Patent Description:
Embodiments described herein relate generally to a post-processing apparatus and an image forming apparatus system.

There is an image forming apparatus that performs post-processing, such as stapling, after an image has been formed on a sheet. Such an image forming apparatus can be provided with a space in which a unit for performing the post-processing can be installed. Since the sheet after the post-processing execution must be discharged, the unit for executing the post-processing is connected to the outside of the apparatus through a discharge port. The unit (including the discharge port) may be pulled from the apparatus after the execution of the post-processing has been completed. A means for arranging a sensor having a light-emitting unit and a light-receiving unit in order to detect foreign substances or objects in the space has been proposed. However, there can be cases where a foreign object such as a hand of a user cannot be detected due to reflected light from a sheet or the like in the space.

<CIT> discloses a sheet carrier mechanism with a sensor mechanism for detecting a sheet passing through a path before it reaches an undetectable state, wherein a light emitting section and a light receiving section are arranged on opposite vertical sides of the path.

<CIT> discloses a sheet handling device capable of preventing abnormal stoppage, wherein a control means determines whether a sheet is normally carried in accordance with detection signals from sheet detection means provided on the upstream side and the downstream side of a sheet carrier means and controls the device to stop handling of the sheet if the sheet is not normally carried.

A post-processing apparatus according to the invention is defined in claim <NUM>, an image forming apparatus according to the invention is defined in claims <NUM> and <NUM> and a sensor according to the invention is defined in claim <NUM>.

According to a first aspect of the invention, it is provided a post-processing apparatus, comprising: a post-processing unit configured to receive sheets from an image forming apparatus, perform processing on the received sheets, and then discharge the processed sheets through a discharge port; a sensor configured to detect a presence of an object at the discharge port, the sensor comprising: a first light emitter on a first side of the discharge port and positioned to emit a light across a width of the discharge port, a reflector on a second side of the discharge port opposite the first side in a first direction corresponding to a width direction of a discharged sheet, and a first light receiver positioned to receive light of the first light emitter from the reflector; and a controller configured to terminate the processing on the received sheets by the post-processing unit when the sensor detects the presence of the object at the discharge port.

Optionally, in the post-processing apparatus according to the first aspect of the invention, the reflector is a mirror.

Optionally, in the post-processing apparatus according to the first aspect of the invention, the reflector is a prism.

Optionally, in the post-processing apparatus according to the first aspect of the invention, the first light receiver is on the first side of the discharge port.

Optionally, in the post-processing apparatus according to the first aspect of the invention, the first light receiver is on the second side of the discharge port.

Optionally, the post-processing apparatus according to the first aspect of the invention further comprises a second light receiver positioned to receive light of the first light from the reflector.

Optionally, in the post-processing apparatus according to the first aspect of the invention, the first and second light receivers are on the second side of the discharge port.

Optionally, in the post-processing apparatus according to the first aspect of the invention, the first and second light receivers are positioned not to overlap any portion of the discharge port.

Optionally, in the post-processing apparatus according to the first aspect of the invention, the first light receiver is positioned not to overlap any portion of the discharge port.

Optionally, in the post-processing apparatus according to the first aspect of the invention, the post-processing unit is a stapler.

Optionally, the post-processing apparatus according to the first aspect of the invention further comprises a discharge tray below the discharge port, the discharge tray positioned to hold sheets discharged through the discharge port.

According to a second aspect of the invention, it is provided an image forming apparatus, comprising: a main housing; an image forming unit in the main housing and configured to print images on sheets; and a post-processing apparatus according to claim <NUM>, wherein the post-processing apparatus according to claim <NUM> is inside the main housing.

According to a third aspect of the invention, it is provided an image forming apparatus, comprising: a main housing with a sheet outlet port; an image forming unit in the main housing and configured to print images on sheets and discharge printed sheets through the sheet outlet port; a post-processing apparatus according to claim <NUM>, wherein the post-processing apparatus is outside the main housing and positioned to receive the discharged printed sheets from the sheet outlet port.

According to a fourth aspect, which is not according to the invention, it is provided a sensor for a post-processing apparatus having a sheet discharge port, the sensor comprising: a first light emitter on a first side of a sheet discharge port, the first light emitter positioned to emit a light across a width of the sheet discharge port; a reflector on a second side of the sheet discharge port opposite the first side in a first direction corresponding to a width direction of a discharged sheet, a first light receiver positioned to receive light of the first light emitter from the reflector, wherein the sensor is configured to detect the presence of an object at the sheet discharge port according to the reception of light by the first light receiver.

Optionally, in the sensor according to the fourth aspect, the reflector is a mirror or prism.

Optionally, in the sensor according to the fourth aspect of the invention, the first light receiver is on the first side of the sheet discharge port.

Optionally, in the sensor according to the fourth aspect, the first light receiver is on the second side of the sheet discharge port.

Optionally, the sensor according to the fourth aspect further comprises a second light receiver positioned to receive light of the first light emitter from the reflector, wherein the sensor is further configured to detect the presence of an object at the sheet discharge port according to the reception of light by the second light receiver.

Optionally, in the sensor according to the fourth aspect, the first and second light receivers are on the second side of the sheet discharge port.

Optionally, in the sensor according to the fourth aspect, the first light receiver is positioned not to overlap any portion of the sheet discharge port.

It is an object of the present invention to provide a post-processing apparatus and an image forming system capable of suppressing occurrence of erroneous detection due to reflected light of a sheet and while also detecting an object at a discharge port with high accuracy.

According to one embodiment, a post-processing apparatus includes a post-processing unit configured to receive sheets from an image forming apparatus, perform processing on the received sheets, and then discharge the processed sheets through a discharge port. A sensor is configured to detect a presence of an object (e.g., a user's hand or portion thereof) at the discharge port. The sensor includes a light emitter on a first side of the discharge port. The light emitter is positioned to emit a light across a width of the discharge port. The sensor further includes a reflector on a second side of the discharge port opposite the first side in a first direction and a first light receiver that is positioned to receive light of the light emitter from the reflector. A controller is configured to terminate the processing on the received sheets by the post-processing unit when the sensor detects the presence of the object at the discharge port.

Hereinafter, a post-processing apparatus and an image forming system according to an embodiment will be described with reference to the drawings.

An image forming system <NUM> according to an embodiment will be described with reference to <FIG>. <FIG> is a schematic side view illustrating an example of a hardware configuration of the image forming system <NUM> according to the embodiment.

<FIG> is a side view illustrating an example of a hardware configuration of a post-processing apparatus <NUM> according to the embodiment.

<FIG> is a side view illustrating an example of a pinch roller <NUM> in a pivot position facing a vertical alignment roller <NUM> in the embodiment.

As shown in <FIG>, the image forming system <NUM> includes an image forming apparatus <NUM> and a post-processing apparatus <NUM>. The image forming apparatus <NUM> may be referred to as a multifunctional peripheral (MFP) apparatus. The image forming apparatus <NUM> forms an image on a sheet-like recording medium (hereinafter referred to as a "sheet S"), such as a sheet of paper. The post-processing apparatus <NUM> performs post-processing on the sheets S conveyed from the image forming apparatus <NUM>. The "post-processing" in this context may be any processing that is performed after the image forming (printing) on the sheet S by the image forming apparatus <NUM>. For example, the post-processing may be stapling processing. Hereinafter, a stapling process will be described as a particular, non-limiting example of post-processing. A bundle or other grouping of stacked sheets S will be referred to as a sheet bundle SS.

