JP3530992B2 - Image reading device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus mounted on a copying machine, an image scanner or the like, and more particularly to an image reading apparatus for optically scanning a document image. 2. Description of the Related Art Conventionally, an image reading apparatus that optically scans a document image has been widely used as an image scanner mounted on a copying machine or used together with a computer or a printer. Such an image reading device is usually
An illuminating device for illuminating a document placed at a predetermined position, a first slider mounted with a first reflection mirror for guiding reflected image light from the document in a predetermined direction, and a reciprocating slider; and an image coming from the first reflection mirror. A second slider that carries a second reflection mirror for guiding light in a predetermined direction and that can reciprocate in the same direction as the first slider; When reading an image, the first slider and the second slider normally accelerate from a home position, a constant speed (image reading), decelerate, reverse, and stop, and return to each home position to read an image. Ends one cycle. Then, image reading is performed at the constant speed. Various means have been proposed for driving each slider.
Japanese Patent No. 324 teaches that each slider is driven and controlled by a separate driving device including a linear motor. Japanese Patent Application Laid-Open No. 60-136731 teaches that each slider is driven by a linear motor and the speed ratio between the first slider and the second slider during driving is 2: 1. Also,
JP-A-2-210468 discloses that an illuminating device, a first mirror, and a second mirror are mounted on three independent sliders, and each slider is provided by three independent rotating motors and wires wound around these. In addition to driving, it is taught to provide a time difference between the start of scanning and the start of return of the three sliders. However, in the apparatus disclosed in Japanese Patent Application Laid-Open No. 60-136731, when the first slider and the second slider are returned to their respective home positions, the respective sliders are moved simultaneously. In addition, since driving is performed at a speed higher than the speed at the time of image reading, the peak value of power consumption is increased. If the peak value of the power consumption is large, the power supply capacity for the slider driving means must be increased accordingly, and the parts around the power supply need to have a correspondingly large capacity, which increases the cost of the apparatus. JP-A-61-59324, JP-A-2-210468
The same applies to the device taught in Japanese Patent Publication No. Accordingly, the present invention relates to an image reading apparatus for optically scanning an original image, wherein when a first and a second slider on which optical components are mounted return to respective home positions, a peak value of power consumption is obtained. It is an object of the present invention to provide an image reading apparatus which can reduce the power supply capacity for the slider driving means, thereby reducing the cost and energy consumption of the apparatus. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to an image reading apparatus for optically scanning a document image, and an illumination device for illuminating a document placed at a predetermined position. A first slider mounted thereon with a first mirror for guiding reflected image light from the document in a predetermined direction and reciprocally movable; and a second mirror mounted on the first mirror for guiding image light from the first mirror in a predetermined direction. A second slider capable of reciprocating in the same direction as the first slider, first slider driving means for reciprocating the first slider, and reciprocatingly driving the second slider independently of the first slider. For controlling the operation of the first slider driving means and the second slider driving means, the control means comprising: a first slider and a second slider. When returning to their home position,
After returning and stopping the second slider to the home position of the second slider before the first slider, the first slider returns and stops the first slider to the home position of the first slider. There is provided an image reading apparatus which controls operations of a driving unit and a second slider driving unit. In the image reading apparatus according to the present invention, an image forming lens is provided on the optical axis of the reflected image light after the second mirror, and the image light is transferred to the electrostatic latent light after the image forming lens. Mirror means leading to the photoreceptor, which is an image carrier,
Alternatively, an image sensor including a CCD image sensor can be provided after the imaging lens. The former image reading device can be applied to an analog copying machine and the like, and the latter image reading device can be applied to a digital copying machine and an image scanner. The number, position, and orientation of the first reflection mirrors mounted on the first slider, and the number, position, and orientation of the second reflection mirrors mounted on the second slider can be determined as appropriate. The first slider driving means may be a linear motor capable of driving the first slider independently of the second slider, or a means for transmitting the power of the rotary motor to the first slider via a transmission mechanism such as a wire pulley mechanism. Can be The same applies to the second slider driving means. When returning the first slider and the second slider to the respective home positions, for example,
