JP2726307B2 - Roof mirror lens array - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanner unit such as a copying machine, a facsimile, and an image scanner, and a roof mirror lens array used for an optical system of an optical print head.

2. Description of the Related Art A conventional roof mirror lens array has a fourth configuration.
Description will be made based on the drawings. Below the document surface 1, an optical path separating mirror 2 having two mirrors 2a and 2b formed to be inclined with respect to each other is provided. Along the longitudinal direction of the optical path separating mirror 2, there is provided a roof mirror array 4 in which a large number of roof mirrors 3 each having two reflecting surfaces 3a and 3b are formed linearly and continuously at a constant arrangement pitch. ing. A lens array 6 having a lens 5 formed between the roof mirror array 4 and the optical path separating mirror 2 and formed in correspondence with the arrangement pitch of the roof mirror 3
Is provided. A light shielding plate 7 is provided between the lens array 6 and the roof mirror array 4 to prevent light emitted from a predetermined lens 5 from entering the roof mirror 3 which does not correspond to the lens 5. ing.

In such a configuration, light from the document surface 1 is reflected by a mirror 2a above the optical path separating mirror 2 located below the document surface 1 and passes through a lens array 5 having a lens 5;
After being reflected once by each of the two reflecting surfaces 3a and 3b forming the roof mirror 3 of the roof mirror array 4 (two times in total), the light passes through the lens array 5 again, and this time, The light is reflected by the lower mirror 2b, its optical path is changed, and an image is formed on the image surface 8, whereby the information written on the original surface 1 is read.

The reason why the light blocking plate 7 in the conventional roof mirror lens array as described above is provided is that, as shown in FIG.
In addition to preventing crosstalk of light between adjacent roof mirrors 3, the roof mirror 3 has an effect of blocking light flux a reflected only on one reflecting surface 3a (or 3b) of the roof mirror 3. It is arranged so that the light flux other than the effective imaging light flux b that is reflected twice at 3 and reaches the image plane 8 is cut so that the resolving power is not further reduced.

Here, the relationship between the thickness of the light shielding plate 7 in the optical axis direction Y and the angle of view for taking in light from the single roof mirror lens system will be described. FIG. 6 is an equivalent configuration diagram in which the roof mirror 3 is developed symmetrically. From the optical system, taking the amount of light at the opening to meet the diameter of about lens 5 closer to the lens optical axis, but farther from the optical axis two lenses 5a _1, 5a
The vignetting of No. ₂ reduces the amount of light taken in, and has a light amount distribution in the image height direction shown in the figure. But,
As shown in Figure 7, identical to the sixth focal length of the lens 5a ₁ of the figure, when the distance Tb between the lens 5a ₁ and the lens 5a ₂ is smaller than the interval Ta in FIG. 6, high more image height Part A can be captured.

In this case, the interval Tb corresponds to the thickness of the light shielding plate 6, and if the size of the roof mirror array 4 is the same,
As the thickness of the light shielding plate 7 is reduced, the angle of view of the single roof mirror lens system can be increased.
The amount of light synthesized as a roof mirror lens system increases,
A roof mirror lens array with even higher light use efficiency can be obtained.

However, since the light-shielding plate 7 is thinned, the light is not reflected twice by the roof mirror 3 but is reflected only once by the reflection surface 3a on one side and reaches the image surface 8 due to light flux. As a result, there arises a problem that optical characteristics are deteriorated, light use efficiency is deteriorated, and a clear image cannot be obtained.

As a condition of the thickness of the light-shielding plate 6 in which only one-time reflection occurs, as a condition of a perpendicular from each of the reflection surfaces 3a and 3b of the roof mirror 3, that is, an inclination of 45 degrees in the arrangement direction X with respect to the optical axis direction Y There is a condition that satisfies that the straight line does not exit from the opening of the light shielding plate 7 to the outside. FIG. 8 shows such ray tracing. In this case, the roof mirror 3 has a finite incident angle with respect to the perpendicular of the reflection surface 3a on one side of the roof mirror 3.
Is reflected once, is shielded by the light shielding plate 7 and does not exit from the opening thereof, and only the effective light beam d reflected twice exits to the outside.

By increasing the thickness of the light shielding plate 7 in this manner, 2
Although it is possible to cut the light flux c other than the effective light flux d that is reflected twice, it is not possible to increase the angle of view this time due to the increase in the thickness of the light flux c. There is a problem that the utilization efficiency is reduced.

