JP4702329B2 - Photodetector, method of using the same, and image forming apparatus - Google Patents

Description

  The present invention relates to a light detection device that detects optical information from a measurement target surface, and in particular, guides light from a light emitting unit to a measurement target surface through a light guide member and guides detection light from the measurement target surface. The present invention relates to a light detection device that is guided to a light receiving portion through a member, a method of using the same, and an improvement of an image forming apparatus.

In general, a photodetection device irradiates light on a measurement target surface and detects optical information from the measurement target surface, and is widely used in various fields.
For example, in an image forming apparatus such as a copying machine, printer, or facsimile employing an electrophotographic system, a toner patch for density detection is formed on an image carrier such as a photoreceptor or an intermediate transfer member, and the toner of the toner patch A method is employed in which the image density is controlled by detecting the amount with a light detection device (here, a toner amount detection device).

Here, a general toner amount detection device will be described.
The first method is called a reflected light detection method and utilizes the fact that the surface of an image carrier such as a photosensitive member or an intermediate transfer member to which toner adheres has a mirror surface structure with high flatness.
That is, in this reflected light detection method, as shown in FIG. 19A, the surface of the image carrier 200 is irradiated with light of a certain intensity from the light source 201, and the specular reflected light is a photodiode that is a light receiving element. It is received at 202 and converted into a voltage corresponding to its strength (see, for example, Patent Document 1).
At this time, the reflected light is scattered at the portion to which the toner 203 as the measurement target surface adheres, and the amount of light decreases accordingly, so that the output voltage at the portion where the amount of light decreases decreases.
Thereby, as shown in FIG. 19B, a relationship between the toner amount and the sensor output voltage is obtained, and the toner amount can be detected in the image forming apparatus.
However, in this reflected light detection system, when the surface of the image carrier is substantially covered with toner, reflected light cannot be obtained, and thus detection is impossible. Therefore, this reflected light detection system can detect the amount of toner in a region where a small amount of toner or about one layer of toner on the image carrier adheres.

The second method is called a scattered light detection method, and is used, for example, in the case of color toner.
That is, in this scattered light detection method, for example, as shown in FIG. 20A, when the color toner 213 on the image carrier 200 is irradiated with light from the light source 211, scattered light is generated by surface reflection or internal reflection. Utilizing this characteristic, a photodiode 212 which is a light receiving element is disposed in a portion other than the light receiving portion of the specular reflection light, and the scattered light is monitored by the photodiode 212.
In the case of this method, as shown in FIG. 20B, the output voltage of the photodiode 212 changes so as to increase as the toner amount increases, and the toner amount can be detected.
In this scattered light detection method, even when a plurality of layers of toner adhere to the image carrier 200, the scattered light from the lower layer toner returns through the surface layer toner. For this reason, this scattered light detection method can obtain an output even for a larger amount of toner than the reflected light detection method.
However, the scattered light detection method cannot be applied to black toner that does not generate scattered light.

These two types of toner amount detection devices (light detection devices) are composed of a light source, lenses, a light receiving element, a drive substrate, and the like, and are often arranged in the vicinity of a measurement point in an integrated configuration.
Therefore, in general, the toner amount detection device is disposed at a position of several mm to several tens of mm from the measurement point with a thickness and a width of about 5 mm to 15 mm.
At this time, the main factor of the restriction on the size of the sensor (toner amount detection device) comes from the necessity that the optical system and the elements and circuits related to the measurement are arranged in the vicinity of the measurement position.
Considering the demand for the irradiation optical system, if the distance between the power source and the light emitting element (light source) is increased, electromagnetic noise is easily applied, and it is difficult to guarantee the stability of the irradiation light amount.
Considering the demand of the light receiving optical system, it is necessary to amplify a weak current generated by the light receiving element as close as possible to obtain a stable analog signal. Therefore, the light receiving element is often directly attached to the drive substrate in the vicinity of the measurement position.
Furthermore, since the light emitting element and the light receiving element have an outer shape in millimeter units, the sensor has the above size as a result.

Japanese Patent Laid-Open No. 6-175501 (Prior Art Column, FIG. 1) JP-A-7-177091 (Example column, FIG. 1) JP 2002-98637 A (column of embodiment of the invention, FIG. 1)

By the way, since this type of toner amount detection device (sensor) is disposed in the vicinity of the measurement point, naturally, it is necessary to secure a space for the sensor in the vicinity of the measurement point.
However, in recent years, various subunits tend to be arranged at high density inside the image forming apparatus due to a demand for downsizing the image forming apparatus.
For example, a so-called tandem type image forming engine in which four image forming units for forming each color component toner image are arranged is becoming mainstream.
In the case of such an apparatus, a space where a sensor can be arranged is often not obtained near the measurement target position.
At this time, the actual amount of toner that should be detected cannot be detected, and a method of performing process control based on prediction from the substitute value is unavoidable.

On the other hand, Patent Document 2 discloses that communication of main digital signals of an image forming apparatus including a toner amount detection device and the like is performed using an optical fiber.
If this method is used, the influence of electromagnetic noise on the signal can be reduced.

If such a prior art is applied, as shown in Patent Document 3, for example, it is conceivable to propagate an analog light amount handled by the toner amount detection device using an optical fiber.
For example, as shown in FIG. 21, the light from the light source 221 is guided to the measurement point P using the incident side optical fiber 222, and the detection light from the measurement point P is transmitted to the emission side optical fiber 224 through the condenser lens 223. The light is guided to the light receiving element 225 such as a photodiode using the output side optical fiber 224.
According to this aspect, it is theoretically possible to place the light source 221 to the measurement point P and the measurement point P to the light receiving element 225 apart from each other.
Further, only the optical fibers 222 and 224 and the condensing lens 223 are arranged in the vicinity of the measurement point P, and accordingly, the sensor (toner amount detection device) can be greatly downsized.
Therefore, even if the installation space near the measurement point P is narrow, the sensor can be effectively arranged.

However, this type of toner amount detection device has the following technical problems.
First, in the toner amount detection device described above, since the detection light from the spot-like measurement point P must be collected, for example, if the measurement target surface that becomes the measurement point P deteriorates, the measurement target surface Technically, the influence is likely to immediately affect the detection accuracy, and it is difficult to reliably collect the detection light from the measurement point P onto the emission side optical fiber 224, and in any case, the detection accuracy is likely to decrease. There are challenges.

In addition, this type of toner amount detection device uses an optical fiber, but the transmittance of the optical fiber is likely to fluctuate due to a change in shape or the like, and therefore it is difficult to stably propagate the analog light quantity.
Here, the following factors can be cited as factors of variation in transmittance.
・ Due to thermal expansion and shape change ・ Diffusion due to dirt on the joint ・ Transmission decrease over time

By the way, considering the influence of the transmittance variation on the detection accuracy, assuming that the reflected light detection method is used for monitoring using the toner amount detection device shown in FIG. 21, for example, as shown in FIG. Results.
At this time, for example, if it is assumed that the transmittance is reduced by 10%, it is understood that the measured toner amount is originally 0.075 mg / cm ² , for example, and is measured as 0.095 mg / cm ^2. .
In such a situation, if the required measurement accuracy is about 0.01 mg / cm ² , the amount of fluctuation of the target value is generated only by the amount of fluctuation of the light amount, and the detection accuracy is lowered. Is confirmed.

