JP2001281764A - Ohp original sensing system, ohp original element, image recording film, and original housing member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an OHP original sensing system which is used in combination with an OHP device and is hardly restricted in an original position to be placed on an original platen in order to allow a sensor to surely respond. SOLUTION: This OHP original sensing system is used in combination with the OHP device having the original platen 3 to be placed with an OHP original 9 having an image for projection and a projection section 5 for projecting the image for projection by receiving the light transmitted through the OHP original 9. (A) The OHP original 9 includes a sensor 7 for sensing whether the original exists in the original platen 3 or not and (B) an optical film for reflecting or absorbing the light signal to which the sensor 7 responds. The light signal is the light of a band exclusive of a visible light band. The optical film includes a wavelength selective transmitting film optically connected to the image for projection. The wavelength selective transmitting film allows the transmission of the light of the visible light band and absorbs or reflects the light signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an OHP (Over H
ead Projector: OHP document sensing used in combination with an apparatus and including an optical sensor for sensing whether an OHP document is on the document table of the device and an optical film to which the sensor responds. Regarding system improvement.

[0002]

2. Description of the Related Art A conventional OHP device having a sensor for detecting an OHP document, that is, having a sensor for detecting whether or not the OHP document is on a document table, is disclosed in, for example, Japanese Utility Model Application Publication No.
No. 100131 and Japanese Utility Model Laid-Open No. 2-48941. In the OHP devices disclosed in these publications, the sensor responds when a part of the document, that is, the peripheral edge of the document or its vicinity covers the sensor. For example, the response of the sensor generates an electric signal, and the ON / OFF of the OHP device and the adjustment of the light amount of the projection light source (lamp) of the device can be performed by the electric signal. For example, the lamp is turned on when a document is placed on the platen, and turned off when the document is removed. Further, when the original is shifted and the original is placed on the original table without securely covering the sensor, the lamp is not turned on.

In the above-described OHP document sensing system, a device including a sensor is usually arranged as a device as small as possible at a corner or an edge of a document table so that it does not become an obstacle to projection. I have. This was for the following reasons. In an OHP apparatus, as much of the document table as possible is used as a light supply surface (light emitting surface that supplies light for projection to the document), and light for projection (usually light in the visible light band) is projected onto the document. Has been supplied. Therefore, the projection can be performed as long as the projection image is arranged on the light supply surface, and the position of the document on the document table is hardly limited. That is, a sensor device that occupies a large portion of the document table makes the area of the light supply surface relatively small, thereby deteriorating the usability of the user.

On the other hand, an image recording film for recording a projection image for forming an OHP document is transparent to light in the visible light band (visible light) such as polyethylene terephthalate (PET) and polypropylene. It comprised a polymer film and had high transparency as a whole. Since such a polymer film not only has a high light transmittance for visible light but also can be manufactured at low cost,
Widely used in general.

[0005] Such an image recording film is a single polymer film (single layer) as described above,
There is also known a laminated film in which a polymer film is used as a light-transmitting substrate and another light-transmitting layer is laminated on the front or back surface of the substrate. Regarding the laminated film, for example, JP-A-9-152736 and JP-A-11-33818
0, JP-A-11-174711, and the like. These image recording films comprise (i) a light-transmitting polymer film substrate and (ii) a light-transmitting image-receiving layer laminated on at least one principal surface of the substrate. Having a configuration. The image receiving layer contains, for example, at least one thermoplastic polymer selected from the group consisting of polyester, styrene-based copolymer, acrylic polymer, polyurethane, polyolefin, and the like, and other additives. This layer is highly transparent to visible light. That is, the image recording film as a whole is transparent to visible light.

Further, in order to protect the projection image recorded on the recording surface of the image recording film or to facilitate the organization and carrying of the film on which the image is recorded, that is, the OHP document, a document storage member is required. It is preferred to use Such a storage member includes an envelope formed of a translucent film and having a space having a shape and a dimension capable of storing an OHP document. In a state where the document is stored in the envelope, the projection image overlaps with the translucent film, but does not hinder the image projection, that is, can be optically connected. In addition, as such a translucent film, the above-mentioned visible light transmissive polymer film (polyester, polyolefin, etc.) is preferably used, and is usually a single-layer film.

