Reflective sensor

Abstract

To provide a reflective sensor capable of improving detection accuracy.SOLUTION: A reflective sensor 100 includes: a light emitting unit 141 that irradiates a measuring object with irradiation light; light reception units 151, 152 for receiving reflected light from an object to be measured with respect to the irradiation light and outputting a voltage signal corresponding to an amount of received light; and output units 161, 162 for outputting to a predetermined control device 200 an output signal generated on the basis of the voltage signal. A first voltage value, which is a power supply voltage value of the light reception units 151, 152 is greater than a second voltage value, which is a power supply voltage value of the control device 200. The output units 161, 162 generate an output signal in which the voltage signal is stepped down to or less than the second voltage value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a reflection type sensor.

Background Art

[0002] As a conventional reflection type sensor, for example, the one described in Patent Document 1 is known. The reflection type sensor described in Patent Document 1 includes a light emitting diode that irradiates light to a measurement object, a first photodiode (PD1) that receives an S-wave component of reflected light from the measurement object with respect to the irradiated light, and a second photodiode (PD2) that receives a P-wave component of the reflected light. The first photodiode (PD1) and the second photodiode (PD2) include an amplifier circuit for output amplification.

[0003] The reflection type sensor described in Patent Document 1 is used, for example, as a media sensor that measures the basis weight and glossiness of printing paper, which is a measurement object, in an image forming apparatus such as a copying machine or a multifunction peripheral. The output of the first photodiode (PD1) has a correlation with the basis weight of the printing paper, and the output of the first photodiode (PD1) tends to increase as the basis weight of the printing paper increases. The output of the second photodiode (PD2) has a correlation with the glossiness of the printing paper, and the output of the second photodiode (PD2) tends to increase as the glossiness of the printing paper increases.

[0004] By the way, in the reflection type sensor described in Patent Document 1, there is a problem that the dynamic range of the voltage signal (first voltage signal) output from the amplifier circuit of the first photodiode (PD1) and the dynamic range of the voltage signal (second voltage signal) output from the amplifier circuit of the second photodiode (PD2) are narrow.

[0005] The first voltage signal and the second voltage signal are input to the microcomputer of the image forming apparatus. However, since the power supply voltage of the microcomputer is mainly 3.0 [V] or 5.0 [V], it is necessary to make the voltage values of the first voltage signal and the second voltage signal equal to or lower than the power supply voltage value of the microcomputer. As a result, the dynamic range of the first voltage signal and the second voltage signal becomes narrow. On the other hand, if the voltage values of the first voltage signal and the second voltage signal are larger than the power supply voltage value of the microcomputer, the microcomputer may not operate normally.

[0006] Fig. 7 shows the relationship between the second voltage signal and the glossiness of the printing paper. There are types of printing paper corresponding to the glossiness. For example, printing paper with a glossiness of less than 20 is plain paper, printing paper with a glossiness of 20 or more and less than 40 is the first intermediate paper, printing paper with a glossiness of 40 or more and less than 60 is the second intermediate paper, and printing paper with a glossiness of 60 or more is classified as glossy paper. Since there is a correlation between the voltage value of the second voltage signal and the glossiness of the printing paper, the microcomputer of the image forming apparatus can determine the type of the printing paper based on the voltage value of the second voltage signal.

[0007] However, the dynamic range of the second voltage signal is as narrow as about 1.5 [V]. In particular, the dynamic range required to distinguish between the first intermediate paper and the second intermediate paper is very narrow, about 0.1 [V]. In addition, for the reflection type sensor, the voltage value of the second voltage signal varies depending on the mounting position (for example, mounting angle, distance from the measurement target) in the image forming apparatus.

[0008] If the variation is large (for example, larger than 0.1 [V]), the microcomputer of the image forming apparatus may misjudge the type of the printing paper. For example, the microcomputer may misjudge the first intermediate paper as the second intermediate paper or misjudge the second intermediate paper as the first intermediate paper.

[0009] As described above, the conventional reflection type sensor has a narrow dynamic range and low detection accuracy, so there is a risk of misjudging the type of the printing paper.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] The present invention has been made in view of the above circumstances, and an object thereof is to provide a reflection type sensor capable of improving detection accuracy.

