JP4479544B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus that reads image information of a document, and can be used as a single unit, and in particular, as an image reading unit in an image forming apparatus such as a copying machine or a multifunction peripheral that uses image information read from a document. The present invention relates to an image reading apparatus that can be used.

  As an image reading apparatus used in a copying machine or a multifunction peripheral, for example, an underside of plantain glass as a document table includes an illumination lamp, a carriage on which optical parts such as a reflection lens are mounted, an electric motor, and the like. By reciprocating by a driving device, and image information of the document placed on the platen glass in the forward path is formed on an image sensor such as a CCD (Charge Coupled Device) linear sensor through an optical system component such as a coupling lens. There is something to read. Some of such image reading apparatuses have an image sensor mounted on the carriage.

In such an image reading apparatus, generally, the movement of the carriage in the forward path is performed under a series of speed conditions of acceleration, constant speed, and deceleration, and an original image reading operation is executed in the constant speed region (Patent Document). 1, 2).
JP 2001-298585 A JP 2001-228560 A Japanese Patent No. 3162788

  However, even such a conventional image reading apparatus has the following problems.

  First, it is not possible to fully meet the demand for higher reading speed.

  Conventionally, it is known to increase the reading speed by, for example, increasing the acceleration in the return path where the image reading operation is not performed, the acceleration in the deceleration area, and the speed in the constant speed area in the return path. However, there is a new problem that an increase in power to be supplied to the electric motor of the drive device or a restriction occurs during the movement of the return path for the correspondence (Patent Document 2).

  In addition to this, an image reading apparatus has also been proposed in which a reading operation is performed including acceleration and deceleration areas other than the constant speed area in the forward path (Patent Document 3). However, in this case, image processing means for obtaining the same image data by scaling the image data in accordance with the reading (scanning) speed in the acceleration and deceleration areas is required, and the configuration becomes complicated. End up.

  In addition, in the case of adopting a countermeasure for constantly increasing the carriage moving speed or the like in order to increase the reading speed, in addition to the problem of the increase in power supplied to the driving device as described above, the carriage Another problem arises that the operating noise during movement increases.

  Furthermore, it is not possible to fully meet the demand for downsizing of the image reading apparatus.

  That is, in order to meet the demand for downsizing, the allowable movement length when the carriage reciprocates may be shortened. For this reason, for example, the moving distance of the carriage in the deceleration area during the forward path is limited, and the speed in the deceleration area cannot be simply increased from the viewpoint of increasing the reading speed. In particular, when the speed is increased too much, there is a risk that the carriage will collide with surrounding parts at a point where the carriage decelerates and stops in the forward deceleration region and then returns to the return path.

  The present invention has been made in view of the above-described problems and the like, and can freely respond to each request such as higher reading speed, smaller apparatus, and reduced noise. Provided is an image reading apparatus capable of performing the above.

  An image reading apparatus according to the present invention reciprocates along a certain direction of a document with a reading unit that reads image information of a document placed on a document table and a moving body on which at least one component of the reading unit is mounted. A driving device to be moved, control means for controlling the movement of the moving body by the driving device at least in the forward path under acceleration, constant speed and deceleration speed conditions, and a deceleration region in the forward path of the moving body by the control means And a changing means for changing the deceleration speed to a special deceleration speed that is increased or decreased from the normal deceleration speed.

  In this image reading apparatus, the changing means can arbitrarily change the deceleration speed of the deceleration area in the forward path of the moving body to a special deceleration speed different from the normal (standard) deceleration speed. By changing the control content, the mobile body can be decelerated at a speed different from that at the normal time. For example, the changing operation of the changing means is configured to be automatically executed when a preset condition is satisfied, or is arbitrarily set by the user at an arbitrary timing (usually immediately before the reading operation). It can be configured to be executed when selected.

  Specifically, when the changing means is changed to a special deceleration speed on the side of increasing the deceleration speed, the moving body decelerates at a speed faster than normal, and the moving distance required for the deceleration is shortened. Therefore, at least the time required for reading is reduced by the shortened amount, and the productivity is improved. Further, in this case, since the required travel distance for the forward path is shortened by the reduction of the required travel distance for deceleration, it is possible to cope with downsizing of the apparatus.

  On the other hand, when the change means is changed to a special deceleration speed on the side to decrease the deceleration speed, the moving body decelerates at a speed slower than normal, and the moving distance required for the deceleration becomes longer, The operation sound of the driving means is reduced by the amount of the deceleration speed, and it becomes possible to cope with quietness.