[0007]

However, in the above-described document sensing system, the sensor is not reliably covered with the document,
Sometimes the sensor did not respond when desired. this is,
This is because, when an OHP apparatus and a document are used, the sensor needs to be covered with a peripheral marker of the document itself or a sensing marker formed of an optical film or the like disposed thereon. Therefore, in order for the sensor to respond reliably, it was necessary to significantly restrict the position of the document placed on the document table. For example, changing the position of the original on the light supply surface and changing the projection position of the image on the screen during use of the OHP device is a normal use range of the OHP device. It was extremely difficult to change the document position.

On the other hand, the polymer film and the light transmitting layer (such as an image receiving layer) of the above-mentioned image recording film are made of visible light (usually, blue band: wavelength = 430 to 490 nm, green band: wavelength = 515 to 515 nm). 575 nm and red band: wavelength =
Not only the three primary color bands of 580 to 640 nm (including the three primary color bands), but also the light in the infrared wavelength band near the visible light band (normally, the band of 800 to 1,100 nm) such as near infrared light.

When an optical sensor is used as a sensor of the above-described document sensing system, a band signal outside the visible light band such as an infrared wavelength band light is preferably used as an optical signal to which the sensor responds. Therefore, an image recording film or OHP used in combination with such a document sensing system
The original had to be separately provided with an optical film for reflecting or absorbing the optical signal responding to the sensor.

[0010] The optical film as described above is generally a film having low visible light transmittance, for example, a white (diffuse) reflection film or a specular reflection film. Therefore,
It is arranged so that it does not overlap with the image for projection contained in the image recording film or the OHP document (that is, it is not optically connected). In order to arrange in this manner, it is inevitable to dispose an optical film having a plane dimension as small as possible at the peripheral edge of the image recording film or the OHP document. However, there has been no choice but to significantly limit the position of the original placed on the platen.

The present invention has been made in view of such conventional circumstances, and an object thereof is to provide an OH
An object of the present invention is to provide an OHP document sensing system used in combination with a P device, in which the position of a document placed on a document table is hardly restricted in order to make a sensor respond reliably. It is another object of the present invention to provide an OHP document element, an image recording film, and a document storage member usefully used in the system. The OHP document element is used to form an OHP document, or to protect the OHP document or to store the OHP document so that it is easy to organize and carry.
It is a member used together with the OHP document, and preferable examples thereof include an image recording film for recording an image for projection, and a document storage member having a translucent envelope.

[0012]

Means for Solving the Problems As means for solving the above problems, the present invention provides an OHP having an image for projection.
A system used in combination with an OHP device including a document table on which a document is placed, and a projection unit that receives the light transmitted through the OHP document and projects the projection image,
(A) a sensor for detecting whether or not the OHP document is on the document table; and (B) an optical film for reflecting or absorbing an optical signal to which the sensor responds, wherein the optical signal Is OHP which is light outside the visible light band.
In the document sensing system, the optical film includes a wavelength selective transmission film optically connected to the projection image, wherein the wavelength selective transmission film transmits light in a visible light band and converts the light signal. An OHP document sensing system characterized by reflecting or absorbing.

Further, the present invention includes an optical film for reflecting or absorbing an optical signal responding by a sensor for detecting whether or not an OHP document is on a document table of the OHP apparatus, and comprising: An OHP document element used to optically connect, wherein the optical signal is light in a band outside a visible light band, the optical film comprises a wavelength selective transmission film, and the wavelength selective transmission film comprises: An OHP document element characterized by transmitting light in the visible light band and reflecting or absorbing the optical signal.

Further, the present invention includes a light-transmitting substrate having a recording surface for recording a projection image on at least one main surface, wherein the projection image recorded on the recording surface is the light-transmitting substrate. An image recording film for an OHP document optically connected to a transparent substrate, wherein the light-transmitting substrate comprises a wavelength-selective transmission film,
Provided is an image recording film, which transmits light in a visible light band and reflects or absorbs light in a band outside the visible light band.