Means for Solving the Problems

[0012] In order to solve the above problems, a reflection type sensor according to the present invention includes: a light emitting unit that irradiates light to a measurement object; a light receiving unit that receives reflected light from the measurement object with respect to the irradiated light and outputs a voltage signal corresponding to the received light amount; an output unit that outputs an output signal generated based on the voltage signal to a predetermined control device; and is a reflection type sensor comprising: a first voltage value that is a power supply voltage value of the light receiving unit is larger than a second voltage value that is a power supply voltage value of the control device; the output unit is characterized in that it generates the output signal obtained by stepping down the voltage signal to equal to or lower than the second voltage value.

[0013] Normally, the power supply voltage value of the light receiving unit and the power supply voltage value of the control device (for example, the microcomputer of the image forming apparatus) are the same value, but in this configuration, the first voltage value that is the power supply voltage value of the light receiving unit is made larger than the second voltage value that is the power supply voltage value of the control device. Thereby, the dynamic range of the voltage signal output by the light receiving unit can be expanded. Further, in this configuration, since the voltage signal is stepped down to equal to or lower than the second voltage value by the output unit and the stepped-down output signal is input to the control device, it is possible to avoid the control device from malfunctioning.

[0014] In the reflection type sensor, the light receiving unit a light receiving element that receives the reflected light; an amplification circuit that amplifies the output of the light receiving element to generate the voltage signal; and includes the output unit includes a subtraction circuit that generates a subtraction signal obtained by subtracting the voltage signal by a predetermined voltage value; a step-down circuit that step-downs the subtraction signal to generate the output signal; and can be configured to include

[0015] In the reflection type sensor, when the region of the dynamic range of the voltage signal is defined as a first area, a second area, a third area, and a fourth area in order from the lower voltage value side, the subtraction circuit sets the predetermined voltage value to a voltage value included in the first area; the step-down circuit can be configured to step-down the subtraction signal so that the voltage width of the fourth area is reduced.

[0016] In the reflection type sensor, the step-down circuit can be configured to step-down the subtraction signal so that the maximum value of the subtraction signal in the first area becomes zero and / or the minimum value of the subtraction signal in the fourth area becomes the second voltage value.

[0017] In the reflection type sensor, the light receiving unit includes a first light receiving unit that receives the S-wave component of the reflected light and the amplification circuit, and a second light receiving unit that receives the P-wave component of the reflected light and the amplification circuit; the output unit includes a first output unit that generates the output signal based on the voltage signal input from the first light receiving unit, and a second output unit that generates the output signal based on the voltage signal input from the second light receiving unit; the first output unit includes the subtraction circuit and outputs the output of the subtraction circuit as the output signal, or further includes the step-down circuit and outputs the output of the step-down circuit as the output signal, while The second output unit includes the subtraction circuit and the step-down circuit, and can be configured to output the output of the step-down circuit as the output signal.

Effects of the Invention

[0018] According to the present invention, it is possible to provide a reflection type sensor capable of improving detection accuracy.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0020] Hereinafter, embodiments of the reflection type sensor according to the present invention will be described with reference to the accompanying drawings.

[0021] [First Embodiment] Figures 1 and 2 show a reflection type sensor 100 according to a first embodiment of the present invention. The reflection type sensor 100 is used as a media sensor for measuring the basis weight and glossiness of printing paper, which is an object to be measured, in an image forming apparatus such as a copying machine or a multifunction peripheral.

[0022] The reflection type sensor 100 includes a substrate 110, a lens holder 120 (including a light shielding wall 127a), a lens 130, a light emitting unit 141, a first light receiving unit 151 and a second light receiving unit 152, and a first output unit 161 and a second output unit 162.

[0023] The output signal (first output signal) output from the first output unit 161 and the output signal (second output signal) output from the second output unit 162 are input to a microcomputer 200 provided in the image forming apparatus. The microcomputer 200 corresponds to the control device of the present invention and is supplied with a power supply voltage of a second voltage value (5.0 [V] in this embodiment).

[0024] The substrate 110 is, for example, a rectangular printed wiring board. The light emitting unit 141, the first light receiving unit 151 and the second light receiving unit 152, and the first output unit 161 and the second output unit 162 are arranged on the upper surface (front surface) of the substrate 110. As shown in FIG. 2, the first light receiving unit 151 and the second light receiving unit 152 are arranged side by side in the longitudinal direction of the substrate 110, and are arranged in the lateral direction of the substrate 110 with the light shielding wall 127a interposed therebetween with respect to the light emitting unit 141.