Means for Solving the Problems In order to solve such a problem, an invention according to claim 1 includes an optical path separating mirror and a roof mirror having a constant arrangement pitch along a longitudinal direction of the optical path separating mirror. A roof mirror array formed linearly and continuously in a row, and a lens array located between the roof mirror array and the optical path separating mirror and formed in correspondence with the arrangement pitch of the roof mirrors And a roof mirror lens array including a light shielding plate disposed between the lens array and the roof mirror array, wherein a flat surface Sa including an opening on a side of the light shielding plate close to the lens and the roof mirror are provided. The distance between the plane Sb including the opening on the side close to the array and Ts is defined as Ts, and the distance between the two reflecting surfaces facing each other forming the individual roof mirrors is set to Ts. The distance between the plane Ra including all the intersections and the plane Rb including all the intersections of the adjacent reflecting surfaces of the adjacent roof mirrors is Tr.
Where Tsr is the distance between Sa and Ra, the relationship Tsr <Ts + Tr is satisfied.

According to a second aspect of the present invention, there is provided an optical path separating mirror, a roof mirror array in which a plurality of roof mirrors are formed linearly and continuously with a constant arrangement pitch along the longitudinal direction of the optical path separating mirror, and the roof mirror A lens array having a lens formed between the array and the optical path separating mirror and corresponding to an arrangement pitch of the roof mirror, and a light-shielding plate disposed between the lens array and the roof mirror array In the roof mirror lens array consisting of, when projecting the cross-section in the arrangement direction of the light shielding plate in the direction of the reflection surface of the roof mirror array orthogonal to the arrangement direction, only the projected portion has the reflection surface An anti-reflection coating having a reflectance lower than the reflectance for the wavelength used in the effective reflection area was formed.

According to the first aspect of the present invention, the size of the light-shielding plate provided between the lens array and the roof mirror array is set so as to satisfy the above-described relational expression, so that the light passes through the lens of the lens array. The reflected light is incident on a predetermined roof mirror of the roof mirror array and is reflected,
The light may be light that has only two reflections that do not include one-time reflection, or light that has two reflections that does not increase the amount of one-time reflection even if there is one-time reflection.

According to the second aspect of the present invention, since the non-reflection coating is formed at the boundary between adjacent roof mirrors, the amount of light reflected once by the roof mirror can be cut or reduced.

First Embodiment First, a first embodiment of the present invention will be described with reference to FIG. The overall configuration of the roof mirror lens array is described in the prior art (see FIGS. 4 and 5).
Therefore, the description is omitted here, and the same parts are denoted by the same reference numerals. Hereinafter, a description will be given focusing on a portion of the light shielding plate 7 provided between the lens array 6 and the roof mirror array 4 according to the present invention.

Now, the plane including the opening on the side close to the lens 5 of the light shielding plate 7 provided between the lens array 5 and the roof mirror array 4 is defined as Sa, and includes the opening on the side close to the roof mirror array 4. A plane is defined as Sb, an interval between these Sa and Sb is defined as Ts, and a plane including all intersections of two reflecting surfaces 3a and 3b facing each other forming the individual roof mirror 3 is defined as Ra, A plane including all the intersections of the reflection surfaces 3a and 3b adjacent to each other of the roof mirror 3 is Rb,
When the interval between Ra and Rb is Tr, and the interval between Sa and Ra is Tsr, the relationship is set so as to satisfy the following relationship: Tsr <Ts + Tr (1).

By making the shape of the roof mirror array 4 in which the mountain portion near the Rb surface is removed in this manner, the plane Rb virtually exists in the light shielding plate 7. Accordingly, the roof mirror array 4 can be brought closer to the lens array 5, and the opening position of the light shielding plate 7 close to the roof mirror array 4 is not changed and the condition that one reflection does not occur is maintained or is maintained. Even if there is a round reflection, part 1
The roof mirror array 4 can be brought closer to the lens array 6 without increasing the amount of the reflected light, thereby reducing the thickness of the light shielding plate 7 (see the related art), that is, the angle of view of a single roof mirror lens system. , The amount of light to be combined can be increased, and the same effect as the effect of improving the light use efficiency can be obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. Here, the peak portion of the roof mirror array 4 is not cut, but a portion corresponding to the peak portion of the light shielding plate 7 is removed instead. Therefore, also in the case of the present embodiment, the planes Sb and Rb intersect with each other, and the same effects as those of the first embodiment can be obtained.

Next, an embodiment of the present invention will be described with reference to FIG. The description of the same parts as those of the first aspect is omitted, and the same reference numerals are used for the same parts.

Now, it is assumed that the section 7a in the arrangement direction of the light shielding plate 7 is projected in the direction of the reflection surfaces 3a and 3b of the roof mirror array 4 orthogonal to the arrangement direction X. At this time, the non-reflection coating 9 was formed only in the area B of the reflection surfaces 3a and 3b corresponding to the projected portions. The non-reflection coating 9 has a reflectance lower than the reflectance for the wavelength used in the effective reflection area C of the reflection surfaces 3a and 3b. In this case, the non-reflection coating section 9 may apply the non-reflection coating after applying the reflection coating to the effective reflection area C of the reflection surfaces 3a and 3b, for example,
Alternatively, the reflection coating may be applied only to the effective reflection area C after the non-reflection coating is applied first.