Further, the present invention includes an envelope formed of a translucent film and having a space having a shape and a size capable of storing an OHP document having a projection image, wherein the OHP document is In the document storage member optically connected to the light-transmitting film, the light-transmitting film includes a wavelength-selective transmission film in a state where the image for projection is stored in the envelope. The transmissive film provides a document storage member that transmits light in the visible light band and reflects or absorbs light in a band outside the visible light band.

[0016]

First, an embodiment of the present invention will be described in terms of operation. An OHP document sensing system according to the present invention includes an OHP device including: a document table on which an OHP document having a projection image is placed; and a projection unit configured to receive the light transmitted through the OHP document and project the projection image. An OHP document sensing system used in combination,
(A) a sensor for detecting whether or not the OHP document is on the document table; and (B) an optical film for reflecting or absorbing an optical signal to which the sensor responds, wherein the optical signal Is the light outside the visible light band.
It has the same configuration as the above-mentioned conventional one. The features of the document sensing system of the present invention are as follows.

That is, in the present invention, the optical film includes a wavelength-selective transmission film optically connected to the image for projection, the wavelength-selective transmission film transmits light in a visible light band, The optical signal is reflected or absorbed.

In the system of the present invention, since the optical film is optically connected to the projection image of the OHP document, the position of the document placed on the document table is hardly limited in order for the sensor to respond reliably.

The phrase “optically linked” between an image for projection and an optical film (or another component such as a light-transmissive substrate of an image recording film) means that the image for projection and the optical film (or And the other component) can transmit a sufficient amount of light to project an image. That is, in the optical path of the light for image projection (usually,
The image for projection and the optical film (or other components) are arranged so as to overlap (forming a laminate) between the platen and the projection unit, but the optical film (or other components) The visible light transmittance of the element is sufficiently high, and the laminate including the projection image and the constituent elements can transmit a sufficient amount of light. Therefore, the addition of the optical film (or other components) to the OHP document does not disturb the image projection (the image is not easily seen). On the other hand, despite having such visible light transmission, the optical film reflects or absorbs the optical signal to which the sensor responds, so that the sensor reliably responds.

The function of such an optical film will be described more specifically. The optical film added (or incorporated) to the OHP document does not need to be arranged at the peripheral edge of the OHP document, and may be arranged so as to overlap with the projection image arranged at the center of the OHP document. It is possible.
Also, the plane dimensions of the optical film can be made as large as possible. Therefore, the optical film can be arranged so that the projection image is optically connected to the whole.

In order to set the arrangement relationship between the projection image and the optical film in this manner, for example, (1) a light-transmissive base material having a recording surface for recording the projection image on at least one main surface may be formed by: An image recording film including the optical film, or (2) an optical film including the optical film as a light-transmitting film covering almost the entirety of a projection image.
Using an HP document element, such as a document storage member,
It is preferable to make an OHP original. Further, the OHP document element may be a coverlay film that covers the image-recorded recording surface of the image recording film. The coverlay film can be used for the purpose of protecting a projection image. The coverlay film is usually fixed to the image recording surface via a transparent adhesive. In addition, other OHP
Details of the document element will be described later.

The arrangement relationship between the projection image and the optical film is as described above, and the document detection sensor is disposed, for example, to detect whether or not a document is present at or near the center of the document table. . In this way, even when the position of the original is changed on the light supply surface of the original platen for the purpose of changing the projection position of the image on the screen during use of the OHP apparatus, the sensor can detect the original. Is possible. Because, even in such a position change, usually, any part of the projection image always exists in the center of the document table and in the vicinity thereof, and the optical film optically connected to the projection image is also present. This is because it exists at the center of the platen and in the vicinity thereof.

The distance that the OHP document moves to change the position of the document on the light supply surface of the document table is usually O
It is smaller than the length dimension and width dimension of the HP document.
Therefore, it is not always necessary to cover almost the entirety of the projection image. However, in order to increase the degree of freedom in changing the position of the original on the light supply surface of the original platen, as described above, the optical film should substantially overlap the entire surface of the projection image. It is suitable.

