the second embodiment. The parts having the same functions as those of the control device in the first embodiment shown in FIG. 6 are designated by the same reference numerals, and the description thereof will be appropriately omitted. In the second embodiment,
The output of the linear encoder 1001 fixed to the first guide shaft 202 side of the second traveling body 204 is connected to the interface device 607 for state detection. The interface device 607 for detecting the state includes a counter that counts the output pulse of the linear encoder.
The output of the state detecting interface device 607 is connected to the microcomputer 601 via the bus line 605, and feedback control is executed based on a control system block diagram described later. The method of detecting the speed, that is, the processing method of the state detection interface device 607 that processes the output of the linear encoder is the same as that described above, and thus the description thereof is omitted here.

FIG. 14 is a block diagram showing a control system in the traveling body drive system of the second embodiment. Here, parts having the same functions as those in FIG. 9 are denoted by the same reference numerals, and the description thereof will be appropriately omitted. The speed v11 (i-1) detected by the linear encoder 1001 is multiplied by the constant ((r-c + d) / (r-c)) given by the above-mentioned formula 4 in block 1401 to obtain the speed of the linear DC motor unit. Seeking vLDM (i-1). At this time, the meanings of c, d, and r used in the constants are as shown in FIG. The obtained speed vLDM (i-1) of the linear DC motor is the feedback loop 9
It is given to the calculation unit 906 via 05. After this,
The same control calculation as in FIG. 9 is performed to obtain the control voltage u (i) for the linear DC motor. Where the control voltage u
(I) is output to the linear DC motor, the traveling body is driven in the sub-scanning, and the above loop is repeated.

As described above, all the control calculations including the calculation of the speed vLDM (i-1) of the linear DC motor section by the mathematical expression 4 are performed by the numerical calculation in the microcomputer 601, so that they can be easily realized. . Although the digital PI control has been described as an example of the control method here, the control method may be analog or P control.
It may be ID control or even modern control. Here, the case where only one linear encoder is attached has been described as an example, but if the number of linear encoders is not particularly one, it is possible to selectively use one of a plurality of attached linear encoders. You may

As described above, according to the second aspect of the invention, the first traveling body and the second traveling body which respectively hold the optical element are provided.
The traveling bodies 8 and 204 are replaced with the first or second traveling bodies 8 and 20.
By directly driving one of the four as the main driving side and driving the other by a transmission means such as a belt or a wire, the image is read by moving in the sub-scanning direction at a speed ratio of 2: 1. In the traveling body drive device used for the apparatus, a coefficient for obtaining the control signal at the position of the linear motor is previously determined from the output of the linear encoder 1001 attached to only one of the traveling bodies, and this coefficient is output from the linear encoder. The feedback signal created from the signal is used as a new feedback signal, and the linear motor is controlled based on that signal.Therefore, only one linear encoder output and simple calculation can be used to obtain an accurate linear motor control signal. Therefore, accurate feedback control can be performed.

Next, the operation when the traveling body drive device is applied to the image reading device will be described with reference to FIG. Here, the traveling body drive device is the same as that in FIGS. 2 and 3, and the block diagram of the control device is the same as that in FIG. When the image reading device starts reading with the start button or the like, it is first determined whether or not the mode is the prescan mode (step 1501). This can be easily realized, for example, by providing a button or signal for setting whether or not to perform pre-scan before reading in the image reading apparatus. If it is determined that the mode is the pre-scan mode (step 1501; Y), the traveling body drive device is driven in the sub-scan mode in the system shown in the control block diagram for pre-scan (details will be described later in FIG. 16) (step). 1052). Then, again, the curvature radius r is determined by the curvature radius determination formula, which will be described later in detail, and is written in the RAM 604 shown in the block diagram of the control device shown in FIG. 6 (step 1503), and the process returns to step 1501. , It is again determined whether or not the pre-scan mode.

When it is determined in step 1501 that the mode is not the pre-scan mode, that is, the image reading mode (step 1501; N), the traveling object is detected in the image reading control block diagram (FIG. 14). The sub-scanning drive (step 1504) is performed, the image is read (step 1505), and when all the images have been read, the flow of the image reading apparatus ends. Here, the radius of curvature r used in block 1401 in the block diagram of the control system at the time of image reading can use the radius of curvature in the state immediately before reading the image by using the value determined in step 1503 of this flowchart. As a result, accurate control can always be performed even when the state changes.