The present invention has been made to solve the above technical problem, and effectively prevents a decrease in detection accuracy with respect to an aspect in which a light guide member is used between a light emitting unit and a light receiving unit. It is an object of the present invention to provide an optical detection device, a method of using the same, and an image forming apparatus.
In particular, the present invention seeks to solve the technical problems described above using a two-wavelength beam system.

Before describing the present invention, a reference invention related to the present invention will be described.
That is, as shown in FIG. 1A, a reference invention related to the present invention is a light detection device that detects light reflected or scattered from a measurement target surface M, and a light emitting unit 1 that emits light, and light. A light receiving unit 2 that senses light and is provided between the light emitting unit 1 and the light receiving unit 2, and guides light from the light emitting unit 1 to the measurement target surface M and guides detection light from the measurement target surface M to the light receiving unit 2. A sheet-like structure in which an optical opening 4c is formed in a portion of the light guide member 3 that is optically transmitted by internal reflection and is opposed to the measurement target surface M. The optical transmission medium 4 is provided.
According to this aspect, since the light guide member is provided between the light emitting unit and the light receiving unit, and the sheet-like optical transmission medium is provided in a portion facing the measurement target surface of the light guide member, the measurement target surface is It can be ensured widely, and the detection light from the measurement target surface can be reliably collected.
For this reason, compared with a conventional photodetector that collects detection light from a spot-like measurement point, it is possible to reduce the influence of deterioration of the measurement target surface and detection light collection failure, and detection accuracy can be reduced. The decrease can be effectively prevented.
Furthermore, when using the photodetection device according to this aspect, if the characteristics of the measurement target surface itself are taken into account, the influence of deterioration of the measurement target surface can be effectively prevented, and the detection accuracy is improved accordingly. Can be maintained.

In such technical means, the photodetection device of the present application is intended to detect either reflected light or scattered light.
And if the light guide member 3 is a member which irradiates the measurement object surface M with the light from the light emission part 1, and guides the detection light from the measurement object surface M to the light-receiving part 2, it will widely contain an optical fiber.
Further, the sheet-like optical transmission medium 4 may have a single-layer structure or a multilayer structure as long as it is a sheet-like light transmitted through internal reflection.
Furthermore, the sheet-like optical transmission medium 4 has an optical opening 4c opposite to the measurement target surface M. The optical opening 4c here refers to a predetermined light with respect to the measurement target surface M. Any material can be selected as long as it can irradiate and has a function of receiving detection light from the measurement target surface M.

Further, in the embodiment of FIG. 1A, the sheet-like optical transmission medium 4 has a long and narrow optical opening 4c, so that a wide measurement target surface M can be secured, and the measurement target surface M is separated from the measurement target surface M. It is easy to collect the detection light.
Furthermore, since the sheet-like optical transmission medium 4 can be installed even in a narrow installation space, the degree of freedom of installation location is high.

Further, in the embodiment of FIG. 1A, the light guide member 3 only needs to include at least the sheet-like optical transmission medium 4, but as a typical embodiment of the light guide member 3, the light emitting unit 1 and the sheet-like member are used. An optical transmission path is formed between the incident side optical transmission member 5 that forms an optical transmission path with the incident section 4 a of the optical transmission medium 4, and the emission section 4 b and the light receiving section 2 of the sheet-like optical transmission medium 4. The thing provided with the output side optical transmission member 6 is mentioned.
According to this aspect, it is possible to set the positional relationship between the light emitting unit 1, the light receiving unit 2, and the sheet-like optical transmission medium 4 apart, and the degree of layout can be increased accordingly.
The incident side light transmission member 5 and the emission side light transmission member 6 are preferably bendable optical fibers.
Furthermore, as another form of the sheet-like optical transmission medium 4, there is one that does not use the optical transmission members 5 and 6 as described above.
For example, the sheet-like optical transmission medium 4 may be integrally provided with an incident side optical transmission unit that guides light from the light emitting unit 1 and an emission side optical transmission unit that guides light to the light receiving unit 2. Absent.

Furthermore, the sheet-like optical transmission medium 4 may have a single member configuration or a multiple member configuration.
As the former, the sheet-like optical transmission medium 4 has, as the optical opening 4c, a light irradiation part to the measurement target surface M and a light detection part from the measurement target surface M, and the light irradiation part and the light detection part are provided. The thing set to the same member is mentioned.
As the latter, the sheet-like optical transmission medium 4 includes, as the optical opening 4c, a light irradiation unit for the measurement target surface M and a light detection unit for the measurement target surface M. The light irradiation unit, the light detection unit, and the like. Is set as a separate member.

Further, in this aspect, when the light detection device is configured as a reflected light detection method, the sheet-like light transmission medium 4 is formed as an optical opening 4c from the light irradiation unit to the measurement target surface M and the measurement target surface M. It is only necessary that the light detection unit can enter the specularly reflected light from the measurement target surface M.
On the other hand, when the light detection device is configured as a scattered light detection method, the sheet-like light transmission medium 4 has a light irradiation unit for the measurement target surface M and a light detection unit for the measurement target surface M as the optical opening 4c. It is only necessary that the light detection unit can prevent regular reflection light from the measurement target surface M from being incident and only allow scattered light to be incident.

At this time, when the light detection device is configured as a scattered light detection method, as a preferred layout example of the optical aperture 4c, the sheet-like optical transmission medium 4 includes a light irradiation unit for the measurement target surface M and the measurement target surface M. What is necessary is just to arrange | position the light detection part from No. 1 apart.
If spaced apart in this manner, it is possible to disable the regular reflection light from entering the light detection unit.

Furthermore, when the light detection device is configured as a scattered light detection method, as a preferable configuration example of the optical opening 4c, the sheet-like optical transmission medium 4 includes a light shielding wall around the light irradiation unit on the measurement target surface M. Should be provided.
As described above, by providing the light shielding wall, it is possible to disable the regular reflection light from entering the light detection unit.

  Further, regarding the layout example of the sheet-like optical transmission medium 4 in the light transmission direction, the light from the light emitting unit 1 is incident to the light receiving unit 2 and the light receiving unit 2 at a portion substantially parallel to the optical opening 4c facing the measurement target surface M. The light emitting part may be set, or the light incident part from the light emitting part 1 and the light to the light receiving part 2 may be placed at a position substantially orthogonal to the optical opening 4c facing the measurement target surface M. The emission unit may be set.

Next, the present invention will be described.
As shown in FIG. 1B , the basic configuration of the present invention irradiates two types of light A and B having different wavelengths in a light detection device that detects light reflected or scattered from the surface M to be measured. A light-emitting unit 1; a light-receiving unit 2 that senses two types of light A and B having different wavelengths; and a light-guiding member 3 provided between the light-emitting unit 1 and the light-receiving unit 2. Includes only the light of one wavelength A (shown by the solid line in the figure) of the two types A and B from the light emitting unit 1 and the detection light from the measurement target surface M. Is provided with an optical transmission line separation means 7 guided to the light receiving unit 2 together with the light of the other wavelength B (indicated by a dotted line in the figure).

In this aspect, the basic configuration of the light detection device corresponding to the two-wavelength beam method is clearly described, and the light transmission path separating means 7 is provided in part of the light guide member 3 .
According to this aspect, the optical transmission line separating means 7 detects “detected light from the measurement target surface M + transmittance variation component of the light guide member 3” with one wavelength light, and with the other wavelength light. Since “the transmittance variation component of the light guide member 3” can be detected, it is possible to detect only the detection light from the measurement target surface M by canceling the transmittance variation component of the light guide member 3. it can.