In such a configuration, of the light reflected by the two reflecting surfaces 3a and 3b forming the individual roof mirrors 3,
Even if the light e only reflected once is incident on the non-reflection coating portion 9, the light amount can be removed by entering the non-reflection coating portion 9, thereby making it possible to perform the light reflection once. Since the amount of reflected light can be cut or reduced, the angle of view of a single roof mirror lens system can be widened, thereby increasing the amount of light to be combined and further improving light use efficiency. .

According to the invention as set forth in claim 1, the distance between the plane Sa including the opening on the side close to the lens of the light shielding plate and the plane Sb including the opening on the side close to the roof mirror array is Ts, The interval between the plane Ra including all the intersections of the two reflecting surfaces facing each other forming each roof mirror and the plane Rb including all the intersections of the adjacent reflecting surfaces of the adjacent roof mirrors is Tr, Assuming that the interval between Sa and Ra is Tsr, the relationship of Tsr <Ts + Tr is satisfied, so that the light that passes through the lenses in the lens array and enters the predetermined roof mirror of the roof mirror array and is reflected is The light quantity of the single reflection can be the light of the double reflection without the single reflection or the light of the double reflection where the light quantity of the single reflection does not increase even if the single reflection exists. Reduce the thickness of the shading plate while reducing it further Rukoto can, thereby, in the more unfolded position the angle of view of a single roof mirror lens system is increased synthesis quantity, but more can be further obtain a clear image up the light use efficiency.

According to the second aspect of the present invention, when the cross section in the arrangement direction of the light shielding plate is projected in the direction of the reflection surface of the roof mirror array orthogonal to the arrangement direction, only the projected portion has the effective reflection area of the reflection surface. Since the non-reflection coating portion having a reflectance lower than the reflectance for the wavelength used is formed, the amount of light reflected once by the roof mirror can be cut or reduced by the non-reflection coating portion. In this case, the same effect as the effect of the first aspect can be obtained.

[Brief description of the drawings]

FIG. 1 is an optical path diagram showing an enlarged area around a light shielding plate according to a first embodiment of the present invention, FIG. 2 is an optical path diagram showing a second embodiment thereof, and FIG. FIG. 4 is an optical path diagram showing one embodiment of the invention described in claim 2, FIG. 4 is a perspective view showing a conventional example,
FIG. 5 is an optical path diagram showing an enlarged area around the light-shielding plate,
FIG. 6 and FIG. 7 are development views showing an optical path centered on the roof mirror array, and FIG. 8 is an optical path diagram when the thickness of the light shielding plate is increased. 2 ... optical path separating mirror, 3 ... roof mirror, 3a, 3b ...
... reflection surface, 4 ... roof mirror array, 5 ... lens,
6 ... lens array, 7 ... light shielding plate, 9 ... non-reflection coated part, B ... projected part, C ... effective reflection area

Claims (2)

(57) [Claims] 1. An optical path separating mirror, a roof mirror array in which a plurality of roof mirrors are formed linearly and continuously at a constant arrangement pitch along a longitudinal direction of the optical path separating mirror, It comprises a lens array having lenses formed between the optical path separating mirrors and corresponding to the arrangement pitch of the roof mirrors, and a light-shielding plate provided between the lens array and the roof mirror arrays. In the roof mirror lens array,
The space between the plane Sa including the opening on the side close to the lens of the light shielding plate and the plane Sb including the opening on the side close to the roof mirror array is Ts, and the individual roof mirrors are formed. The interval between the plane Ra including all the intersections of the two reflecting surfaces facing each other and the plane Rb including all the intersections of the adjacent reflecting surfaces of the roof mirror adjacent to each other is Tr, and the distance between the Sa and the Ra is A roof mirror lens array characterized by satisfying a relationship of Tsr <Ts + Tr, where Tsr is an interval between the mirrors. 2. An optical path separating mirror, a roof mirror array in which a large number of roof mirrors are formed linearly and continuously at a constant arrangement pitch along a longitudinal direction of the optical path separating mirror, It comprises a lens array having lenses formed between the optical path separating mirrors and corresponding to the arrangement pitch of the roof mirrors, and a light-shielding plate provided between the lens array and the roof mirror arrays. In the roof mirror lens array,
When projecting the cross-section in the arrangement direction of the light-shielding plate in the direction of the reflection surface of the roof mirror array orthogonal to the arrangement direction,
A roof mirror lens array, wherein a non-reflection coating portion having a reflectance lower than a reflectance for a used wavelength in an effective reflection area of the reflection surface is formed only on the projected portion.