JP2006261899A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader of a light source moving type wherein the circuit configuration and a communication path can be simplified. <P>SOLUTION: The image reader includes: a transparent original platen whereon an original is placed; a carriage mounted with an optical system for allowing an image sensor to form an image of a part region of the original; a first drive section for reciprocating the carriage on a platen face of the original platen in parallel; a light source provided on an option unit and for emitting light to the part region of the original; a second drive section for reciprocating the light source in parallel with the platen face of the original platen; a control means for outputting a first drive signal of the first drive section parts of bits of which are in common to those of a second drive signal of the second drive section, and a stop state control signal parts bit of which are equal to a stop signal of the first and second drive sections and parts of the remaining bits of which are equal to a light source control signal for controlling the light source at the drive of the first and second drive sections to same parallel signal lines; a latch circuit for latching the remaining bits of the stop state control signal during the driving; and a serial communication unit electrically connected to the parallel signal lines and the option unit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus.

2. Description of the Related Art Conventionally, an image reading apparatus that moves a light source that illuminates a transparent original in conjunction with movement of an image sensor, a so-called light source moving type image reading apparatus is known. In such a light source moving type image reading apparatus, the main scanning line of the image sensor can be illuminated with light with less unevenness in light quantity, so that the image quality of the read image can be improved.
However, since the light source moving type image reading apparatus controls both the movement of the image sensor and the light source, the circuit configuration of the light source moving type image reading apparatus is more complicated than that of the fixed light source type image reading apparatus. There is a problem of doing. Further, since the light source moving type image reading apparatus includes a drive unit for moving the light source in the transmission original unit, there is a problem that a communication line connecting the main body of the image reading apparatus and the transmission original unit becomes complicated.

  The present invention has been made in view of the above problems, and an object thereof is to provide a light source moving type image reading apparatus capable of simplifying a circuit configuration and a communication path.

(1) An image reading apparatus for achieving the above object connects a transparent document table on which a document is placed, an image sensor, and a partial region of the document placed on the document table to the image sensor. A carriage having an optical system for imaging, a first drive unit for reciprocating the carriage in parallel with the platen surface of the document table, an option unit, and the option unit provided on the document table and placed on the document table A light source that illuminates a partial area of the document; a second drive unit that reciprocates the light source in parallel with the platen surface of the document table; and a bit that is common to the second drive signal of the second drive unit The first drive signal of the first drive unit, the partial bits are stop signals of the first drive unit and the second drive unit, and at least some of the remaining bits are the first drive unit and the second drive unit. The light source when driving Control means for outputting a control signal at the time of stop, which is a light source control signal to be controlled, to the same parallel signal line, and the remaining bits of the control signal at the time of stop while driving the first drive unit and the second drive unit And a serial communication unit that is electrically connected to the parallel signal line and the option unit.
In general, in a light source moving type image reading apparatus, a light source follows the movement of a carriage on which an optical system is mounted so that an original on a main scanning line of an image sensor can be illuminated by the light source. Therefore, common information is included in the signal for controlling the movement of the carriage and the signal for controlling the movement of the light source. Accordingly, in the first aspect of the invention, paying attention to this point, a part of the first drive signal for moving the carriage and the second drive signal for moving the light source are shared. If it does in this way, a control means can control a 1st drive part and a 2nd drive part by one channel. Therefore, according to the first aspect of the present invention, the configuration of the control means can be simplified as compared with the control means for a plurality of channels.
In general, the illumination range of the light source is wider than the main scanning line of the image sensor. Therefore, if the image sensor main scanning line can be illuminated with a light source and the image quality of an image read under the illumination conditions is within the specification range, the light source does not have to be positioned more strictly than the carriage. That is, the movement of the light source can be controlled with a control signal having a smaller amount of information compared to the control signal for controlling the movement of the carriage. In the first aspect of the invention, paying attention to this point, some bits and the second drive signal are made common instead of all the bits of the first drive signal. Then, at least a part of the remaining bits of the stop control signal is used as the light source control signal. That is, in the first aspect of the invention, the parallel signal line is used as the signal line for transmitting the signal (the first drive signal and the stop signal) for controlling the first drive unit, while the second drive unit is controlled. It is also used as a signal line for transmitting two types of control signals, a signal to be transmitted (second drive signal and stop signal) and a signal to control the light source (light source control signal). Therefore, according to the first aspect of the present invention, it is possible to reduce signal lines for transmitting the light source control signal.
However, the remaining bits of the first drive signal corresponding to the light source control signal are signals for controlling the first drive unit, not for controlling the light source. Therefore, when a signal line for transmitting a light source control signal is connected to the light source, the light source malfunctions when the control means outputs the first drive signal. Therefore, in the first aspect of the present invention, the latch circuit holds the remaining bits of the control signal at the time of stoppage while the first drive unit and the second drive unit are being driven, that is, when the first drive signal is being output. In this way, even when the control means outputs the first drive signal, the light source control signal held by the latch circuit is input to the light source. Therefore, according to the first aspect of the present invention, the first drive unit and the second drive unit can be controlled by one channel of the control means without causing the light source to malfunction, and the configuration of the control means can be simplified.
According to the first aspect of the present invention, the serial communication unit is connected to the parallel signal line and the option unit. That is, the serial communication unit transmits the first drive signal transmitted through the parallel signal line and the stop control signal to the option unit by serial communication. Therefore, according to the first aspect of the invention, the communication line for transmitting the first drive signal and the stop time control signal to the option unit can be simplified.