In order to allow such a change in the original position while ensuring that the sensor responds, and to make the original position change as free as possible, the sensor must be positioned near the projection unit of the OHP device. , OHP devices. This will be specifically described with an example in which the optical film reflects an optical signal to which the sensor responds. The projection unit of the OHP device is located at a position where visible light from the document can always be received as long as there is a document on the platen. Therefore, the optical signal reflected by the optical film incorporated in the document can always be received at a position near the projection unit. That is, the sensor disposed near the projection unit of the OHP device can always receive the optical signal from the optical film as long as there is a document on the document table.

The light emitting unit for transmitting the optical signal sensed by the sensor may be arranged at any place of the OHP device as long as the effect of the present invention is not impaired. Preferably, it is preferably located near the sensor or integrated with the sensor.

Next, the wavelength selective transmission film will be described. The wavelength selective transmission film is a film that selectively transmits light of a predetermined wavelength and selectively reflects or absorbs light of another predetermined wavelength different from the transmission wavelength. Therefore, when this film selectively reflects light of another predetermined wavelength, it is also called a wavelength selective reflection film. The optical signal to which the sensor responds is light outside the visible light band, and is usually infrared light such as near infrared light. Therefore, the wavelength selective transmission film is usually a film that selectively reflects or absorbs infrared rays such as near infrared rays.

The wavelength selective transmission film preferably includes a dielectric reflection layer, reflects a light signal in a specific wavelength band at a predetermined ratio, and transmits a visible light band light at a predetermined ratio. It is a transmission film (wavelength selective reflection film). The dielectric reflection layer has a reflectance of 70 for the reflected light.
% Or more and a blue band (wavelength: 430 to 490).
nm), a green band (wavelength: 515 to 575 nm) and a red band (wavelength: 580 to 640 nm) preferably have a light transmittance of 60% or more in three primary color bands. The light transmittance of the three primary color bands is preferably 70% or more, particularly preferably 8%.
0% or more.

Although the reflection effect of the dielectric reflection layer will be described in detail later, at least one of the first and second sets of dielectric reflection layer units included in the dielectric reflection layer has a thickness (d, unit is nm). The product uses the so-called dielectric reflection principle by including a quarter-wave layer in which the product (nd) of the refractive index of the polymer and the refractive index (n) of the polymer is one-quarter of the wavelength of the reflected light. . That is, the above product (nd) is a quarter.
Light having a wavelength not corresponding to the wavelength can be transmitted, and light having a wavelength corresponding to the product (nd) equal to a quarter wavelength can be reflected. Further, since the dielectric reflection layer is substantially composed of a polymer, the transparency to visible light can be increased.

For example, when the optical signal is in the infrared region (near infrared ray or the like), preferably, the product (nd) of the quarter wavelength layer is in the range of 200 to 250 nm and 8
The light reflectance in the wavelength band of 00 to 1,100 nm is 7
0% or more. The reflectance of the predetermined wavelength band light is preferably 80% or more, particularly preferably 90% or more. The light transmittance of the entire wavelength selective transmission film is usually 70%.
%, Preferably at least 80%, particularly preferably at least 90%. In addition, the thickness of the entire wavelength selective transmission film is usually 20 μm, including additional layers used as necessary.
m to 7 mm.

Note that “light transmittance” in the present specification is used.
Alternatively, the “light reflectance” is a value measured using a spectrophotometer. Further, hereinafter, when simply referred to as “light transmittance” without particularly limiting the wavelength band, it means “transmittance of visible light in three primary color bands”.

The dielectric reflection layer is not limited to a polymer, but may be a thin film layer in which a metal such as silver is thinly formed by a vacuum evaporation method or the like. On the other hand, a wavelength selective transmission film that does not include a dielectric reflection layer can also be used. For example, in a polymer film having high transparency to visible light, an infrared absorbing dye is contained, a light signal composed of infrared light is absorbed at a predetermined ratio, and a wavelength at which light in a visible light band is transmitted at a predetermined ratio. A permselective film can be formed. Specific examples of such a polymer film containing a dye include Lumicle UCF-02 (trademark) manufactured by Kureha Chemical Co., Ltd.