  The changing means can be configured to change to a special deceleration speed when the original is of a specific original size.

  The specific document size is a size that needs to be set to the special speed or an appropriate size, and can be arbitrarily set. For example, when changing to a special deceleration speed that is faster than normal, the document size is effective for reducing the maximum allowable travel distance on the outbound path, or the size of the original that you want to improve reading productivity. It can be. In addition, when changing to a special deceleration speed slower than the normal time, it is possible to set the document size so that the number of copies to be read is a predetermined amount or more in a use environment where quietness is required.

  In this case, if the document size to be set for the special deceleration speed is set in advance as the operating condition of the changing means or selected immediately before the reading operation, the document to be read becomes the specific document size. The change means changes the deceleration speed of the deceleration area in the forward path to a special deceleration speed. As a result, the corresponding operational effects in the case of each special deceleration speed as described above can be similarly obtained.

  Further, the above-mentioned changing means is not limited to the normal deceleration when the document is of a document size larger than the maximum travelable length of the moving object in the forward path minus the required travel distance at the normal deceleration speed. It can be configured to change to a special deceleration speed increased from the speed.

  The length obtained by subtracting the required travel distance at the normal deceleration speed from the maximum length that can be moved is that when the mobile body decelerates at the normal deceleration speed in the deceleration area during the forward path, the stop position is the movement of the mobile body. This substantially corresponds to the size (length) in the reading direction of the document that is closest to the maximum possible length. In other words, when the moving body decelerates at a speed higher than the normal deceleration speed, the stop position of the moving body is located inside the position where the movable body becomes the maximum movable length.

  In this way, when reading a document having a document size larger than the maximum length obtained by subtracting the required moving distance, the changing unit changes the deceleration speed on the side where the deceleration speed on the forward path is higher than the normal deceleration speed. Therefore, the moving body decelerates at a speed faster than normal, and the moving distance required for the deceleration is shortened. Therefore, in particular, since the maximum movable length can be shortened, it is possible to cope with downsizing of the reading apparatus. In addition, since the moving distance required for the reading at the time of reading the document of the corresponding document size is shortened, at least the time required for reading is reduced by the shortened amount, and the productivity is improved.

  In each reading apparatus as described above, when the power source of the driving means is an electric motor and the changing means changes to a special deceleration speed, the current value supplied to the electric motor is reduced to the normal deceleration. Power supply control means for switching to a current value increased or decreased from the current value at the time of speed can be provided.

  In this power supply control means, when the deceleration speed in the deceleration area in the forward path is changed to a special deceleration speed increased from the normal deceleration speed, it is necessary to increase the torque for controlling the electric motor at a high speed. Therefore, the current value supplied to the electric motor is switched to a current value increased from that in the normal state. On the other hand, when the deceleration speed is changed to a special deceleration speed that is lower than the normal deceleration speed, it is not necessary to increase the torque for controlling the deceleration of the electric motor (it can be reduced in some cases). Therefore, the current value supplied to the electric motor is switched to a current value that is smaller than that at the normal time.

 If this power supply control means is provided, the power consumption will increase when the speed is changed to the special deceleration speed on the side where the deceleration speed has been increased. When the speed is changed to the special deceleration speed on the other side, the power consumption is not increased, and when the reduced current value is applied, the consumption can be suppressed.

In addition, when a document of a standard size (for example, A4 size such as JIS standard) that is used frequently as a document is to be read, the document is reduced by changing to a special deceleration speed on the side that has been reduced than usual. By switching to the current value, it is possible to reduce the load generated between the moving body and the sliding part (for example, a guide rail) during the deceleration. In other words, in general, when an image reading apparatus repeatedly reads a document of the same size, in the vicinity of the acceleration start position or the deceleration start position of the moving body, the sliding portion of the part sliding with the moving body The amount of wear tends to increase compared to other positions. Therefore, when image reading of a standard-size original document that is frequently used as described above is repeated, uneven wear tends to occur near the acceleration / deceleration position of the moving body in the sliding part. For example, the surface of the guide rail In other words, a dent due to uneven wear is created, and the movement of the moving body becomes unstable, and abnormalities (such as line fluctuations) tend to occur in the read image. In this regard, when the current value is changed to the special deceleration speed as described above and switched to a reduced current value, the occurrence of such a problem can be suppressed in advance, and as a result, the image reading apparatus can be used. It is also possible to improve the reliability.