Is the case. After reading the original image, moving each slider to each home position to prepare for the next image reading. A case where, after turning on the power of the image reading device, each slider is moved to each home position to prepare for the first document image reading. When an operation failure occurs during image reading, each slider is temporarily moved to each home position,
When restarting image reading. According to the image reading apparatus of the present invention, when returning the first slider and the second slider to the respective home positions, the first slider driving unit and the second slider driving unit first control the operation by the control unit. ,
After returning the second slider to the home position of the slider and stopping the second slider, the first slider is returned to the home position of the slider and stopped. The arrival of each slider at the home position can be detected by a home position detecting means (for example, a home sensor). In this case, each slider may be stopped according to the detection of the arrival of each slider at the home position by the detection means. During the image reading, the first slider and the second slider are driven at a predetermined speed. The speed is typically such that the speed ratio between the first slider and the second slider is 2: 1. When both sliders are driven at the predetermined speed, light is applied to the original image by an illuminating device mounted on the first slider, and the reflected light is reflected by a first mirror disposed on the same optical axis. The original image is read by being guided to an imaging lens or the like by a second mirror mounted on the second slider. The driving speed of each slider when returning the first slider and the second slider to each home position can be set arbitrarily, and the speed of the first slider and the second slider during image reading can be set. That is, typically, the speed ratio between the first slider and the second slider is not limited to 2: 1. Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show an image reading apparatus according to an embodiment of the present invention, which is mounted on a digital copying machine. FIG. 1 is a schematic plan view of the device, and FIG. 2 is a schematic side view showing a part of the device in cross section. In FIG. 1, the platen glass is not shown. The image reading apparatus includes a platen glass 5
A first slider SL1 and a second slider SL2 reciprocally movable along both a rod-shaped stator 3 and a guide rail 4 disposed below the platen glass 5, a reading unit 6, a control unit, 70 (see FIG. 4). The first slider SL1 has an illumination lamp 10 for illuminating an original placed on the original platen glass 5, an illumination lamp 10
Reflection mirrors M11 and M1 for directing the irradiation light of
2, and a reflection mirror M13 for guiding the reflected light from the document toward the second slider SL2. The second slider SL2 is provided with reflection mirrors M21 and M22 for guiding the original image light guided from the reflection mirror M13 to the reading unit 6. The reading unit 6 includes a lens 61 and a CCD 62 serving as an image sensor. The lens 61 includes a second slider SL
The image light guided by the second reflection mirrors M21 and M22 is imaged on the CCD 62. This reading unit 6
Is fixed to the image reading device by supporting means (not shown). The first slider SL1 has a constant width in a direction perpendicular to the traveling direction, one end 13 of which is fixed to the mover yoke 113 of the mover 11, and the other end 14 of which is a support roller 12 Which can run on a guide rail 4 parallel to the stator 3. The mover 11 is one component of a linear motor LDM1 that is a driving unit of the first slider SL1. The linear motor LDM1 also includes the stator 3 as a component, and the mover 11 is fitted around the stator 3 so as to be able to reciprocate. The second slider SL2 is also the first slider SL1.
In the same manner as described above, it has a constant width in a direction perpendicular to its traveling direction, and its one end 23 is
3, the other end 24 is provided with a support roller 22, which can run on a guide rail 4 parallel to the stator 3.
The mover 21 is one component of a linear motor LDM2 that is a driving means of the second slider SL2, and the mover 21 is fitted on the stator 3 that is common to the stator of the motor LDM1 so as to be able to reciprocate. A stator 3 common to both motors is formed by forming a field magnet 31 for propulsion and a magnetic scale 32 on a rod-shaped member having a circular cross section formed from a material which can be machined and magnetized and has a smooth surface. And is arranged in parallel with the platen glass 5. As shown in FIG. 3, the field magnet 31 is formed by alternately magnetizing N-poles and S-poles on the surface of the rod 30 at a pitch of 30 mm in the longitudinal direction of the rod 30, and the magnetic force distribution has a peak. Is 1500 Gauss and cycle is 60
1 shows a sine curve in mm. The magnetic scale 32 has N poles and S poles alternately arranged on the surface of the rod 30 at a fine pitch.