The image forming apparatus <NUM> includes a processor, a memory, an auxiliary storage, and the like connected by a bus, and executes a program. The image forming apparatus <NUM> includes a control panel <NUM>, a scanner unit <NUM>, a printer unit <NUM>, a sheet feed unit <NUM>, and a sheet discharge unit <NUM>.

The control panel <NUM> includes various keys, a touch panel, and the like that accept a user input operation. The control panel <NUM> receives input relating to a type of the post-processing of the sheet(s) S. Information on the type of post-processing input by the control panel <NUM> is sent to the post-processing apparatus <NUM>.

The scanner unit <NUM> includes a reading unit that reads image information of a document or the like. The scanner unit <NUM> transmits the read image information to the printer unit <NUM>. The printer unit <NUM> forms an image with a developer, such as toner, based on the image information (data) transmitted from the scanner unit <NUM> or an external device. The printer unit <NUM> applies heat and pressure to the toner image that has been transferred to the sheet S, thereby fixing the toner image to the sheet S. The sheet feed unit <NUM> supplies the sheets S one by one to the printer unit <NUM> in accordance with the timing at which the printer unit <NUM> forms the toner image. The sheet discharge unit <NUM> conveys the sheets S discharged from the printer unit <NUM> to the post-processing apparatus <NUM>.

Next, the post-processing apparatus <NUM> will be described. As shown in <FIG>, the post-processing apparatus <NUM> is located adjacent to the image forming apparatus <NUM>. The post-processing apparatus <NUM> executes the particular post-processing (designated through the control panel <NUM>) on the printed sheet S conveyed from the image forming apparatus <NUM>. The post-processing apparatus <NUM> includes a processor <NUM>, a memory <NUM>, a storage unit <NUM>, and the like connected by a bus, and executes a program.

As shown in <FIG> and <FIG>, the post-processing apparatus <NUM> includes a standby unit <NUM>, a processing unit <NUM>, a discharge unit <NUM>, a post-processing controller <NUM>, a sensor <NUM> (including a sensor transmitter <NUM>-<NUM>, and a sensor receiver <NUM>-<NUM>).

The standby unit <NUM> temporarily holds (buffers) the sheet(s) S conveyed from the image forming apparatus <NUM>. The standby unit <NUM> includes a standby tray <NUM>. For example, while the post-processing of a preceding sheet S is being performed by the processing unit <NUM>, the standby unit <NUM> causes the succeeding sheets S to wait. The standby unit <NUM> is disposed above the processing unit <NUM>. For example, the standby unit <NUM> causes the sheets S to be stacked while waiting. When the processing unit <NUM> is empty, the standby unit <NUM> causes the previously retained sheet S to fall toward the processing unit <NUM>.

The processing unit <NUM> includes a processing tray <NUM> for receiving the sheet S dropped from the standby unit <NUM>. The processing unit <NUM> executes post-processing on the conveyed sheet S. The processing unit <NUM> executes post-processing on the sheet bundle SS in which a plurality of sheets S are aligned. For example, the post-processing executed by the processing unit <NUM> is a binding processing (stapling processing) performed by a stapler <NUM>. The processing unit <NUM> discharges the sheet (s) S that have been subjected to the post-processing to the discharge unit <NUM>.

As shown in <FIG>, the discharge unit <NUM> includes a movable tray 14a and a fixed tray 14b. The movable tray 14a is provided on a side of the post-processing apparatus <NUM>, and is capable of discharging the sheet S from the processing unit <NUM>. The movable tray 14a is movable in an up-down direction along the side of the post-processing apparatus <NUM>. The fixed tray 14b is provided on an upper portion of the post-processing apparatus <NUM>. For example, it is possible to appropriately discharge the sheet S from the standby unit <NUM> to the fixed tray 14b.

The discharge unit <NUM> includes a discharge port for discharging the sheets S to any movable trays 14a or fixed trays 14b outside of the apparatus main body of the post-processing apparatus <NUM>. The sensor <NUM> of an object detection device <NUM> is provided in a discharge port <NUM> for the movable tray 14a.

The post-processing controller <NUM> controls overall operation of the post-processing apparatus <NUM>. The post-processing controller <NUM> includes a control circuit including a processor <NUM>, a memory <NUM>, and a storage unit <NUM>. The post-processing controller <NUM> controls operation of each functional unit of the post-processing apparatus <NUM>. For example, the post-processing controller <NUM> controls the standby unit <NUM>, the processing unit <NUM>, and the discharge unit <NUM>. The post-processing controller <NUM> controls the operation of inlet rollers 20a and 20b and outlet rollers 21a and 21b. The inlet rollers 20a and 20b and the outlet rollers 21a and 21b cause the sheet S to be conveyed to the standby tray <NUM>.

Herein, an "upstream side" and a "downstream side" in the present context refers to an upstream side (that is, the image forming apparatus <NUM> side) and a downstream side (that is, the discharge unit <NUM> side) along a conveyance direction of the sheet S, respectively, through the post-processing apparatus <NUM>. A "front end portion" and a "rear end portion" in this context refer to the "downstream end portion" and the "upstream end portion" in the sheet conveyance direction, respectively. In the present disclosure, a direction parallel to a plane of the sheet S (sheet surface direction) and perpendicular to the sheet conveyance direction is referred to as a width direction W.

As shown in <FIG> and <FIG>, the post-processing apparatus <NUM> includes a conveyor unit <NUM> that conveys or otherwise moves the sheet S after passing the sheet discharge unit <NUM> of the image forming apparatus <NUM>. The conveyor unit <NUM> includes a sheet supply port 26a provided with a pair of inlet rollers 20a and 20b, and a sheet discharge port 26b provided with a pair of outlet rollers 21a and 21b. The sheet supply port 26a faces the sheet discharge unit <NUM> of the image forming apparatus <NUM>. The sheet S is thusly supplied from the image forming apparatus <NUM> to the sheet supply port 26a. The seat discharge port 26b faces the standby unit <NUM>. The sheet S passing through the conveyor unit <NUM> is conveyed from the sheet discharge port 26b to the standby unit <NUM>.

The standby unit <NUM> includes a standby tray <NUM> (also referred to as a buffer tray <NUM>) and an assist guide <NUM>. The rear end portion of the standby tray <NUM> is located in the vicinity of the outlet rollers 21a and 21b. The rear end portion of the standby tray <NUM> is located lower than the sheet discharge port 26b of the conveyor unit <NUM>. The standby tray <NUM> is inclined with respect to the horizontal direction so as to gradually increase in height toward its downstream side end in the sheet conveyance direction. The standby tray <NUM> holds sheets S while the processing unit <NUM> performs the post-processing.

