JP6817479B1 - Reflective sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflective sensor capable of suppressing fluctuation of sensor output according to a distance to a measurement object. SOLUTION: This is a reflection type sensor that irradiates an object to be measured with irradiation light and receives the reflected light from the object to be measured, and is a substrate 110, a light emitting element 140 that irradiates the irradiation light, and an S wave of the reflected light. A first light receiving element 151 for receiving a component, a second light receiving element 152 for receiving a P wave component of reflected light, a lens, and a light shielding wall 170 are provided. The light-shielding wall 170 provides a first reflection region in which a part of the reflected light is shielded and the reflected light can enter the first light receiving element 151 and a second reflection region in which the reflected light can enter the second light receiving element 152. It is characterized in that each ratio of the first reflection region and the second reflection region to the irradiation region of the measurement target becomes larger as the distance to the measurement target becomes larger. [Selection diagram] Fig. 2

Description

The present invention relates to a reflective sensor.

FIG. 5 shows a conventional reflective sensor 300. The reflection type sensor 300 includes a substrate 310, a lens holder 320, a lens 330, a light emitting element 340, and a light receiving element 3513 to 353. In the reflection type sensor 300, the light emitting element 340 irradiates the measurement object with irradiation light, and the light receiving elements 351 and 352 receive the reflected light from the measurement object. The light receiving element 353 is used for measuring the irradiation light amount of the light emitting element 340.

When the reflective sensor 300 is used as a toner adhesion amount sensor, stains such as toner powder and paper dust may adhere to the upper surface of the lens 330. In that case, the dirt adhering to the lens 330 generates the internally reflected light, and the internally reflected light is incident on the light receiving elements 351 and 352.

In this regard, in the reflective sensor described in Patent Document 1, by forming a light-shielding groove on the upper surface side of the lens, the internally reflected light is reflected or refracted, and the internally reflected light is suppressed from being incident on the light receiving element. ing.

Japanese Unexamined Patent Publication No. 2017-116636

By the way, in the conventional reflection type sensor 300, the sensor output (output signals of the light receiving elements 351 and 352) is proportional to the amount of reflected light from the object to be measured. Further, as shown in FIG. 6, the irradiation region of the irradiation light in the measurement object coincides with the first reflection region in which the reflected light can enter the light receiving element 351 of the measurement object. The irradiation region also coincides with the second reflection region where the reflected light can enter the light receiving element 352 of the object to be measured.

The amount of reflected light decreases as the distance from the reflective sensor 300 to the object to be measured increases. This is because the light is attenuated as the distance increases. In FIG. 6, the amount of reflected light becomes large, medium, and small in the order of the distance to the object to be measured, X1, X2, and X3. As described above, the conventional reflective sensor 300 has a problem that the amount of reflected light, that is, the sensor output fluctuates according to the distance to the object to be measured.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a reflective sensor capable of suppressing fluctuations in sensor output according to a distance to a measurement object.

In order to solve the above problems, the reflective sensor according to the present invention is used.
A reflective sensor that irradiates an object to be measured with irradiation light and receives the reflected light from the object to be measured with respect to the irradiation light.
With the board
A light emitting element that irradiates the irradiation light and is arranged on one side in the lateral direction of the substrate surface.
A first light receiving element that receives the S wave component of the reflected light and a second light receiving element that receives the P wave component of the reflected light, which are arranged on the other side of the substrate surface in the lateral direction.
A lens that guides the irradiation light to the measurement object and guides the reflected light to the first light receiving element and the second light receiving element.
A light-shielding wall located between the light-emitting element, the first light-receiving element, and the second light-receiving element,
With
The light-shielding wall shields a part of the reflected light received by the first light-receiving element to limit the first reflection region where the reflected light can enter the first light-receiving element, and the second light-shielding wall. A part of the reflected light received by the light receiving element is shielded to limit the second reflection region where the reflected light can enter the second light receiving element.
The ratio of the second reflective region relative proportions and the irradiation region of the first reflective region to the irradiation region of the irradiation light on the object to be measured, Ri as large name distance to the measurement object is increased,
The first, such that the decrease in the amount of reflected light in response to the increase in the distance to the measurement object is offset by the increase in the ratio of the first reflection region and the increase in the ratio of the second reflection region. The light receiving element and the second light receiving element are arranged side by side in the vertical direction on the surface of the substrate .

According to this configuration, the light-shielding wall limits the first and second reflection regions so that the ratio of the first and second reflection regions to the irradiation region increases as the distance to the object to be measured increases. Therefore, the decrease in the amount of reflected light due to the increase in distance is offset by the increase in the above ratio (the increase in the amount of reflected light due to the increase in the reflective region). Therefore, according to this configuration, it is possible to suppress fluctuations in the sensor output according to the distance to the object to be measured.