  According to such an image reading apparatus, in particular, the changing means can change the deceleration speed of the deceleration area during the traveling of the moving body by the control means to a special deceleration speed that is increased or decreased from the normal deceleration speed. Therefore, even if there are requests such as an increase in reading speed, a reduction in size of the apparatus, and a reduction in noise, it is possible to respond freely to these requests as necessary.

  FIG. 1 is an explanatory diagram showing a main part of an image reading apparatus according to an embodiment of the present invention. The image reading apparatus 1 is used as an image reading unit of a digital copying machine, for example.

  The image reading apparatus 1 includes a box-shaped housing 10 having an upper surface portion opened, and a platen glass (document platen) 12 on which the document 2 is placed on the upper surface opening of the housing 10 with the document surface facing down. It is installed in place. The image reading apparatus 1 includes the first carriage 20 and the second carriage 25 constituting the reduction imaging optical system and the image information of the document 2 in the internal space of the housing 10 below the platen glass 12. A reading unit 30 for finally reading the image and a driving device 40 for reciprocating the carriages 20 and 30 are installed.

  The first carriage 20 is a full-rate scanning moving body that reciprocates in a sub-scanning direction (arrow directions C and D extending in the left and right directions in the figure) on a guide rail (not shown) in parallel with the platen glass 12. The first carriage 20 mainly includes a lamp (halogen lamp, fluorescent lamp, etc.) 21 that is a light source for illuminating the document surface of the document 2, and reflected light H (from the document 11 illuminated by the lamp 21. A reflecting mirror 23 and the like for reflecting the optical axis) to the second carriage 25 side are mounted.

  The second carriage 25 is a half-rate scanning moving body that reciprocates at a half speed in the same sub-scanning direction in conjunction with the movement of the first carriage 20 on a guide rail (not shown). Mounted on the first carriage 25 are two reflecting mirrors 26 and 27 that reflect and guide the reflected light H from the document 2 reflected by the reflecting mirror 23 toward the reading unit 30.

  The two carriages 20 and 25 are arranged such that the rotational power of an electric motor 41 such as a stepping motor, which is a rotational drive source of the driving device 40, is provided with pulleys and movable pulleys attached to the carriages and the like (not shown) and the pulleys. Each of them is transmitted through a power transmission mechanism that is a combination of wires and the like that are hung and connected in a predetermined relationship, thereby reciprocating in the sub-scanning direction.

  In particular, in this power transmission mechanism, by arranging the pulleys and winding the wires so as to use the principle of the moving pulley, the displacement at the time of movement of the second carriage 25 at the half rate is the first carriage 20 at the full rate. It is comprised so that it may become half of the displacement at the time of movement. Incidentally, the carriages 20 and 25 shown by solid lines in FIG. 1 show the state when they are at their standby reference positions (home positions), and the carriages 20 and 25 shown by two-dot chain lines show the turn-back positions during reciprocating movements (outward path). It shows the state when it is at the stop position.

  The reading unit 30 reflects the reflected light H from the document reflected by the reflecting mirrors 26 and 27 in the second carriage 25 at a predetermined position (a position near the folding position of the carriages 20 and 25) on the bottom surface side of the housing 10. And an imaging element 33 such as a line CCD sensor that reads reflected light H from the original image formed by the imaging lens 32 by photoelectric conversion. Among these, the image sensor 33 is mounted on a circuit board 35 for driving the image sensor 33, and the circuit board 35 is fixed to the housing via a bracket or the like (not shown). The reading unit 30 is covered with a shielding cover 38 that covers a part of the imaging lens 32 that is the reading optical system component and the image sensor 33.

  Such basic image reading by the image reading apparatus 1 is performed as follows.

  First, when the document 2 to be read is placed on the platen glass 12 with the document surface facing downward, the document surface of the document 2 is illuminated by the lamp 21 to thereby move in the main scanning direction (sub-scanning). 1 in the direction perpendicular to the direction of FIG. 1, and the driving device 40 operates to move the first carriage 20 and the second carriage 25 in the direction of arrow C, thereby moving in the sub-scanning direction. A scan is made.

  When this scanning is performed, the reflected light H from the illuminated original 2 is incident on the imaging lens 32 via the mirror 23 and the mirrors 26 and 27, and then the imaging element 32 uses the imaging lens 32. The image is formed on the image pickup surface 33, whereby the image information of the document 11 is electrically read. The document image information (electrical signal) read by the image sensor 33 is transmitted to the image processing unit on the copier body side through the circuit board 35.