The dielectric reflection layer acts to reflect light (electromagnetic waves) in a specific wavelength band at a predetermined ratio, but transmits light in a predetermined visible light band at a predetermined ratio. That is,
The term "dielectric reflective layer", as used herein, is formed by laminating a plurality of light-transmitting dielectric layers in close contact with each other, and the relationship between the thickness of each layer and the refractive index is as described above. Is defined as a layer made of a reflector determined to have a wavelength selectivity (a property of transmitting light in a certain wavelength band and reflecting light outside the wavelength band). The expression of wavelength selectivity is that the product of the thickness and the refractive index of a dielectric layer sandwiched between two substances is one-fourth of the wavelength of light incident on that layer, and the refractive index of the layer is It utilizes the principle of wavelength selective reflection, in which the reflected light at the two interfaces between the material and the layer is higher or lower than the refractive index of either material, so that the light reflected at the two interfaces is in phase with each other and strengthened.

As described above, the dielectric reflection layer may be, for example,
A first set of dielectric reflective layer units composed of a plurality of layers of the first polymer, and a second set of dielectric reflective layer units composed of a plurality of layers of a second polymer having a different refractive index from the first polymer A set of dielectric reflection layer units can be used in the form of a dielectric reflection film formed by alternately laminating a first polymer layer and a second polymer layer.

Usually, one polymer layer (dielectric layer)
Works effectively in a wavelength band of about 10 to several tens of nm, so that if it includes a finite number of layers, it functions effectively as a desired wavelength selective reflector. Therefore, in order to reflect a single-wavelength optical signal, at least two or more polymer layers are required. In addition, a relatively wide band, for example, 800 to
To effectively reflect light in the 1,100 nm wavelength band,
It suffices if there are at least 20 or more polymer layers. However, in order to improve the reflectivity, it is usually preferable that the number of layers having different thicknesses is larger. Further, although each layer is light-transmitting, light is slightly absorbed, and therefore, if the number of layers is too large, light transmittance and reflectance may decrease. Therefore, the number of laminated polymer layers in the dielectric reflection layer used in the present invention is 50 to 2,000.
Is suitable.

The dielectric reflection film is formed by (a) a method in which a dielectric layer is formed by multi-layer coating on a transparent polymer film, and (b) a multilayer film formed by a co-extrusion method using a dielectric made of a polymer material. It can be formed by a known method such as a method of forming as. The method for producing such a dielectric reflection film is disclosed, for example, in International Patent Publication (W
O) No. 95/17303.

As the above-mentioned dielectric, a light-transmitting material having a refractive index of 1.1 or more, for example, polyester (polyethylene naphthalate, polyethylene terephthalate, ethylene naphthalate-ethylene terephthalate copolyester, etc.), Polymers such as acrylic polymers (polymethyl methacrylate, copolymers of methyl methacrylate and other (meth) acrylates, etc.) are suitable. Further, the dielectric reflection film may be formed by the method (b).
It is preferred to form a multilayer polymer film by the method described above. This is because the workability is good and it is easy to manufacture the optical filter according to the present invention.

For example, the dielectric reflection film alternately includes a first layer including one or more of the above-described dielectrics and a second layer similarly including the dielectric. It is formed by lamination. Virtually all layers have a thickness of 1μ
m, and a plurality of layers having different thicknesses are included so as to exhibit the wavelength selectivity as described above. The refractive index of each layer is usually 1.1 or more, preferably 1.2 to 2.8. Further, the refractive index n ₁ of the first layer, the difference between the refractive index n ₂ of the second layer _{Δn (= | n 1 -n 2} |) is usually 0.05
It is in the range of 1.5, preferably in the range of 0.1 to 1.0.
When each layer contains a polymer, in order to effectively improve the wavelength selective reflectivity (reflectance for light of a predetermined wavelength),
Preferably, each of the polymer layers is biaxially oriented.