In particular, in the present invention, the light guide member 3 is disposed in a portion facing the measurement target surface M as a typical aspect of a light detection device corresponding to the two-wavelength beam method, and two kinds of light from the light emitting unit 1 are used. An incident part 4a for incident A and B light and an emitting part 4b for emitting two kinds of A and B light toward the light receiving part 2 are provided, and light is transmitted by internal reflection and is transmitted to the measurement target surface M. A sheet-shaped optical transmission medium 4 having an optical opening 4c formed opposite thereto, and two types of light A and B from the light-emitting section 1 provided on the sheet-shaped optical transmission medium 4 and incident from the incident section 4a. Among them, only the light of one wavelength A (shown by a solid line in the drawing) is irradiated on the measurement target surface M, and the detection light from the measurement target surface M is combined with the light of the other wavelength B (shown by a dotted line in the drawing). and an optical transmission path separating means 7 is guided to the exit portion 4b, the optical transmission path separating means 7, optical Only light of one wavelength A from the light-emitting portion 1 through the opening 4c uptake reflected or scattered light from the irradiated and measured surface M on the object surface M, the light of the other wavelength B from the light-emitting portion 1 A mode in which the outside is not irradiated from the optical opening 4c is mentioned.
Thus, the use of the sheet-like optical transmission medium 4 is preferable in that the measurement target surface M can be secured widely and can be installed even if the space near the measurement target surface M is small.

Further, in the embodiment of FIG. 1B, the light guide member 3 includes an incident side optical transmission member 5 that guides the two types of light A and B from the light emitting unit 1 to the incident unit 4 a of the sheet-like optical transmission medium 4. In addition, an emission-side optical transmission member 6 that guides the two types of light A and B emitted from the emission part 4 b of the sheet-like optical transmission medium 4 to the corresponding sensing part of the light-receiving part 2 may be provided.
In this aspect, the incident side optical transmission member 5 includes, for example, a light combining member that combines light irradiated from a plurality of directions of the light emitting unit 1 in one direction, and a bendable optical fiber.
On the other hand, the emission side optical transmission member 6 includes, for example, a light separation member that separates light in one direction in a plurality of directions toward the light receiving unit 2 and an optical fiber.

Further, as a typical aspect of the optical transmission line separating means 7, the optical opening 4c of the sheet-like optical transmission medium 4 is subjected to a reflection process having a high wavelength dependency, and can be reflected with a transmissive wavelength light. In this case, the light having a different wavelength is set as two types of light A and B emitted from the light emitting unit 1.
Furthermore, as a typical aspect of the optical transmission line separating means 7 in the case where the sheet-like optical transmission medium 4 has a plurality of configurations, the sheet-like optical transmission medium 4 is irradiated with light on the measurement target surface M as an optical opening 4c. And the light detection part from the measurement target surface M, the light irradiation part and the light detection part are set as separate members, and the light transmission path separating means 7 constitutes the sheet-like light transmission medium 4 In this case, the joint surface 4d of the plurality of members is subjected to a reflection process in which only the wavelength light that can be reflected by the optical opening 4c is transmitted and the wavelength light that can be transmitted from the optical opening 4c is reflected. .

Further, for example, as a preferable method of using the photodetecting device shown in FIG. 1A, a color material for a visible image on an image carrier in an image forming apparatus that forms a visible image with a color material on an image carrier. When using the light detection device of FIG. 1A as a device for detecting the amount, the output of the light receiving unit 2 for each time is V (t), and the average of the light receiving unit 2 output V (t) of the portion where no color material is placed. When the value is Vmax and the average value of the state in which the light receiving unit 2 output V (t) is saturated due to the adhering color material is Vmin,
S (t) = {Vmax−V (t)} / {Vmax−Vmin}
And determining the light detection result based on the information S (t) that has been subjected to the arithmetic processing by.
Here, the arithmetic expression is intended to compensate for deterioration or the like of the measurement target surface M.

In addition, as a preferable method of using the two-wavelength beam type photodetector shown in FIG. 1B, the output of the light receiving unit 2 for each time of wavelength light (for example, light of wavelength A) irradiated on the measurement target surface M is obtained. VA (t), when the light receiving unit 2 output for each time of wavelength light (for example, light of wavelength B) that is not irradiated on the measurement target surface M is VB (t),
S (t) = VA (t) / VB (t)
And determining the light detection result based on the information S (t) obtained by performing the division process according to.
In this method of use, the processing by “S (t) = VA (t) / VB (t)” cancels the transmittance change of the light guide member 3 and extracts only the detected light change from the measurement target surface M. Means that.
Thereby, the transmittance | permeability fluctuation | variation of the light guide member 3 can be compensated, and a detection accuracy can be improved.

Furthermore, as another method of using the two-wavelength beam type photodetector, in an image forming apparatus that forms a visible image with a color material on the image carrier, the amount of the color material of the visible image on the image carrier is set. When the photodetector shown in FIG. 1B is used as the detection device, the output of the light receiving unit 2 for each time of wavelength light (for example, light of wavelength A) irradiated on the measurement target surface M is expressed as VA (t), color The average value of the light receiving unit 2 output VA (t) of the portion where no material is placed is VAmax, the average value of the state where the light receiving unit 2 output VA (t) is saturated due to the adhering color material is VAmin, and the measurement target surface M is When the light receiving unit 2 output for each time of wavelength light not irradiated (for example, light of wavelength B) is VB (t) and the initial setting value of the light receiving unit 2 output VB (t) is VBini,
S (t) = {VAmax−VA (t)} / [{VAmax−VAmin} · VB (t) / VBini]
And determining the light detection result based on the information S (t) that has been subjected to the arithmetic processing by.
This calculation formula is intended to cancel the change in transmittance of the light guide member 3 and correct the deterioration of the measurement target surface M.
Furthermore, the present invention is not limited to the above-described photodetection device and the method for using the same, but also targets an image forming apparatus itself incorporating the above-described photodetection device.
In this case, the present invention is shown in FIG. 1B as an apparatus for detecting the color material amount of the visible image on the image carrier in the image forming apparatus for forming a visible image with the color material on the image carrier. A light detection device may be used.
As a reference invention related to the present invention, it is possible to construct an image forming apparatus incorporating the photodetection device shown in FIG.