FIG. 16 is a block diagram showing the configuration of the control system for prescan. Here, the same parts as those of the control system of FIG. 9 are designated by the same reference numerals, and the description thereof will be appropriately omitted. The velocity v (i detected by a certain linear encoder (for example, 210 or 211 in FIGS. 2 and 3)
-1) is given to the calculation unit 906 via the feedback loop 1601. After that, the same control calculation as in FIG. 9 is performed, and the control voltage u (i) to the linear DC motor is obtained.
Are seeking. Here, the control voltage value u (i) is output to the linear DC motor, the traveling body is sub-scanning driven, and the above loop is repeated. Since all control calculations are performed by numerical calculations in the microcomputer 601, they can be easily realized. Although the digital PI control has been described as an example of the control method here, the control method may be analog, PID control, or even modern control.

FIG. 17 shows the states of the sub-scanning start position and the sub-scanning end position of the traveling body controlled by the control system block diagram of FIG. α is the sub-scanning start position, and β is the sub-scanning end position. The position outputs of the two linear encoders, for example, 210 and 211 in FIGS. 2 and 3, have different values such as S1 and S2 because the traveling body is inclined by θ as shown in FIG. 17 due to the curvature of the guide shaft and the like. Show. Therefore, if the distance between the two linear encoders is a , the radius of curvature r can be easily obtained from the following Equation 5.

[0040]

[Equation 5]

Position measurement by the linear incremental encoder is performed by counting the number of output pulses of the linear incremental encoder, which has a one-to-one relationship with the position, by the microcomputer in the block diagram of the control device shown in FIG. Easy to achieve.

As shown in FIG. 18 , if the linear encoders, for example, the velocity outputs of 210 and 211 in FIGS. 2 and 3, or some average values of these velocity outputs are v1 and v2, respectively, the curvatures are The radius r is calculated by the following formula 6.
It can also be expressed as.

[0043]

[Equation 6]

As described above, the invention according to claim 3
Then, the first traveling body and the first traveling body, which respectively hold the optical elements,
2 runners, either the first or second runner
Direct drive as main drive side, belt on the other side,
By using a transmission means such as a wire,
Scan an image by moving it in the sub-scanning direction at a speed ratio of 1: 1
Install two linear encoders separately on the same
Drive unit used for the image reading device
At the time of pre-scanning of the image reading device, the feedback signal based on the output signals of the two linear encoders, the distance between at least one linear encoder and the linear motor, and the distance between the two linear encoders are used to control the linear motor. Since the coefficient for creating the feedback signal from the feedback signal based on the output signal of one linear encoder is determined,
Even if the state changes, it is possible to always control the traveling body accurately. In the invention according to claim 4,
In the traveling body driving device of the image reading device described in 3,
Position information from the two linear encoders, Riniaen
A feedback signal based on the output signal of the coder is used, and a feedback signal for linear motor control is obtained from the position information, the distance between at least one linear encoder and the linear motor, and the distance between the two linear encoders. Since the coefficient to be created from the feedback signal based on the output signal of the encoder is determined, it is possible to always accurately control the traveling body even when the state changes. Further, in the invention according to claim 5,
Is a moving body driving device of the image reading device according to claim 3.
In, the speed information from the two linear encoders is
A feedback signal based on the output signal of the linear encoder is used. Based on these speed information, the distance between at least one linear encoder and the linear motor, and the distance between the two linear encoders, a feedback signal for linear motor control is provided. Since the coefficient to be created from the feedback signal based on the output signal of the linear encoder is determined, it is possible to always accurately control the traveling body even when the state changes.

