JP2003025625A - Optical printing head and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical printer head capable of easily increasing the light amount. SOLUTION: An optical element 3 having a refractive index higher than that of the air is disposed each between a light emitting element array 1 and a magnification imaging element array 2, and between the equivalent magnification imaging element array 2 and the imaging surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical print head and an image forming apparatus, and more particularly, to a solid writing type optical print head used in an image forming apparatus such as a digital copying machine, a printer, a digital facsimile apparatus. And a digital copying machine using the optical print head,
The present invention relates to an image forming apparatus such as a printer or a digital facsimile machine.

[0002]

2. Description of the Related Art In recent years, there has been a demand for miniaturization of image forming apparatuses such as digital copying machines, printers and digital facsimile machines, and miniaturization of digital writing apparatuses used therein. . An electrophotographic process is an example of an image forming process used in an image forming apparatus. FIG. 8 shows a schematic diagram of an image forming apparatus using such an electrophotographic process.

The image forming apparatus shown in FIG. 8 has a photoconductor 20 which is a drum-shaped image carrier, a charging unit 21 for charging the photoconductor 20, and a laser generator or a light emitting diode (LED) arrayed to emit light. An exposure unit 22 configured by an optical print head using an element array or the like, for writing an electrostatic latent image on the photoconductor 20, and a photoconductor 20.
A developing unit 23 that develops the electrostatic latent image written above with toner or the like to form a toner image, a transfer unit 24 that transfers the toner image on the photoconductor 20 onto a recording sheet, and a transfer unit 24 that is transferred onto the recording sheet. A fixing unit 25 for fixing the toner image, a charge removing unit 26 for removing charge to remove the toner remaining on the photoconductor 20, and a cleaning unit 27 for mechanically cleaning the toner remaining on the photoconductor 20 are provided. ing.

The electrophotographic process of the image forming apparatus will be briefly described. First, the charging unit 22 causes the photoconductor 2
After charging 0 (charging process), the exposure unit 22
The light emitted from is irradiated as a light spot on the photoconductor 20 to form an electrostatic latent image on the photoconductor 20 (exposure process). Subsequently, the developing unit 23 attaches toner to the electrostatic latent image on the photoconductor 20 to form a toner image (developing process). Thereafter, the transfer unit 24 transfers the toner image formed on the photoconductor 20 onto the recording paper (transfer process), and the fixing unit 25 applies pressure and heat to the toner image transferred onto the recording paper to apply the recording paper. The toner is fixed by fusing (fixing process).

The digital writing methods used for exposure in the electrophotographic process are roughly classified into an optical scanning method and a solid writing method. In the optical scanning method, a light beam emitted from a light source such as a semiconductor laser is optically scanned by an optical deflector such as a polygon mirror, and the light is condensed on a photoconductor by a scanning imaging lens. In the solid-state writing method, a light flux emitted from a light source of a light emitting element array such as a light emitting diode (LED) array is condensed on a photoconductor by an imaging element array.

In the optical scanning method, the light path is lengthened because the light is scanned by the light deflector, whereas in the solid writing method, the light path length can be shortened because it is not necessary to scan the light. Therefore, the solid-state writing method can downsize the entire image forming apparatus as compared with the optical scanning method.
Further, there is an advantage that no mechanical driving component such as an optical deflector is required.

Next, the structure of a conventional solid writing type exposure unit (optical print head) will be described. In the solid-state writing type exposure unit (optical print head), there are a method in which light is straightened by an equal-magnification imaging element to form an image and a method in which light is bent at a right angle by an equal-magnification imaging element to form an image. .

FIG. 9 shows a configuration of a conventional solid writing type exposure unit (optical print head) (a type in which light is made to go straight by an equal-magnification image forming element to form an image). FIG. 1A shows a conventional solid writing type exposure unit (optical print head).
2B is a schematic perspective view of the unity-magnification imaging element array of FIG. 1A, and FIG. 7C is a cross-sectional view of the unity-magnification imaging element array.