  In addition, as shown in FIG. 1, the image reading apparatus 1 automatically feeds a plurality of originals 2 one by one onto the platen glass 12 (reading position) automatically and discharges them automatically. The document conveying device 70 is attached in a state where it can be opened and closed.

  The automatic document feeder 70 is composed of a box-shaped casing 71 having a width that covers at least the platen glass 12, and mainly a document tray for stacking and storing a plurality of documents 2 to be read. Unit 72, a feeding device 73 that feeds documents 2 from the document tray unit 72 toward the platen glass 12 one by one, and the documents 2 fed one by one from the feeding device 73 are carried onto the platen glass 12. Both a belt conveying device 74 for carrying in and discharging the document so as to discharge the document 2 after the reading is completed, and a discharge tray unit 76 for storing the document 2 discharged by the belt conveying device 74 and the discharge roll pair 75, It consists of

  The delivery device 73 is provided with a main conveyance path R1 for appropriately arranging a plurality of pairs of conveyance rolls and feeding the originals 2 on the discharge tray portion 72 one by one as they are. 2 is formed after the reading of the first surface of the plate 2 is reversed and the front and back surfaces are reversed, and then the reversing conveyance path R2 is sent again to the platen glass 12 with the second surface down. ing. Thus, when only one side of the document 2 is read, the document 2 is sent out to the platen glass 12 side through the main transport path R1 of the sending device 73. When reading both sides of the document 2, the document 2 is once sent to the platen glass 12 side through the main transport path R1 of the sending device 73, and the reverse transport path after the reading of the first surface is completed. It returns to R2 and is sent out again to the platen glass 12 side with the front and back surfaces reversed.

  In the image reading apparatus 1 equipped with such an automatic document conveying device 70, the automatic document conveying device 70 automatically conveys a plurality of copies of the document 2 one by one to the reading position of the platen glass 12. Therefore, the image reading as described above is continuously executed.

  Further, the image reading apparatus 1 is equipped with a control device 50 for controlling the driving operation of the electric motor 41 in the driving device 40, as shown in FIGS.

The controller 50, when performing an image reading operation to read the placed image information of the document 2 the reading position of the platen glass 12 at a predetermined timing, the drive control of the electric motor 41 via a Motadora Lee Bas 51 As a result, drive control for performing movement of the carriage 20 (25) in the forward path under a series of speed conditions of acceleration, constant speed, and deceleration, and the electric motor 41 reversely rotated after the stop operation and stop, the carriage 20 ( The driving control for performing the movement on the return path of 25) under a series of speed conditions of acceleration, constant speed, and deceleration is sequentially performed.

  Various control signals are input to the control device 50 from an input unit 15 provided on an operation panel installed on the image reading device 1 or the copying machine side. The command signal is a signal indicating, for example, the size of the document 2, the type of one or both sides of the document 2 and the reading start. Further, the control device 50 includes a sensor 17 that detects the size of the document installed inside the platen glass 12 in the casing 10 of the image reading device 1 or the main transport of the sending device 73 of the document transport device 70. Sensors 77 (for detecting the feed width size) and 78 (for detecting the feed length size) for detecting the document size installed in the path R1 are connected. The control device 50 also receives the size (width and length) of the document 2 to be read from such sensors 17, 77 and 78. Further, the control device 50 is connected to a power supply control unit 55 that controls a drive current (value) applied to the electric motor 41 from a power supply (not shown).

  The main part of such a control device 50 is composed of a microcomputer or the like, reads a control program, a table and data stored in the memory unit, and performs predetermined arithmetic processing in the arithmetic processing unit according to the control program. Then, the motor driver 51 and the like are appropriately controlled. The motor driver 51 includes a pulse divider that finally establishes a motor clock pulse for controlling the driving of the electric motor 41 and an amplifier that amplifies the amplitude of a pulse supplied from the pulse divider.

  The main part of the control device 50 controls the number of motor clock pulses in accordance with the size information of the document 2, and controls the frequency divider that generates the motor clock pulse to be supplied to the pulse divider, thereby adjusting the frequency of the motor clock pulse. Control. The number of motor clock pulses corresponds to the rotation angle of the stepping motor of the electric motor 41, that is, the travel distance of the carriage 20. The frequency of the motor clock pulse corresponds to the rotational speed of the stepping motor, that is, the traveling speed of the carriage 20.

