JP2007168329A - Method of supporting designing of light emitting device, light emitting device, image forming device, and design supporting program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of supporting designing of a light emitting device which can improve a printing speed and productivity, and to provide the light emitting device, an image forming device, and a design supporting program. <P>SOLUTION: According to the method, provided that the number c of light emitting elements of a single light emitting element array (c is a natural number of 2 or more), the number n of element-side connection portions (n is a natural number), the total number a of the light emitting elements in a plurality of light emitting element arrays (a is a natural number), the number b of driving side connection portions (b is a natural number), and the number m of driving devices (m is a natural number) hold the equation of a/c=(b×m)/n, and that when the n element-side connection portions connected to the a1 light emitting elements (a1 is a natural number satisfying a1<a), are separately connected to the b driving-side connection portions of the m1 driving devices (m1 is a natural number satisfying m1<m), a1, n, c, b, and m1 hold the equation of a1/c=(b×m1)/n, where a, a1, c, and n are set to known numbers, the number of driving devices is determined based on b, m, and m1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting device design support method, a light emitting device, an image forming apparatus including the light emitting device, and a light emitting device design support program.

As a light-emitting device used as an optical printer head that is one of exposure apparatuses in an electrophotographic printer, a light-emitting element array formed by arranging a plurality of light-emitting element arrays is formed by a dynamic drive method or a static drive method. Some are driven and used as light sources. For example, a light emitting diode (Light Emitting)
Diode (abbreviation: LED) is used. For example, any one of 64, 128, and 256 light emitting elements is formed in one light emitting element array. In one light-emitting element array in which the number of light-emitting elements as described above is formed, it is easy to drive all the light-emitting elements by ^2k division (k is a natural number), and light emission is made by designing the value of variable k to be large. The number of wires and necessary electrode pads in the element array, and the number of bonding wires for connecting the light emitting element array and the drive circuit can be reduced, and the yield of the manufacturing process can be improved. It is effective in.

  In addition, instead of LEDs, a light-emitting thyristor, which is a negative resistance element having a PNPN structure, is used as a light-emitting element, and this light-emitting thyristor is arranged as a light-emitting element array to realize light-emission state transfer, in other words, self-scanning of light emission. A light-emitting device that can be used has been proposed. By using a light-emitting device that can realize self-scanning of light emission, when used in an optical printer head, mounting on a substrate becomes simple, and a light-emitting element array can be made compact (see, for example, Patent Documents 1 and 2). ).

  FIG. 8 is an electric circuit diagram showing a schematic configuration of the basic structure of the light emitting device 1 of the prior art. In the light emitting device 1, the start light emitting thyristor T0 and the light emitting thyristors T1, T2,..., Tn−1, Tn are arranged in a substantially straight line, and when a predetermined light emitting thyristor emits light, the light from the light emitting thyristor is arranged in the arrangement direction. It is configured to enter an adjacent light emitting thyristor. The start light-emitting thyristor T0 and the light-emitting thyristors T1, T2,..., Tn−1, Tn may be simply referred to as “light-emitting thyristor T”.

The light-emitting thyristor T has a characteristic that its threshold voltage or threshold current is reduced by receiving light, so that the threshold voltage or threshold of the light-emitting thyristor T that is close to the light-emitting thyristor T is close. The threshold current will decrease. In addition, three transfer clock lines CL1, CL2, and CL3 are repeatedly connected to the anode of each light emitting thyristor T for each of the three light emitting thyristors. Each transfer clock line CL1, CL2, CL3 is connected to current sources I ₁ , I ₂ , I ₃ , respectively, and the current amount is configured to be controlled by a light emission clock pulse φI (for example, (See Patent Documents 2 and 3).

  In addition, a light emitting device having a structure in which elements for transferring a switching signal are separated and these elements are electrically controlled has been proposed (see, for example, Patent Document 4).

JP 49-124992 A Japanese Patent No. 2577034 Japanese Patent No. 3020177 Japanese Patent No. 2577089

  Even when a light-emitting thyristor is used as a light-emitting element as in the prior art shown in FIG. 8 described above, one light-emitting thyristor array (hereinafter sometimes simply referred to as “light-emitting element array”) has 64 or 128 elements. And 256 light emitting thyristors (hereinafter sometimes simply referred to as “light emitting elements”) are formed. In a light emitting device used for an optical printer head or the like, 5120 light emitting elements are formed in the A4 size, and 7680 light emitting elements are formed in the A3 size. When these light emitting elements are configured according to the specification of 600 dpi (dots per inch) having 128 light emitting elements in one light emitting element array, 40 light emitting element arrays in A4 size and 60 light emitting element arrays in A3 size. Is required.

  FIG. 9 is a diagram schematically showing the prior art light emitting device 1 shown in FIG. The light emitting device 1 includes a plurality of self-scanning light emitting devices (SLED) arrays A1, A2,..., Ak-1, Ak (symbol k is a natural number of 2 or more) and a light emitting IC. (Integrated Circuit) 5 is included. Hereinafter, when the SLED arrays A1, A2,..., Ak−1, Ak are collectively referred to and unspecified light emitting elements are indicated, they may be simply referred to as “SLED array A”. The SLED array A includes a plurality of light emitting element arrays 2 in which a plurality of light emitting elements are arranged in a straight line and a connection terminal 3 for inputting a control signal for light emission. The light emitting IC 5 includes an output terminal individually connected to the connection terminal 3 of each SLED array A.