The standby tray <NUM> has a pair of tray members that can be moved closer to and away from each other in the width direction W. In the case where the sheet S stands by in the standby tray <NUM>, the pair of tray members can be brought close to each other to support the sheet S. When moving the sheet S from the standby tray <NUM> toward the processing tray <NUM> of the processing unit <NUM>, the pair of tray members are separated from each other. Accordingly, the standby tray <NUM> causes the supported sheet S to fall (move) toward the processing tray <NUM>.

A paddle portion <NUM> is provided between the upstream side of the standby tray <NUM> and the upstream side of the processing tray <NUM>. The paddle portion <NUM> rotates about a rotation axis along the width direction W, thereby pressing the sheet S toward the processing tray <NUM>. The paddle portion <NUM> presses the rear end portion of the sheet S toward the processing tray <NUM> when the sheet S moves from the standby tray <NUM> toward the processing tray <NUM>. The paddle portion <NUM> has a paddle 30a formed of an elastic material such as rubber, and the rear end portion of the sheet S is pressed to the processing tray <NUM> by the paddle 30a.

The processing unit <NUM> includes a processing tray <NUM>, a horizontal alignment plate <NUM>, a rear end stopper <NUM>, a stapler <NUM> (also referred to as binding processing unit), an ejector <NUM>, a thruster 36a, a bundle claw belt <NUM>, a vertical alignment roller <NUM> (also referred to as a conveyance roller), and belt pulleys 43a and 43b.

The processing tray <NUM> is provided below the standby tray <NUM>. The processing tray <NUM> is inclined with respect to the horizontal direction so as to gradually increase in the direction toward the downstream end side in the sheet conveyance direction. The processing tray <NUM> is inclined, for example, to parallel the standby tray <NUM>. The processing tray <NUM> has a conveyance surface 18a that supports the sheet S (that is, the sheet S can be placed thereon).

A pair of horizontal alignment plates <NUM> are provided facing each other on both sides in the width direction W of the conveyance surface 18a of the processing tray <NUM>. The pair of horizontal alignment plates <NUM> are provided to be spaced apart from each other in the width direction W. The horizontal alignment plate <NUM> is movable in the width direction W in a direction approaching each other and a direction separating from each other. The horizontal alignment plate <NUM> constitutes a horizontal alignment device that performs alignment of the sheet S in the width direction W (so-called horizontal alignment).

The rear end stopper <NUM> is provided at an upstream end portion of the processing tray <NUM>. The sheet S placed on the processing tray <NUM> is conveyed toward the rear end stopper <NUM> by the vertical alignment roller <NUM> being reversibly driven in the clockwise direction in the figure. The vertical alignment roller <NUM> cooperates with the paddle portion <NUM> to bring the upstream end of the sheet S into contact with the rear end stopper <NUM>, thereby performing longitudinal alignment of the sheet S. The vertical alignment roller <NUM> forwardly rotates in the counterclockwise direction in the figure, thereby bending or flexing the sheet S in cooperation with the paddle portion <NUM> that presses the rear end portion of the sheet S.

The stapler <NUM> is disposed at the rear of the processing tray <NUM>. The stapler <NUM> includes a staple clinch 35a. The stapler <NUM> can bind the aligned ends of the sheet S in contact with the rear end stopper <NUM>. The stapler <NUM> performs stapling processing on the end of the sheet bundle SS, which is aligned with the rear end stopper <NUM>, with the staple clinch 35a. The stapler <NUM> is capable of moving within a prescribed range so as to staple the sheet bundle SS at the position indicated by a user via the control panel.

The ejector <NUM> is provided at the initial position of an upstream end portion of the processing tray <NUM>. The ejector <NUM> is provided so as to overlap the rear end stopper <NUM>. The ejector <NUM> is capable of moving the sheet S toward the downstream side in the conveyance direction. When the ejector <NUM> moves toward the downstream side in the conveyance direction, the ejector <NUM> advances the sheet bundle SS on which the post-processing has been performed. The ejector <NUM> is disposed at a position at which the end portion of the sheet bundle SS can be delivered to a bundle claw. The ejector <NUM> is biased toward the initial position before movement.

The bundle claw belt <NUM> includes a bundle claw (an extrusion member). The bundle claw belt <NUM> spans the pair of belt pulleys 43a and 43b located on the upstream side and the downstream side in the conveyance direction of the processing tray <NUM>. The bundle claw belt <NUM> and the belt pulleys 43a and 43b constitute a bundle claw drive mechanism <NUM> for driving the bundle claw. The bundle claw drive mechanism <NUM> includes a bundle claw drive motor <NUM> as a drive source shared by the bundle claw, the ejector <NUM>, and the thruster 36a. The bundle claw drive motor <NUM> is always connected to the belt pulley 43a, but is disconnectable and connectable to the ejector <NUM> and the thruster 36a via an electromagnetic clutch <NUM>.

When the belt pulley 43a is driven in the counterclockwise direction in the figure, the bundle claw, ejector <NUM>, and thruster 36a move from the upstream side in the conveyance direction to the downstream side (the left side in the figure) on the conveyance surface 18a of the processing tray <NUM>. When the belt pulley 43a is driven in the clockwise direction in the figure, the bundle claw, ejector <NUM>, and thruster 36a move on the conveyance surface 18a of the processing tray <NUM> toward the upstream side in the conveyance direction (the right side in the figure).

The vertical alignment roller <NUM> forwardly rotates in the counterclockwise direction in the figure, thereby transporting the sheet S placed in the processing tray <NUM> toward the movable tray 14a of the discharge unit <NUM>. The vertical alignment roller <NUM> applies a driving force to the sheet S by coming into contact with the sheet S placed in the processing tray <NUM> from below. As illustrated in <FIG>, when the sheet S on the processing tray <NUM> is bent and separated from the vertical alignment roller <NUM>, the driving force of the vertical alignment roller <NUM> cannot be applied to the sheet S. Therefore, a pinch roller <NUM> for sandwiching the sheet S between the processing tray <NUM> and the vertical alignment roller <NUM> is provided as a pressing roller above the processing tray <NUM> (which is also above the standby tray <NUM> in the embodiment).

The pinch roller <NUM> is a driven roller. The pinch roller <NUM> is movable between a standby position located above the standby tray <NUM> (see <FIG>) and a pivot position facing the vertical alignment roller <NUM> (see <FIG>). The pinch roller <NUM> is driven by the roller drive mechanism <NUM> so as to move between the standby position and the pivot position. The pinch roller <NUM> is pushed toward the vertical alignment roller <NUM> by being moved (lowered) to the downward rotation position, and the sheet S is sandwiched between the pinch roller <NUM> and the vertical alignment roller <NUM>. This makes it possible to stably transmit the driving force of the vertical alignment roller <NUM> to the sheet S.

The drive mechanism <NUM> has a support arm <NUM> that supports the pinch roller <NUM> at a distal end portion (front end portion) and is swingable about an axis along which a proximal end portion (rear end portion) is along the width direction W. A solenoid <NUM> is connected to the proximal end portion of the support arm <NUM>. As shown in <FIG>, when the solenoid <NUM> is driven to cause a plunger to protrude, the support arm <NUM> swings upward about the axis. As the support arm <NUM> swings, the pinch roller <NUM> swings upward and moves to the standby position. As shown in <FIG>, when the solenoid <NUM> is immersed in the plunger, the support arm <NUM> swings downward around the axis. With the swinging of the support arm <NUM>, the pinch roller <NUM> swings downward via the support arm <NUM> and moves to the pivot position. The pinch roller <NUM> is pressed toward the vertical alignment roller <NUM> in the pivot position.