(2) A position detection circuit that is provided in the option unit and outputs a position signal that changes depending on whether or not the light source is located at a standby position to the control unit may be further provided.
According to the second aspect of the invention, since the position detection circuit outputs a position signal to the control unit, the control unit can recognize from the position signal whether the light source is located at the standby position.

(3) An identification signal output circuit provided in the option unit and outputting an identification signal specific to the type of the option unit to the control unit may be further provided.
According to the invention described in claim 3, since the identification signal output circuit outputs the identification signal to the control unit, the control unit can recognize the type of the option unit from the identification signal. Therefore, according to the second aspect of the present invention, the control unit can appropriately control the option units connected according to the type of option unit.

(4) A part of the remaining bits of the stop-time control signal is a selection signal that causes the position detection circuit or the identification signal output circuit to output either the position information or the identification signal, and the position detection The circuit and the identification signal output circuit may output the position information and the identification information to the same serial signal line according to the selection signal, respectively.
According to the fourth aspect of the present invention, the position detection circuit and the identification signal output circuit respectively transmit the position information and the identification information to the control unit in order to output the position information and the identification information to the same serial signal line. The number of signal lines can be reduced

The functions of the plurality of means provided in the present invention are realized by hardware resources whose functions are specified by the configuration itself, hardware resources whose functions are specified by a program, or a combination thereof. The functions of the plurality of means are not limited to those realized by hardware resources that are physically independent of each other.
The present invention can be specified not only as an apparatus invention but also as a program invention, a recording medium recording the program, and a method invention.

Hereinafter, an embodiment of the present invention will be described based on an example.
(Example)
FIG. 2 is a schematic diagram showing a scanner 1 according to an embodiment of the present invention.

  The scanner 1 includes a scanner main body 2 and a transparent original unit 4 connected to the scanner main body 2 with a cable 6, and moves the transparent original light source 24 to read the transparent original 10 placed on the surface of the original table 8. This is a light source moving type image reading apparatus. The document table 8 is a transparent plate such as a glass plate and is locked to the upper portion of the scanner body 2. The scanner 1 can be connected to a scanner body 2 with a document cover for a reflected document and an automatic document feeder (hereinafter referred to as an ADF unit) instead of the transparent document unit 4 as an optional unit. At this time, the ADF unit is connected to the scanner main body 2 by the cable 6 similarly to the transparent original unit 4. The scanner 1 can also read a reflection original by connecting a document cover or ADF unit for the reflection original to the scanner body 2. The image reading apparatus may be a scanner that can read only a transparent original. The image reading apparatus may be a multifunction machine, a copying machine, a facsimile machine having a copying function, or the like.