[0025] The lens holder 120 is made of a material that is opaque to the irradiation light irradiated from the light emitting unit 141 and reflects the irradiation light. The lens holder 120 is arranged on the substrate 110, has a first accommodating portion 121, a second accommodating portion 122, and a third accommodating portion 123 on the lower surface side (rear surface), and has a lens fixing portion 124 on the upper surface side (front surface side).

[0026] The first accommodating portion 121 forms a first accommodation space on the substrate 110 and accommodates the light emitting portion 141 in the first accommodation space. The second accommodating portion 122 forms a second accommodation space on the substrate 110 and accommodates the first light receiving portion 151 and the second light receiving portion 152 in the second accommodation space. The third accommodating portion 123 forms a third accommodation space on the substrate 110 and accommodates the first output portion 161 and the second output portion 162 in the third accommodation space. The lens fixing portion 124 is configured in a shape capable of fixing the lens 130.

[0027] Further, the lens holder 120 has a first opening 125 connected to the first accommodating portion 121, a second opening 126 connected to the second accommodating portion 122, and a light shielding portion 127 positioned between the first opening 125 and the second opening 126.

[0028] The first opening 125 is positioned above the light emitting portion 141 and functions as a diaphragm portion that restricts the irradiation range of the irradiation light of the light emitting portion 141. A first polarizing filter 171 is provided at the upper end of the first opening 125. The first polarizing filter 171 is a P-wave transmission polarizing filter that shields the S-wave component of the irradiation light and transmits the P-wave component.

[0029] The second opening 126 is formed to be substantially the same size as the second accommodating portion 122. The second opening 126 and the second accommodating portion 122 may be constituted by one through hole. At the upper end of the second opening 126, a second polarizing filter 172 positioned above the first light receiving portion 151 and a third polarizing filter 173 positioned above the second light receiving portion 152 are provided. The second polarizing filter 172 is an S-wave transmission polarizing filter that shields the P-wave component of the reflected light from the measurement object and transmits the S-wave component. The third polarizing filter 173 is a P-wave transmission polarizing filter.

[0030] The light-shielding portion 127 has an upper part protruding into the lens 130 and can block the irradiation light propagating within the lens 130. Meanwhile, the lower part is fitted into the through-hole of the substrate 110 and can block the irradiation light propagating within the substrate 110. The upper end portion of the light-shielding portion 127 corresponds to the light-shielding wall 127a and is formed by protruding the light-shielding portion 127 up to the upper surface (front surface) of the lens 130. The light-shielding wall 127a blocks a part of the reflected light received by the first light-receiving portion 151 and also blocks a part of the reflected light received by the second light-receiving portion 152. Note that the light-shielding wall 127a may be formed as a separate member from the light-shielding portion 127.

[0031] The lens 130 is made of a material transparent to the irradiation light of the light-emitting portion 141 and is fixed to the lens fixing portion 124 of the lens holder 120. The lens 130 has a convex lens portion 131 on the upper surface side (front surface side), and a light-emitting lens portion 132 and a light-receiving lens portion 133 on the lower surface side (back surface side).

[0032] The convex lens portion 131 faces the light-emitting lens portion 132 and the light-receiving lens portion 133 on the lower surface side. The upper surface of the convex lens portion 131 is flat, and the length of the convex lens portion 131 in the width direction (vertical direction) is larger than the length of the light-shielding wall 127a in the width direction. The light-emitting lens portion 132 is located above the light-emitting portion 141 and condenses the irradiation light of the light-emitting portion 141. Meanwhile, the light-receiving lens portion 133 is located above the first light-receiving portion 151 and the second light-receiving portion 152 and condenses the reflected light from the printing paper, which is the measurement object. Due to the relationship of narrowing the light through the cylindrical opening (first opening 125) of the lens holder 120, the light-emitting lens portion 132 is formed at a higher position than the light-receiving lens portion 133.

[0033] The light-emitting portion 141 includes a light-emitting element and irradiates the printing paper, which is the measurement object, with irradiation light through the first polarizing filter 171 and the lens 130. As the light-emitting element of the light-emitting portion 141, for example, an infrared light-emitting diode (infrared LED) that irradiates infrared rays or a red light-emitting diode (red LED) that irradiates red light can be used.

