JPH07270475A - Unit detection device - Google Patents

Abstract

PURPOSE:To reduce the number of cords and easily replace wiring upon occurrence of a break by detecting a unit not mounted on a body on the basis of a signal determined for every sensor and a signal outputted in synthesized state from both ends of each of a plurality of sensors connected in series. CONSTITUTION:The detecting section of a sensor 2 has a photo interrupter 3 formed out of a light emitting section 31 and a light receiving section 32. A unit 20 corresponding to the photo interrupter 3 is provided with a shading section 21 and light is shaded, when the unit 20 is mounted at a prescribed position. When the section 32 is exposed to light, a low impedance appears, and a low level voltage is applied to the input end of a Schmitt trigger 4. As a result, the trigger 4 outputs a prescribed low level voltage to a terminal T2. On the other hand, when the section 32 is shaded against light, a high impedance appears and a high level voltage is applied to the input end of the trigger 4. Then, the trigger 4 outputs the prescribed high level voltage V.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a unit detecting device for detecting whether or not each part of a unitized device is mounted on the device.

[0002]

2. Description of the Related Art Conventionally, there is an apparatus configured so that each part of the apparatus is unitized and the unit is exchanged as needed. For example, some laser beam printers include an exposure unit, a development unit, a transfer unit, a charge removal unit, and a fixing unit as detachable units. As described above, when each unit of the apparatus is provided with a detachably configured unit, it becomes necessary to detect whether or not all the units are attached to the apparatus. For this reason, a sensor is provided in the mounting portion of each unit. Each sensor detects the presence or absence of the unit and transfers the information to the control unit of the device.

[0003]

FIG. 7 is a schematic block diagram for explaining the relationship between the sensor provided in the mounting portion of each unit and the control unit of the apparatus in the apparatus 100 as described above. Sensors SA to SZ are provided in each of the unit mounting parts of the device 100, and each of them is a control part 1.
01 is connected by a signal line. In the case of such a configuration, since all the sensors SA to SZ are respectively connected to the control unit, many cords are concentrated in one place, and when a disconnection occurs between the sensor and the control unit, the device There has been a problem that the wiring stretched inside has to be replaced, which makes the work extremely complicated.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a unit detecting device and a sensor connecting method in which the number of cords is relatively small and the wiring can be easily replaced when a trouble such as disconnection occurs. Is.

Therefore, the unit detecting device of the present invention is a plurality of sensor means connected in series, and detects whether or not the plurality of units are respectively mounted on the main body, and mounts them. If not, the one outputting a predetermined signal different from each other, which is determined for each sensor means, and the predetermined one output in a combined state from both ends of the plurality of sensors connected in series. And a detection unit that detects an unattached unit based on the signal.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a schematic structure of a unit detecting device to which the present invention is applied. In the present invention, the sensor S
1 to Sn are connected in series, and only the sensors S1 and Sn located at both ends of the sensors connected in series are connected to the control unit 11 of the apparatus. The details of the apparatus and the sensor connection method will be described below with reference to FIGS. 2 to 5.

FIG. 2 is a diagram showing the circuit configuration of one of the sensors 2 shown in FIG. 1 taken out. Sensor 2 is
It is divided into three parts: a detection part, a voltage application part, and a circuit part. The detection unit has a photo interrupter 3 including a light emitting unit 31 and a light receiving unit 32. The unit side 20 corresponding to the photo interrupter 3 is provided with a light shielding unit 21, and when the unit 20 is mounted at a predetermined position, the light shielding unit 21 enters between the light projecting unit 31 and the light receiving unit 32. (Shown by a one-dot chain line in the figure), it is configured to block light.

The Schmitt trigger 4 is connected to one end of the light receiving section 32 in the voltage applying section. In the state where the light receiving section 32 receives light (the state where the unit 20 is not attached to the device), the light receiving section 32 has a low impedance, and a low level voltage is applied to the input end of the Schmitt trigger 4. At this time, the Schmitt trigger 4 outputs a predetermined low level voltage to the terminal T2 (0V in the embodiment). When the light receiving unit 32 does not receive light (when the unit 20 is attached to the device), the light receiving unit 32 has a high impedance, and a high level voltage is applied to the input end of the Schmitt trigger 4. At this time, the Schmitt trigger 4 outputs a predetermined high-level voltage V.