FIG. 1 is a block diagram of the scanner 1. In FIG. 1, the interface unit 56 is abbreviated as an IF unit, and the first motor 52 and the second motor 68 are abbreviated as M.
The image sensor 12 includes a CCD linear image sensor, a CMOS linear image sensor, or the like that includes a group of photoelectric conversion elements arranged in a straight line. The image sensor 12 photoelectrically converts light in a predetermined wavelength region such as light in the visible region (hereinafter referred to as visible light) and light in the infrared region (hereinafter referred to as infrared light) by each photoelectric conversion element. An electrical signal correlating with the density of the image on the scanning line is output. Although a lens reduction type image sensor has been exemplified, the image sensor 12 may be a contact type image sensor.

The reflection original light source 18 is constituted by a tube illumination device using a xenon lamp or the like, and the longitudinal axis is arranged in a posture parallel to the main scanning line of the image sensor 12. The reflected document light source 18 emits visible light to illuminate the reflected document placed on the document table 8 from below the document table 8 (see FIG. 2). The light source 18 for the reflection original may be a lighting device including a light emitting diode and a light guide that uniformly spreads light emitted from the light emitting diode in a direction parallel to the main scanning line.
The mirror 16 and the lens 14 are an optical image of a reflection original that is emitted from the light source 18 for the reflection original and reflected by the reflection original, or a transmission original that is emitted from the light source 24 or the infrared light source 26 described later and is transmitted through the transmission original 10. Ten optical images are formed on the light receiving surface of the image sensor 12. The mirror 16 and the lens 14 correspond to an “optical system” recited in the claims.
A sensor carriage 20 as a carriage is slidable on a guide rod 22 extending in a direction (hereinafter referred to as a sub-scanning direction) parallel to the surface of the document table 8 and perpendicular to the main scanning line of the image sensor 12. It is mated. The sensor carriage 20 accommodates the image sensor 12, the mirror 16, and the lens 14, and has a reflection original light source 18 mounted thereon.

  The first drive unit 50 drives the first motor 52 under the control of the control unit 40. Specifically, the first drive unit 50 performs the A channel phase control signal, the A channel current control signal, the B channel phase control signal, the B channel current control signal, and the A channel current shown in FIG. It is controlled by an attenuation rate setting signal, a B channel current attenuation rate setting signal, and a torque setting signal. Here, the phase control signal of each channel is a signal for controlling the rotation direction of the motor connected to each channel, and the current control signal of each channel is the rotation angle of the motor connected to each channel. The current attenuation rate setting signal for each channel is a signal for setting the load current attenuation rate for controlling the motor connected to each channel, and the torque setting signal is It is a signal for setting the torque of the motor.

  Since the phase control signal of each channel and the current control signal of each channel are signals that control the rotation of the motor, their signal levels are controlled to change over time when the motor is driven, and controlled to a predetermined fixed value when the motor is stopped. Is done. On the other hand, since the current attenuation rate setting signal and torque setting signal of each channel are signals for setting the drive mode, their signal levels are controlled to predetermined fixed values indicating the drive mode at that time when the motor is driven. Thus, no matter what value is controlled when the motor is stopped, the operation of the stopped motor is not affected. The first drive unit 50 is connected to the controller 48 by 16 first signal line groups 100.

  When the first motor 52 is rotated by being driven by the first drive unit 50, the sensor carriage 20 is pulled by a belt hung on a pulley (not shown) by the rotation of the first motor 52, and the sensor carriage 20 is moved in the sub-scanning direction (arrow shown in FIG. (See X, Y). As a result, the main scanning line of the image sensor 12 moves in the sub-scanning direction. The first motor 52 is a stepping motor and can accurately position the main scanning line of the image sensor 12. The image reading apparatus may be a mirror moving type scanner that moves the main scanning line in the sub-scanning direction by fixing the positions of the image sensor and the lens with respect to the document table and moving a plurality of mirrors in conjunction with each other.