In FIG. 1A, reference numeral 1 is a light emitting element array, 2 is a unity magnification imaging element array, and the optical axis of the unity magnification imaging element array 2 is indicated by a chain line. The equal-magnification imaging element array 2 has a linear shape, and the light emitted from the equal-magnification imaging element array 2 is directed toward the incident optical axis Xin on which the light from the light-emitting element array 1 is incident and the image carrier. Output optical axis X
out is on a straight line. As the unity-magnification imaging element array 2, as shown in FIGS.
A rod lens array or the like in which rod lenses are arranged in a bale stack is used. In FIG. 1C, 15 is a rod lens, 16 is an opaque member, and 17 is a side plate.

FIG. 10 shows the structure of a conventional solid writing type exposure unit (optical print head) (a type in which light is bent at a right angle by an equal-magnification image forming element to form an image). 1A is a schematic diagram of a conventional solid writing type exposure unit (optical print head), and FIG. 1B is a schematic perspective view of the unity-magnification imaging element array of FIG. 1A. ing.

In FIG. 1A, reference numeral 1 is a light emitting element array, 2 is a unity magnification imaging element array, and the optical axis of the unity magnification imaging element array 2 is shown by a chain line. The equal-magnification imaging element array 2 has a total reflection surface, and the incident optical axis Xin and the emission optical axis Xout of this total reflection surface are orthogonal to each other. As the unity-magnification imaging element array 2, a roof prism lens array whose total reflection surface is composed of a roof prism portion 1a as shown in FIG. 1B, a roof mirror lens array (not shown), or the like is used. It

In the image forming apparatus using the optical print head having such a structure, there is a method of increasing the amount of light emitted from the optical print head as a method of improving the recording speed.

As a method for increasing the amount of light emitted from the optical print head, for example, Japanese Patent Application Laid-Open No. 2001-1010.
There is a technique described in Japanese Patent No. In the publication, a mold layer having a high refractive index is inserted between the light emitting element array and the unity magnification imaging element array, and the light emitting element array and the mold layer and the mold layer and the unity magnification imaging element array are bonded to each other. The amount of light emitted from the optical print head is increased by narrowing the angle of light emitted from the light emitting element array and increasing the amount of light incident on the equal-magnification imaging element array.

However, in the technique disclosed in the above publication,
It takes time and effort to bond the light emitting element array and the mold layer, and an LED array using LEDs for the light emitting element array may use wire bonding as wiring for supplying a current to each light emitting element. In this case, there is a problem that the wire bonding is pressed by the mold layer to damage the adjacent wire bonding or short-circuit with the adjacent wire bonding. Further, in order to bond the mold layer and the unit-magnification imaging element, the incident surface side of the unit-magnification imaging element needs to be a flat surface, and when the lens surface of the unit-magnification imaging element array is a spherical surface, There is a problem that it is not easy to bond them.

Further, in the optical print head having the structure shown in FIGS. 9A and 10A, the light is emitted from the optical print head by reducing the distance between the equal-magnification imaging element array and the light emitting element array. It is possible to increase the amount of light emitted.

In the optical print head for forming an image by bending the light emitted from the light emitting element array 1 shown in FIG. 10 at a right angle by the same size image forming element array 2, the same size image forming element from the light emitting element array 1 is formed. Since the distance L1 from the incident side lens surface of the child array 2 to the distance L2 from the exit side lens surface of the equal-magnification imaging element array 2 to the image forming surface is designed to be substantially equal, L1 is shortened. In this case, L2 also needs to be shortened.

As the light emitting element array 1, a surface emitting type LED array as shown in FIG. 11 is often used. Figure 1
FIG. 1 is a diagram showing a schematic configuration of a surface-emitting type LED array, FIG. 1 (a) is a plan view thereof, and FIG. 1 (b) is a sectional view thereof. In the figure, 11 is an LED that constitutes an LED array, and 12 is a drive driver for driving the LED 11.

In the optical print head having the structure shown in FIG. 10A, the surface emitting type LED as shown in FIG.
When the array is used as a light emitting element array, as shown in FIG. 11, since there is a distance H from the LED, which is a light emitting element section, to the end face of the substrate, for example, as shown in FIG.
If L2 is made shorter than H, there is a problem in that the end face of the LED array substrate and the photoconductor as the image carrier interfere with each other.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an optical print head capable of easily increasing the amount of light and an image forming apparatus using the optical print head. The purpose is to

The present invention has been made in view of the above, and an optical print head in which the end face of the LED array and the photoconductor do not interfere with each other even if the amount of light emitted from the optical print head is increased, and the same. An object is to provide an image forming apparatus using an optical print head.