According to the light detection device of the present invention, the light guide member is provided between the light emitting portion and the light receiving portion, and the sheet-like optical transmission medium is provided at the portion of the light guide member facing the measurement target surface. The measurement target surface can be secured widely, and the detection light from the measurement target surface can be reliably condensed.
For this reason, compared with a conventional photodetector that collects detection light from a spot-like measurement point, it is possible to reduce the influence of deterioration of the measurement target surface and detection light collection failure, and detection accuracy can be reduced. The decrease can be effectively prevented.
Furthermore, according to the light detection device of the present invention, the sheet-like optical transmission medium as the light guide member irradiates the measurement target surface with only one of the two types of light from the light receiving unit. And a light transmission path separating means that guides the detection light from the measurement target surface to the light receiving unit together with the light of the other wavelength, so that the detection light from the measurement target surface + the light guide member it can be a transmittance fluctuation component "is detected and detects the" transmittance fluctuation component of the light guide member "in the other wavelength light.
For this reason, it becomes possible to cancel the transmittance | permeability fluctuation | variation of a light guide member based on both wavelength light data, and only the detection light from a measurement object surface can be detected correctly.
Therefore, it is possible to effectively prevent a decrease in detection accuracy due to the transmittance variation of the light guide member.
Furthermore, when using the two-wavelength beam photodetection device according to the present invention, it is possible to accurately detect only the detection light from the measurement target surface if the transmittance variation of the light guide member is canceled. Therefore, the detection accuracy can be maintained better.
In addition, according to the image forming apparatus of the present invention, it is possible to accurately detect the amount of color material accompanying image formation by using a photodetection device with high detection accuracy. Can be easily realized.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2A shows Embodiment 1 of an image forming apparatus incorporating a toner amount detection device (photodetection device) according to the present invention.
In the present embodiment, the image forming apparatus is an intermediate transfer type tandem machine, and four image forming units 20 (each toner image of yellow, magenta, cyan, and black in this example) are formed. Specifically, the intermediate transfer belt 30 is disposed at a portion facing each image forming unit 20.

In the present embodiment, the image forming unit 20 employs, for example, an electrophotographic system, and includes a photosensitive drum 21 that rotates in a predetermined direction, and a charging roll or the like is provided around the photosensitive drum 21. A charging device 22; an exposure device 23 such as a laser scanning device for writing an electrostatic latent image; a developing device 24 that accommodates each color component toner and visualizes the electrostatic latent image on the photosensitive drum 21; A primary transfer device 25 such as a primary transfer roll for transferring the toner image on the drum 21 to the intermediate transfer belt 30, a cleaning device 26 for cleaning residual toner on the photosensitive drum 21, and the like are provided. .
In this example, the exposure device 23 is shared by the image forming units 20, and the primary transfer device 25 is provided on the back side of the intermediate transfer belt 30.

Further, in the present embodiment, the intermediate transfer belt 30 is stretched around, for example, a plurality of stretching rolls 31 and 32, and circulates and rotates in a predetermined direction using, for example, one stretching roll 31 as a driving roll.
A secondary transfer device 35 is disposed on the downstream side of the image forming unit 20 d located on the most downstream side of the intermediate transfer belt 30.
This secondary transfer device 35 has a tension roll 32 as a backup roll and a secondary transfer roll 36 arranged opposite to the secondary transfer apparatus 35. For example, a predetermined transfer bias is applied to the secondary transfer roll 36 and the tension roll 32 is grounded. As a result, the toner image on the intermediate transfer belt 30 is electrostatically transferred to the recording material S.
Reference numeral 34 denotes a belt cleaner for cleaning residual toner on the intermediate transfer belt 30.

  Further, in the present embodiment, the recording material conveyance system has a recording material conveyance path from the lower side to the upper side, and after the recording material S sent from the recording material supply tray (not shown) is positioned by the resist roll 37. Then, the recording material S is conveyed to the secondary transfer portion at a predetermined timing, the toner image secondarily transferred onto the recording material S is fixed by the fixing device 38, and then discharged to a discharge tray (not shown) by the discharge roll 39. And the recording material S are discharged.

In particular, in the present embodiment, as shown in FIGS. 2A and 2B, a toner amount detection device (light detection device) is provided upstream of the primary transfer portion of the photosensitive drum 21 and downstream of the development portion. 50) are arranged opposite to each other.
As the measurement principle of the toner amount detection device 50, both the reflected light detection method and the scattered light detection method can be applied. In this example, a configuration example of the reflected light detection method is shown.
More specifically, as shown in FIGS. 2B and 3, the toner amount detection device 50 includes a pair of light emitting elements 51 (specifically 51 a, 51 a, and 51 b) that emit light of different wavelengths A and B, respectively. 51 b), a pair of light receiving elements 52 (specifically 52 a and 52 b) that sense light of different wavelengths A and B, and the light emitting element 51 and the light receiving element 52. Of the light of seeds A and B, one wavelength light (A) is irradiated onto the measurement target surface M, and the detection light (reflected light in this example) from the measurement target surface M is guided to the light receiving element 52, and the other A light guide member 53 that guides the wavelength light (B) to the light receiving element 52 without irradiating the measurement target surface M is provided.
In this example, the light emitting element 51 (51a, 51b) and the light receiving element 52 (52a, 52b) are both arranged so that the light irradiation direction or the light sensing direction is substantially orthogonal.

  In the present embodiment, the light guide member 53 includes an optical sheet bus 54 that is a sheet-like optical transmission medium disposed to face the measurement target surface M, and an incident connected to an incident portion of the optical sheet bus 54. The side optical fiber 55, the emission side optical fiber 56 connected to the emission part of the optical sheet bus 54, and the two types A and B of light from the light emitting elements 51 (51 a and 51 b) are guided to the incident side optical fiber 55. An incident-side beam splitter 58 and an exit-side beam splitter 59 that separates two types of light A and B from the exit-side optical fiber 56 into light receiving elements 52 (52a and 52b) are provided.

Here, as shown in FIG. 4A, the incident-side beam splitter 58 substantially uses the two types A and B of light from the light emitting elements 51 (51 a and 51 b) with a predetermined transmittance (or reflectance), for example. The light is guided to the inclined reflection surface 581 inclined at 45 °, and the one wavelength light (A) is transmitted as it is, and the other wavelength light (B) is reflected to be guided in the same direction.
Incidentally, condensing lenses 511 and 512 for condensing are provided between the light emitting elements 51 (51a and 51b) and the incident side beam splitter 58.
Further, as shown in FIG. 4C, the exit side beam splitter 59 is inclined by tilting the light of the two types A and B from the exit side optical fiber 56, for example, by approximately 45 ° with a predetermined transmittance (reflectance). The light is guided to the reflecting surface 591, and the one wavelength light (A) is transmitted as it is to the one light receiving element 52 a, and the other wavelength light (B) is reflected and guided to the other light receiving element 52 b. .

In the present embodiment, as shown in FIG. 4B, the optical sheet bus 54 is adjacent to one end surface of two sheet bus pieces 61 and 62 having a thickness of about 0.1 mm to 2.0 mm, for example. The incident side optical fiber 55 is coupled to the incident portion 61 a of the incident side sheet bus piece 61, and the emission side optical fiber 56 is coupled to the emission portion 62 b of the emission side sheet bus piece 62.
These sheet bus pieces 61 and 62 are formed in a sheet shape as shown in FIGS. 4B and 5, and diffuse and propagate the input signal light while repeating total reflection on the inner end face.

In particular, in the present embodiment, the sheet bath pieces 61 and 62 have optical openings 61c and 62c through which only one wavelength light (A) is transmitted on the end face facing the measurement target surface M, and the optical opening 61c. Is set so that the measurement target surface M is irradiated with light and detection light (reflected light) from the measurement target surface M is received by the optical opening 62c, and the other wavelength light is applied to the joint surface between the two. It has a reflection processing section 64 through which only (B) is transmitted.
Here, the optical openings 61c and 62c and the reflection processing unit 64 are configured by applying, for example, a wavelength-dependent coating.
Further, a total reflection processing unit 65 is applied to the other end surfaces of the sheet bus pieces 61 and 62 and the sheet surface.