The analog front end (AFE) 36 has functions such as noise removal by CDS (correlated double sampling), amplification, A / D conversion, and the like.
The image processing unit 38 is an ASIC having functions such as gamma correction, sharpening processing, moire removal processing, shading correction, defective pixel interpolation, and white balance correction. These functions may be realized by software executed by the control unit 40 or may be realized by an external system such as a personal computer (PC) 11.
The interface unit 56 connects an external system such as the PC 11 and the scanner 1 so that they can communicate with each other. Accordingly, the scanner 1 can be controlled by the PC 11 and the read image can be transmitted to the external system.

  The control unit 40 as a control unit includes a CPU 42, a ROM 46, a RAM 46, and a controller 48. The CPU 42 executes programs stored in the ROM 46 to control each unit of the scanner 1. The ROM 46 is a non-volatile memory that stores various programs and various data, and the RAM 46 is a memory that temporarily stores various programs and various data. The controller 48 is connected to the first drive unit 50 and the parallel / serial conversion circuit 54 by 16 first signal line groups 100 as parallel signal lines, and the first drive unit 50 and the transparent original unit 4 of the scanner body 2. 2nd drive part 66 grade | etc., Is controlled. The function of the controller 48 may be realized by the control unit 40 and a program executed by the control unit 40. The number of the first signal line group 100 is not limited to 16 and may be any number.

The parallel / serial conversion circuit 54 converts the parallel signal transmitted by the first signal line group 100 into a serial signal under the control of the control unit 40, and converts the converted serial signal via the connector 32, the cable 6, and the connector 34. Is transmitted to the transparent original unit 4.
The serial / parallel conversion circuit 58 receives the serial signal transmitted by the parallel / serial conversion circuit 54 under the control of the control unit 40, and converts the received serial signal into a parallel signal. As described above, the parallel / serial conversion circuit 54 and the serial / parallel conversion circuit 58 cooperate with each other under the control of the control unit 40 to connect the scanner body 2 and the transparent original unit 4 by serial communication. The number of terminals of the connector 34 and the number of cables 6 can be reduced. The parallel / serial conversion circuit 54, the connector 32, the cable 6, the connector 34, and the serial / parallel conversion circuit 58 correspond to the “serial communication unit” recited in the claims. Hereinafter, these are referred to as serial communication units.

The latch circuit 60 is connected to the serial / parallel conversion circuit 58 through the six second signal line groups 102 and holds signals transmitted by the second signal line group 102 at a predetermined timing.
The transmissive original light source 24 is connected to the latch circuit 60 by a single signal line. The transmissive original light source 24 is constituted by a tube illuminating device using a xenon lamp or the like, and the longitudinal axis is arranged in a posture parallel to the main scanning line of the image sensor 12. The light source 24 for the transmissive document emits visible light to illuminate a predetermined illumination range of the transmissive document 10 placed on the document table 8 from above the document table 8 (see FIG. 2). The transmissive original light source 24 may be an illumination device including a light emitting diode and a light guide that uniformly spreads light emitted from the light emitting diode in the sub-scanning direction.

The infrared light source 26 is connected to the latch circuit 60 by one signal line. The infrared light source 26 emits infrared light to illuminate a predetermined illumination range of the transparent document 10 placed on the document table 8 from above the document table 8 (see FIG. 2). Here, the infrared rays are transmitted through the transparent original 10 regardless of the image recorded on the transparent original 10, but if the transparent original 10 is scratched or dust is attached, the transmittance changes due to the scratch or dust. . Therefore, the scanner 1 can recognize the scratches on the transparent original 10 and the dust attached to the transparent original 10 by reading the transparent original 10 illuminated by the infrared light source 26. Thus, when the scanner 1 reads the transparent original 10 illuminated by the light source 18 for transparent originals, the scanner 1 can remove the influence of recognized scratches and dust by image processing.
The light source carriage 28 is mounted with a transmissive original light source 24 and an infrared light source 26, and is slidably fitted to a guide rod 22 extending in the sub-scanning direction (see FIG. 2).