  Therefore, the control device 50 controls the travel distance and speed of the carriage 20 (25) by controlling the number and frequency of the motor clock pulses. Further, the control device 50 transmits a forward / reverse rotation command of the electric motor 41 to the pulse divider of the motor driver 51 depending on whether the carriage 20 (25) travels in the forward path or the backward path during the reciprocating movement. It has become. In the pulse divider of the motor driver 51, for example, when the stepping motor of the electric motor 41 has five phases, the motor clock pulse is divided into five phases.

  FIG. 3 shows a normal control mode for the electric motor 41 at the time of image reading by the control device 50. The relationship (profile) between the carriage moving speed and the elapsed time, the applied current value to the electric motor, and the like. Shows the relationship.

  In other words, when the image reading start command is received, the control device 50 causes a current consisting of a constant current value Ia for acceleration to flow through the electric motor (stepping motor) 41 at time t1, whereby the power of the driving device 4 is transferred to the carriage 20. , 25 and the carriages 20, 25 start the forward movement (movement in the direction of arrow C in FIG. 1). Actually, the movement in the acceleration region during the forward path is started at time t2.

  When the predetermined constant speed (constant speed) region is reached after passing through the acceleration region, the value of the applied current to the electric motor 41 is changed to the constant current for acceleration at time t3 after a specific time has elapsed from the time of reaching the predetermined region. The value Ia is switched to the constant current value Ib for constant speed. While the constant current value Ib is applied, the carriages 20 and 25 move at a constant speed. Further, image reading is performed in this constant speed region. Moreover, the time t3 when the constant current value Ib for constant speed is switched substantially corresponds to the reading start position (a position with an inverted triangle in the figure).

  Subsequently, after the image reading is completed, the current value applied to the electric motor 41 is switched to the constant current value Ic for deceleration at time t4 when deceleration is started. The constant current value Ic at this time is set to a value equal to or greater than the acceleration constant current value Ia. As a result, a deceleration region where the electric motor 41 is stopped is entered. Thereafter, the rotation of the electric motor 41 is stopped at a time t5 when the required time has elapsed.

  After this stop, the order of the current values applied to the electric motor 41 is reversed (however, the current values themselves remain Ic). As a result, the motor 41 starts to rotate in the reverse direction, power in the opposite direction is transmitted to the carriages 20 and 25, and the carriages 20 and 25 start the return path operation (movement in the direction of arrow D in FIG. 1). During the return path operation, the electric motor 41 is continuously applied with the current having the deceleration current value Ic. As a result, the motor 41 finally stops after passing through the acceleration region, the constant speed region, and the low speed region in this return path.

  At this time, since the same current continues to be applied even in the constant speed region, the carriages 20 and 25 move at a higher speed than the moving speed in the forward constant speed region, and thereby the position on the reading start side in a relatively short time. It will return to (Home position). In addition, the applied current is switched from the current value Ib to the current value Ic at the deceleration start time t4 on the forward path, and the current of the current value Ic (≧ Ia) is continuously applied until the deceleration area on the return path is completed. This is to suppress the vibrations of the carriages 20 and 25 that occur between the forward deceleration region and the return acceleration region.

  In the image reading apparatus 1, as shown in FIG. 2, a changing unit 60 that can change the deceleration speed of the deceleration area in the forward path, which is one of the objects to be controlled by the control apparatus 50, to a special deceleration speed. Is equipped.

  The changing means 60 is a “control program for changing to a special deceleration speed (SH) increased from the normal deceleration speed (SN)” or “normal deceleration” as a control program for the forward path of the electric motor 41 in the control device 50. A control program for changing to a special deceleration speed (SL) reduced from the speed (SN) "is prepared, and any one of the control programs can be arbitrarily selected by an input instruction from the input unit 15 by the user. Or can be selected automatically based on predetermined information in advance, or both can be selected.