[0034] The first light-receiving unit 151 receives the S-wave component of the reflected light and outputs a voltage signal (first voltage signal) corresponding to the received light amount. As shown in FIG. 3, the first light-receiving unit 151 includes a first photodiode PD1 (corresponding to the "first light-receiving element" of the present invention) that receives the S-wave component of the reflected light, and an amplifier circuit that amplifies the output of the first photodiode PD1 to generate a first voltage signal.

[0035] The amplifier circuit of the first light-receiving unit 151 includes a first operational amplifier IC1 and a first T-type feedback circuit. The first photodiode PD1 is connected between the inverting input terminal and the non-inverting input terminal of the first operational amplifier IC1. A power supply voltage of a first voltage value is supplied from the DC power supply Vcc to the positive power supply terminal of the first operational amplifier IC1, while the negative power supply terminal of the first operational amplifier IC1 is connected to the ground. The first voltage value is larger than the second voltage value (5.0 [V] in this embodiment), which is the power supply voltage value of the microcomputer 200, and is 24.0 [V] in this embodiment.

[0036] The first T-type feedback circuit is composed of resistors R1 to R3 and a capacitor C1. By using the first T-type feedback circuit, the amplifier circuit of the first light-receiving unit 151 can achieve a desired amplification factor without increasing the size of the circuit.

[0037] The second light-receiving unit 152 receives the P-wave component of the reflected light and outputs a voltage signal (second voltage signal) corresponding to the received light amount. The second light-receiving unit 152 includes a second photodiode PD2 (corresponding to the "second light-receiving element" of the present invention) that receives the P-wave component of the reflected light, and an amplifier circuit that amplifies the output of the second photodiode PD2 to generate a second voltage signal.

[0038] The amplifier circuit of the second light-receiving unit 152 includes a second operational amplifier IC2 and a second T-type feedback circuit. The second photodiode PD2 is connected between the inverting input terminal and the non-inverting input terminal of the second operational amplifier IC2. A power supply voltage of the first voltage value (24.0 [V] in this embodiment) is supplied from the DC power supply Vcc to the positive power supply terminal of the second operational amplifier IC2, while the negative power supply terminal of the second operational amplifier IC2 is connected to the ground.

[0039] The second T-type feedback circuit has the same circuit configuration as the first T-type feedback circuit, and is composed of resistors R4 to R6 and a capacitor C2. By using the second T-type feedback circuit, the amplifier circuit of the second light receiving unit 152 can achieve a desired amplification factor without increasing the size of the circuit.

[0040] The first output unit 161 is composed of a subtraction circuit (first subtraction circuit) that generates a subtraction signal, and generates a first output signal (subtraction signal) obtained by stepping down the first voltage signal to a value equal to or less than the second voltage value.

[0041] The first subtraction circuit is composed of a third operational amplifier IC3 and resistors R7 to R10. The inverting input terminal of the third operational amplifier IC3 is connected to the connection point between the other end of resistor R7 and one end of resistor R8. One end of resistor R7 is connected to the voltage division point of the voltage division resistor circuit composed of resistors R11 and R12, and the voltage division resistor circuit is connected across the DC power supply Vcc. The voltage division resistor circuit composed of resistors R11 and R12 may be included in the first subtraction circuit. The other end of resistor R8 is connected to the output terminal of the third operational amplifier IC3, that is, the first output terminal T1 of the first subtraction circuit.

[0042] The non-inverting input terminal of the third operational amplifier IC3 is connected to the connection point between the other end of resistor R9 and one end of resistor R10. One end of resistor R9 is connected to the output terminal of the first operational amplifier IC1 included in the first light receiving unit 151, and the other end of resistor R10 is connected to the ground. A power supply voltage of the first voltage value (24.0 [V] in this embodiment) is supplied from the DC power supply Vcc to the positive power supply terminal of the third operational amplifier IC3, while the negative power supply terminal of the third operational amplifier IC3 is connected to the ground.

[0043] The first subtraction circuit generates a subtraction signal obtained by subtracting a predetermined voltage value (12.0 [V] in this embodiment) from the first voltage signal input from the first light receiving unit 151, and outputs the subtraction signal as the first output signal from the first output terminal T1. The first output signal output from the first output terminal T1 is input to the microcomputer 200 provided in the image forming apparatus.

[0044] The second output unit 162 includes a subtraction circuit (second subtraction circuit 163) that generates a subtraction signal, and a step-down circuit (second step-down circuit 164) that step-downs the subtraction signal to generate a second output signal, and generates a second output signal obtained by step-down the second voltage signal to a value equal to or less than the second voltage value.