[0021]

In order to solve the above-mentioned problems, the invention according to claim 1 provides a light-emitting element array configured by arranging a plurality of light-emitting elements, and a plurality of lenses arranged in an array. In an optical print head including an equal-magnification imaging element array configured as described above, between the light-emitting element array and the equal-magnification imaging element array and / or the equal-magnification imaging element array and the imaging surface. An optical element having a refractive index higher than that of air is disposed between According to the above invention, an optical element having a refractive index higher than that of air is arranged between the light emitting element array and the unit-magnification imaging element array and / or between the unit-magnification imaging element array and the image plane. By doing
Increase the amount of light.

The invention according to claim 2 is the same as claim 1.
In the present invention, the optical element is a parallel plate. According to the above invention, the parallel plate is used for the optical element.

The invention according to claim 3 is the same as that of claim 1.
In the invention according to the above aspect, when the optical element is arranged between the light emitting element array and the equal-magnification imaging element array, the thickness of the optical element is d, the refractive index of the optical element is n, and the light emission is When the distance from the element array to the incident-side lens surface of the unity-magnification imaging element array is L1, the thickness d of the optical element and the refractive index n of the optical element are expressed by the following formula:
It is set to satisfy the condition of 7 × L1 ≦ d × (1-1 / n). According to the above invention, when the optical element is arranged between the light emitting element array and the unity magnification imaging element array, the thickness d of the optical element and the refractive index n of the optical element are 0.17. The light quantity of the optical print head is increased by 20% by setting so as to satisfy the condition of × L1 ≦ d × (1-1 / n).

The invention according to claim 4 is the same as claim 1.
In the invention according to above, when the optical element is arranged between the light emitting element array and the unity magnification imaging element array, a process for suppressing stray light generated on the side surface of the optical element is performed on the optical element. It has been given. According to the above invention, flare light is prevented by performing a process for suppressing stray light generated on the side surface of the optical element on the optical element.

The invention according to claim 5 is the same as claim 1.
In the invention according to the first aspect, when the optical element is arranged only between the unit-magnification image-forming element array and the image-forming surface, the light-emitting element array is composed of a surface-emitting LED array. According to the above invention, when the optical element is arranged only between the equal-magnification image-forming element array and the image-forming surface, the light-emitting element array is composed of a surface-emitting LED array.

The invention according to claim 6 is the same as claim 1.
The optical print head according to claim 5 is used in an exposure unit. According to the above invention, the optical print head according to any one of claims 1 to 5 is applied to an optical writing unit of an image forming apparatus.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an optical print head and an image forming apparatus according to the present invention will be described below with reference to the drawings (configuration of optical print head), (optical print head of the present invention The applied image forming apparatus will be described in detail in this order.

(Structure of Optical Print Head) With reference to FIGS. 1 to 6, the optical print head of the present invention will be described in order of [Structural example 1], [Structural example 2], and [Structural example 3].

[Structural Example 1] An optical print head of Structural Example 1 will be described with reference to FIGS. 1 and 2. FIG. 1 is a configuration example 1
FIG. 3 is a schematic configuration diagram showing the configuration of the optical print head of FIG. The configuration example 1 is an optical print head (FIG. 10) in which an optical axis is bent at a right angle in an equal-magnification imaging element array, and the light-emitting element array and the equal-magnification imaging element array are connected to and between the equal-magnification imaging element array. The optical element 3 is inserted between the optical element 3 and the image plane. In the figure, 1 is a light emitting element array, 2 is an equal-magnification imaging element array, and 3 is an optical element.

In the figure, a refractive index higher than that of air is provided between the light emitting element array (LED array) 1 and the unity-magnification imaging element array 2, and between the unity-magnification imaging element array 2 and the image plane. High optical elements 3 are respectively inserted. These optical elements 3 are parallel flat plates whose surfaces on the incident side and the emission side are parallel to each other.