Further, the rod-shaped members 30 are formed in several rows by being magnetized in the longitudinal direction. This magnetic scale will be described later in detail. The mover 11 of the motor LDM1 and the motor L
The mover 21 of the DM 2 is substantially the same in configuration although the size of each part is slightly different. That is, the mover 1
1 (21), as shown in FIG. 3 (B), includes a coil bobbin B which is fitted to the stator 3 and can reciprocate along the stator, and a u-phase coil, a v-phase coil, w Three-phase armature coils U, V, and W composed of phase coils are provided, and the mover yokes 113 (213) are fitted to these coils. These armature coils are arranged at positions shifted by an electrical angle of 2π / 3 (or may be in the same phase as the position shifted by 2π / 3) so that the motor can be operated by a three-phase driving method. At both ends of the coil bobbin B and the mover yokes 113 (213), ring-shaped guide members G that are fitted to the stator 3 are provided. Also, on the inner surface of the mover yoke 113 (213), there is provided a field magnet 31 for controlling the energization of each phase coil in accordance with the position so that a mover thrust can be obtained regardless of the position of the mover. There is a sensor to detect the position,
In this example, as the sensor, a Hall element hu is used as a position detecting element for the u-phase coil, a Hall element hv is also used for the v-phase coil, and a Hall element hv is also used for the w-phase coil.
w are provided respectively. The coil bobbin B has a magnetic scale 3
A magnetic sensor group for reading magnetic information from the magnetic sensors 2 is provided. That is, the magnetic sensor group SMR1 for the motor LDM1, and the magnetic sensor group SMR for the motor LDM2.
MR2 is provided. For the motor LDM1, the magnetic scale 32 and the magnetic sensor group SMR1 form a magnetic absolute linear encoder. For the motor LDM2, the same magnetic scale 32 and the magnetic sensor group SMR2 form a magnetic absolute linear encoder. An encoder is formed. These encoders
This is for detecting the absolute position of the mover 11 (21) on the stator 3, in other words, the absolute position of the slider SL1 (SL2). However, as described later, the magnetic scale 3
The finely magnetized magnetized train of 2 is also used for speed control of the mover 11 (21). The magnetic pole pitch of the finest fine magnetization is 200 μm. As shown in FIG. 3 (C), the magnetic scale 32 is formed on the stator 3 by fine magnetizing N poles and S poles alternately and in a plurality of rows in the longitudinal direction of the stator. The magnetic pole pitch and magnetic force distribution (indicating a sine curve) in each fine magnetized train are different from those of other fine magnetized trains. In the illustrated example, the half cycle of the magnetized train of the first row (shown at the top of FIG. 3C) is the cycle of the second magnetized train, and the half cycle is three rows. It is like the period of the eyes. That is, n (here 6)
When the magnetized train has the ^2n- bit information, the address (absolute position) of the mover (and thus the slider) can be represented. The sensor group SMR1 (SMR2) for reading magnetic information from the magnetic scale 32 is shown in FIG.
As shown in (C), the sensor S11 using a magnetoresistive element called an MR element here, although not limited thereto.
To S16 (S21 to S26). Sensor S
11 to S16 constitute a sensor group SMR1 on the motor LDM1, and the sensors S21 to S26 correspond to the motor LDM2.
An upper sensor group SMR2 is formed. In each motor, the plurality of sensors are arranged in a line in a direction perpendicular to the longitudinal direction of the stator 3 and in one magnetized line in the magnetic scale 32. The sensors are arranged to face each other and attached to the mover. Each magnetic sensor detects a magnetic change (sine wave) from the S pole and N pole accompanying the mover movement from the corresponding fine magnetized train, and converts this to a rectangular wave.
By converting to a digital signal, the N pole is set to “1” and S
By setting the pole to "0" and using six magnetic sensors for six magnetized rows, 6-bit address information can be obtained.
Address information output from each magnetic sensor is input to a signal input port of a computer 71 in a control unit 70 described later. In the magnetic scale 32, the finely magnetized finely magnetized train and the sensor S16 (S26) for reading magnetic information from the fine magnetized train are, as described later, the movable element 11 (21), If so, it also serves as an encoder for controlling the speed of the slider SL1 (SL2) connected to the mover. Now, the linear motor LDM described above
1, LDM2 is used for the armature coils of the movers 11, 21;
Thrust is generated by energization under the control of the control unit 70, and the movers 11, 21 are driven along the stator 3, whereby the sliders SL1, SL2 are also driven. In this image reading apparatus, the home position of the first slider SL1 and the home position of the second slider SL2 correspond to the home sensor H shown in FIG.