[0045]

According to the first aspect of the present invention, one of the first traveling body and the second traveling body, each of which holds the optical element, is directly driven as a main drive side, and the other is a transmission means such as a belt or a wire. In a moving body driving device used for an image reading device that reads an image by moving in the sub-scanning direction at a speed ratio of 2: 1 by using the following, two linear encoders are installed separately on the same traveling body. Since the feedback signal to be added to the linear motor is created from the feedback signal based on the output signals of the two linear encoders, the distance between at least one linear encoder and the linear motor, and the distance between the two linear encoders, Accurate feedback control can be performed by obtaining an accurate linear motor control signal. According to a second aspect of the present invention, the first traveling body and the second traveling body that respectively hold the optical element are the first traveling body and the second traveling body.
An image in which one of the traveling bodies is directly driven with the main drive side and the other is driven with a transmission means such as a belt or a wire to move in the sub-scanning direction at a speed ratio of 2: 1 to read an image. In the traveling body driving device used for the reading device, a coefficient for obtaining the control signal at the position of the linear motor is determined in advance from the output of the linear encoder attached to the traveling body only, and this coefficient is used as the output signal of the linear encoder. The feedback signal created from is used as a new feedback signal, and the linear motor is controlled based on that signal, so an accurate linear motor control signal can be obtained with only one linear encoder output and simple calculation. It is possible to obtain accurate feedback control. In the invention according to claim 3, the first traveling body and the second traveling body that respectively hold the optical elements are directly driven with one of the first traveling body and the second traveling body as the main drive side, and the other is a belt,
By being driven by a transmission means such as a wire, the image is read by moving in the sub-scanning direction at a speed ratio of 2: 1.
In a traveling body drive device used for an image reading apparatus, in which two linear encoders are installed separately on the same traveling body, a feedback signal based on the output signals of the two linear encoders during prescanning of the image reading apparatus, From the distance between at least one of the linear encoders and the linear motor, and the distance between the two linear encoders, a coefficient for creating a feedback signal for controlling the linear motor from the feedback signal based on the output signal of a certain linear encoder is determined. because in that, even if the state has changed, it is always possible to perform the accurate control of the running body. According to a fourth aspect of the present invention , in the traveling body driving device of the image reading apparatus according to the third aspect, the positional information from the two linear encoders is used as a feedback signal based on the output signals of the linear encoders, and the positional information is obtained. From the distance between at least one linear encoder and the linear motor and the distance between the two linear encoders, a coefficient for generating a feedback signal for controlling the linear motor from the feedback signal based on the output signal of one linear encoder is determined. Therefore, even if the state changes, the traveling body can always be controlled accurately. According to a fifth aspect of the present invention, in the traveling body driving device of the image reading apparatus according to the third aspect, the speed information from the two linear encoders is used as a feedback signal based on the output signals of the linear encoders, and the speed information is obtained. From the distance between at least one linear encoder and the linear motor and the distance between the two linear encoders, a coefficient for generating a feedback signal for controlling the linear motor from the feedback signal based on the output signal of one linear encoder is determined. Therefore, even if the state changes, the traveling body can always be controlled accurately.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an optical system of an image reading device in which a traveling body driving device according to an embodiment of the present invention is used.

FIG. 2 is a configuration diagram of a traveling body drive device when a second traveling body is directly driven by using a linear DC motor as a direct drive of the traveling body drive device.

FIG. 3 is a left side view showing a relative positional relationship between a second traveling body of the traveling body drive device, a linear DC motor, and two linear encoders.

FIG. 4 is an explanatory view showing a driven method of the first traveling body in the traveling body drive device.

FIG. 5 is an explanatory diagram showing a relationship between speed measurement results by two linear encoders and speed to be fed back at the position of the linear DC motor.

FIG. 6 is a block diagram of a control device according to the first embodiment.

FIG. 7 is an explanatory diagram showing a relationship between an output (OB) pulse of a linear encoder and a clock (CLK).

FIG. 8 is a flowchart showing an operation of an interrupt routine to the microprocessor of the control device.

FIG. 9 is a block diagram of a control system in the traveling body drive apparatus according to the first embodiment.

FIG. 10 is a configuration diagram of a traveling body drive device when a second traveling body is directly driven by using a linear DC motor as a direct drive of the traveling body drive device according to the second embodiment.

FIG. 11 is a left side view showing the relative positional relationship between the second traveling body, the linear DC motor, and the two linear encoders of the traveling body drive device according to the second embodiment.