The post-processing controller <NUM> illustrated in <FIG> determines an operation mode of the image forming system <NUM>. Specifically, when the automatic processing mode is selected in the control panel <NUM>, the post-processing controller <NUM> determines that the operation mode of the post-processing apparatus <NUM> is an automatic post-processing mode. When a manual operation mode is selected in the control panel <NUM>, the post-processing controller <NUM> determines that the operation mode of the post-processing apparatus <NUM> is the manual operation mode. The post-processing controller <NUM> acquires sensor information acquired by the sensor <NUM>.

The post-processing controller <NUM> instructs the pinch roller <NUM> to raise or lower the pinch roller <NUM>. When the pinch roller <NUM> is raised in response to an instruction for raising, a substantial opening area of the discharge port <NUM> that allows the post-processing interior space and the space outside the apparatus to communicate with each other is widened. The opening area provided when the pinch roller <NUM> is in its most raised position is typically large enough for a person's hand to enter the post-processing space. When the pinch roller <NUM> is lowered upon receiving an instruction for lowering, the once substantial opening area of the discharge port <NUM> becomes narrow. For example, when the pinch roller <NUM> is in its lowest position, the discharge port <NUM> is substantially closed off and prevents an external object (foreign object) B from entering the post-processing space.

The post-processing controller <NUM> instructs the processing unit <NUM> to execute matching processing. The matching processing is a process for aligning positions of the end portions in the width direction and the end portions in the length direction of the plurality of sheets S. When the processing unit <NUM> performs the matching processing, the horizontal alignment plate <NUM> and the vertical alignment roller <NUM> operate to align the positions of the end portions in the width direction and the length direction of the plurality of sheets S. The length direction of the sheet S refers to a direction along the sheet conveyance direction in the sheet surface direction.

The post-processing controller <NUM> instructs the stapler <NUM> to execute post-processing. The stapler <NUM>, which has received an instruction to perform the post-processing, executes post-processing on the sheet bundle SS.

The post-processing controller <NUM> instructs the ejector <NUM> to execute sheet discharge processing. The ejector <NUM>, which has received an instruction to execute the sheet discharge processing, discharges the sheet bundle on which the post-processing has been executed to the outside of the post-processing apparatus <NUM>.

Next, an object detection apparatus <NUM> will be described.

<FIG> is a perspective view illustrating an arrangement of a sensor transmitter <NUM>-<NUM> and a sensor receiver <NUM>-<NUM> in an object detection apparatus 50a according to a comparative example. <FIG> is an explanatory diagram illustrating a first action of the sensor transmitter <NUM>-<NUM> and the sensor receiver unit <NUM>-<NUM> in the object detection apparatus 50a of the comparative example. <FIG> is an explanatory diagram illustrating a second operation of the sensor transmitter <NUM>-<NUM> and the sensor receiver unit <NUM>-<NUM> in the object detection apparatus 50a according to the comparative example.

As shown in <FIG>, the sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> form a transmission type sensor 16a in pairs. In the comparative example, the object detection apparatus 50a includes a pair of sensors 16a1 and 16a2. Hereinafter, the pair of sensors 16a1 and 16a2 will be referred to as a first sensor 16a1 and a second sensor 16a2. In this context, the sensor transmitter <NUM>-<NUM> of sensor 16a1 is denoted by the reference numeral <NUM>-<NUM> and the sensor transmitter <NUM>-<NUM> of the sensor 16a2 is denoted by the reference numeral <NUM>-<NUM>. Furthermore, the sensor receiver <NUM>-<NUM> of the first sensor 16a1 is denoted by the reference numeral <NUM>-<NUM>, and the sensor receiver <NUM>-<NUM> of the first sensor 16a2 is denoted by the reference numeral <NUM>-<NUM>.

Each of the sensors 16a1 and 16a2 positions the respective sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> to opposite sides of the discharge port <NUM> in the width direction W. The arrows F1 and F2 in the figure indicate detection light emitted from the sensor transmitter <NUM>-<NUM> and <NUM>-<NUM> respectively. Each detection light F1 and F2 is emitted along the width direction W at the discharge port <NUM>.

In the comparative example, the first sensor 16a1 is disposed on the upper portion of the discharge port <NUM>, and the second sensor 16a2 is disposed on the lower portion of the discharge port <NUM>. Thereby, it is possible to detect the object B in a wide range in the height direction (vertical direction H) of the discharge port <NUM>.

The first sensor 16a1 and the second sensor 16a2 are configured such that the arrangement of the sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> is opposite to each other in the width direction W. Accordingly, the detection light of from sensor transmitters <NUM>-<NUM> of the first sensor 16a1 and the second sensor 16a2 is not detected by the sensor receiver <NUM>-<NUM> of the other one of the first sensor 16a1 and the second sensor 16a2.

<FIG> and <FIG> illustrate the operation of the first sensor 16a1, but the second sensor 16a2 operates with a similar a symmetrical effect in the width direction W.

As shown in <FIG> and <FIG>, in the object detection apparatus 50a of the comparative example, when the object B having a size of a finger is present in the approximate center of the width direction W of the discharge port <NUM>, the object B may not be properly detected. This occurs when a direct light (arrow F1a) from the sensor transmitter is blocked by the object B, and a reflected light (arrow F1b), reflected by the sheet S passing through the discharge port <NUM>, reaches the sensor receiver <NUM>-<NUM> while avoiding the object B.

<FIG> is a perspective view illustrating an arrangement of the sensor transmitter <NUM>-<NUM>, the reflector <NUM>-<NUM>, and the sensor receiver <NUM>-<NUM> of the object detection apparatus <NUM> according to the embodiment. <FIG> is an explanatory diagram illustrating a first action of the sensor transmitter <NUM>-<NUM>, the reflector <NUM>-<NUM>, and the sensor receiver <NUM>-<NUM> of the object detection apparatus <NUM> according to the embodiment. <FIG> is an explanatory diagram illustrating a second action of the sensor transmitter <NUM>-<NUM>, the reflector <NUM>-<NUM>, and the sensor receiver <NUM>-<NUM> of the object detection apparatus <NUM> according to the embodiment.

As illustrated in <FIG>, the object detection apparatus <NUM> according to the embodiment has the following configuration as a sensor <NUM> for detecting an object (foreign object) B entering the apparatus from the discharge port <NUM>. The sensor <NUM> includes a sensor transmitter <NUM>-<NUM> that irradiates the width direction path F1, F2 extending in the width direction W with light in the discharge port <NUM>, a reflector (mirror) <NUM>-<NUM> that reflects a light that has passed through the width direction paths F1 and F2 to the reflection paths R1 and R2, and a sensor receiver <NUM>-<NUM> that receives the light reflected by a reflection portion.