  When the user can make an arbitrary selection, when the special deceleration speed (SH) on the increase side is selected, the time required for reading is slightly shortened as described above. For example, a selection button or a selection screen having a selection input unit such as “efficiency priority reading mode” is formed. On the other hand, when a special deceleration speed (SL) on the reduced side is selected, the operation sound is reduced as described above. Therefore, a selection input unit such as “silent priority reading mode” is displayed on the operation panel. A selection button or selection screen having

  On the other hand, when automatic selection based on certain information is performed, the size of the original 2 (particularly, the length in the reading direction, the length in the conveyance direction in the case of the automatic document feeder) is set to a specific original size. Is selected and stored in advance in association with a control table or the like in the memory unit of the control device 50, while the sensor 17 can detect the size of the document input to the control device 50 as described above. Based on the detection information from (77, 78) and the input instruction information from the operation panel, it is determined whether or not the document 2 to be read is a document larger than the specific document size. When it becomes clear, the control program is configured so that, for example, a special deceleration speed (SH) on the increasing side is automatically selected.

  Then, the changing means 60, when setting the special deceleration speed (SH) on the side of increasing the deceleration speed in the deceleration area, sets the frequency of the motor clock pulse to the normal deceleration speed (SN) as described above. With respect to the amount of change in the frequency, control is performed so that the main part of the control device 50 operates so as to increase the amount of change, and the current value (Id) applied to the motor 41 is set to a normal deceleration speed (SN ), The operation of the power supply controller 55 is controlled to be larger than the applied current value Ia. On the other hand, when a special deceleration speed (SH) for decreasing the deceleration speed is used, the frequency of the motor clock pulse is changed to the amount of change in the frequency at the normal deceleration speed (SN) as described above. On the other hand, the main part of the control device 50 operates so that the amount of change becomes large, and the value (Ie) of the current applied to the motor 41 is greater than the applied current value Ia at the normal deceleration speed (SN). The operation of the power control unit 55 is controlled so as to decrease.

  Hereinafter, a control mode, operation, and the like at the time of image reading by the control device 50 having such a changing unit 60 will be described with reference to FIGS.

  First, as shown in FIG. 4, when a reading operation start command is received, the control device 50 determines whether or not there is an input for selecting a special deceleration speed from the input unit 15 (step S10). That is, it is determined whether or not the input unit 15 has selected and input the “efficiency priority reading mode” or “silent priority reading mode” as described above.

  Subsequently, the control device 50 obtains information on the size (length in the reading direction) of the document 2 to be read (step S11), and whether the size is a specific document size for which a special deceleration speed should be selected. Is determined (step S12). As the document size information at this time, detection information of the sensor 17 (78) and input information from the input unit 15 are used.

  If there is no input for selecting a special deceleration speed in step S10, and the document size is not a specific document size in step S12, the deceleration speed in the forward path of reading is “normal deceleration speed (SN)”. The control conditions are maintained (step S13).

  On the other hand, when there is an input for selecting a special deceleration speed in step S10, or when the size of the document is a specific document size in step S12, the deceleration speed during the reading forward path is “special deceleration speed (SH, SL) "is changed to the control condition (step S14). Even if it is determined in step S10 that there is an input for selecting a special deceleration speed, if the document size is not a specific document size in step S12, the determination in step 12 is given priority. Thus, the control may be performed so that the control condition is “normal deceleration speed (SN)”.

  Then, after the deceleration speed in the reading forward path is determined as a control condition of either “normal deceleration speed (SN)” or “special deceleration speed (SH, SL)”, the electric motor 41 is driven as a drive source. The driving device 40 is activated and the reciprocating movement of the carriages 20 and 25 is started (step S15). Reading is performed in the constant speed region during the forward path, and image information of the document 2 is obtained (step S16).

  In the deceleration area in the forward path, when the deceleration speed is selected as “normal deceleration speed (SN)”, the current is applied to the motor at the timing as described above and the carriage speed is set. Change. (Figure 3).

  When the deceleration speed is selected as “increase special deceleration speed (SH)”, as shown in FIG. 5, the electric motor 41 is started at time t4 at which deceleration is started after image reading is completed. Is switched to a constant current value Id (> Ic) for deceleration. As a result, the electric motor 41 decelerates at a speed (SH) faster than the normal deceleration speed (SN), and as a result, from time t5 until the electric motor 41 stops at the normal deceleration speed (SN). It stops at an earlier (short) time t6. That is, the moving distance required for the deceleration is shortened. Further, the current (Id) applied to the motor at this time is the timing of time t7 after the motor is stopped, for the reason described above, for the normal deceleration region (respective speed regions during the return path). The current value is switched to Ic (> Ia). Incidentally, even after the time t7, the high deceleration current value Id in the forward path may be continuously applied as it is.