1, detected by H2. The detection signals of the home sensors H1 and H2 are input to a control unit 70 described later. Control unit 7
0 indicates a predetermined operation of the motors LDM1 and LDM2 as shown in FIG.
A microcomputer 71 for outputting a reference clock signal to the input / output ports 72, 72 'of the computer 71,
Amplifiers 73, 73 ', switching units 74, 74', the above-mentioned phase synchronization control units 75, 75 ', compensation circuits 76, 76
′, Amplifier circuits 77 and 77 ′. According to the control circuit shown in FIG. 5, the reference clock signal corresponding to the target speed is input from the computer 71 to the phase synchronization control units 75 and 75 ', and is movable from the encoder including the magnetic sensors S16 and S26. Child 1
The moving speed signals 1, 21 are fed back to the control units 75, 75 '. The phase synchronization control units 75, 75 '
A signal corresponding to the difference between the frequency and the phase of the pulse of the reference clock and the pulse of the feedback signal from the encoder is output. Compensation circuits 76 and 76 'compensate for the advance / delay of the transmission system. Input voltage.
The Hall element outputs a voltage corresponding to the magnitude and direction of the magnetic flux at a certain position, and the output voltage has a characteristic proportional to the reference input voltage. Therefore, an output voltage corresponding to the difference between the reference clock signal and the feedback signal is output from the Hall element. The output voltage from the Hall element is proportionally amplified by the amplifier circuits 77 and 77 '.
The armature coil is energized. As described above, the motors LDM1 and LDM2 are operated so that the frequency and phase of the pulse of the reference clock and the pulse of the feedback signal are matched, in other words, the target speeds of the movers 11 and 21 match. During image scanning, the speed of the slider SL1 and the speed of the slider SL2 are set to 2: 1. Hereinafter, the operation of the image reading apparatus according to the present invention, in particular, the first and second processes will be described with reference to the flowchart of FIG.
A description will be given of how the second sliders SL1 and SL2 are returned to the respective home positions. In this image reading apparatus, the first slider SL1 and the second slider SL2 return to their respective home positions in the following three cases. After reading the original image, moving each slider to each home position to prepare for the next image reading. This case is considered to be performed most frequently, and generally, the moving speed to each home position is considerably higher than the speed at the time of image reading. After turning on the power of the image reading device (or the copier in which the image reading device is mounted), each slider is moved to each home position to prepare for the first document image reading. This is performed to confirm the position of each slider after turning on the power since the power of the apparatus may be turned off during image reading, or the slider may move from the home position due to transportation or movement of the apparatus. . When an operation failure occurs during image reading, each slider is temporarily moved to each home position to restart image reading. This is because when the positional relationship between the first slider SL1 and the second slider SL2 is lost or when an error occurs in an encoder signal for detecting the position of each slider, or when an operation error occurs, the position of each slider SL1 is changed. This is done for confirmation. In the above cases, the first slider SL1 and the second slider SL2 are driven by the control unit 70 based on the flowchart shown in FIG. FIG. 5 is a flowchart showing the processing performed by the control unit 70 when returning each slider to each home position. That is, first, the second slider SL2 is moved to the second
The slider is moved until the home sensor H2 is turned on (S1, S5). When the home sensor H2 of the second slider is turned on (S1: YES), the second slider SL2 is stopped (S2). As a result, the second slider SL2 is located at the home position. Then, the second slider SL
After 2 stops, the first slider is moved until the home sensor H1 of the slider is turned on (S3, S6). When the home sensor H1 of the first slider is turned on (S3: YE
S), the first slider SL1 is stopped (S4). Thereby, the first slider SL1 is located at the home position. Thus, the return of both sliders to the respective home positions is completed. Incidentally, the first slider SL1 and the second slider SL2 move toward each home position (S
6, S5), the speed ratio is not limited to 2: 1 as in image reading, but can be set arbitrarily. For example, the speed can be increased by driving each slider at the maximum speed. As described above, in the image forming apparatus according to the present invention, when returning each slider to each home position, first, only the second slider SL2 is moved to the home position of the slider, and the second slider SL2 is returned to the home position. After stopping, the first slider is moved to the home position of the slider. Therefore, when each slider is moved to each home position after image reading is completed as in the above case, both sliders are driven simultaneously and at a higher speed than in image reading as in the conventional apparatus. Since the sliders are driven one by one, the peak of power consumption can be shifted, whereby the peak value of power consumption can be suppressed.