Next, the operation of the toner amount detection device according to the present embodiment will be described.
Now, two types of light A and B having different wavelengths are guided from the light emitting element 51 (51a, 51b) to the incident side optical fiber 55 by the incident side beam splitter 58 and transmitted to the optical sheet bus 54.
At this time, the light of the two wavelengths A and B is transmitted to the incident-side sheet bus piece 61 in the optical sheet bus 54, and one of the light beams (A) among them is the measurement target surface M through the optical opening 61c. The reflected light from the toner T on the measurement target surface M is received by the optical opening 62 c of the exit side sheet bus piece 62.
The other wavelength light (B) is transmitted to the exit-side sheet bath piece 62 through the reflection processing section 64 formed on the joining surface of the sheet bath pieces 61 and 62 without being irradiated onto the measurement target surface M. .

As a result, the output side sheet bath piece 62 has detection light (reflected light) that is one wavelength light (A) from the measurement target surface M, and the other wavelength light (B) that is not irradiated on the measurement target surface M. Are transmitted together, and the light of both wavelengths A and B is guided to the output side optical fiber 56.
Thereafter, the light of the two wavelengths A and B that has passed through the output side optical fiber 56 is separated again into the respective wavelength light (A, B) by the output side beam splitter 59, and then the light receiving element 52 (52a, 52b). Respectively.

Here, when a photodiode, for example, is used as the light receiving element 52 (52a, 52b), the photodiode linearly converts the received light amount into a voltage.
At this time, the product of the light amount fluctuation information according to the presence or absence of the toner amount and the transmittance fluctuation amount of the optical fibers 55 and 56 is included in one wavelength light (A), and the optical fibers 55 and 56 are included in the other wavelength light (B). A transmittance fluctuation amount of 56 appears.
Therefore, if the output of the light receiving element 52a receiving one wavelength light (A) is VA (t) and the output of the light receiving element 52b receiving the other wavelength light (B) is VB (t), FIG. Output characteristics as shown in (a) and (b) are obtained.
In this state, if arithmetic processing (division processing) as shown in the following equation (1) is performed and the output of one wavelength light (A) is divided by the output of the other wavelength light (B), The influence of the transmittance variation of the optical fibers 55 and 56 can be removed, and a sensor output value S (t) corresponding to the toner on the measurement target surface M can be obtained.
S (t) = VA (t) / VB (t) (1)

  The performance evaluation of the toner amount detection device according to this embodiment is supported by the examples described later.

In the present embodiment, since the light sheet bus 54 corresponding to the measurement head portion of the toner amount detection device and the light emitting element 51 and the light receiving element 52 are spaced apart from each other, the electricity to the light emitting element 51 and the light receiving element 52 is separated. The circuit system can be attached to a location different from the optical sheet bus 54, and as an installation space in the vicinity of the measurement target surface M, it is sufficient to secure a narrow space that allows the optical sheet bus 54 to be installed. .
Furthermore, since the optical system is simply constituted by inexpensive optical fibers 55 and 56 and an optical sheet bus 54, the present embodiment can be adopted without increasing the cost even in the tandem machine as described above. is there.
Furthermore, if the detection of the amount of each color toner is performed at different timings for each color, the light emitting element 51, the light receiving element 52, the drive substrate, etc. can also be used.
Therefore, in such a configuration, the light emitting element 51, the light receiving element 52, and the drive substrate may be only one set, or two sets of light emission for the four image forming units 20 (20a to 20d). A configuration in which processing is performed by the element 51, the light receiving element 52, and the drive substrate may be employed.

Embodiment 2
7A and 7B are explanatory views showing an outline of the second embodiment of the toner amount detection device according to the present invention.
In the figure, the basic configuration of the toner amount detection device 50 is substantially the same as that of the first embodiment, but unlike the first embodiment, there is a long optical sheet bus 54 extending in the axial direction of the photosensitive drum 21. It is a thing.
In the present embodiment, the optical sheet bus 54 is obtained by laminating two sheet bus pieces 61 and 62 in the thickness direction, and one wavelength light is applied to a portion facing the measurement target surface (photosensitive drum 21 surface). Optical apertures 61c and 62c through which only (A) can be transmitted are formed, and a reflection processing unit 64 through which only the other wavelength light (B) can be transmitted is formed at the joint portion between the optical apertures 61c and 61c. An incident side optical fiber 55 and an emission side optical fiber 56 are coupled to the opposite end of 62c.

According to the present embodiment, since the long optical sheet bus 54 is used, a portion along the axial direction of the photosensitive drum 21 can be set as a measurement target surface over a wide range.
For this reason, even if a situation in which a part of the photosensitive drum 21 is locally deteriorated, the measurement target surface covers a wide range, so that the detection light from the measurement target surface is averaged. Thus, local deterioration of the measurement target surface does not greatly affect the detection accuracy of the toner amount detection device.

Embodiment 3
FIGS. 8A and 8B are explanatory views showing an outline of the third embodiment of the toner amount detection device according to the present invention.
In the figure, the basic configuration of the toner amount detection device 50 is substantially the same as that of the second embodiment, and includes a long optical sheet bus 54 (two sheet bus pieces 61 and 62 extending in the axial direction of the photosensitive drum 21). However, unlike the second embodiment, in the optical sheet bus 54, the incident side optical fiber 55 and the emission side light are disposed at a position substantially orthogonal to the optical openings 61c and 62c facing the measurement target surface. The coupling portion of the fiber 56 has been determined.
In addition, the same code | symbol as Embodiment 2 is attached | subjected about the component similar to Embodiment 2, and the detailed description is abbreviate | omitted here.

  According to the present embodiment, since the light from the incident side optical fiber 55 is diffused and irradiated along the longitudinal direction of the optical sheet bus 54, the optical openings 61c and 62c are irradiated with more uniform light. be able to.

Embodiment 4
FIG. 9 shows Embodiment 4 of the toner amount detection apparatus according to the present invention.
In the figure, unlike the first embodiment, the toner amount detection device 50 is a configuration example in which the reflected light detection method and the scattered light detection method are combined, and the light guide member 53 (particularly the light) that is different from the first embodiment. The seat bus 54) is used.
In the present embodiment, the optical sheet bus 54 that constitutes the light guide member 53 includes three sheet bus pieces 61 to 63 in one plane.

Here, the sheet bath piece 61 has an optical opening 61c as an irradiating portion, and is set to have a thickness / width of 1 mm and a length of 10 mm, for example.
A pair of sheet bus pieces 62 and 63 are joined to both side ends of the seat bus piece 61, and the sheet bus piece 62 has an optical opening 62 c as a specular reflection light detection unit. Has an optical aperture 63c as a scattered light detector.
Each of these optical apertures 61c, 62c, and 63c is provided with a reflection processing portion that transmits only light of wavelength A, and a reflection portion that transmits only light of wavelength B at the joint portion of each sheet bath piece 61-63. A processing unit 64 is provided.
Further, an incident side optical fiber 55 is connected to the incident portion of the sheet bus piece 61, and emission side optical fibers 56 and 57 are connected to the emission portions of the sheet bus pieces 62 and 63, respectively.

Further, by the combination of the mounting angles of the sheet bus pieces 61 and 62, the light irradiated on the measurement target surface M is incident on the optical opening 62c of the sheet bus piece 62 only as a regular reflection light. The specularly reflected light is not incident on the optical opening 63c of the bath piece 63, and only scattered light is incident.
In particular, the seat bath piece 63 is disposed so as to protrude from the seat bus piece 61 toward the measurement target surface M, and the protruding step portion 67 functions as a light shielding wall that suppresses the incidence of regular reflection light. Yes.