The optical element 3 made of a parallel plate is inserted between the light emitting element array (LED array) 1 and the equal-magnification imaging element array 2 and between the equal-magnification imaging element array 2 and the imaging surface. This eliminates the need for adhering the light emitting element array (LED array) 1 to the optical element 3 and the equal-magnification imaging element array 2, and since the optical element 3 is a parallel plate having no refractive power, the optical element 3 There is no need to make the position accuracy so severe.

Next, with reference to FIG. 2, the principle of increasing the amount of light by inserting the optical element 3 in the optical print head having the configuration of FIG. 1 will be described. FIG. 2 is an explanatory diagram for explaining the principle of increasing the amount of light by inserting the optical element 3 in the optical print head having the configuration of FIG. In the figure, the broken line shows the actual optical path, and the fine broken line shows the virtual optical path.

In the figure, when the light emitted from the emission point (O) of the light emitting element array 1 at an angle θ enters the optical element 3 (incident side), it is refracted by the refractive index of the optical element 3. The output angle is θ ′. Then, in the optical element 3,
The light is emitted again at the angle θ.

When the light emitted from the optical element 3 is viewed from the unity-magnification imaging element array 2, it can be considered that the light is emitted from O '(virtual emission point) of the optical element 3, and its optical path is The virtual optical path shown in FIG.

The distance Δd1 between the emission point (O) of the light emitting element array 1 and O ′ (virtual emission point) of the optical element 3 is given by the following formula, where the refractive index of the inserted optical element 3 is n and the thickness is d: It can be expressed as the following formula (1).

Δd1 = d (1-1 / n) (1)

Similarly, in the exit side optical element 3, S '
An image is formed at a position (S) separated from the (imaginary image formation point) by Δd2. That is, a pair of optical elements having a refractive index higher than that of air before and after the equal-magnification imaging element array 2 that images the light emitted from O ′ (virtual emission point) on S ′ (virtual imaging point). By inserting 3, the light emitted from the emission point (O) of the light emitting element array 1 can be imaged at the image forming position (S), and the light emitting element array 1 and the equal-magnification image forming element array 2 are brought close to each other. You can get the same effect. The amount of increase in the amount of light in this case can be expressed by the following equation (2).

[0038] (L1 / L1 ') ^ 2x0.96 ^ 4 (2)

However, "0.96" means that the transmittance L1 on the incident side and the outgoing side of the inserted optical element 3 is the outgoing point (O) of the light emitting element array 1 and the incident side of the equal-magnification imaging element array 2. The distance L1 ′ between the lens surfaces is the distance between O ′ (virtual emission point) of the optical element 3 and the incident-side lens surface of the unity-magnification imaging element array 2.

For example, when L1 = 8 mm, the two optical elements 3 to be inserted have both a refractive index n = 1.56 and a thickness d = 5 mm, Δd1 = Δd2 = 2.1 according to the above formula (1).
5, the light quantity can be increased 1.57 times from the above equation (2).

It is desirable to increase the light quantity by 20% or more. The refractive index n and the thickness d of the optical element 3 required to increase the light quantity by 20% or more can be expressed by the following formula (3). In the present embodiment, the refractive index n and the thickness d of the optical element 3 are set so as to satisfy the condition of the following expression (3).

[0042] 0.17 × L1 ≦ d (1-1 / n) (3)

Here, for example, L1 = 8 mm, d = 3 m
When m and n = 1.56, the condition of the above formula (3) is not satisfied, and when this condition is substituted into the above formula (2), the light amount increases 1.12 times.

On the other hand, L1 = 8 mm, d = 5 mm, n =
When it is set to 1.56, the condition of the above formula (3) is satisfied, and when this condition is substituted into the above formula (2),
This means that the amount of light increased by 1.40 times. That is, when the condition of the above expression (3) is satisfied, the light amount can be increased by 20% or more.

By the way, when the optical element 3 is inserted between the light emitting element array 1 and the equal-magnification imaging element array 2, FIG.
As shown in FIG. 3, the light that has entered the optical element 3 from the light emitting element array 1 is reflected by the side surface of the optical element 3 and becomes stray light. When this stray light enters the equal-magnification imaging element array 2, it is condensed at a position where it should not be imaged. This stray light is called flare light.