In the above reflective sensor,
A lens holder which is arranged on the surface of the substrate and is separated from each other in the lateral direction of the surface of the substrate is formed, and further includes a lens holder on which the lens is arranged on the surface side.
The light emitting element is arranged in the first accommodation space.
The first light receiving element and the second light receiving element are arranged in the second accommodating space.
The light-shielding wall may be formed by projecting a part of the lens holder.

In the above reflective sensor,
The surface of the light-shielding wall and the surface of the lens can be configured to form the same plane.

According to the present invention, it is possible to provide a reflective sensor capable of suppressing fluctuations in sensor output according to a distance to a measurement object.

It is a figure which shows the reflection type sensor of this invention. It is a partial plan view of the reflection type sensor of this invention. It is a figure which shows the relationship between the 1st reflection area and the irradiation area in the reflection type sensor of this invention. It is a figure for demonstrating the basis weight measurement using the reflection type sensor of this invention. It is a figure which shows the conventional reflection type sensor. It is a figure which shows the relationship between the 1st reflection area and the irradiation area in the conventional reflection type sensor.

Hereinafter, embodiments of the reflective sensor according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a reflective sensor 100 according to an embodiment of the present invention, and FIG. 2 shows a partial plan view of the reflective sensor 100. As shown in FIG. 1, the reflection type sensor 100 constitutes the basis weight measuring device 1 together with the control circuit 200. In the present embodiment, the reflection type sensor 100 and the control circuit 200 will be described separately, but the control circuit 200 may be included in the reflection type sensor 100.

The basis weight measuring device 1 is used as a media sensor for discriminating the type of printing paper (corresponding to the “measurement object” of the present invention) in an image forming device such as a laser printer or a multifunction device.

The reflective sensor 100 includes a substrate 110, a lens holder 120, a lens 130, a light emitting element 140, a first light receiving element 151, a second light receiving element 152, a third light receiving element 153, and a signal processing circuit 160. The object to be measured is irradiated with the irradiation light, and the reflected light (first reflected light) from the object to be measured with respect to the irradiation light is received.

The board 110 is, for example, a rectangular printed wiring board. A light emitting element 140, a first light receiving element 151, a second light receiving element 152, a third light receiving element 153, and a signal processing circuit 160 are arranged on the upper surface (board surface) of the substrate 110. As shown in FIG. 2, the first light receiving element 151 and the second light receiving element 152 are arranged side by side in the vertical direction on the upper surface of the substrate 110. The substrate 110 is provided with a through groove into which a part of the lens holder 120 is fitted.

The lens holder 120 is made of a material that is opaque to the irradiation light of the light emitting element 140 and reflects the irradiation light. The lens holder 120 is arranged on the upper surface of the substrate 110, and has a first accommodating portion 121, a second accommodating portion 122, and a third accommodating portion 123 on the lower surface side.

The first accommodating portion 121 forms a first accommodating space on the substrate 110. The light emitting element 140 and the third light receiving element 153 are accommodated in the first accommodation space. The second accommodating portion 122 forms a second accommodating space on the substrate 110. The first light receiving element 151 and the second light receiving element 152 are housed in the second accommodating space. The third accommodating portion 123 forms a third accommodating space on the substrate 110. A signal processing circuit 160 is arranged in the third accommodation space.

The first accommodation space, the second accommodation space, and the third accommodation space are laterally separated from each other on the substrate 110. By separating the accommodation space between the first to third light receiving elements 151 to 153 and the signal processing circuit 160 in this way, light is reflected by the signal processing circuit 160 such as a signal processing chip, and the first to third light receiving elements are reflected. It is possible to prevent the entry into 151 to 153.

The lens holder 120 has a lens fixing portion 124 on the upper surface side (front surface side). Although omitted in FIG. 1, the lens fixing portion 124 is configured to have a shape capable of fixing the lens 130.

Further, the lens holder 120 is placed between the first opening 125 connected to the first accommodating portion 121, the second opening 126 connected to the second accommodating portion 122, and the first opening 125 and the second opening 126. It has a light-shielding portion 127 located.

The first opening 125 is located above the light emitting element 140 and functions as a diaphragm portion that limits the irradiation range of the irradiation light of the light emitting element 140. A first polarizing filter 171 is provided at the upper end of the first opening 125. The first polarizing filter 171 is a polarizing filter for P wave transmission that blocks the S wave component of the irradiation light and transmits the P wave component.