The second drive unit 66 drives the second motor 68 under the control of the control unit 40. Specifically, the second drive unit 66 generates the A channel phase control signal, the A channel current control signal, the B channel phase control signal, the B channel current control signal, and the A channel current shown in FIG. It is controlled by an attenuation rate setting signal, a B channel current attenuation rate setting signal, and a torque setting signal. The functions of these signals are substantially the same as the functions of the signals for controlling the first drive unit 50 described above. The second drive unit 66 is connected to the serial / parallel conversion circuit 58 by ten third signal line groups 104.
When the second motor 68 is rotated by being driven by the second drive unit 66, the light source carriage 28 is pulled by the belt hung on the pulley by the rotation of the second motor 68, and the light source carriage 28 is moved in the sub-scanning direction (arrow X, FIG. (See Y). As a result, the illumination range of the transmissive original light source 24 moves in the sub-scanning direction. The second motor 68 is a stepping motor and can accurately position the illumination range of the light source 24 for transmissive originals.

  The home sensor circuit 62 is connected to the latch circuit 60 by one signal line. The home sensor circuit 62 serving as a position detection circuit outputs a home sensor signal indicating whether or not the light source carriage 28 is in the standby position to one signal line 106. Specifically, for example, the home sensor circuit 62 includes a photo interrupter 200 having a light emitting diode 202 and a phototransistor 204 that detects light emitted from the light emitting diode 202 and a pull-up resistor 206 as shown in FIG. it can. When such a circuit is used as the home sensor circuit 62, a part of the light source carriage 28 may be configured to shield light emitted from the light emitting diode 202 at the standby position. The control unit 40 can recognize whether or not the light source carriage 28 is in the standby position based on the home sensor signal.

  The ID output circuit 64 is connected to the latch circuit 60 by one signal line. An ID output circuit 64 serving as an identification signal output circuit outputs an option ID signal indicating whether or not the option unit connected to the scanner body 2 is the transparent original unit 4 to one signal line 106. Specifically, for example, the ID output circuit 64 that outputs an option ID signal indicating the unit number “0000” of the transparent original unit 4 can be configured by a transistor 212 as shown in FIG. This circuit outputs a low level when an ID request signal described later is at a high level. When the controller 48 outputs the ID request signal four times to the ID output circuit 64, four low level outputs, that is, the unit number “0000” is output from the ID output circuit 64. Here, a circuit corresponding to the ID output circuit 64 is also mounted in another option unit (for example, an ADF unit) connected to the scanner body 2. Therefore, the control unit 40 can recognize the type of the option unit from the option ID signal and appropriately control the connected option unit according to the recognition result.

  It has been described that the unit number of the transparent document unit 4 is “0000” composed of four “0” s. However, the unit number of the transparent original unit 4 may be “0” composed of one “0” or a plurality of “0” in the circuit illustrated in FIG. It may be a number. At that time, the controller 48 may output a high-level ID request signal for the number of times corresponding to the number of “0” s constituting the unit number to the circuit shown in FIG.

FIG. 5 is a diagram for explaining a drive control signal output to the signal line group 100 by the controller 48 when the motor is driven and a stop control signal output to the signal line group 100 by the controller 48 when the motor is stopped. (A) shows a control signal at the time of driving (indicated as A (15: 0) in the drawing), and (B) shows a control signal at the time of stopping (indicated as B (15: 0) in the drawing). Yes.
As shown in FIG. 5A, in the scanner 1, a signal for controlling the first drive unit 50 (first drive signal and stop signal) and a signal for controlling the second drive unit 66 (second drive signal and stop signal). And is common. In the scanner 1, in order to cause the light source carriage 28 to follow the movement of the sensor carriage 20 so that the original on the main scanning line of the image sensor 12 can be illuminated by the light source 24 for transmissive originals, The signal for controlling the two driving units 66 includes common information. Specifically, in the scanner 1, all bits of a signal output from the controller 48 to the first signal line group 100 (hereinafter referred to as an output signal of the controller 48) are used as signals for controlling the first drive unit 50. The 6th to 15th bits of the output signal are used as signals for controlling the second drive unit 66.