[0045] The second subtraction circuit 163 includes a fourth operational amplifier IC4 and resistors R13 to R16, and has the same circuit configuration as the first subtraction circuit. The second step-down circuit 164 is configured by a voltage dividing resistor circuit including resistors R17 and R18. The voltage dividing resistor circuit including resistors R17 and R18 has one end connected to the output terminal of the second subtraction circuit 163 (the output terminal of the fourth operational amplifier IC4), the other end connected to the ground, and the voltage dividing point connected to the second output terminal T2.

[0046] The second subtraction circuit 163 generates a subtraction signal obtained by subtracting a predetermined voltage value (18.0 [V] in this embodiment) from the second voltage signal input from the second light receiving unit 152. The second step-down circuit 164 step-downs the subtraction signal so that the voltage value of the subtraction signal becomes equal to or less than the second voltage value (5.0 [V] in this embodiment), and outputs it from the second output terminal T2 as the second output signal. The second output signal output from the second output terminal T2 is input to a microcomputer 200 provided in the image forming apparatus.

[0047] FIG. 4(A) and FIG. 4(B) show the relationship between the first voltage signal and the basis weight of the printing paper. FIG. 4(A) shows the detection result of the conventional reflection type sensor, and FIG. 4(B) shows the detection result of the reflection type sensor 100 according to this embodiment.

[0048] The conventional reflection type sensor is different from the reflection type sensor 100 according to this embodiment in that the voltage value of the power supply voltage supplied to the first light receiving unit 151 and the second light receiving unit 152 is 5.0 [V], the first light receiving unit 151 does not include a first T-type feedback circuit, the second light receiving unit 152 does not include a second T-type feedback circuit, and the first output unit 161 and the second output unit 162 are not provided.

[0049] As can be seen from FIGS. 4(A) and 4(B), the first voltage signal has a correlation with the basis weight of the printing paper, and the greater the basis weight of the printing paper, the greater the voltage value of the first voltage signal tends to be. Note that the curve Y1' shown in FIG. 4(A) and the curve Y1 shown in FIG. 4(B) are approximate lines of the detection results.

[0050] In the conventional reflection sensor, the dynamic range of the first voltage signal is as narrow as about 0.3 [V], whereas in the reflection sensor 100, the dynamic range of the first voltage signal is significantly extended to about 3.3 [V]. Thereby, in the reflection sensor 100, the variation in the voltage value of the first voltage signal due to the mounting position of the reflection sensor 100 (for example, mounting angle, distance from the measurement target) in the image forming apparatus can be made relatively small with respect to the dynamic range of the first voltage signal.

[0051] In the reflection sensor 100, the minimum value of the first voltage signal is 12.3 [V] and the maximum value is 15.6 [V], but the first voltage signal is subtracted by 12.0 [V] by the first output unit 161 (first subtraction circuit). Thereby, the first output signal input to the microcomputer 200 becomes 5.0 [V] or less, which is the power supply voltage value of the microcomputer 200, so that it is possible to avoid the microcomputer 200 from malfunctioning.

[0052] FIGS. 5(A) and 5(B) show the relationship between the second voltage signal and the glossiness of the printing paper. FIG. 5(A) is the detection result of the conventional reflection sensor, and FIG. 5(B) is the detection result of the reflection sensor 100 according to the present embodiment.

[0053] As can be seen from FIGS. 5(A) and 5(B), the second voltage signal has a correlation with the glossiness of the printing paper, and the greater the glossiness of the printing paper, the greater the voltage value of the second voltage signal tends to be. Note that the straight line Y2' shown in FIG. 5(A) and the straight line Y2 shown in FIG. 5(B) are approximate lines of the detection results.

[0054] Printing papers exist in types according to the glossiness. In the present embodiment, printing papers with a glossiness of less than 20 are plain papers, those with a glossiness of 20 or more and less than 40 are first intermediate papers, those with a glossiness of 40 or more and less than 60 are second intermediate papers, and those with a glossiness of 60 or more are classified as glossy papers. The microcomputer 200 of the image forming apparatus discriminates the type of the printing paper based on the voltage value of the second voltage signal.