In addition to the above two types of dielectrics,
One or more dielectric layers may be added to form a laminate. The dielectric reflection layer may contain additives such as an ultraviolet absorber, an antioxidant, an antifungal agent, a rust preventive, a humectant, and a surfactant as long as the effects of the present invention are not impaired. Furthermore, as long as the effects of the present invention are not impaired, a light-transmitting protective film or an adhesive layer can be formed on the front surface, the back surface, or both surfaces of the dielectric reflection film.

As described above, if the wavelength selective transmission film as described above is used as the optical film used in the OHP document sensing system, light in the visible light band is transmitted, and the optical signal is reflected or absorbed. , To ensure that the sensors of the sensing system respond. Further, since the wavelength selective transmission film as described above has high visible light transmittance, even when optically connected to the image for projection, it does not hinder image projection.

A preferred OHP document element according to the present invention is:
As described above, the one that forms an OHP document, that is,
It can take the form of an image recording film. The image recording film includes a light-transmissive substrate having a recording surface for recording a projection image on at least one main surface, and as the light-transmissive substrate, for example, a wavelength selection including the dielectric reflection film. Use transmissive film.

An OHP document formed using such an image recording film is used in combination with an OHP document sensing system having a sensor for detecting an optical signal such as near infrared light, and the position of the film to be placed on the document table is determined. The degree of freedom can be increased.

The film for image recording includes (i) a substrate made of the wavelength selective transmission film, and (ii) a light-transmissive image-receiving layer laminated on at least one principal surface of the substrate. Can be provided. In this case, the surface of the image receiving layer is a recording surface on which an image is recorded.

The image receiving layer is, for example, polyester,
Styrene copolymer, acrylic polymer, albumin, gelatin, starch, cationic starch, gum arabic, sodium alginate, cellulose polymer, polyamide, polyacrylamide, polyethyleneimine, polyvinylpyrrolidone, polymethylpyrrolidone, polyvinyl alcohol, polyvinyl acetal, polyethylene It contains a simple polymer such as glycol or acrylic resin, or a polymer mixture of two or more selected from these, and other additives. Also, silica, alumina,
It can also be formed from a porous inorganic material such as alumina hydrate. The polymer-containing image-receiving layer preferably has thermoplasticity in the case of a heat-fixing image forming method. The image receiving layer is a layer having high transparency to visible light. That is, the image recording film as a whole is transparent to visible light.

The image receiving layer can be formed by applying a coating containing a raw material such as the above-mentioned thermoplastic polymer on at least one main surface of the substrate. Further, a primer layer (such as polyvinylidene chloride) can be provided between the substrate and the image receiving layer. The thickness of the image receiving layer is not particularly limited, but is usually in the range of 5 to 100 μm. On the other hand, when the outermost layer of the wavelength selective transmission film is a polymer layer, an image for projection can be formed directly on the outermost layer. In addition, the thickness of the whole wavelength selective transmission film used for the image recording film is usually in the range of 20 to 200 μm.

OH according to another preferred form according to the invention
As described above, the P-document element has a member used together with the document, that is, a light-transmitting envelope, for protecting the document and storing it for easy organization and carrying. Document storage member.

The light-transmitting envelope is formed, for example, from a light-transmitting film made of the wavelength-selective transmitting film. In addition, a space having a shape and dimensions capable of storing an OHP document having a projection image is provided. That is,
With the OHP document stored in the envelope,
The projection image of the P original is optically connected to the translucent film.

The envelope can be formed, for example, by folding a light-transmitting film having a length direction into two, and sealing both ends (sides) in the length direction with a light-transmitting adhesive or the like. The thickness of the entire wavelength selective transmission film used as an envelope is usually 10 to 100 μm.
m.