  Further, as shown in FIG. 5B, the scanner 1 uses a bit that is not used as the second drive signal of the output signal of the controller 48 as an option control signal. Here, the option control signal is a signal for controlling the latch circuit 60, the infrared light source 26, the transmissive original light source 24, the ID output circuit 64, and the home sensor circuit 62. In the scanner 1, the illumination range of the transmissive original light source 24 is wider than the main scanning line of the image sensor 12. Therefore, if the image sensor 12 main scanning line can be illuminated by the light source 24 for the transmissive document and the image quality of the image read under the illumination condition is within the specification range, the light source carriage 28 is positioned more strictly than the sensor carriage 20. It does not have to be. Therefore, the movement of the light source carriage 28 can be controlled with a signal having a small amount of information as compared with the signal for controlling the movement of the sensor carriage 20. Specifically, as shown in FIG. 5, the number of bits of the signal that controls the second drive unit 66 is 10 bits, which is smaller than 16 bits that is the number of bits of the signal that controls the first drive unit 50.

  Further, as described above, some bits of the signal for controlling the first drive unit 50 may be controlled to any value when the motor is stopped, and these bit values affect the operation of the stopped motor. (See FIG. 4 (A)). Therefore, in the scanner 1, a bit that is not used as the second drive signal of the output signal of the controller 48 and can be controlled to an arbitrary value when the motor is stopped is used as an option control signal when the motor is stopped. Specifically, as shown in FIG. 5B, the scanner 1 uses the 0th to 5th bits of the output signal of the controller 48 as an option control signal.

  However, a bit that is not used as the second drive signal of the output signal of the controller 48 is used as a first drive signal for controlling the first drive unit 50 when the motor is driven. Specifically, the 0th to 5th bits of the output signal of the controller 48 are used as a current attenuation rate setting signal for each channel and a torque setting signal for each channel. Therefore, bits that are not used as the second drive signal of the output signal of the controller 48 (indicated as A (15: 6) in the drawing) are the infrared light source 26, the transmissive original light source 24, the ID output circuit 64, the home When input to the sensor circuit 62, these circuits malfunction when the motor is driven.

  Therefore, the scanner 1 holds an option control signal when the motor is stopped, and inputs the option control signal held when the motor is driven to the infrared light source 26, the transmission original light source 24, the ID output circuit 64, and the home sensor circuit 62. Here, the infrared light source 26, the transmissive original light source 24, the ID output circuit 64, and the home sensor circuit 62 are circuits that are dynamically controlled only when the motor is stopped, as will be described later. Therefore, when the motor is stopped, the scanner 1 controls the infrared light source 26, the transmissive original light source 24, the ID output circuit 64, and the home sensor circuit 62 by the option control signal output by the control unit 40 at that time to drive the motor. Sometimes, these circuits are controlled by option control signals held when the motor is stopped. Specifically, in the scanner 1, a latch control signal described later is assigned to 1 bit of the option control signal, and the latch control signal holds the option control signal signal when the motor is stopped by the latch control signal. More specifically, the control unit 40 changes the latch signal from the low level to the high level in the option control signal signal when the motor is stopped, and the latch circuit 60 holds the option control signal when the latch control signal rises. In the scanner 1, the output of the latch circuit 60 is input to the infrared light source 26, the transmissive original light source 24, the ID output circuit 64, and the home sensor circuit 62. As a result, the infrared light source 26, the transmissive original light source 24, the ID output circuit 64, and the home sensor circuit 62 can be dynamically controlled when the motor is stopped, without malfunctioning the motor.

  As described above, in the scanner 1, the signal for controlling the first drive unit 50 and the signal for controlling the second drive unit 66 are shared, and bits that are not used as the second drive signal of the output signal of the controller 48 are set. Used as an option control signal. Accordingly, in the scanner 1, the first output unit 50, the second drive unit 66, the latch circuit 60, the infrared light source 26, and the transmissive original light source 24 are signals output from the controller 48 to the 16 first signal line groups 100. The ID output circuit 64 and the home sensor circuit 62 can be controlled.

  The circuit that is not used as the second drive signal of the output signal of the controller 48 and is controlled by a bit that can be controlled to an arbitrary value when the motor is stopped may be a circuit that is controlled only when the motor is stopped. The illustrated infrared light source 26, transmissive original light source 24, ID output circuit 64, and home sensor circuit 62 are not limited thereto. Further, the number of bits of a signal transmitted by serial communication may be increased, and the option control signal may be assigned to a bit different from the signal for controlling the first drive unit 50 and the second drive unit 66 of the signal. In this case, the serial / parallel conversion circuit 58 and the infrared light source 26, the transmissive original light source 24, the ID output circuit 64, and the home sensor circuit 62 can be connected without the latch circuit 60, respectively.