The circuit section includes two sets of connector sections A and B.
Is provided. The connector parts A and B have three connection terminals A1 to A3 and B1 to B3, respectively. The connection terminal A1 is connected to the terminal T1. The connection terminal A2 is connected to the terminal T2 via a resistor 5 having a predetermined resistance value 2R. The connection terminal A3 is connected to the terminal T3. The connection terminal B1 is connected to the connection terminal A1. The connection terminal B2 is connected to the connection terminal A2 via a resistor 6 having a predetermined resistance value R. The connection terminal B3 is connected to the connection terminal A3. Connection terminal A1
-A3 is connected to the connection terminals B1-B3 at the next stage, respectively. That is, wiring of the sensor is completed only by connecting the connector portion A and the connector portion B of another sensor.

It should be noted that the connector portions of the sensors (the connector portion 7 of the sensor S1 and the connector portion 8 of the sensor Sn in FIG. 1) located at both ends of the sensors connected in series and not connected to other sensors are the control portions. 11 (see FIG. 1).

FIG. 3 is a schematic view showing a state in which the sensor 2 configured as described above is connected. By connecting the sensors, an R-2R ladder circuit is constructed as shown in the figure. In addition, 2A in the drawing corresponds to the detection unit and the voltage application unit of each sensor. A disconnection detection circuit (described later) provided on the control unit side is further connected in series to the sensors connected in series, and is connected to the detection means 12.

FIG. 4 is a circuit diagram corresponding to the state where the sensors are connected in series. The disconnection detection circuit 40 described above is connected to the last stage of the circuit. The disconnection detection circuit 40 is provided in the control unit 11 and is connected to the connector unit 8 of the last sensor. The connection terminal B2 of the connector portion 8 of the sensor Sn has two resistors 4 each having a predetermined resistance value 2R.
1, 42 are connected. The other end of the resistor 41 has the control unit 11
Is connected to the switch S0 that is switched by the control signal of, and is connected to the connection terminal B1 or B3.

In the circuit constructed as shown in FIG. 4, k
Only the th (kth) switch Sk is turned on,
Consider the case where all others are OFF. in this case,
The circuit shown in FIG. 4 is equivalent to the circuit shown in FIG. 5, and the potential at the point a becomes V / 2 \ tk \ t (according to the Ho-Thevenin principle). In other words, a voltage value weighted according to the number of stages of the switch being turned on appears at the point a. The above has described only the case where a certain switch is turned on, but when a plurality of switches are turned on, the weighting is performed according to the number of stages of each switch by the reason of overlapping. The sum of voltage values appears at point a.

The sum of the weighted voltages obtained as described above is input to the detection circuit 12 shown in FIG. 3 to identify which sensor is turned on. That is,
From the voltage value at the point a in the circuit of FIG. 4, it is possible to identify the unit that has not been mounted.

In the circuit of FIG. 4, the switch S0 at the last stage does not depend on whether or not the unit is mounted, but the control means 1
The switch is turned on / off by 1. In the circuit of FIG. 4, assuming that the switch S0 is the nth (nth stage) switch, the voltage value appearing at the point a is V when the switch S0 is ON and when it is not.
The difference of / 2 \ tn \ t occurs. However, this difference in voltage value when the switch S0 is switched does not occur (or does not take this value) when the circuit is broken. Therefore, it is possible to detect whether or not the circuit is normal by turning on the switch S0 and then turning it off, measuring the difference between the voltage values at the point a in both cases, and determining whether or not the voltage reaches a predetermined value. That is, the disconnection detection circuit 40 enables self-diagnosis.

FIG. 6 shows an A / D converter 13 connected to the circuit as the detecting means 12 of the circuit of FIG. As described above, since the voltage at the point a is a value weighted for each sensor, it is A / D converted and n-bit 2
It can be converted to a base number. In this case, since the binary numbers representing the mounted states of all the units are 1 and 0, the mounted states of all the units can be known at the same time. Further, since ON / OFF of the switch S0 corresponds to the minimum bit of the A / D-converted n-bit binary number, it can be easily determined whether the circuit is normal or not.