Further, two light emitting elements not shown are provided in the same manner as in the first embodiment, and are guided to the incident side optical fiber 55 by a beam splitter not shown.
In addition, two light receiving elements (not shown) are provided for the respective outgoing-side optical fibers 56 and 57, and light beams having different wavelengths A and B are sensed by a beam splitter (not shown). ing.

Therefore, according to the present embodiment, since the regular reflection light from the measurement target surface M is detected from the sheet bath piece 62, the toner amount can be detected by the reflected light detection method.
On the other hand, when color toner adheres to the measurement target surface M, the toner generates scattered light with low directivity. At this time, since the scattered light from the measurement target surface M is detected from the sheet bath piece 63, the toner amount can be detected by the scattered light detection method.

Embodiment 5
FIG. 10 shows Embodiment 5 of the toner amount detection apparatus to which the present invention is applied.
In the figure, unlike the first embodiment, the toner amount detection device 50 uses a scattered light detection method. Components similar to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted here.
In the present embodiment, as in the first embodiment, the toner amount detection device 50 includes a light emitting element (not shown), a light receiving element (not shown), and a light guide member 53 (optical sheet bus 54, optical fibers 55 and 56). , A beam splitter (not shown), but an optical sheet bus 54 different from that of the first embodiment is provided.

That is, in the present embodiment, the optical sheet bus 54 is obtained by joining two sheet bus pieces 61 and 62 at the end portions on a plane, but the width dimension of the incident side sheet bus piece 61 is the emission side sheet. The optical opening 61c of the entrance-side sheet bus piece 61 is formed at a portion spaced from the exit-side sheet bus piece 62, and the measurement target surface M of the exit-side sheet bus piece 62 is formed larger than the width dimension of the bath piece 62. An optical opening 62c as a light detection unit is formed at a portion facing the side.
The optical openings 61c and 62c are configured to transmit only light having a wavelength A, and a reflection processing unit 64 that transmits only light having a wavelength B is formed at the joint between the sheet bath pieces 61 and 62. Yes.

Therefore, according to the present embodiment, the light having the wavelength A guided to the incident-side sheet bath piece 61 is irradiated on the measurement target surface M through the optical opening 61c, and then the scattered light from the measurement target surface M is scattered. The light is taken into the exit side sheet bus piece 62 side and transmitted to the light receiving element side together with the light of wavelength B that has passed through the joint portion (reflection processing portion 64) between the both sheet bus pieces 61 and 62.
As a result, in the signal processing of the light receiving element, if processing is performed in substantially the same manner as in the first embodiment, as in the first embodiment, the influence of the transmittance variation of the optical fibers 55 and 56 is removed, The amount of toner that approaches the scattered light can be accurately detected.

Embodiment 6
FIG. 11 shows Embodiment 6 of the toner amount detection apparatus according to the present invention.
In the same figure, the toner amount detection device 50 uses the scattered light detection method as in the fifth embodiment, but unlike the fifth embodiment, the incident-side sheet bus piece 61 of the light sheet bus 54 is different. The width dimension is set to be narrower than the width dimension of the exit-side sheet bath piece 62, and directivity is given to the light irradiated from the optical opening 61c of the incident-side sheet bath piece 61 toward the measurement target surface M. is there.
Components similar to those in the fifth embodiment are denoted by the same reference numerals as those in the fifth embodiment, and detailed description thereof is omitted here.

According to this Embodiment, the light of the wavelength A guide | induced to the entrance side sheet bus piece 61 is irradiated to the measuring object surface M through the optical opening part 61c.
At this time, since the irradiation light from the optical opening 61c has directivity, the specularly reflected light from the measurement target surface M does not go to the optical opening 62c of the exit-side sheet bath piece 62, but from the measurement target surface M. Scattered light is taken into the exit-side sheet bath piece 62 side.
In addition, the light is transmitted to the light receiving element side (not shown) together with the light of wavelength B that has passed through the joint portion (reflection processing portion 64) between the sheet bus pieces 61 and 62.
As a result, in the signal processing of the light receiving element, if processing is performed in substantially the same manner as in the first embodiment, as in the first embodiment, the influence of the transmittance variation of the optical fibers 55 and 56 is removed, The amount of toner due to scattered light can be accurately detected.

◎ Embodiment 7
FIG. 12 shows Embodiment 7 of the toner amount detection device according to the present invention.
In the figure, the toner amount detection device 50 is configured in substantially the same manner as in the first embodiment, but unlike the first embodiment, the toner amount detection device 50 is formed with the optical opening 61c of the incident-side sheet bath piece 61 narrowed, In addition, a cylindrical light shielding wall 70 is provided between the optical opening 61c and the measurement target surface M. Components similar to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted here.

Therefore, according to the present embodiment, the light with the wavelength A guided to the incident-side sheet bath piece 61 is irradiated to the measurement target surface M through the optical opening 61 c and the light shielding wall 70.
At this time, since the specularly reflected light from the measurement target surface M is blocked by the light shielding wall 70, it is not incident on the optical opening 62 c of the exit side sheet bath piece 61, and the output side sheet bath piece 62 does not enter the measurement target surface M. Only scattered light from is taken in.
For this reason, the toner amount can be detected by the scattered light detection method as in the fifth and sixth embodiments.

◎ Eighth embodiment
FIG. 13A shows an eighth embodiment of the toner amount detection apparatus according to the present invention.
In the figure, the toner amount detection device is different from the first to seventh embodiments in that the optical sheet bus 54 is composed of one sheet bus piece 61 and uses light of one wavelength A. is there.
Here, the optical sheet bus 54 has an optical opening 61 c on one end side of one sheet bus piece 61, and an incident side optical fiber 55 and an emission side optical fiber 56 are connected to the other end side.
In this example, the light emitting element 51 emits light of one wavelength A, and the light receiving element 52 senses light of one wavelength A.

In the present embodiment, the light emitting element 51 emits light of one wavelength A, and transmits the light to the optical sheet bus 54 through the incident side optical fiber 55.
Then, in the optical sheet bus 54, light is irradiated from the optical opening 61c to the measurement target surface M, and reflected light and scattered light from the light return to the optical sheet bus 54, and then in the optical sheet bus 54. After being superimposed on the reflected light, it is transmitted to the light receiving element 52 via the emission side optical fiber 56.
An output example of the light receiving element 52 at this time is shown in FIG.
According to the figure, the light quantity component detected by the light receiving element 52 is mostly reflected light generated in the optical sheet bus 54, and the toner presence / absence information component remains at about 10% at most.

For this reason, by processing both of them as shown in the following equation (2), it is possible to extract the detection signal S (t) having only the fluctuation due to the toner amount.
Here, the output of the light receiving unit for each time is V (t), the average value of the light receiving element output V (t) of the portion where the toner is not placed is Vmax, and the light receiving element output V (t) is saturated due to the adhesion of the toner. When the average value of the state is Vmin,
S (t) = {Vmax−V (t)} / {Vmax−Vmin} (2)
In performing such processing, the actual measurement process is a preprocess for measuring the amount of toner on the measurement target surface M, in which no toner is present and a toner image having a sufficiently high amount of toner is generated. Measure the value of.
Further, by measuring the difference between Vmax and V (t) and normalizing with the difference between Vmax and Vmin, the light quantity fluctuations of the optical fibers 55 and 56 can be canceled out.