The OHP document sensing system of the present invention preferably includes a sensor responsive to an optical signal such as near-infrared light, and is combined with an OHP document element having a wavelength selective transmission film that reflects the optical signal. used. As shown in FIG. 1, an OHP document sensing system according to a preferred embodiment of the present invention is incorporated in an OHP device and used as an OHP device with a document sensing system. In the illustrated form, (1) a light source 1, (2) a document table 3 having a condenser lens provided in front of the light source 1, and (3) a projection including a projection lens disposed above the document table 3. (5) a sensor 7 fixed in the vicinity of the projection unit 5 and responsive to an optical signal such as near-infrared light; and (5) electrically connected to the sensor 7 to adjust the light amount of the light source 1. Control unit (power switch 11
And a light source lighting control device 13).

In the above OHP device, for example,
The light amount of the light source 1 is adjusted to the first level only when the OHP document 9 is placed on the document table 3, and the light amount of the light source 1 is set to the second level when the OHP document 9 is removed from the document table 3. It is very easy to do. Here, the first-level light amount is set to a relatively high level at which the image for projection can be viewed sufficiently brightly, and at the second level, the brightness of light reaching the projection screen without an image is determined by the observer. It is preferable to keep it at a relatively low level (zero light amount, that is, including power-off) that does not cause glare.

Accordingly, when the document is removed from the document table for the purpose of (a) energy saving and (b) document replacement, the light from the light source reaches the screen without an image, and is relatively high. It can be avoided that the light is directly reflected by the screen at the luminance and gives an observer an uncomfortable feeling such as glare.

As the sensor 7, for example, a sensor commercially available as an infrared (including near infrared) sensor can be used. Among commercially available sensors, there is a sensor called a photo implanter in which a sensor element (light receiving element) and a light emitting element (LED) are integrated. If this is used, light outside the visible light band emitted by the light emitting element (near infrared ray, etc.)
Is reflected by an irradiated object (for example, a wavelength-selective transmission film included in an OHP document), and the sensor element receives and responds to the reflected light, whereby a sensing system can be easily formed. Also, the sensor element can emit an electric signal as a response to the reflected light. The illustrated example receives such an electric signal and controls the light source lighting (ON
-OFF) or a control circuit or device for adjusting the amount of light and the above sensing system are combined in an OHP device.

As shown in the figure, a photo implanter (including a near-infrared sensor element and a light-emitting element) 7 emits near-infrared light as an optical signal toward the document table 3. Platen 3
When the OHP document 9 is placed on the photo implanter 7, the wavelength selective transmission film included in the OHP document 9
, And the sensor element of the photo implanter 7 receives the near infrared ray and responds.

The platen 3 incorporates ordinary transparent glass or transparent plastic, and their reflectance to near infrared rays is usually 10% or less. On the other hand, as the wavelength selective transmission film, a film that reflects near-infrared light, which is an optical signal, with a high reflectance as described above (normally, a reflectance of 70% or more) is used. Therefore, when there is no document on the document table 3 (empty state), the sensor element does not respond and the document table 3
The sensor element responds only when a document is placed on the device (use condition). On the other hand, when the OHP document 9 is removed from the document table 3, the document table 3 becomes empty, and the sensor element does not respond. Note that the sensitivity of the sensor element can be adjusted so that the sensor does not respond due to the near-infrared reflection of the platen itself.

When the sensor element of the photo implanter 7 senses a certain use state of a document, an electric signal is transmitted as a response of the sensor element. As shown in the drawing, such an electric signal is received by a control device 13 which performs light source lighting control (ON-OFF) or light amount adjustment, and turns on or off the light source 1 and adjusts to increase or decrease the light amount. . The above control circuit or device is also commercially available, and is also commercially available in the form of a kit in combination with the photoimplanter.

[0055]

EXAMPLES Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

An OHP with a document sensing system using the document sensing system of the present invention as shown in FIG.
A device can be made. For example, an overhead projector (OHP device, product number: 95 manufactured by 3M Co., Ltd.)
An example using (50) will be described.