The 0th to 4th bits of the option control signal are a home sensor output request signal, an ID request signal, an infrared light source control signal, a transmissive original light source control signal, and a latch control signal, respectively.
The transparent document light source control signal as the light source control signal is a signal for turning on or off the over-document light source 24. The infrared light source control signal is a signal for turning on or off the infrared light source 26. The latch control signal is a signal for controlling the timing at which the latch circuit 60 holds the home sensor output request signal, the ID request signal, the infrared light source control signal, and the transmissive original light source control signal.

FIG. 3 is a circuit diagram showing the home sensor circuit 62 and the ID output circuit 64 described above. The home sensor circuit 62 and the ID output circuit 64 are controlled by a home sensor output request signal and an ID request signal.
In the scanner 1, any one of a plurality of circuits that generate one type of signal on the same signal line among a plurality of types of 1-bit signals that are exclusively required in time. Is output. Specifically, in the scanner 1, one of the home sensor signal and the option ID signal is output to one of the home sensor circuit 62 and the ID output circuit 64 on the same signal line 106. Yes. The signal line 106 is a so-called RXD signal line for serial communication. The option ID signal is a signal for recognizing the option unit connected to the scanner body 2 as described above, and the home sensor signal is a signal indicating whether or not the light source carriage 28 is in the standby position as described above. It is. Therefore, the option ID signal is requested only when the scanner 1 is initialized, and the home sensor signal is requested after the scanner 1 is initialized. That is, the home sensor signal and the option ID signal are signals that are exclusively requested in terms of time.

  More specifically, in the home sensor circuit 62, as shown in FIG. 3, when the home sensor output request signal is at a high level and the ID request signal is at a low level, the output of the photo interrupter 200 is valid. At this time, the home sensor circuit 62 outputs the above-described home sensor signal to the signal line 106. The ID output circuit 64 outputs a low level option ID signal to the signal line 106 when the home sensor output request signal is at a low level and the ID request signal is at a high level. Therefore, the scanner 1 outputs the low level home sensor output request signal and the high level ID request signal for the number of times corresponding to the number of “0” s constituting the unit number of the transparent original unit 4 as described above. The transparent original unit 4 can be distinguished from other optional units.

  In this way, in the scanner 1, either the home sensor signal or the option ID signal is output to the same signal line 106 to either the home sensor circuit 62 or the ID output circuit 64. Therefore, according to the scanner 1, one type of signal among a plurality of types of 1-bit signals that are exclusively required in terms of time is applied to any one of a plurality of circuits that generate those signals on the same signal line. In order to output, the circuit for transmitting these signals can be simplified. The home sensor output request signal and the ID request signal correspond to a “selection signal” recited in the claims, and the signal line 106 corresponds to a “serial signal line”. The selection signal may be a 1-bit signal or a 3-bit or more signal.

FIG. 6 is a timing chart for explaining the operation of the scanner 1 in a state in which the drive control signal or the stop control signal is output.
When the controller 48 outputs a stop control signal to the first signal line group 100, the stop signal is transmitted to the first drive unit 50 via the first signal line group 100, and the first signal line group 100, serial communication. The signal is transmitted to the second drive unit 66 through the module and the third signal line group 104. The first drive unit 50 and the second drive unit 66 stop the movement of the sensor carriage 20 and the movement of the light source carriage 28, respectively, according to the stop signal.

  The option control signal is transmitted to the latch circuit 60 via the serial communication module and the second signal line group 102. The latch circuit 60 transmits a transmissive document light source control signal, an infrared light source control signal, a home sensor output request signal, and an ID request signal corresponding to the input option control signal to the transmissive document light source 24 and the infrared light source 26, respectively. And output to the home sensor circuit 62 and the ID output circuit 64. At this time, the option control signal is also transmitted to the first drive unit 50, but the first drive unit 50 is stopped by the stop signal, so that it does not malfunction.