A method of removing such flare light will be described with reference to FIG. FIG. 4 is an explanatory diagram for explaining a method of removing flare light. FIG. 3A shows a configuration in which the side surface of the optical element 3 is coated with the light absorption film 3a. In order to prevent reflection on the side surface of the optical element 3, reflection can be reduced by applying a light absorption film 3a on the side surface of the optical element 3 as shown in FIG. Stray light incident on the child array 2 can be prevented. As the light absorption film 3a, a film having an absorption property with respect to the wavelength of the light emitting element array 1 used can be used. In general, the light emitting wavelength of the light emitting element array 1 is around 700 nm, so black or a solution similar thereto may be applied to the side surface of the optical element 3 as the light absorbing film 3a.

FIG. 11B shows a structure in which the side surface of the optical element 3 is roughened to form the light scattering surface 3b. The same figure (b)
As shown in FIG.
To form a side surface of the optical element 3 (the light scattering surface 3
Light can be diffusely reflected in b), and stray light that enters the equal-magnification imaging element array 2 can be prevented.

FIG. 6C shows a structure in which the light absorbing film 3c is applied to the incident surface of the optical element 3 in a window shape. As shown in FIG. 3C, the light absorption film 3 is formed on the incident surface of the optical element 3.
By applying c in a window shape, it is possible to prevent light from hitting the side surface of the optical element 3 and prevent stray light from entering the unity-magnification imaging element array 2.

As the structure for preventing flare light, the structures shown in FIGS. 4 (a), 4 (b) and 4 (c) may be used independently, but these structures are combined. May be.

As described above, according to the configuration example 1,
An optical element 3 having a refractive index higher than that of air is arranged in the space between the light emitting element array 1 and the unity-magnification imaging element array 2 and in the space between the unity-magnification imaging element array 2 and the image plane. Therefore, it is possible to increase the amount of light as compared with the conventional optical print head with a simple configuration.

Since the thickness d and the refractive index n of the optical element 3 are set to satisfy the condition of 0.17 × L1 ≦ d × (1-1 / n), the light quantity of the optical print head is 20%. It is possible to increase the above.

Further, since the optical element 3 is subjected to the processing for suppressing the stray light generated on the side surface of the optical element 3 inserted between the light emitting element array 1 and the unity magnification image forming element array 2, It becomes possible to prevent unnecessary light from entering the same-magnification imaging element array 2.

(Structure Example 2) The structure of the optical print head of Structure Example 2 will be described with reference to FIG. FIG. 5 is a schematic configuration diagram showing a configuration of the optical print head of the configuration example 2. The configuration example 2 is the same as the configuration example 1 in the optical print head in which the optical axis is bent at a right angle by the same-magnification imaging element array, and the optical element 3 is inserted only between the equal-magnification imaging element array and the image plane. It is a composition.

In FIG. 5, reference numeral 1 denotes a light emitting element array composed of a surface emitting LED array as shown in FIG.
Reference numeral 2 is an equal-magnification imaging element array, and 3 is an optical element made of a parallel plate. As shown in the figure, an optical element 3 is inserted between the unity-magnification imaging element array 2 and the imaging surface.

In the figure, even if the light emitting element array 1 and the unity-magnification imaging element array 2 are made closer to each other, the optical element 3 is inserted between the unity-magnification imaging element array 2 and the image plane. Therefore, due to the refractive index n and the thickness d of the optical element 3, the optical path can be made longer than the distance H from the light emitting element array 1 to the edge of the substrate.

Further, in the configuration example 2, the light emitting element array 1
Since the optical element 3 is not inserted between the light emitting element array 1 and the unity-magnification imaging element array 2,
The distance D between the light-emitting element array 1 and the unity-magnification imaging element array 2 can be made narrower than in the configuration example 1 in which the optical element 3 is inserted between Can be reduced.

[Configuration Example 3] The configuration of the optical print head of Configuration Example 3 will be described with reference to FIG. FIG. 6 is a schematic configuration diagram showing the configuration of the optical print head of the configuration example 2. In the configuration example 2, as shown in FIG. 9, the incident optical axis Xin of the light emitted from the light emitting element array to the unity-magnification imaging element array and the emission optical axis Xout from the one-magnification imaging element array are aligned. A configuration for increasing the amount of light in an arrayed optical print head will be described.