[FIG. 12] Same as above, when the guide rail has a curvature, 2
It is explanatory drawing which shows the relationship between the speed measurement result by two linear encoders, and the speed which should be fed back in the position of a linear DC motor.

FIG. 13 is a block configuration diagram of a control device in the traveling body drive system according to the second embodiment.

FIG. 14 is a block diagram of a control system in the traveling body drive system according to the second embodiment.

FIG. 15 is a flowchart showing an operation when the traveling body driving device is applied to both image reading devices.

FIG. 16 is a block diagram of a control system for prescan in the traveling body drive device.

17 is an explanatory diagram showing states of a sub-scanning start position and a sub-scanning end position of the traveling body controlled by the control system block diagram of FIG.

[18] Ibid, rate of state at some time during the sub-scan of the running body or some average speed state between when the
FIG.

[Description of Reference Signs] 0 Image Original 1 Contact Glass 2 Halogen Lamp 3, 4, 5, First Mirror, Second Mirror, Third Mirror 6 Lens 7 CCD Sensor 8 First Traveling Body 201A, B, C, D Bearing Unit 202, 203 1st guide shaft, 2nd guide shaft 204 2nd traveling body 205A, B, C, D bearing 206 movable back yoke 207 coil 208 magnet 209 fixed back yoke 210, 211, 1001 linear encoder 212, 213 1st belt , 2nd belt 300, 300 'Belt end 214A, 214B, 214C, 214D Dynamic pulley

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

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FIG. 14

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FIG. 18

Claims (5)

[Claims] 1. A pair of a first traveling body and a second traveling body, each of which holds an optical element, is directly driven with the main drive side as the main driving side, and the other is driven by a transmission means such as a belt or a wire to form two pairs. In a traveling body driving device used for an image reading device that reads an image by moving in the sub-scanning direction at a speed ratio of 1, two linear encoders are arranged separately on the same traveling body, and output signals of these two linear encoders are arranged. A traveling body drive comprising: a feedback signal based on the feedback signal, a distance between at least one of the linear encoders and the linear motor, and a distance between the two linear encoders to generate a feedback signal to be applied to the linear motor. apparatus. 2. By directly driving one of the first traveling body and the second traveling body, each of which holds an optical element, with the main driving side as the main driving side, and driving the other by using a transmission means such as a belt or a wire, In a traveling body drive unit used in an image reading apparatus that reads an image by moving in the sub-scanning direction at a speed ratio of 1: 1, one linear encoder is arranged on the traveling body, and the output of this linear encoder changes the position of the linear motor. A coefficient for obtaining the control signal is determined in advance, the feedback signal created from the output signal of the linear encoder is multiplied to obtain a new feedback signal, and control means for controlling the linear motor based on the signal is provided. A traveling body drive device comprising: 3. One of the first traveling body and the second traveling body, each of which holds an optical element, is directly driven as a main drive side, and the other is driven by a transmission means such as a belt or a wire, so that two pairs are formed. In a traveling body driving device used for an image reading device that moves in the sub-scanning direction at a speed ratio of 1 to read an image, two linear encoders are separately arranged on the same traveling body, and at the time of prescanning of the image reading device, Based on the feedback signals based on the output signals of the two linear encoders, the distance between at least one of the linear encoders and the linear motor, and the distance between the two linear encoders, a feedback signal for controlling the linear motor is output from one linear encoder. Coefficient deciding means for deciding the coefficient to be created from the feedback signal based on the output signal Traveling body drive device for characterized by comprising. 4. The coefficient determining means uses the position information from the two linear encoders as a feedback signal based on the output signals of the linear encoders, and the position information and the distance between at least one of the linear encoders and the linear motor. 4. The traveling according to claim 3, wherein a coefficient for generating a feedback signal for controlling a linear motor from a feedback signal based on an output signal of a certain linear encoder is determined from a distance between the two linear encoders. Body drive. 5. The coefficient determining means uses the speed information from the two linear encoders as a feedback signal based on the output signals of the linear encoders, and the speed information and the distance between at least one of the linear encoders and the linear motor. 4. The traveling according to claim 3, wherein a coefficient for generating a feedback signal for controlling a linear motor from a feedback signal based on an output signal of a certain linear encoder is determined from a distance between the two linear encoders. Body drive.