In an embodiment, the object detection apparatus <NUM> includes a pair of sensors <NUM> and <NUM>. Hereinafter, the pair of sensors <NUM> and <NUM> are referred to as a first sensor <NUM> and a second sensor <NUM>.

Each sensor <NUM> and <NUM> includes a sensor transmitter <NUM>-<NUM> that emits light such as infrared rays and a sensor receiver <NUM>-<NUM> that receives the light emitted by the sensor transmitter <NUM>-<NUM>. A reflector <NUM>-<NUM> is provided between the sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM>. The sensor transmitter <NUM>-<NUM> may be referred to as a light source, an emitter, an emitting unit, or the like. The sensor receiver <NUM>-<NUM> may be referred to as light receiver unit or a light sensor.

Each sensor receiver <NUM>-<NUM> includes a first sensor receiver <NUM>-<NUM> and a second sensor receiver <NUM>-<NUM> having different optical path lengths from the respective sensor transmitters <NUM>-<NUM>. In the embodiment shown in <FIG>, each sensor transmitter <NUM>-<NUM> includes a first transmitter <NUM>-<NUM> and a second transmitter <NUM>-<NUM>.

The sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> of the sensor <NUM> operate in conjunction with each other to detect an object B of the discharge port <NUM>. The sensor transmitter <NUM>-<NUM> includes a light-emitting element that is a light source such as a light emitting diode (LED). The sensor receiver <NUM>-<NUM> includes a light receiving element that receives the electromagnetic wave emitted by the sensor transmitter <NUM>-<NUM>. The sensor receiver <NUM>-<NUM> outputs information (hereinafter referred to as "sensor information") to the post-processing controller <NUM> indicating whether or not the object B has been detected within a detection range covering the relevant space of the post-processing apparatus <NUM>. The detection range in this context is the space in which the electromagnetic waves radiated by the sensor transmitter <NUM>-<NUM> propagate. That is, the detection range is a space in which the object B can be detected by the sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> operating in conjunction with each other.

The sensor receiver <NUM>-<NUM> detects the object B based on a reception of the electromagnetic waves transmitted by the sensor transmitter <NUM>-<NUM>. If a reception satisfies a predetermined condition (hereinafter referred to as a "detection condition"), the sensor receiver <NUM>-<NUM> indicates a detection of the object B in the detection range. The sensor receiver <NUM>-<NUM> may output the sensor information indicating that the object B has been detected for any reception state. For example, the sensor information may indicate that the object B has been detected when the sensor receiver <NUM>-<NUM> does not receive the electromagnetic wave transmitted by the sensor transmitter <NUM>-<NUM>. For example, the sensor information may indicate that the object B has been detected when a light intensity received by the sensor receiver <NUM>-<NUM> is equal to or less than some predetermined intensity.

Note that the sensor <NUM> is not limited to the transmission type sensor and, in general, as long as the sensor <NUM> is capable of detecting the object B in some predetermined detection range cover the space above the processing tray <NUM> and the space in the discharge port <NUM>, any sensor type may be adopted.

The sensor <NUM> may be disposed at any position satisfying a transmission unit condition and a reception unit condition. The transmission unit condition is a condition that the sensor transmitter <NUM>-<NUM> is arranged at a position capable of radiating an electromagnetic wave along the sheet surface direction in the relevant detection range. The reception unit condition is that the sensor receiver <NUM>-<NUM> is arranged at a position where the electromagnetic wave radiated by the sensor transmitter <NUM>-<NUM> can be received.

For example, when the height (vertical width) of the discharge port <NUM> is denoted by V1, the sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> may be arranged at a position V2 where the height from the lower end of the discharge port <NUM> is lower than V1. For example, since an average thickness of a child's hand is <NUM>, V2 may be <NUM>. When V2 is <NUM>, the sensor <NUM> can detect a hand of a child inserted in the detection range. On the other hand, when V2 is <NUM>, the image forming system <NUM> does not detect the sheets S or the sheet bundles SS that are thinner than <NUM>.

When the sensor <NUM> detects the object B having a thickness greater than or equal to the predetermined value at the determination timing, the post-processing apparatus <NUM> determines that the object B is present in the post-processing space and makes an emergency stop. This prevents the post-processing from being performed in a state in which the object B is in the post-processing space.

As described above, the post-processing apparatus <NUM> makes an emergency stop if the object which has a thickness greater than some predetermined thickness (hereinafter, referred to as a "reference thickness") is in the post-processing space. The "thickness" refers to a thickness in a deposition direction of a sheet S on a processing tray. The "predetermined thickness" is a thickness corresponding to a position (e.g., a position in the detection range) through which the electromagnetic wave from the sensor transmitter <NUM>-<NUM> propagates normally. That is, the "predetermined thickness" is a distance corresponding to the height from the processing tray <NUM> to a position through which the electromagnetic waves pass through. For example, when the electromagnetic wave radiated by the sensor transmitter <NUM>-<NUM> propagates through the position where the height from the processing tray <NUM> is V2, the "predetermined thickness" is V2. That is, the detection range of the sensor <NUM> is a space in which the distance from the processing tray <NUM> is at a distance equal to or more than a predetermined distance V2. The detection range includes the space above the processing tray (post-processing space) and the space in the discharge port <NUM> adjacent to the downstream side of the processing tray.

The post-processing controller <NUM> determines whether or not the sensor <NUM> detects the object B at a predetermined timing (hereinafter referred to as a "determination timing") on the basis of the sensor information. If it is possible to determine whether or not the sensor <NUM> has detected the object B at the determination timing based on the sensor information, the post-processing controller <NUM> may determine whether or not the detection sensor <NUM> has detected the object B at the determination timing based on the sensor information in any way. The determination timing may be any timing as long as it is before execution of the post-processing and the possibility that the sensor <NUM> detects the sheet bundle SS is lower than some predetermined value.

The determination timing is a timing other than the timing at which the sheet bundle SS passes through the path on which the electromagnetic wave radiated by the sensor transmitter <NUM>-<NUM> propagates. The determination timing may be any timing as long as it is a timing other than the timing at which the sheet bundle SS passes through the path. For example, the determination timing may be after the pinch roller <NUM> has been lowered. For example, the determination timing may be after the matching processing is completed. For example, the determination timing may be after a drop processing is completed. For example, the determination timing may be a timing at which the sheet bundle SS is transported to the processing tray <NUM>. When the determination timing is after the end of the drop processing or after the end of the matching processing, the possibility that the sensor <NUM> detects the falling sheet S becomes low. For example, the post-processing controller <NUM> may cause the sensor <NUM> to operate only at determination times.

As shown in <FIG>, a first reflector <NUM>-<NUM> and a second reflector <NUM>-<NUM> are disposed in the optical paths from the sensor transmitters <NUM>-<NUM> and <NUM>-<NUM> to the respective sensor receivers <NUM>-<NUM> and <NUM>-<NUM>, respectively.

The reflectors <NUM>-<NUM> and <NUM>-<NUM> extend the optical path length of each sensor <NUM> and <NUM> by reflecting the optical path at a position avoiding the discharge port <NUM>. For example, the optical path lengths of the respective sensors <NUM> and <NUM> are different from each other.