The second opening 126 is formed to have substantially the same size as the second accommodating portion 122. The second opening 126 and the second accommodating portion 122 may be composed of one through hole. At the upper end of the second opening 126, a second polarizing filter 172 located above the first light receiving element 151 and a third polarizing filter 173 located above the second light receiving element 152 are provided. The second polarizing filter 172 is an S wave transmitting polarizing filter that shields the P wave component of the reflected light from the measurement object and transmits the S wave component, and the third polarizing filter 173 is a P wave transmitting polarizing filter. Is.

The light-shielding portion 127 is provided so that the upper portion protrudes into the lens 130 and can block the irradiation light propagating in the lens 130, while the lower portion is fitted into the through groove of the substrate 110 and the inside of the substrate 110. It is possible to block the propagating irradiation light. The upper end of the light-shielding portion 127 corresponds to the light-shielding wall 170. The light-shielding wall 170 will be described later.

The lens 130 is made of a material that is transparent to the irradiation light of the light emitting element 140, 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 has a light emitting lens portion 132 and a light receiving lens portion 133 on the lower surface side (back surface side).

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 portion 127 in the width direction.

The light emitting lens unit 132 is located above the light emitting element 140 to collect the irradiation light of the light emitting element 140, while the light receiving lens unit 133 is located above the first light receiving element 151 and the second light receiving element 152. Condenses the reflected light from the object to be measured. The light emitting lens portion 132 is formed at a position higher than that of the light receiving lens portion 133 because the light is focused through the tubular opening (first opening 125) of the lens holder 120.

Under the control of the control circuit 200, the light emitting element 140 irradiates the object to be measured with irradiation light via the first polarizing filter 171 and the lens 130. As the light emitting element 140, 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.

The first light receiving element 151 receives the S wave component of the first reflected light and outputs a current signal corresponding to the amount of received light to the signal processing circuit 160. The second light receiving element 152 receives the P wave component of the first reflected light and outputs a current signal corresponding to the amount of received light to the signal processing circuit 160. As the first light receiving element 151 and the second light receiving element 152, for example, a photodiode or a phototransistor can be used.

The third light receiving element 153 receives the reflected light (second reflected light) from the lens holder 120 with respect to the irradiation light of the light emitting element 140. In addition, in order to prevent the direct light from entering the third light receiving element 153 from the light emitting element 140, a shield such as a protrusion may be provided between the light emitting element 140 and the third light receiving element 153. In the present embodiment, the amount of irradiation light applied to the object to be measured and the amount of light of the second reflected light are about the same. The third light receiving element 153 outputs a current signal corresponding to the amount of received light of the second reflected light to the signal processing circuit 160. As the third light receiving element 153, for example, a photodiode or a phototransistor can be used.

In the present embodiment, the light emitting element 140, the first light receiving element 151, the second light receiving element 152, and the third light receiving element 153 are mounted on the substrate 110 as bare chips that are not packaged (resin-sealed). As a result, the size of the entire sensor can be reduced.

The signal processing circuit 160 includes a voltage signal (first output signal) corresponding to the current signal of the first light receiving element 151, a voltage signal (second output signal) corresponding to the current signal of the second light receiving element 152, and a third. A voltage signal (third output signal) corresponding to the current signal of the light receiving element 153 is generated and output to the control circuit 200.

The signal processing circuit 160 includes, for example, a plurality of current amplification circuits composed of operational amplifiers. The signal processing circuit 160 includes a differential amplification circuit, generates a voltage signal corresponding to the amount of positively reflected light of the first reflected light corresponding to the potential difference between the first output signal and the second output signal, and generates the voltage. The signal may be output to the control circuit 200.

The light-shielding wall 170 is located between the light-emitting element 140, the first light-receiving element 151, and the second light-receiving element 152, similarly to the light-shielding portion 127. The light-shielding wall 170 is formed by projecting a part of the lens holder 120, and specifically, the light-shielding portion 127 is formed by projecting the light-shielding portion 127 to the upper surface (surface) of the lens 130. That is, the upper end portion of the light-shielding portion 127 is the light-shielding wall 170.

As shown in FIG. 3, the light-shielding wall 170 blocks a part of the reflected light received by the first light-receiving element 151, and the reflected light can enter the first light-receiving element 151 in the measurement object (the first region (first). 1 Reflection area) is limited. Similarly, the light-shielding wall 170 shields a part of the reflected light received by the second light-receiving element 152, and the reflected light can enter the second light-receiving element 152 in the measurement object (second reflection area). To limit. The reflective area becomes larger as the distance to the object to be measured increases.