[0055] In a conventional reflection type sensor, the dynamic range of the second voltage signal is as narrow as about 1.5 [V], whereas in the reflection type sensor 100, the dynamic range of the second voltage signal is significantly extended up to about 11.0 [V]. In particular, the dynamic range required for differentiating between the first intermediate paper and the second intermediate paper is extended from about 0.1 [V] to about 1.8 [V]. Thereby, in the reflection type sensor 100, the variation in the voltage value of the second voltage signal due to the mounting position of the reflection type sensor 100 within the image forming apparatus can be made relatively small with respect to the dynamic range of the second voltage signal.

[0056] In the reflection type sensor 100, the minimum value of the second voltage signal is 13.0 [V] and the maximum value is 24.0 [V]. The reason why the second voltage signal corresponding to the glossy paper is fixed at 24.0 [V] is that the output upper limit of the amplifier circuit of the second light receiving portion 152 is 24.0 [V].

[0057] In the reflection type sensor 100, when the regions of the dynamic range of the second voltage signal are sequentially set as the first area, the second area, the third area, and the fourth area from the side with a lower voltage value, and plain paper is included in the first area, the first intermediate paper is included in the second area, the second intermediate paper is included in the third area, and the glossy paper is included in the fourth area, the first area is 13.0 [V] or more and less than 18.4 [V], the second area is 18.4 [V] or more and less than 20.0 [V], the third area is 20.0 [V] or more and less than 21.0 [V], and the fourth area is 21.0 [V] or more and 24.0 [V] or less.

[0058] The second voltage signal output from the second light-receiving unit 152 is subtracted by 18.0 [V] by the second subtraction circuit 163. As a result, for example, the second voltage signal corresponding to plain paper shown in FIG. 5(B) becomes a subtraction signal of 0 [V], and the second voltage signal corresponding to glossy paper becomes a subtraction signal of 6.0 [V].

[0059] The second step-down circuit 164 steps down the subtraction signal so that the maximum value of the subtraction signal in the first area becomes 0 [V] and the minimum value of the subtraction signal in the fourth area becomes 5.0 [V]. As a result, the second output signal corresponding to plain paper sticks to 0 [V], and the second output signal corresponding to glossy paper sticks to 5.0 [V]. Consequently, the voltage width of the areas (the second area and the third area) corresponding to the first intermediate paper and the second intermediate paper can be widened.

[0060] Therefore, according to the reflection type sensor 100 according to the present embodiment, the detection accuracy can be improved, and it is possible to avoid the microcomputer 200 from malfunctioning.

[0061] [Second Embodiment] The reflection type sensor according to the second embodiment of the present invention has the same configuration as the reflection type sensor 100 according to the first embodiment, except that it includes a second step-down circuit 164' instead of the second step-down circuit 164.

[0062] FIG. 6 shows a circuit diagram of the second subtraction circuit 163 and the second step-down circuit 164'. The second subtraction circuit 163 is the same circuit as in the first embodiment, and the second step-down circuit 164' is a voltage follower circuit composed of the fifth operational amplifier IC5.

[0063] The non-inverting input terminal of the fifth operational amplifier IC5 is connected to the output terminal of the fourth operational amplifier IC4 of the second subtraction circuit 163, and the inverting input terminal is connected to the output terminal of the fifth operational amplifier IC5. A power supply voltage of a second voltage value (5.0 [V] in this embodiment) is applied between the positive power supply terminal and the negative power supply terminal of the fifth operational amplifier IC5 from a DC power supply V1. As a result, the output of the fifth operational amplifier IC5 is limited to the second voltage value. Note that the fifth operational amplifier IC5 preferably has a breakdown voltage higher than the second voltage value.

[0064] In this embodiment, similar to the first embodiment, the detection accuracy can be improved, and since the second output signal becomes 5.0 [V] or less, which is the power supply voltage value of the microcomputer 200, it is possible to avoid the microcomputer 200 from malfunctioning.

[0065] [Modification Example] As described above, embodiments of the reflection type sensor according to the present invention have been described, but the present invention is not limited to the above embodiments.

[0066] The reflection type sensor according to the present invention includes a light emitting unit that irradiates light to a measurement object, a light receiving unit that receives reflected light from the measurement object with respect to the irradiated light and outputs a voltage signal according to the received light amount, and an output unit that outputs an output signal generated based on the voltage signal to a predetermined control device. In the reflection type sensor, a first voltage value that is the power supply voltage value of the light receiving unit is larger than a second voltage value that is the power supply voltage value of the control device, and the output unit can appropriately change the configuration as long as it generates an output signal obtained by stepping down the voltage signal to be equal to or less than the second voltage value.