The arrows F1 and F2 in the figure indicate light beams emitted from the sensor transmitters <NUM>-<NUM> and <NUM>-<NUM> of the sensors <NUM> and <NUM>. Line segments L1 and L2 of the arrows F1 and F2 indicate the center line of the width direction path (detection areas) extending in the width direction W in the discharge port <NUM>. The length of the line segment L1 indicates the length of the optical path from the sensor transmitter <NUM>-<NUM> of the first sensor <NUM> to the reflector <NUM>-<NUM>. The length of the line segment L2 indicates the length of the optical path from the sensor transmitter <NUM>-<NUM> of the second sensor <NUM> to the reflector <NUM>-<NUM>.

The arrows F3 and F4 in the figure indicate reflected light reflected from the reflectors <NUM>-<NUM> and <NUM>-<NUM> to the sensor receivers <NUM>-<NUM> and <NUM>-<NUM> respectively. The reflection lights F3 and F4 are reflected toward reflection paths R1 and R2 extending downward from both sides of the discharge port <NUM> in the width direction W. The reflection paths R1 and R2 are provided using dead space on the side wall inside the housing of the post-processing apparatus <NUM>. The length of the line segment L3 of the arrow F3 indicates the length of the optical path from the reflectors <NUM>-<NUM> of the first sensor <NUM> to the sensor receiver <NUM>-<NUM>. The length of the line segment L4 of the arrow F4 indicates the length of the optical path from the reflective portion <NUM>-<NUM> of the second sensor <NUM> to the sensor receiver <NUM>-<NUM>.

The optical path lengths L3 and L4 are different from each other, and the respective optical path lengths from the sensor transmitters <NUM>-<NUM> and <NUM>-<NUM> to the sensor receivers <NUM>-<NUM> and <NUM>-<NUM> are thus made different from each other. Note that, although the optical path length L1 and the optical path length L2 are depicted as approximately the same as each other in the illustrated example in the drawings, these optical path lengths may be different from each other in length.

In the present embodiment, the sensor transmitter <NUM>-<NUM> and <NUM>-<NUM> and the reflector <NUM>-<NUM> and <NUM>-<NUM> are disposed on both sides of the discharge port <NUM> in the width direction W to cover the appropriate detection range around the discharge port <NUM>. The sensor receivers <NUM>-<NUM> and <NUM>-<NUM> are disposed at positions avoiding the discharge port <NUM> in the vertical direction H orthogonal to the width direction W. The sensor transmitters <NUM>-<NUM> and <NUM>-<NUM> emit light along width direction paths F1 and F2 extending in the width direction W in the discharge port <NUM>. The mirrors that are the reflectors <NUM>-<NUM> and <NUM>-<NUM> reflect the light that has passed through the width direction path F1 and F2 toward the sensor receivers <NUM>-<NUM> and <NUM>-<NUM>, respectively. In other words, the reflectors <NUM>-<NUM> and <NUM>-<NUM> reflect the light toward the reflection paths R1 and R2 avoiding the width direction path F1 and F2. The light reflected by the reflecting portion is denoted by a reference sign F1c (reflected light F1c) in the figure. The sensor receivers <NUM>-<NUM> and <NUM>-<NUM> are capable of receiving the reflected light F1c after the reflected light F1c passes through the reflection paths R1 and R2. When the reception intensity of the reflected light F1c is equal to or less than the predetermined intensity, the sensor receivers <NUM>-<NUM> and <NUM>-<NUM> detect that the object B is present in the space within the detection range.

The sensor receivers <NUM>-<NUM> and <NUM>-<NUM> detect the presence or absence of the object (foreign object) B at the discharge port <NUM> based on whether or not detection light (reflected light) emitted by the sensor transmitter <NUM>-<NUM> and <NUM>-<NUM> is detected at a predetermined amount or more than a predetermined amount of detection light (reflected light). When the sensor <NUM> detects the object B, it is possible to perform a corresponding operation such as stopping the processing of the apparatus.

When the reflectors <NUM>-<NUM> and <NUM>-<NUM> reflect the detection light along the width direction paths F1 and F2, the sensor <NUM> may not detect the object B of the discharge port <NUM> as in the above-described comparative example.

The detection light emitted from the sensor transmitters <NUM>-<NUM> and <NUM>-<NUM> includes a direct light F1a passing through the discharge port <NUM> along the width direction paths F1 and F2, and a reflected light F1b reflected by the sheet at the discharge port <NUM>. If the reflected light F1b passes through the discharge port <NUM>, the sensor <NUM> does not detect the object B even if the object B in the discharge port <NUM> blocks the direct light F1a along the width direction path F1 and F2. That is, even if the object B is present in the discharge port <NUM>, the sensor <NUM> may not detect the object B in some cases.

In the embodiment, the light that has passed through the width direction path F1 and F2 is reflected toward the reflection paths R1 and R2 that avoid the width direction path F1 and F2, and thus the following effects are obtained. That is, it is possible to detect the object B in any one of the width direction paths F1 and F2 and the reflection paths R1 and R2, which are all different from each other, and it is possible to suppress erroneous detection. When the reflectors <NUM>-<NUM> and <NUM>-<NUM> reflect the detection light along the width direction paths F1 and F2, the detection light may be reflected by the sheet S under the same conditions. In this case, there is a possibility that the light will pass through the discharge port <NUM> while avoiding the object B in both the reciprocating directions. On the other hand, by having the width direction path F1 and F2 and the reflection path R1 and the reflection path R2, which are different from each other, it is possible to prevent the light from being reflected by the sheet S in the reciprocating direction in the same condition. This makes it possible to suppress the occurrence of erroneous detection due to reflected light on the sheet S, and detect the object B of the discharge port <NUM> with high accuracy.

In the embodiment, the sensor transmitters <NUM>-<NUM> and <NUM>-<NUM> are arranged on one side in the width direction W of the discharge port <NUM>, and the reflectors <NUM>-<NUM> and <NUM>-<NUM> are arranged on the other side of the discharge port <NUM> in the width direction W. The sensor receivers <NUM>-<NUM> and <NUM>-<NUM> are arranged so as to avoid the discharge port <NUM> in the vertical direction H that intersects with the width direction W. According to this configuration, the reflected light F1b on the sheet S has the following effects because the incident angles on the reflectors <NUM>-<NUM> and <NUM>-<NUM> are different from the direct light F1a from the sensor transmitters <NUM>-<NUM> and <NUM>-<NUM>. The reflected light F1b on the sheet S may be set to have a configuration that does not reach the sensor receivers <NUM>-<NUM> and <NUM>-<NUM> after reflection by the reflectors <NUM>-<NUM> and <NUM>-<NUM>.

Therefore, it is possible only the direct light F1a from the sensor transmitters <NUM>-<NUM> and <NUM>-<NUM> reaches the sensor receiver <NUM>- <NUM> and <NUM>-<NUM> after the reflection by the reflectors <NUM>-<NUM> and <NUM>-<NUM>. Therefore, the influence of the reflected light F1b on the sheet S can be suppressed, and the object B at the discharge port <NUM> can be detected with high accuracy. Further, the optical path length is increased in the direction intersecting with the width direction W, and the reflected light is less likely to reach the sensor receivers <NUM>-<NUM> and <NUM>-<NUM>. This makes it possible to suppress an increase in the size of the object detection apparatus <NUM>.