[0016]

As described above, according to the unit detection device of the present invention, the wiring in the device can be simplified by connecting a plurality of sensor means in series. Also,
It also becomes very easy to take measures such as disconnection of the wiring connecting the sensor means. Further, since it has a self-diagnosis function, it is possible to easily detect whether or not the detection device itself is functioning normally, as well as detecting whether the unit is mounted or not mounted.

[Brief description of drawings]

FIG. 1 is a diagram showing a sensor connection state in a unit detection device of the present invention.

FIG. 2 is a circuit diagram showing a circuit configuration of a sensor.

FIG. 3 is a simplified circuit diagram showing a connection state of sensors.

FIG. 4 is a circuit diagram equivalent to a state in which a sensor is connected.

FIG. 5 is a circuit diagram when only the k-th stage sensor is turned on.

FIG. 6 is an example in which an A / D converter is further connected to the circuit of FIG.

FIG. 7 is a diagram showing a sensor connection structure of a conventional detection device.

[Explanation of symbols]

 2 sensor 3 photo interrupter 5 resistance (resistance value: 2R) 6 resistance (resistance value: R) 7 connector 8 connector 11 control means 20 unit 21 light-shielding portion 40 disconnection detection circuit S1, S2, ..., Sn sensor means

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[Procedure amendment]

[Submission date] February 3, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

In the circuit constructed as shown in FIG. 4, k
Only the th (kth) switch Sk is turned on,
Consider the case where all others are OFF. in this case,
The circuit shown in FIG. 4 is equivalent to the circuit shown in FIG. 5, and the potential at the point a becomes V / 2k (according to the Feng-Thevenin principle). In other words, a voltage value weighted according to the number of stages of the switch being turned on appears at the point a. There is one above
Only the case where one switch is turned on has been described, but when a plurality of switches are turned on, the sum of the voltage values weighted according to which stage each switch is, by the reason of superposition. Appears at point a.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

Claims (9)

[Claims] 1. A plurality of sensor means connected in series, each of which detects whether or not a plurality of units are attached to a main body, and when not attached, is determined for each sensor means. And a detection means for detecting an unattached unit based on the predetermined signals output in a combined state from both ends of the plurality of sensors connected in series. And a unit detection device having. 2. The unit detection device according to claim 1, wherein the predetermined signals different from each other defined for each of the sensor means have predetermined voltage values different from each other. 3. The predetermined signal is a voltage value obtained by weighting a reference voltage value with a power of 1/2.
The unit detection device according to claim 1. 4. A D / which converts the digital data represented by a binary number in which the mounting / non-mounting of the plurality of units corresponds to 1/0 into an analog value by the plurality of sensor means connected in series. The unit detection device according to claim 1, wherein the unit detection device constitutes an A converter. 5. An information adding unit that is connected in series to the serially connected sensor unit and that adds the least significant bit to the binary number, and a control unit that changes the value of the least significant bit. 5. The detecting means diagnoses whether or not the device is functioning normally by checking whether or not the D / A conversion is correctly performed in response to the change in the least significant bit. Unit detection device. 6. The unit detecting device according to claim 1, wherein each of the plurality of sensor means outputs the predetermined signal only when all of them are connected in series. apparatus. 7. The unit detection device according to claim 3, wherein the detection means has a self-diagnosis means for diagnosing whether or not the detection is properly performed. 8. The self-diagnosis means is smaller than the weighted voltage value output from the sensor means, 1 /
The device has a voltage output circuit capable of outputting a voltage value weighted by a power of 2, and the device normally functions depending on whether or not the voltage received by the receiving means changes by a predetermined amount when the voltage output circuit is turned on / off. The unit detection device according to claim 7, wherein it is determined whether or not to perform. 9. The sensor means detects a presence / absence of a unit, a circuit portion which constitutes a ladder D / A conversion circuit when the sensor means is connected in series, and a detection portion of the detector. A voltage applying unit that applies a predetermined voltage to the circuit unit according to a result, and a voltage applying unit.
9. The unit detection device according to any one of 1 to 8.