[0067] For example, if the reflection type sensor according to the present invention is used as a media sensor that measures only the basis weight of printing paper, the light receiving element of the light receiving unit can be configured by only the first photodiode PD1 that receives the S-wave component of the reflected light.

[0068] If the reflection type sensor according to the present invention is used as a media sensor that measures only the glossiness of printing paper, the light receiving element of the light receiving unit can be configured by only the second photodiode PD2 that receives the P-wave component of the reflected light.

[0069] In the above embodiment, the first light receiving unit 151 and the second light receiving unit 152 are arranged side by side in the vertical direction of the substrate 110, but they may be arranged side by side in the horizontal direction of the substrate 110.

[0070] The subtraction circuit of the present invention can appropriately change the circuit configuration as long as it generates a subtraction signal obtained by subtracting a predetermined voltage value from the voltage signal input from the light receiving unit. Further, it is preferable that the subtraction circuit sets the above-mentioned predetermined voltage value to a voltage value included in the first area of the dynamic range of the voltage signal.

[0071] The step-down circuit of the present invention can appropriately change the circuit configuration as long as it generates an output signal obtained by stepping down the subtraction signal input from the subtraction circuit to a value equal to or less than the second voltage value. Further, it is preferable that the step-down circuit steps down the subtraction signal so that at least the voltage width of the fourth area is reduced.

[0072] In the above embodiment, the second output unit 162 includes a step-down circuit (the second step-down circuit 164 or the second step-down circuit 164'), and the first output unit 161 does not include a step-down circuit. However, the reflection type sensor according to the present invention may include a first output unit including a step-down circuit.

[0073] In the reflection type sensor according to the present invention, if the first voltage value, which is the power supply voltage value of the light receiving unit, is larger than the second voltage value, which is the power supply voltage value of the control device, it can be set to any voltage value. Also, the power supply voltage value of the first light receiving unit and the power supply voltage value of the second light receiving unit can be set to different values. For example, in image forming apparatuses such as copiers and multifunction printers, there are power supplies of 12 [V], 24 [V], 30 [V], etc., so they can be appropriately selected and used.

Explanation of Reference Numerals

[0074] 100 Reflection type sensor 110 Substrate 120 Lens holder 121 First housing portion 122 Second housing portion 123 Third housing portion 124 Lens fixing part 125 First opening 126 Second opening 127 Light-shielding part 127a Light-shielding wall 130 Lens 131 Convex lens part 132 Light-emitting lens part 133 Light-receiving lens part 141 Light-emitting part 151 First light-receiving part 152 Second light-receiving part 161 First output part 162 Second output part 163 Second subtraction circuit 164, 164’ Second step-down circuit 171 First polarizing filter 172 Second polarizing filter 173 Third polarizing filter 200 Microcomputer (control device)

Claims

1. A light-emitting unit that irradiates the object to be measured with irradiation light; A light-receiving unit that receives the reflected light from the object to be measured with respect to the irradiation light and outputs a voltage signal corresponding to the received light amount; An output unit that outputs an output signal generated based on the voltage signal to a predetermined control device; A reflection-type sensor comprising: The output unit: A subtraction circuit that generates a subtraction signal obtained by subtracting the voltage signal by a predetermined voltage value; A step-down circuit that steps down the subtraction signal to generate the output signal, and A first voltage value that is the power supply voltage value of the light-receiving unit is larger than a second voltage value that is the power supply voltage value of the control device, The light-receiving unit outputs the voltage signal larger than the second voltage value to the output unit, The output unit is supplied with the power supply voltage of the first voltage value to the subtraction circuit, and after generating the subtraction signal by subtracting the voltage signal by the predetermined voltage value in the subtraction circuit, the subtraction signal is stepped down to the second voltage value or less in the step-down circuit to generate the output signal. The reflection-type sensor is characterized in that.

2. The light-receiving unit: A light-receiving element that receives the reflected light; An amplification circuit that amplifies the output of the light-receiving element to generate the voltage signal, and The reflection-type sensor according to claim 1, characterized in that it comprises.

3. When the region of the dynamic range of the voltage signal is defined as a first area, a second area, a third area, and a fourth area in order from the lower voltage value side, The subtraction circuit sets the predetermined voltage value to a voltage value included in the first area, The step-down circuit steps down the subtraction signal so that the voltage width of the fourth area is reduced The reflection-type sensor according to claim 2, characterized in that.

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