When two or more sensor receivers <NUM>-<NUM> and <NUM>-<NUM> and two or more sensor transmitters <NUM>-<NUM> and <NUM>-<NUM> are used, the sensor transmitters <NUM>-<NUM> and <NUM>-<NUM> and the reflectors <NUM>-<NUM> and <NUM>-<NUM> are disposed across a detection target range in the width direction W in the discharge port <NUM>. Further, the sensor receiver <NUM>-<NUM> and <NUM>-<NUM> is disposed outside the detection target range. Accordingly, the reflected light F1b reflected by the sheet S in the detection target range is prevented from reaching the sensor receivers <NUM>-<NUM> and <NUM>-<NUM>. With this, it is possible to detect the influence of the reflected light F1b on the sheet S, and it is possible to detect the foreign object with a plurality of conditions having different detection characteristics. Then, when the foreign matter is detected under even one condition, the apparatus can be immediately stopped.

In the embodiment, the sensor <NUM> includes a plurality of sensor transmitters <NUM>-<NUM> and <NUM>-<NUM>, a plurality of reflectors <NUM>-<NUM> and <NUM> -<NUM>, and a plurality of sensor receivers <NUM>-<NUM> and <NUM>-<NUM>. The plurality of sensor transmitters <NUM>-<NUM> and <NUM>-<NUM> include a first sensor transmitter <NUM>-<NUM> disposed on a first side of the discharge port <NUM>, and a second sensor transmitter <NUM>-<NUM> disposed on a second side of the discharge port <NUM> opposite the first side in the width direction W. The plurality of reflectors <NUM>-<NUM> and <NUM>-<NUM> are both disposed on the second side of the discharge port <NUM>. The first reflector <NUM>-<NUM> reflects the light emitted by the first sensor transmitter <NUM>-<NUM>, and a second reflector <NUM>-<NUM> reflects the light radiated by the second sensor transmitter <NUM>-<NUM>. The plurality of sensor receivers <NUM>-<NUM> and <NUM>-<NUM> are disposed so as to not overlap the discharge port <NUM> in any direction perpendicular to the width direction W. A first sensor receiver <NUM>-<NUM> receives the light reflected by the first reflector <NUM>-<NUM>, and a second sensor receiver <NUM>-<NUM> receives the light reflected by the second reflector <NUM>-<NUM>.

According to this configuration, the plurality of sensor transmitters <NUM>-<NUM> and <NUM>-<NUM> and the plurality of reflectors <NUM>-<NUM> and <NUM>-<NUM> are distributed on both sides of the discharge port <NUM>. The plurality of sensor receivers <NUM>-<NUM> and <NUM>-<NUM> are disposed at positions not overlapping with the discharge port <NUM>. The reflection light F1b on the sheet S has an effect similar to that described above because the incident angles on the reflectors <NUM>-<NUM> and <NUM>-<NUM> are different from the direct light from the sensor transmitters <NUM>-<NUM> and <NUM>-<NUM>. That is, it is possible to suppress the influence of the reflected light F1b on the sheet S, and to detect the object B of the discharge port <NUM> with high accuracy. Further, it is possible to increase the optical path length in the direction intersecting the width direction W, and it is possible to suppress an increase in size of the object detection apparatus <NUM>.

Further, by providing the plurality of sensor transmitters <NUM>-<NUM> and sensor receiver <NUM>-<NUM>, a redundancy for failure of any one of the sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> can be achieved.

In an embodiment, the length L3 of the reflection path R1 from the first reflector <NUM>-<NUM> to the first sensor receiver <NUM>-<NUM> is different from the length L4 of the reflection path R2 from the second reflector <NUM>-<NUM> to the second sensor receiver <NUM>-<NUM>.

According to this configuration, it is possible to detect the object B under a plurality of conditions having different detection characteristics, and it is possible to suppress erroneous detection even in a state in which the reflected light F1b on the sheet S is generated.

<FIG> illustrates a first modification (reference numeral 50b) of the object detection apparatus <NUM> according to the embodiment.

The sensor 16b of the object detection apparatus 50b illustrated in <FIG> includes one sensor transmitter <NUM>-<NUM> and two sensor receivers <NUM>-<NUM> and <NUM>-<NUM>. A reflector <NUM>-<NUM> is provided in the optical path between the sensor transmitter <NUM>-<NUM> and the two sensor receivers <NUM>-<NUM> and <NUM>-<NUM>.

In this case, the sensor receivers <NUM>-<NUM> and <NUM>-<NUM>, the sensor transmitter <NUM>-<NUM>, and the reflector <NUM>-<NUM> are positioned such that the optical path lengths from the sensor transmitter <NUM>-<NUM> to each of the sensor receivers <NUM>-<NUM> and <NUM>-<NUM> are different. With this, it is possible to detect the influence of the reflected light F1b on the sheet S, and it is possible to detect the foreign object with a plurality of conditions having different detection characteristics. Then, when the foreign matter is detected under any one of the conditions, the apparatus can be immediately stopped.

That is, in the first modification, the sensor 16b includes a single sensor transmitter <NUM>-<NUM> but a plurality of sensor receivers <NUM>-<NUM> and <NUM>-<NUM>, and the plurality of sensor receivers <NUM>-<NUM> and <NUM>-<NUM> include at least a first sensor receiver <NUM>-<NUM> and a second sensor receiver <NUM>-<NUM> having different lengths L3 and L4 of reflection paths R1 and R2 from the reflector <NUM>-<NUM>.

According to this configuration, since the lengths L3 and L4 of the reflection paths R1 and R2 are different from each other, it is possible to detect the object B under a plurality of conditions having different detection characteristics. This makes it possible to suppress erroneous detection even in a situation in which the reflected light F1b on the sheet S is generated, and to achieve redundancy against failures of the sensor receiver <NUM>-<NUM> and <NUM>-<NUM>.

<FIG> illustrates a second modified example (reference numeral 50c) of the object detection apparatus <NUM> according to the embodiment.

The sensor 16c of the object detection apparatus 50c illustrated in <FIG> and <FIG> includes a sensor transmitter <NUM>-<NUM>, a sensor receiver <NUM>-<NUM>, and a reflector <NUM>-<NUM>, respectively. The sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> are disposed on the same side, in the width direction W, of the discharge port <NUM>, and the reflector <NUM>-<NUM> is disposed on the other (opposite) side of the discharge port <NUM> in the width direction W.

In other words, the sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> are on the same side in the width direction W, and the reflector <NUM>-<NUM> is on the other side in the width direction W. The sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> are disposed so as to be spaced apart in the depth direction (sheet conveyance direction) (see <FIG>).

As shown in <FIG> and <FIG>, the light (direct light F1a) entering the reflector <NUM>-<NUM> from the angle θ1 with respect to the perpendicular direction is returned to the sensor receiver <NUM>-<NUM> at the angle θ2 with respect to the right angle (reflected light F1c), by utilizing the properties of the angle of incidence and the reflection angle of the reflecting portion <NUM>-<NUM>. The line VL in the drawing indicates an extension line perpendicular to the reflection surface of the reflector <NUM>-<NUM>.