The sensor output (in this embodiment, the first output signal and the second output signal) is proportional to the amount of reflected light from the object to be measured. The amount of reflected light decreases as the distance to the object to be measured increases. This is because the light is attenuated as the distance increases. On the other hand, as shown in FIG. 3, the ratio of the first reflection region to the irradiation region increases as the distance from the reflection sensor 100 to the object to be measured increases. For example, the above ratios are small, medium, and large in the order of the distances to the measurement object being X1, X2, and X3. Similarly, the ratio of the second reflection region to the irradiation region also increases as the distance to the measurement target increases. The larger the ratio, the larger the amount of reflected light.

That is, the decrease in the amount of reflected light (attenuation of light) as the distance to the object to be measured increases is offset by the increase in the above ratio (increase in the amount of reflected light as the reflective region increases). Therefore, according to the reflective sensor 100, it is possible to suppress fluctuations in the sensor output according to the distance to the object to be measured. Further, in the reflection type sensor 100, since the first light receiving element 151 and the second light receiving element 152 are arranged side by side in the vertical direction on the upper surface of the substrate 110, the sensor output of the first light receiving element 151 and the second light receiving element 152 Fluctuations can be suppressed to the same extent.

Further, in the reflective sensor 100, even when the inner surface reflected light is generated due to dirt or the like adhering to the upper surface of the lens 130, the inner surface reflected light is transmitted by the light shielding wall 170 to the first light receiving element 151 and the second light receiving element 152. It is possible to suppress the incident on the lens.

The control circuit 200 controls a basis weight measuring unit that measures the basis weight of the object to be measured, a glossiness measuring unit that measures the glossiness of the object to be measured, and a light emitting element 140 so that the amount of irradiation light is constant. It is provided with a light emission control unit. The control circuit 200 is composed of, for example, a microcomputer.

As shown in FIG. 4, the basis weight measuring unit measures the basis weight of the object to be measured based on the pseudo transmitted light Vt'which is a pseudo calculation of the transmitted light Vt of the object to be measured with respect to the irradiation light V (I). To do. The pseudo transmitted light Vt'is obtained by subtracting the P wave component V (P) and the S wave component V (S) of the first reflected light from the second reflected light V (R) as shown in the following equation (1). Is calculated by. V (R) is calculated based on the third output signal, and V (P) and V (S) are calculated based on the second output signal and the first output signal.

Since the transmitted light Vt and the basis weight have a correlation, and the transmitted light Vt and the pseudo transmitted light Vt'have a correlation (in the present embodiment, the values are almost the same), the pseudo transmitted light Vt'and the basis weight have a correlation. Has a correlation. Therefore, the basis weight measuring unit can measure the basis weight based on the pseudo transmitted light Vt'.

Since the internal diffuse reflected light Vi of the object to be measured is so small that it can be ignored, the internal diffuse reflected light Vi is not taken into consideration when calculating the pseudo transmitted light Vt'in this embodiment. As a result, the light receiving element that detects the pseudo transmitted light Vt'can be omitted, so that the size of the entire sensor can be reduced. If the internal diffuse reflection light Vi for each type of the object to be measured can be measured in advance, the pre-measured Vi is stored in the basis weight measuring unit, and V (R) to V (P), V (S). ), Vi may be subtracted to calculate the pseudo-transmitted light Vt'.

In the present embodiment, the amount of irradiation light V (I) irradiated to the object to be measured and the amount of light of the second reflected light V (R) are about the same, but if there is a difference between the two, the difference is It is preferable to correct the second reflected light V (R) accordingly and apply the corrected second reflected light V (R) to the above equation (1). For example, even if the light amount of the irradiation light V (I) and the light amount of the second reflected light V (R) are measured in advance to calculate the correction coefficient, and the second reflected light V (R) is corrected by the calculated correction coefficient. Good.

The glossiness measuring unit measures the glossiness of the object to be measured based on the reflected light (first reflected light) from the object to be measured with respect to the irradiation light. For example, the glossiness measuring unit responds to the amount of specularly reflected light (P wave component in the present embodiment) of the first reflected light based on the potential difference between the first output signal and the second output signal. The glossiness of the object to be measured is measured based on the voltage signal.

The light emitting control unit feedback-controls the light emitting element 140 so that the amount of irradiation light of the light emitting element 140 becomes constant based on the third output signal. In the present embodiment, one third light receiving element 153 functions as a sensor element for performing feedback control of the light emitting element 140, and also functions as a sensor element for measuring the basis weight of the object to be measured. Therefore, the size of the entire device can be reduced.

Although the embodiment of the reflective sensor according to the present invention has been described above, the present invention is not limited to the above embodiment.