First, a near-infrared photo implanter (product number: E) manufactured by OMRON Corporation is provided outside the housing of the projection unit including the projection lens and the projection mirror of the OHP apparatus.
3JK-DS30M1) 7 was fixed. Also, the power switch 11 of the light source 1 and the photo implanter 7 are electrically connected via the light source lighting control device 13, and when the original (wavelength selective transmission film) 9 is sensed, the light source 1 is turned on. The light source 1 was turned off.

An OHP document was produced using an image recording film including a wavelength selection film including a dielectric reflection layer as a base material as described above. The wavelength selection film has a light transmittance of 90% or more in the above-described three primary color bands, and a reflectance of a light signal (near infrared) emitted from the photo-implanter 7 is 9%.
0% or more.

When the power of the OHP device was turned on with the platen 3 empty, the light source 1 of the OHP device did not light up.
Next, when the OHP document 9 produced as described above was placed on the document table 3, the light source 1 was turned on. Subsequently, when the OHP document 9 was removed from the document table 3, the light source 1 was turned off. As a result, according to the present invention, when replacing a document,
It has been shown that the light of the light source 1 can be effectively prevented from being directly reflected by the screen in the absence of an image and giving an observer discomfort such as glare.

In the above-described OHP device with the document sensing system, one of the light emitting element and the light receiving element is fixed near the projection unit 5, and the other element is arranged below the condenser lens of the document table 3. You can also. In this case, contrary to the case of the above example, when the light receiving element receives (receives) the optical signal, it can be sensed that there is no original on the platen, and when the light receiving element does not receive the optical signal, On the table,
It can be considered that there is an original including a wavelength selective transmission film that reflects or absorbs an optical signal.

[0061]

As described above, according to the present invention, the position of the OHP document placed on the platen is set so that the sensor for detecting whether the OHP document is on the platen or not is responsive. Since there is almost no need to limit the position of the OHP apparatus, the O.P.
It is easy to change the position of the HP document.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an example of an OHP apparatus with a document detection system in which an OHP document detection system according to the present invention is incorporated.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source, 3 ... Original table, 5 ... Projection part, 7 ... Sensor (photo implanter), 9 ... OHP original, 11 ... Power switch, 13 ... Light source lighting control device.

Claims (5)

[Claims] 1. An OHP apparatus comprising: a document table on which an OHP document having a projection image is placed; and a projection unit that receives the light transmitted through the OHP document and projects the projection image. A system comprising: (A) a sensor for detecting whether or not the OHP document is on the document table; and (B) an optical film for reflecting or absorbing an optical signal responsive to the sensor. In the OHP document sensing system, wherein the optical signal is light in a band outside a visible light band, the optical film includes a wavelength selective transmission film optically connected to the projection image; The transmission film transmits light in a visible light band and reflects or absorbs the optical signal.
HP document detection system. 2. The OHP document sensing system according to claim 1, wherein the sensor is incorporated in the OHP device at a position near the projection unit. 3. An optical film, comprising: an optical film for reflecting or absorbing an optical signal responding to a sensor for detecting whether or not an OHP original is on an original platen of the OHP apparatus, and optically connected to an image for projection. An OHP document element used to perform the optical signal, wherein the optical signal is light in a band outside a visible light band, the optical film comprises a wavelength selective transmission film, and the wavelength selective transmission film is O is characterized by transmitting light and reflecting or absorbing the optical signal.
HP manuscript element. 4. A light-transmitting base material having a recording surface for recording a projection image on at least one main surface, wherein the projection image recorded on the recording surface is formed of the light-transmitting base material. An optically coupled OHP document image recording film, wherein the light-transmitting substrate includes a wavelength-selective transmission film, wherein the wavelength-selective transmission film transmits light in a visible light band, An image recording film, which reflects or absorbs light in a band outside the visible light band. 5. An envelope formed of a translucent film and having a space having a shape and dimensions capable of storing an OHP document having a projection image, wherein the OHP document is stored in the envelope. In this state, the projection image is a document storage member optically connected to the light-transmitting film, wherein the light-transmitting film includes a wavelength-selective transmission film, and the wavelength-selective transmission film is visible. A document storage member that transmits light in an optical band and reflects or absorbs light in a band outside the visible light band.