1. The power supply capacity for driving the LDM 2 can be reduced, so that a low wattage type power supply component can be used, and the cost of the apparatus can be reduced. In addition, since the peak value can be suppressed, a current having a high current / magnetic force (driving force) conversion efficiency can flow through each phase coil, so that energy can be saved. In the case where each slider is moved to each home position after the power of the apparatus is turned on as in the above case, the apparatus can be reduced in cost and energy consumption as in the above case, and can be moved to the home position. Since the second slider SL2 on the near side is moved first, the risk of collision between the two sliders can be reduced. Also,
As in the above case, when each slider is moved to each home position at the time of defective operation, similarly to the above, the device can be reduced in cost and energy can be saved.
The risk of collision between the two sliders can be reduced. Although each encoder in the image reading apparatus described above is a magnetic encoder, an optical encoder may be used instead. When this optical encoder is used, an optical scale is used instead of the magnetic scale 32 on the stator 3, and the magnetic sensor groups SMR1 and SMR2 on the mover 11 (21) are used.
May be replaced by an optical sensor group. Instead of the absolute encoder, an incremental encoder may be used. Further, the image reading apparatus of the present invention can be applied to, for example, an analog copying machine, an image scanner and the like other than the digital copying machine described above. According to the present invention, there is provided an image reading apparatus for optically scanning a document image, wherein when the first and second sliders on which optical components are mounted return to their respective home positions, The peak value of the power consumption can be suppressed, and the power supply capacity for the slider driving unit can be reduced accordingly, so that an image reading apparatus that can reduce the cost and energy consumption of the apparatus can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of an image reading device mounted on a digital copying machine according to an embodiment of the present invention. FIG. 2 is a schematic side view showing a cross section of a part of the image reading apparatus shown in FIG. 3A is a side view of a linear motor as first and second slider driving means of the image reading apparatus shown in FIG. 1, FIG. 3B is a sectional view of the motor, and FIG. It is an enlarged plan view of a magnetic scale on a motor stator. 4 is a circuit diagram of a control unit of a linear motor of the image reading device shown in FIG. FIG. 5 is a flowchart showing a process of returning each slider to each home position, which is a part of a process performed by a control unit of the image reading apparatus shown in FIG. 1; [Description of Signs] SL1 first slider 10 illumination lamp LDM1 linear motor (first slider driving means) 11 mover B coil bobbin U, V, W armature coil 113 mover yokes hu, hv, hw Hall element SMR1 Magnetic sensor group S11 to S16 Magnetic sensor 12 Support roller 13 One end of first slider 14 Other end M11, M12 of first slider Reflection mirror M13 Reflection mirror (first reflection mirror) SL2 Second slider LDM2 Linear motor (second slider driving means) 21) mover 22 support roller SMR2 magnetic sensor group S21 to S26 magnetic sensors M21, M22 reflection mirror (second reflection mirror) 3 stator 31 field magnet 32 magnetic scale 4 guide rail 5 document placing glass 6 reading unit 61 lens 62 CCD image sensor 70 control (Control means) 71 computer H1, H2 home sensor

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-210468 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 1/10

Claims (1)

(57) [Claim 1] An image reading apparatus for optically scanning an original image, an illuminating device for illuminating an original placed at a predetermined position, and a reflecting image light from the original for a predetermined time. A first mirror mounted with a first mirror for guiding the light in a predetermined direction and reciprocally movable; and a second mirror mounted with a second mirror for guiding the image light from the first mirror in a predetermined direction, in the same direction as the first slider. A second slider capable of reciprocating; a first slider driving means for reciprocatingly driving the first slider; a second slider driving means for reciprocatingly driving the second slider independently of the first slider; Control means for controlling operations of the first slider driving means and the second slider driving means, wherein the control means returns the first slider and the second slider to their home positions. When the second slider returns to the home position of the second slider prior to the first slider and stops, the first slider returns to the home position of the first slider and stops. An image reading apparatus for controlling operations of a first slider driving unit and a second slider driving unit.