In FIG. 6, 1 is a light emitting element array, 2 is an equal-magnification imaging element array, and 3 is an optical element made of a parallel plate. As shown in the figure, an optical element 3 is inserted between the light emitting element array 1 and the unity-magnification imaging element array 2. Further, in the figure, S2 shows the image forming position before the insertion of the optical element 3, and S1 shows the image forming position after the insertion of the optical element 3.

In the configuration example 3, as in the configuration example 1, it is necessary to insert an optical element between the light emitting element array 1 and the equal-magnification imaging element array 2 and between the equal-magnification imaging element array 2 and the image plane. Instead, it is possible to increase the amount of light simply by inserting the optical element 3 between the light emitting element array 1 and the unity magnification imaging element array 2.

Note that, in the configuration example 3 as well, as in the configuration example 1, the processing for preventing flare light (see FIG. 4 above) may be performed. Further, similarly to the configuration example 1, the refractive index n and the thickness d of the optical element 3 may be set so as to satisfy the above expression (3).

(Image forming apparatus to which the optical print head of the present invention is applied) FIG. 7 shows optical writing of the optical print heads of the above configuration examples 1 to 3 by an electrophotographic image forming apparatus (1 drum type). FIG. 1 is a schematic configuration diagram of an image forming apparatus when applied to a unit.

The image forming apparatus shown in FIG. 7 performs photoconductor 20 which is a drum-shaped image carrier, a charging unit 21 which charges the photoconductor 20, and an electrostatic latent image is written on the photoconductor 20. An optical print head (optical writing unit) 30 of the above-described configuration examples 1 to 3, a developing unit 23 that develops the electrostatic latent image written on the photoconductor 20 with toner or the like to form a toner image, A transfer unit 24 for transferring the toner image on the photoconductor 20 onto the recording paper, a fixing unit 25 for fixing the toner image transferred on the recording paper, and a charge erasing for removing the electric charge to remove the toner remaining on the photoconductor 20. A unit 26 and a cleaning unit 27 for mechanically cleaning the toner remaining on the photoconductor 20 are provided.

The electrophotographic process of the image forming apparatus will be briefly described. First, the charging unit 21 causes the photoreceptor 2
After charging 0 (charging process), the light emitted from the optical print head (optical writing unit) 30 is applied to the photoconductor 20 as a light spot to form an electrostatic latent image on the photoconductor 20 (exposure). process). Next, the developing unit 23
Thus, toner is attached to the electrostatic latent image on the photoconductor 20 to form a toner image (developing process). Thereafter, the transfer unit 24 transfers the toner image formed on the photoconductor 20 onto the recording paper (transfer process), and the fixing unit 25 applies pressure and heat to the toner image transferred onto the recording paper to apply the recording paper. The toner is fixed by fusing (fixing process).

Since the optical print heads of Configuration Examples 1 to 3 are applied to the optical writing unit (exposure unit) of the electrophotographic image forming apparatus, image formation using the conventional optical print head is performed. Light emitted from the optical print head can be increased as compared with the apparatus, and high-speed recording can be performed.

Here, the optical print head of the present invention is
Although the case of applying to the one-drum type image forming apparatus has been described, it may be applied to the tandem type image forming apparatus.

The present invention is not limited to the above-described embodiments, but can be modified as appropriate without departing from the spirit of the invention.

[0067]

As described above, according to the optical print head of the first aspect, the light emitting element array formed by arranging a plurality of light emitting elements and the plurality of lenses are arranged in an array. In the optical print head provided with the equal-magnification imaging element array described above, between the light-emitting element array and the equal-magnification imaging element array, and / or between the equal-magnification imaging element array and the image plane, Since an optical element having a refractive index higher than that of air is arranged, it is possible to provide an optical print head capable of increasing the amount of light with a simple configuration as compared with a conventional optical print head. Play.

According to the optical print head of the second aspect, in the invention of the first aspect, since the parallel plate is used for the optical element, in addition to the effect of the invention of the first aspect, It is possible to increase the light quantity of the optical print head by using the optical element having a simple structure.

According to the optical print head of the third aspect, in the invention of the first aspect, when the optical element is arranged between the light emitting element array and the equal-magnification imaging element array, Since the thickness d and the refractive index n of the optical element are set so as to satisfy the condition of 0.17 × L1 ≦ d × (1-1 / n), the effect of the invention according to claim 1 is obtained. In addition, the light quantity of the optical print head is 20%.
It is possible to increase the above.