  Further, when the deceleration speed is selected as “special deceleration speed (SL) on the decreasing side”, as shown in FIG. 6, the electric motor is started at time t8 when the deceleration is started after the image reading is completed. The applied current value to 41 is switched to a constant current value Ie (<Ic) for deceleration. As a result, the electric motor 41 decelerates at a speed (SL) slower than the normal deceleration speed (SN), and as a result, the time t5 until the electric motor 41 stops at the normal deceleration speed (SN). Stop at the same time.

  At this time, the deceleration start time t8 is a little earlier than the start time t4 in the case of the normal deceleration speed (SN) from the viewpoint of aligning the motor stop times, and therefore the travel distance required for the deceleration is It is getting longer. For this reason, when the deceleration start time t8 is set to the same time as the start time t4 in the case of the normal deceleration speed (SN), the stop time is later than the normal stop time t5. On the other hand, in any case, when a special deceleration speed (SL) is selected, the deceleration speed of the motor 41 becomes slow, so that the operation sound is reduced accordingly. Further, the current (Ie) applied to the motor at this time is the current value Ic (> Ie and ≧) in the normal deceleration region (each speed region during the return path) at the timing of time t7 after the motor is stopped. Ia).

  Such reciprocation of the carriages 20 and 25 and acquisition of the image information of the original 2 are obtained when all the originals 2 (if the originals to be read are all in the same condition) when there are a plurality of originals 2. ) Is repeated in the same manner until the reading of the original document 2 is completed (step S17), and is completed after the reading of the last document 2 is completed (step S18).

  In this image reading apparatus 1, when the deceleration speed of the carriage in the forward path is changed to “special deceleration speed (SH) on the increasing side”, the moving distance required for the deceleration is shortened as described above ( 5), the time required for reading at least a part of the original is reduced by the shortened amount, and the reading productivity is improved.

Therefore, as illustrated in FIG. 7, for example, when the document 2 to be read is an A4 size (JIS standard) size document and is frequently used, a special deceleration speed (SH) on the increasing side is used. By changing to, it is possible to shorten the time required for reading one unit of the original document, and hence the time required for reading the entire original document, and improve the productivity of the entire reading. Thereby, when selection input of the efficiency priority reading mode is performed, efficient reading is realized by the arbitrary input by the user. Further, in the case where the increasing deceleration speed (SH) is automatically selected when the document 2 is a specific document size, as shown in FIG. When it is determined that the size is larger than a specific document size, efficient reading is always realized. The black inverted triangles in FIG. 8 indicate the deceleration start time for each document size document (the same applies to other drawings).

  Further, when the original 2 to be read is an original of a maximum original size that can be read (for example, 17-inch size), by changing to a special deceleration speed (SH) on the increasing side, when the original reading is decelerated on the forward path Is shorter by a length ΔW than when the required travel distance is a normal deceleration speed (SN). For this reason, since the required moving distance (maximum movable distance) of the carriage 20 in the forward path is shortened by the shortened amount (ΔW), the reading apparatus 1 can be downsized.

  On the other hand, when the deceleration speed of the carriage in the forward direction of the image reading apparatus 1 is changed to “special deceleration speed (SL) on the reduction side”, the moving distance required for the deceleration becomes longer as described above. However, since the deceleration speed of the motor 41 is slowed down (FIG. 6), the operation sound of the motor is reduced by that slowing down, and quietness at the time of reading is realized.

Therefore, as illustrated in FIG. 7, for example, when the document 2 to be read is an A4 size (JIS standard) size document and is frequently used, a special deceleration speed (SL) on the decreasing side is used. Although the productivity of the entire reading of the original document is lowered by changing to the above, it is possible to reduce the operation sound during the forward reading of each original document. Thereby, when the selection input of the silent priority reading mode is performed, the operation sound is quietly read by the arbitrary input by the user. In addition, when the document 2 is a specific document size or when the number of copies of the document 2 is a specific number, the decreasing deceleration speed (SL) is automatically selected. Good.

  Incidentally, the selection change to the deceleration speed (SL) on the decreasing side cannot be adopted in the case of a document having a large document size because the carriage 20 cannot stop at the maximum movable point. When the document to be read has a document size that cannot be changed, the selection to the deceleration speed (SL) may not be changed.