  On the other hand, when the controller 48 outputs the drive control signal to the first signal line group 100, the first drive signal is transmitted to the first drive unit 50 through the first signal line group 100, and the second drive signal is The signal is transmitted to the second drive unit 66 via the first signal line group 100, the serial communication module, and the third signal line group 104. The first drive unit 50 and the second drive unit 66 move the sensor carriage 20 and the light source carriage 28, respectively, according to the first drive signal and the second drive signal, respectively.

  At this time, the remaining bits (0th to 5th bits) of the drive control signal are also transmitted to the latch circuit 60. However, the controller 48 causes the latch circuit 60 to hold the option control signal at the time of stopping the motor by the latch control signal of the stop time control signal immediately before outputting the drive time control signal. For this reason, the transmissive original light source 24, the infrared light source 26, the home sensor circuit 62, and the ID output circuit 64 are respectively provided with a transparent original light source control signal and an infrared light source control signal held by the latch circuit 60 when the motor is stopped. Since the home sensor output request signal and the ID request signal are input, these circuits do not malfunction.

1 is a block diagram of a scanner according to an embodiment. 1 is a schematic diagram of a scanner according to one embodiment. FIG. The circuit diagram of the home sensor circuit and ID signal output circuit which concern on one Example. (A) is a schematic diagram for demonstrating the signal for controlling a 1st drive part. (B) is a schematic diagram for demonstrating the signal for controlling a 2nd drive part. The schematic diagram for demonstrating the drive time control signal and stop time control signal which concern on one Example. The timing chart for demonstrating the action | operation of the scanner which concerns on one Example. The schematic diagram for demonstrating the position request signal and ID request signal which concern on one Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Scanner (image reading apparatus), 2 Scanner main body, 4 Transparent original unit (option unit), 6 Cable (serial communication unit), 8 Original stand, 10 Transparent original (original), 12 Image sensor, 14 Lens (optical system) , 16 mirror (optical system), 20 sensor carriage (carriage), 24 light source (transmission light source), 32 connector (serial communication unit), 34 connector (serial communication unit), 40 control unit (control means), 48 controller (Control means), 50 first drive unit, 54 parallel / serial conversion circuit (serial communication unit), 56 interface unit, 58 serial / parallel conversion circuit (serial communication unit), 60 latch circuit, 62 home sensor circuit (position detection) Circuit), 64 ID output circuit (intelligence) Signal output circuit), 66 a second drive unit, 100 first signal line group (parallel signal lines), 106 signal lines (serial signal line)

Claims (4)

A transparent platen on which the document is placed;
An image sensor;
A carriage equipped with an optical system that forms an image on a part of the document placed on the document table on the image sensor;
A first drive unit that reciprocates the carriage in parallel with the surface of the platen;
Optional unit,
A light source that is provided in the option unit and that illuminates a partial area of the document placed on the document table;
A second drive unit that reciprocates the light source in parallel with the platen surface of the document table;
The first drive signal of the first drive unit, in which some bits are common to the second drive signal of the second drive unit, and the partial bits are stop signals of the first drive unit and the second drive unit. Control means for outputting a stop control signal, which is a light source control signal for controlling the light source when at least a part of the remaining bit is driven by the first drive unit and the second drive unit, to the same parallel signal line; ,
A latch circuit for holding the remaining bits of the control signal at the time of stop during driving of the first drive unit and the second drive unit;
A serial communication unit electrically connected to the parallel signal line and the option unit;
An image reading apparatus comprising:   The image according to claim 1, further comprising a position detection circuit that is provided in the option unit and outputs a position signal that can recognize whether or not the light source is located at a standby position to the control unit. Reader.   The image reading apparatus according to claim 2, further comprising an identification signal output circuit that is provided in the option unit and outputs an identification signal specific to the type of the option unit to the control unit. A part of the remaining bits of the stop control signal is a selection signal that causes the position detection circuit or the identification signal output circuit to output either the position information or the identification signal,
4. The image reading apparatus according to claim 3, wherein the position detection circuit and the identification signal output circuit output the position information and the identification information to the same serial signal line according to the selection signal, respectively. .

Images