Ninth embodiment
FIG. 14A shows Embodiment 9 of the toner amount detection device according to the present invention.
In the figure, the toner amount detection device 50 satisfies the requirement that a high toner amount reference image is not desired. Unlike the first to seventh embodiments, the optical sheet bus 54 is replaced with one sheet bus piece 61. In addition, light of different wavelengths A and B is used.
Here, the optical sheet bus 54 has an optical opening 61c that transmits only one wavelength light (A) on one end side of one sheet bus piece 61, and the incident side optical fiber 55 and the emission side on the other end side. An optical fiber 56 is connected.
In this example, the light emitting element 51 (51a, 51b), the light receiving element 52 (52a, 52b), and the beam splitters 58, 59 are the same as those in the first embodiment.

Therefore, according to the present embodiment, the light of the two wavelengths A and B from the light receiving element 52 (52a, 52b) is transmitted to the incident side optical fiber 55 through the incident side beam splitter 58 and guided to the optical sheet bus 54. It is burned.
Then, in the optical sheet bus 54, as shown in FIGS. 14A and 14B, the measurement target surface M is irradiated with light from the optical opening 61c, and reflected light and scattered light therefrom are converted into the optical sheet bus. After returning to 54, the light is superimposed on the reflected light in the optical sheet bus 54 and then transmitted through the output side optical fiber 56, and then the light of the respective wavelengths A and B is output by the output side beam splitter 59. Then, the light is incident on the light receiving element 52 (52a, 52b).

For the light of wavelength A, both the toner amount information and the transmittance fluctuation amount of the optical fibers 55 and 56 are measured, and for the light of the wavelength B, only the transmittance fluctuation amount of the optical fibers 55 and 56 is measured as the output value. Is done.
However, most of the light amount of the wavelength A is reflected light generated in the optical sheet bus 54, and the toner presence / absence information component remains at about 10% at most.
By processing both of them as shown in the following equation (3), it is possible to extract the detection signal S (t) only of the fluctuation due to the toner amount.

Here, VA (t) represents the light receiving element output for each time of the wavelength light (A) irradiated onto the measurement target surface M, VAmax represents the average value of the light receiving element output VA (t) of the portion where no toner is placed, and toner. Is the average value of the state where the light receiving element output VA (t) is saturated and VAmin, the light receiving unit output for each time of the wavelength light (B) not irradiated to the measurement target surface M is VB (t), and the light receiving element output VB When the initial setting value of (t) is VBini,
S (t) = {VAmax−VA (t)} / [{VAmax−VAmin} · VB (t) / VBini] (3)

[Embodiment 10]
FIG. 15 is an explanatory view showing Embodiment 10 of the toner amount detecting apparatus according to the present invention.
In the same figure, the toner amount detection device includes a light emitting element 51, a light receiving element 52, and a light guide member 53 provided therebetween, as in the first to ninth embodiments. 53 is different from the first to ninth embodiments.
In the present embodiment, the light guide member 53 includes, for example, an optical sheet bus 54 in which two sheet bus pieces 61 and 62 are joined, and is disposed at a portion facing the measurement target surface of each sheet bus piece 61 and 62. While the optical openings 61c and 62c are formed, the incident side light transmission unit 61e is integrally formed in a part of the sheet bus piece 61, and the light emitting element 51 is disposed at the entrance of the incident side light transmission unit 61e. In addition, an emission side light transmission unit 62e is integrally formed on a part of the seat bus piece 62, and a light receiving element 52 is disposed at the exit of the emission side light transmission unit 62e. .

  According to the present embodiment, it is not necessary to use the optical fibers 55 and 56 as shown in the first to ninth embodiments, and the apparatus configuration can be simplified correspondingly.

Example This example is a more specific example of the toner amount detection device according to the first embodiment, and its detection accuracy is examined.
In FIG. 3, a laser diode having the following wavelength is used as the light receiving element 52 (52a, 52b).
・ Wavelength A 650nm 2mW
・ Wavelength B 970nm 2mW
Both are low-cost laser diodes that are easily available.
These two-wavelength lights (A, B) are collected by condensing lenses 511 and 512 (see FIG. 4), and the two light paths are combined into one by the incident-side beam splitter 58, and then incident-side. Guided to the optical fiber 55.
The incident side beam splitter 58 used in this example may be any one that is sensitive to the wavelength of the light source (light emitting element 51), and a general one can be used. Here, a mass-produced product having a transmittance of 50% for both wavelengths A and B was used.
On the other hand, the optical fiber 55 is made of PCF (polycarbonate fiber), and may be any one that can cover the wavelength of the light source (light emitting element 51).
Further, the thickness was 0.5 mm, and there was no problem in wiring in the image forming apparatus, but a connector part was inserted in the middle, and the transmittance was 80% ± 5%. The error is the amount of fluctuation of the transmittance due to thermal deformation.

Next, the configuration of the optical sheet bus 54 will be described.
Here, two sheet bath pieces (61, 62) with a thickness of 0.5 mm are joined.
A configuration directly connected to the optical fibers 55 and 56.
The optical sheet bus 54 itself has a transmittance of about 100% for both wavelengths A and B.
A coating that transmits 400 to 700 nm and reflects 780 to 970 nm is applied to the optical aperture (61c, 62c) that is the measurement target side end surface, and only the light of wavelength A is transmitted.
A coating that transmits 760 to 1600 nm and reflects 550 to 650 nm is applied to the joint surface of the sheet bath pieces 61 and 62, and only light of wavelength B is transmitted.
-The maximum reflected light (wavelength A) from the measurement target surface M is 10%, and the transmitted light at the joint surface of the sheet bath pieces 61 and 62 is 50%.

The measurement head portion (the optical sheet bus 54 portion) of the toner amount detection device having the above-described configuration is disposed to face the measurement target surface M. The installation method only needs to be attached substantially perpendicular to the measurement target surface M, and a simple method such as double-sided tape adhesion can be used.
The light emitted from the optical sheet bus 54 is guided to the emission side optical fiber 56 again.
At this time, the transmittance is 80% ± 5%.
Further, the light guided from the output-side optical fiber 56 is spectrally separated by the output-side beam splitter 59 that is wavelength-dependent coated, and the light amounts of the wavelengths A and B are detected by the photodiode that is the light receiving element 52 (52a, 52b). At this time, the transmittance of the exit side beam splitter 59 is 50%.

When adopting the above configuration,
Wavelength A (with toner presence / absence information) 0 to 0.016 mW ± 13%
Wavelength B (for reference) 0.08mW ± 13%
Is obtained.
89, and can be used for sufficiently accurate measurement (detection).

FIG. 16 shows a specific example of measurement results obtained in this example.
In this example, the gain is set so that the sensor output averages VAini and VBini in the state where the toner is not attached to the measurement target surface M (photosensitive drum 21) are 4V.
On the other hand, as a result of measuring a certain toner, the output decreased to 93.7% due to the transmittance variation of the optical fibers 55 and 56.
The result of correcting this is shown in FIG.

FIG. 18 shows the relationship between the toner amount of the toner and the sensor output by the toner amount detection device (sensor) 50 according to the present embodiment.
At this time, when the toner amount and the sensor output in the comparative example (toner amount detection device adopting the method shown in FIG. 19) were examined, substantially the same results were obtained in the example and the comparative example.
As described above, according to this embodiment, the thickness can be configured to be 1 mm, and it can be sufficiently used in an image forming apparatus having a dense configuration.