[Modification]
As shown in FIG. 9, the image reading apparatus 1 according to this embodiment is closest to a point where the maximum movable length (SE) of the carriage 20 in the forward path is reached in order to reduce the size of the apparatus 1. When a certain component 18A is arranged in such a state that it enters the inside of the forward path by a distance ΔJ (position of the component indicated by reference numeral 18), and its maximum movable length (SE) must be shortened. Can be configured as follows.

  That is, a length (SE-DL) obtained by subtracting a required movement distance (DL) of the carriage 20 at a normal deceleration speed (SN) from the maximum movable length (SE) is set as a specific document size. When the document 2 to be read has a document size larger than the reduced length (SE-DL), a special deceleration speed (SH) for increasing the deceleration speed in the forward path is set (automatically). Configure to change.

  In this case, when the document 2 has a document size equal to or larger than the reduced length (SE-DL), the carriage 20 is decelerated at a speed higher than the normal deceleration speed (SN), and the deceleration is performed. The moving distance required for the operation is shortened, and the vehicle can be stopped reliably before the maximum movable length (SE). The carriage 20 that decelerates and stops during the forward path does not collide with the component 18 arranged in the vicinity. As a result, since the maximum movable length (SE) can be shortened, it is possible to cope with downsizing of the reading apparatus 1. Moreover, since the moving distance required for deceleration when reading a document of the corresponding document size is shortened, at least the time required for scanning can be reduced by that shortening, and the productivity of the reading can be improved. become.

It is explanatory drawing which shows the principal part of the image reading apparatus of this invention. It is a block diagram which shows the main structures of the control system of the drive device of a carriage. It is explanatory drawing which shows the relationship between the speed profile with respect to the elapsed time of a carriage, and the applied current value to an electric motor when the normal deceleration speed is set as the deceleration speed at the time of an outward path. It is a flowchart which shows the flow of the control system in a reading operation | movement, and each operation | movement. It is explanatory drawing which shows the relationship between the speed profile with respect to the elapsed time of a carriage, and the applied electric current value to an electric motor when the special deceleration speed of the increase side is set. It is explanatory drawing which shows the relationship between the speed profile with respect to the elapsed time of a carriage, and the applied electric current value to an electric motor when the special deceleration speed of the side to reduce is set. It is explanatory drawing which shows the relationship between the document size and the state of the speed profile of a carriage when each speed is set as the deceleration speed at the time of an outward path. FIG. 6 is an explanatory diagram showing the state of each speed profile of a carriage when a special deceleration speed on the side to be increased is automatically selected when a document is a specific document size or larger. When the document is automatically selected as a special deceleration speed on the side that increases when the document size is longer than the maximum travel distance minus the required distance at the normal deceleration speed, each speed profile of the carriage It is explanatory drawing which shows a state.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image reading apparatus, 2 ... Original, 5 ... Drive shaft, 12 ... Platen glass (original plate), 20, 25 ... Carriage (moving body), 21 ... Illumination lamp (one component of reading means), 23 ... Reflection Mirror (one component of reading means), 33 ... imaging element (reading means), 40 ... drive device, 41 ... electric motor, 50 ... control device (part of control means), 51 ... motor driver (one of control means) Part), 55 ... power supply control part, 60 ... changing means, C, D ... sub-scanning direction (constant direction), SN ... normal deceleration speed, SH ... special deceleration speed on the increase side, SL ... reduction side Special deceleration speed.

Claims (2)

Reading means for reading image information of a document placed on a document table;
A driving device for reciprocating a moving body on which at least one component of the components of the reading unit is mounted along a certain direction of the document;
Control means for controlling the movement of the moving body by the drive device at least in the forward path under acceleration, constant speed and deceleration speed conditions;
Change means for changing the deceleration speed of the deceleration area in the forward path of the moving body by this control means to a special deceleration speed that is increased or decreased from the normal deceleration speed ;
Selecting means for selecting a silent priority reading mode for reducing the operation sound by changing to a special deceleration speed reduced from the normal deceleration speed by the changing means ,
The control means, when the silent priority read mode is selected by the selection means, the change when the original is a document size that cannot stop the moving body at the maximum movable position at the reduced special deceleration speed. An image reading apparatus characterized in that a change to the reduced special deceleration speed by means is made impossible . The changing means is configured such that when the document has a document size that is equal to or longer than a length obtained by subtracting a required moving distance at a normal deceleration speed from a maximum length that the movable body can move on the forward path of the moving body , the change speed is higher than the normal deceleration speed. The image reading device according to claim 1, wherein the image reading device is changed to an increased special deceleration speed.

Images