The reflective sensor according to the present invention includes a substrate, a light emitting element that irradiates irradiation light, a first light receiving element that receives the S wave component of the reflected light, and a second light receiving element that receives the P wave component of the reflected light. It is provided with a lens that guides the irradiation light to the object to be measured and guides the reflected light to the first light receiving element and the second light receiving element, and a light shielding wall located between the light emitting element and the first light receiving element and the second light receiving element. If the ratio of the first reflection region to the irradiation region of the irradiation light in the measurement target and the ratio of the second reflection region to the irradiation region increase as the distance to the measurement target increases, the configuration can be appropriately changed.

For example, the arrangement of the first light receiving element 151 and the second light receiving element 152 can be changed. However, when the first light receiving element 151 and the second light receiving element 152 are arranged side by side in the horizontal direction on the upper surface of the substrate 110, for example, the second light receiving element 152 on the side close to the light shielding wall 170 can suppress the output fluctuation due to the distance change. On the other hand, the output of the first light receiving element 151 on the side far from the light shielding wall 170 may fluctuate as the distance to the object to be measured changes. Therefore, the light-shielding wall 170 blocks a part of the reflected light received by the first light receiving element 151 to limit the first reflection region, and a part of the reflected light received by the second light receiving element 152 is blocked. It is necessary to change the arrangement of the first light receiving element 151 and the second light receiving element 152 under the condition that the light is shielded to limit the second reflection region.

In the above embodiment, the upper end portion of the light-shielding portion 127 is a light-shielding wall 170, but the light-shielding wall 170 is a member different from the light-shielding portion 127, that is, the lens holder 120 (a member opaque to the irradiation light of the light emitting element 140). Can be configured with.

In the above embodiment, the upper surface of the light-shielding wall 170 and the upper surface of the lens 130 are configured to form the same plane, but the upper surface of the light-shielding wall 170 may be located higher than the upper surface of the lens 130. , May be in a low position.

The reflective sensor according to the present invention is not limited to the media sensor, and can be applied to other sensors, for example, a toner adhesion amount sensor that measures the adhesion amount of toner adhering to a measurement object. Can be applied.

1 Basis weight measuring device 100 Reflective sensor 110 Substrate 120 Lens holder 121 1st accommodating unit 122 2nd accommodating unit 123 3rd accommodating unit 124 Lens fixing unit 125 1st opening 126 2nd opening 127 Light-shielding unit 130 Lens 131 Convex lens Part 132 Light-emitting lens part 133 Light-receiving lens part 140 Light-emitting element 151 First light-receiving element 152 Second light-receiving element 153 Third light-receiving element 160 Signal processing circuit 170 Light-shielding wall 171 First polarization filter 172 Second polarization filter 173 Third polarization filter 200 Control circuit

Claims (3)

A reflective sensor that irradiates an object to be measured with irradiation light and receives the reflected light from the object to be measured with respect to the irradiation light.
With the board
A light emitting element that irradiates the irradiation light and is arranged on one side in the lateral direction of the substrate surface.
A first light receiving element that receives the S wave component of the reflected light and a second light receiving element that receives the P wave component of the reflected light, which are arranged on the other side of the substrate surface in the lateral direction.
A lens that guides the irradiation light to the measurement object and guides the reflected light to the first light receiving element and the second light receiving element.
A light-shielding wall located between the light-emitting element, the first light-receiving element, and the second light-receiving element,
With
The light-shielding wall shields a part of the reflected light received by the first light-receiving element to limit the first reflection region where the reflected light can enter the first light-receiving element, and the second light-shielding wall. A part of the reflected light received by the light receiving element is shielded to limit the second reflection region where the reflected light can enter the second light receiving element.
The ratio of the second reflective region relative proportions and the irradiation region of the first reflective region to the irradiation region of the irradiation light on the object to be measured, Ri as large name distance to the measurement object is increased,
The first, such that the decrease in the amount of reflected light in response to the increase in the distance to the measurement object is offset by the increase in the ratio of the first reflection region and the increase in the ratio of the second reflection region. A reflective sensor in which the light receiving element and the second light receiving element are arranged side by side in the vertical direction of the substrate surface . A lens holder which is arranged on the surface of the substrate and is separated from each other in the lateral direction of the surface of the substrate is formed, and further includes a lens holder on which the lens is arranged on the surface side.
The light emitting element is arranged in the first accommodation space.
The first light receiving element and the second light receiving element are arranged in the second accommodating space.
The reflective sensor according to claim 1 , wherein the light-shielding wall is formed by projecting a part of the lens holder. The reflective sensor according to claim 1 or 2 , wherein the surface of the light-shielding wall and the surface of the lens form the same plane.

Images