Therefore, when the object B exists within the detection target range, any one of the direct light F1a emitted from the sensor transmitter <NUM>-<NUM> and the reflected light F1c reflected by the reflector <NUM>-<NUM> can be blocked by the object B. Therefore, the sensor receiver <NUM>-<NUM> does not return the light from the sensor transmitter <NUM>-<NUM>, and the sensor 16c correctly recognizes that the object is present.

As shown in <FIG>, even if the direct light F1a is reflected at a location other than the object B, and the reflected light Fb1 enters the reflector <NUM>-<NUM>, the reflected light Fb1 is incident at a predetermined angle that is not a right angle with respect to the reflector <NUM>-<NUM>, and therefore, the reflected light F1c reflected by the reflector <NUM>-<NUM> does not travel toward the sensor receiver <NUM>-<NUM>, and is attenuated or diverged. According to this configuration, the reflector <NUM>-<NUM> reflects the light. Therefore, even in the case of light reflected at any location in the discharge port <NUM> and not blocked by the object B, the light other than the light reflected by the reflector <NUM>-<NUM> can be set to not return to the sensor receiver <NUM>-<NUM>. Accordingly, it is possible to detect the object B at the discharge port <NUM> with high accuracy.

In <FIG>, for convenience of description, the sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> are disposed separated from each other in the width direction W, but the sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> may be disposed in close proximity to each other.

Here, since the incident angle θ1 (the angle with respect to the extension line VL) when light enters the reflector <NUM>-<NUM> from the sensor transmitter <NUM>-<NUM> and the reflection angle θ2 (the angle with respect to the extension line VL) of the light reflected by the reflector <NUM>-<NUM> are equal to each other, the sensor receiver <NUM>-<NUM> is required to be disposed on the optical path of the reflected light F1c. That is, as described above, if the sensor receiver <NUM>-<NUM> can be disposed, for example, as illustrated in <FIG>, the reflective surface of the reflector <NUM>-<NUM> may be disposed so as to incline with respect to the depth direction D. At this time, the extension line VL also inclines with respect to the width direction W.

In addition, in the above-described modification, the sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> are separated in the depth direction D, but may instead, or in addition, be spaced apart from each other in the up-down direction H. Further, if the angle of the reflector <NUM>-<NUM> is appropriately adjusted, it may be arranged at a three dimensionally spaced position separated in each of the width direction W, the vertical direction H, and the depth direction. In this way, the arrangement of the sensor transmitter <NUM>-<NUM>, the sensor receiver <NUM>-<NUM>, and the reflector <NUM>-<NUM> has a high degree of freedom.

<FIG> illustrates a third modified example of the object detection apparatus <NUM> according to the embodiment. The sensor 16d of an object detection apparatus 50d illustrated in <FIG> is different from the sensor 16c of the second modification in that the reflector <NUM>-<NUM> is a prism <NUM>-3p. The sensor transmitter <NUM>-<NUM> and the sensor receiver <NUM>-<NUM> are disposed in one side of the discharge port <NUM>, and the prism <NUM>-3p (reflection portion <NUM>-<NUM>) is disposed in the other side of the discharge port <NUM> in the width direction W. Then, as shown in <FIG>, the light entering from an irradiation direction substantially orthogonal to the prism <NUM>-3p (direct light F1a) is reflected in the prism <NUM>-3p and returns to the sensor receiver <NUM>-<NUM> from the reflection direction at a substantially right angle, by utilizing the properties of the incident angle and the reflection angle of the prism <NUM>-3p. Therefore, when the object B is present in the detection target range, either the direct light F1a emitted from the sensor transmitter <NUM>-<NUM> or the reflected light F1c reflected by the prism <NUM>-3p thereafter is blocked by the object B. Therefore, the light from the sensor transmitter <NUM>-<NUM> does not return to the sensor receiver <NUM>-<NUM>, and the sensor 16d correctly recognizes that the object is present.

As shown in <FIG>, even if the direct light F1a is reflected at a location other than the object B, and the reflected light Fb1 enters the prism <NUM>-3p, the reflected light Fb1 enters the prism <NUM>-3p at a predetermined angle with respect to the irradiation direction, and therefore the reflected light F1c reflected by the prism <NUM>-3p does not travel toward the sensor receiver <NUM>-<NUM> and is attenuated or diverged.

According to this configuration, since the light is reflected by the prism <NUM>-3p, even when the light is reflected at any location in the discharge port <NUM> and is not blocked by the object B, the light other than the light entering the prism <NUM>-3p in the prescribed direction can be set so as not to return to the sensor receiver <NUM>-<NUM>. Accordingly, it is possible to detect the object B of the discharge port <NUM> with high accuracy.

As described above, in the object detection apparatus <NUM> according to the second modified example and the third modified example, the arrangement of the sensor transmitter <NUM>-<NUM>, the sensor receiver <NUM>-<NUM>, and the reflector <NUM>-<NUM> can be compactly accommodated.

In the above-described embodiment, the post-processing apparatus <NUM> is separate from the image forming apparatus <NUM>. However, the post-processing apparatus <NUM> may be an image forming apparatus having an in-body finisher in a main housing of the image forming apparatus <NUM> and relevant aspects of post-processing apparatus <NUM> can be applied to such an in-body finisher. The post-processing apparatus <NUM> includes a stapler as a sheet binding processing unit. However, the post-processing apparatus <NUM> may also or instead include a sheet binding processing unit using an adhesive tape.

According to at least one embodiment described above, the sensor <NUM> of the object detection apparatus <NUM> of the post-processing apparatus <NUM> includes the sensor transmitter <NUM>-<NUM>, the reflector <NUM>-<NUM>, and the sensor receiver <NUM>-<NUM>, thereby suppressing the occurrence of erroneous detection due to the reflected light reflected by the sheet S, and detecting the object B of the discharge port <NUM> with high accuracy.

Claim 1:
A post-processing apparatus (<NUM>), comprising:
a post-processing unit (<NUM>) configured to receive sheets (S) from an image forming apparatus (<NUM>), perform processing on the received sheets (S), and then discharge the processed sheets (S) through a discharge port (<NUM>);
a sensor (<NUM>) configured to detect a presence of an object (B) at the discharge port (<NUM>), the sensor (<NUM>) comprising:
a first light emitter (<NUM>-<NUM>) on a first side of the discharge port (<NUM>) and positioned to emit a light across a width of the discharge port (<NUM>),
a reflector (<NUM>-<NUM>), and
a first light receiver (<NUM>-<NUM>) positioned to receive light of the first light emitter (<NUM>-<NUM>) from the reflector (<NUM>-<NUM>); and
a controller (<NUM>) configured to terminate the processing on the received sheets (S) by the post-processing unit (<NUM>) when the sensor (<NUM>) detects the presence of the object (B) at the discharge port (<NUM>), characterized in that
the reflector (<NUM>-<NUM>) is on a second side of the discharge port (<NUM>) opposite the first side in a first direction corresponding to a width direction (W) of a discharged sheet (S).