(A) is explanatory drawing which shows the outline | summary of the photodetector concerning the reference invention relevant to this invention, (b) is explanatory drawing which shows the outline | summary of the photodetector concerning this invention. (A) is explanatory drawing which shows an example of the image forming apparatus with which Embodiment 1 of the photodetector (sensor) which concerns on this invention was integrated, (b) is explanatory drawing which shows the outline | summary of the photodetector. FIG. 3 is an explanatory diagram illustrating details of the light detection device according to the first embodiment. (A) is explanatory drawing which shows the periphery of the light emission part of Embodiment 1, (b) is explanatory drawing which shows the periphery of the optical sheet bus | bath, (c) is explanatory drawing which shows the periphery of the light receiving part. It is a schematic diagram which shows the optical transmission principle of the optical sheet bus | bath used by this Embodiment. (A) is explanatory drawing which shows an example of sensor output VA (t), (b) is explanatory drawing which shows an example of sensor output VB (t). (A) is explanatory drawing which shows the outline | summary of the photon detection apparatus based on Embodiment 2, (b) is the principal part detail drawing. (A) is explanatory drawing which shows the outline | summary of the photon detection apparatus based on Embodiment 3, (b) is the principal part detail drawing. FIG. 10 is an explanatory diagram illustrating an outline of a light detection device according to a fourth embodiment. FIG. 10 is an explanatory diagram illustrating an outline of a light detection device according to a fifth embodiment. FIG. 10 is an explanatory diagram showing an outline of a light detection device according to a sixth embodiment. FIG. 10 is an explanatory diagram showing an outline of a light detection device according to a seventh embodiment. (A) is explanatory drawing which shows the outline | summary of the photon detection apparatus based on Embodiment 8, (b) is explanatory drawing which shows an example of the sensor output VA (t). (A) is explanatory drawing which shows the outline | summary of the photon detection apparatus based on Embodiment 9, (b) is explanatory drawing which shows the optical sheet bus | bath used by this Embodiment. FIG. 32 is an explanatory diagram showing an outline of a light detection device according to a tenth embodiment. It is explanatory drawing which shows an example of sensor output VA (t) of an Example, VB (t). It is explanatory drawing which shows an example of sensor output S (t) after correction | amendment of an Example. It is explanatory drawing which shows the sensor output example with respect to the toner amount in an Example and a comparative example. (A) is explanatory drawing which shows the outline | summary of a reflected light detection system, (b) is explanatory drawing which shows a sensor output characteristic. (A) is explanatory drawing which shows the outline | summary of a scattered light detection system, (b) is explanatory drawing which shows a sensor output characteristic. It is explanatory drawing which shows the outline | summary of the conventional photon detection apparatus. It is explanatory drawing which shows the sensor output characteristic of the photon detection apparatus shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light-emitting part, 2 ... Light-receiving part, 3 ... Light guide member, 4 ... Sheet-like optical transmission medium, 4a ... Incident part, 4b ... Outgoing part, 4c ... Optical opening part, 4d ... Joint surface, 5 ... Incident side light Transmission member, 6 ... Emission side optical transmission member, 7 ... Optical transmission line separation means, M ... Measurement target surface, A, B ... Two wavelengths

Claims (8)

In a light detection device that detects light reflected or scattered from the surface to be measured,
A light emitting unit that emits two types of light having different wavelengths, and
A light receiving unit that senses two types of light with different wavelengths, and
A light guide member provided between the light emitting unit and the light receiving unit,
The light guide member is disposed at a part facing the measurement target surface, and includes an incident part for entering two kinds of light from the light emitting part and an emitting part for emitting two kinds of light toward the light receiving part, respectively. A sheet-like optical transmission medium that is optically transmitted by internal reflection and has an optical opening formed facing the surface to be measured;
Of the two types of light from the light emitting part incident on the sheet-shaped optical transmission medium and incident from the incident part , only the light of one wavelength is irradiated onto the measurement target surface and the detection light from the measurement target surface Has an optical transmission line separating means guided to the emitting part together with the light of the other wavelength ,
The optical transmission path separating means irradiates only the light of one wavelength from the light emitting unit through the optical aperture to the surface to be measured, takes in the reflected or scattered light from the surface of the measuring object, and has the other wavelength from the light emitting unit. A light detection apparatus characterized in that light is not irradiated outside from an optical opening . The light detection device according to claim 1,
The sheet-like optical transmission medium is composed of an optical sheet bus in which two sheet bus pieces are provided adjacent to each other, and one sheet bus piece is used as an incident portion where two types of light from the light emitting portion are incident, and the other sheet. A light detection apparatus characterized in that a bath piece is an emission part from which light is emitted to a light receiving part . The light detection device according to claim 1 ,
The light guide member is an incident side optical transmission member that guides two types of light from the light emitting unit to the incident part of the sheet-like optical transmission medium;
A light detection apparatus comprising: an emission-side optical transmission member that guides two types of light emitted from an emission part of a sheet-like optical transmission medium to corresponding sensing parts of a light-receiving part, respectively. The light detection device according to claim 1 ,
The optical transmission line separation means performs reflection processing with high wavelength dependency on the optical aperture of the sheet-like optical transmission medium, and irradiates the reflection processing with wavelength light that can be transmitted and wavelength light that can be reflected from the light emitting section. The light detection device is characterized by being set as two types of light. The light detection device according to claim 1 ,
The sheet-like optical transmission medium has a light irradiation part to the measurement target surface and a light detection part from the measurement target surface as an optical opening, and the light irradiation part and the light detection part are set as separate members. ,
In the optical transmission line separating means, only the wavelength light that can be reflected by the optical opening is transmitted to the joint surface of the plurality of members constituting the sheet-like optical transmission medium, and the wavelength light that can be transmitted from the optical opening is reflected. A photodetection device characterized by being subjected to a reflection process. In using the photodetection device according to claim 1,
When the light receiving unit output for each time of the wavelength light irradiated on the measurement target surface is VA (t) and the light receiving unit output for each time of the wavelength light not irradiated on the measurement target surface is VB (t),
S (t) = VA (t) / VB (t)
A method for using a photodetection device, comprising: determining a photodetection result based on information S (t) obtained by performing division processing according to. In an image forming apparatus that forms a visible image with a color material on an image carrier,
When using the light detection device according to claim 1 as a device for detecting the amount of color material of a visible image on an image carrier,
The light receiving unit output for each time of the wavelength light irradiated on the measurement target surface is VA (t), the average value of the light receiving unit output VA (t) of the portion where the color material is not placed is VAmax, and the color material is attached and received. The average value in the state where the output VA (t) is saturated is VAmin, the light receiving unit output for each time of wavelength light not irradiated on the measurement target surface is VB (t), and the initial setting value of the light receiving unit output VB (t) is VBini And when
S (t) = {VAmax−VA (t)}
/ [{VAmax−VAmin} · VB (t) / VBini]
A method for using a photodetection device, comprising: judging a photodetection result based on information S (t) obtained by performing the arithmetic processing according to the above. In an image forming apparatus that forms a visible image with a color material on an image carrier,
An image forming apparatus using the photodetection device according to claim 1 as a device for detecting a color material amount of a visible image on an image carrier.

Images