According to the optical print head of the fourth aspect, in the invention of the first aspect, when the optical element is arranged between the light emitting element array and the equal-magnification imaging element array, Since the optical element is subjected to the processing for suppressing the stray light generated on the side surface, in addition to the effect of the invention according to claim 1, it is possible to prevent unnecessary light from entering the equal-magnification imaging element. Is possible.

Further, according to the optical print head of the fifth aspect, in the invention of the first aspect, when the optical element is arranged only between the equal-magnification image-forming element array and the image-forming surface, the light-emission is performed. Since the element array is constituted by the surface emitting type LED array, in addition to the effect of the invention according to claim 1, it becomes possible to reduce the occupation ratio of the optical print head to the image carrier as compared with the conventional case. .

According to the image forming apparatus of the sixth aspect, the optical print head according to any one of the first to fifth aspects is applied to the optical writing unit of the image forming apparatus. Therefore, as compared with the image forming apparatus using the conventional optical print head, the light emitted from the optical print head can be increased and high-speed recording can be performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a configuration of an optical print head of configuration example 1.

FIG. 2 is an explanatory diagram for explaining the principle of increasing the amount of light by inserting an optical element in the optical print head having the configuration of FIG.

FIG. 3 is an explanatory diagram for describing stray light that is generated by being reflected on a side surface of an optical element.

FIG. 4 is an explanatory diagram for explaining a method of removing flare light.

5 is a schematic configuration diagram showing a configuration of an optical print head of configuration example 2. FIG.

FIG. 6 is a schematic configuration diagram showing a configuration of an optical print head of configuration example 3;

FIG. 7 is a diagram showing a schematic configuration of an image forming apparatus using the optical print heads of configuration examples 1 to 3.

FIG. 8 is a schematic diagram of an image forming apparatus using an electrophotographic process.

FIG. 9 is a diagram showing a configuration of a conventional solid writing type exposure unit (optical print head) (a type in which light is linearly advanced by an equal-magnification image forming element to form an image).

FIG. 10 is a diagram showing a configuration of a conventional solid writing type exposure unit (optical print head) (a type in which light is bent at a right angle by an equal-magnification image forming element to form an image).

FIG. 11 is a diagram showing a schematic configuration of a surface-emitting type LED array.

FIG. 12 is a diagram for explaining interference between the end surface of the substrate of the LED array and the photoconductor that is an image carrier.

[Explanation of symbols]

1 Light emitting element array 2x image sensor array 3 optical elements 3a 3c light absorption film 3b Light scattering surface 20 photoconductor 21 Charging unit 23 Development Unit 24 Transfer unit 25 fixing unit 26 Static elimination unit 27 Cleaning unit 30 Optical print head (optical writing unit)

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Claims (6)

[Claims] 1. An optical print head comprising a light emitting element array formed by arranging a plurality of light emitting elements, and an equal-magnification imaging element array formed by arranging a plurality of lenses in an array, Between the light emitting element array and the unity magnification imaging element array,
And / or an optical print head in which an optical element having a refractive index higher than that of air is arranged between the equal-magnification image forming element array and the image forming surface. 2. The optical print head according to claim 1, wherein the optical element is a parallel plate. 3. When the optical element is arranged between the light emitting element array and the unity magnification imaging element array, the thickness of the optical element is d, the refractive index of the optical element is n, and the light emission is performed. When the distance from the element array to the incident-side lens surface of the unity-magnification imaging element array is L1, the thickness d of the optical element and the refractive index n of the optical element are expressed by the following equation: 0.17 × L1 ≦ d × The optical print head according to claim 1, wherein the optical print head is set to satisfy the condition of (1-1 / n). 4. A process for suppressing stray light generated on the side surface of the optical element when the optical element is arranged between the light emitting element array and the unit-magnification imaging element array is applied to the optical element. The optical print head according to claim 1, wherein the optical print head is applied. 5. The light emitting element array is constituted by a surface emitting LED array when the optical element is arranged only between the unity magnification image forming element array and the image forming surface. The optical printhead according to Item 1. 6. An image forming apparatus, wherein the optical print head according to claim 1 is used in an optical writing unit.