  As the light emitting IC 5 for driving each SLED array A, a light emitting IC having 64 output terminals is widely used. In the light-emitting device 1 having the self-scanning function, when the light-emitting device is configured using the above-described light-emitting element arrays of the first and second prior arts, 40 output terminals are provided in the A4 size having the total number of light-emitting elements of 5120. In addition, in the case of the A3 size in which the total number of light emitting elements is 5120, 60 output terminals are required. Therefore, when a light emitting IC having 64 output terminals is used, the output terminal of the light emitting IC 5 is left as shown in FIG. 9 in both cases of A4 size and A3 size.

  In this way, when the light emitting device 1 including the light emitting IC 5 having the surplus output terminal portion indicated by the reference symbol “r” in FIG. 9 is driven, whether the output terminal portion is connected to the SLED array A in the light emitting IC 5. Regardless of whether or not each output terminal portion of the plurality of output terminal portions is selected in order, a light emission control signal for controlling each light emitting element of each SLED array A is output to the selected output terminal portion. Accordingly, the surplus output terminal portion r is also selected, and the output of the light emission control signal to the SLED array A is waited for the time during which the surplus output terminal portion r is selected. When the light-emitting device in which the output standby time of the light-emission control signal for the SLED array A is generated by using the light-emission IC having the surplus output terminal portion r as described above is applied to, for example, an electrophotographic printer, the output described above is used. It becomes difficult to improve the image printing speed due to the waiting time.

  Further, if the light emitting IC 5 has an excessive output terminal portion, the use efficiency of the output terminal portion with respect to the light emitting IC 5 is reduced, so that the power consumption is increased as compared with the light emitting IC having no excessive output terminal portion. . In such light emitting devices 1 and 2 of the prior art, in order to prevent the excessive output terminal portion r from being generated in any of the A3 size and the A4 size, the A3 size and the A4 size are separately provided. Since it is necessary to design and manufacture the light emitting IC 5 or the SLED array A, there is a problem that the manufacturing process becomes complicated and the productivity is lowered.

  Accordingly, an object of the present invention is to provide a light emitting device design support method, a light emitting device, an image forming apparatus, and a design support program capable of improving the printing speed and improving the productivity.

The light emitting device design support method of the present invention includes c (c is a natural number of 2 or more) light emitting elements, and n (n is a natural number) element side connection portions connected to the respective light emitting elements, A plurality of light emitting element arrays having a (a is a natural number) light emitting elements in total;
A light-emitting device design support method including b (b is a natural number) drive-side connection portions and m (m is a natural number) drive devices individually connected to the element-side connection portions of the light-emitting element array. There,
C, n, a, b, m are
a / c = (b × m) / n
And n element-side connection portions respectively connected to each of a1 (a1 is a natural number satisfying a1 <a) of the a light-emitting elements, and m of the driving devices When m1 (m1 is a natural number satisfying m1 <m) and b drive side connection units respectively provided in the drive devices are individually connected,
A1, n, c, b, m1 are:
a1 / c = (b × m1) / n
The drive device is determined based on b, m, and m1 when a, a1, c, and n are known numbers so as to satisfy the above.

The light-emitting device of the present invention includes c (c is a natural number of 2 or more) light-emitting elements and n (n is a natural number) element-side connection portions connected to the respective light-emitting elements. A plurality of light emitting element arrays each including (a is a natural number) light emitting elements;
b (b is a natural number) driving side connection portions, and a light emitting device including m (m is a natural number) driving devices individually connected to the element side connection portions of the light emitting element array,
The driving device includes:
C, n, a, b, m are
a / c = (b × m) / n
And n element-side connection portions respectively connected to each of a1 (a1 is a natural number satisfying a1 <a) of the a light-emitting elements, and m of the driving devices When m1 (m1 is a natural number satisfying m1 <m) and b drive side connection units respectively provided in the drive devices are individually connected,
A1, n, c, b, m1 are
a1 / c = (b × m1) / n
It is determined based on b, m, and m1 where a, a1, c, and n are known numbers so as to satisfy the above.

The image forming apparatus of the present invention includes the light emitting device,
Driving means for driving the light emitting device based on image information;
Condensing means for condensing light from the light emitting element of the light emitting device on the photosensitive drum;
Developer supplying means for supplying the developer to the exposed photosensitive drum by which light from the light emitting device is condensed on the photosensitive drum by the condensing means;
Transfer means for transferring an image formed by a developer on the photosensitive drum to a recording sheet;
And fixing means for fixing the developer transferred to the recording sheet.

  The design support program of the present invention causes a computer to execute the design support method for the light emitting device.

  According to the design support method for a light emitting device of the present invention, the number c of light emitting elements in one light emitting element array (c is a natural number of 2 or more), and the number n of element side connection portions connected to each light emitting element (n is Natural number), the total number a of light emitting elements in a plurality of light emitting element arrays (a is a natural number), a driving side connection provided in the driving device, and a driving side connection individually connected to the element side connecting part of the light emitting element array The number b of parts (b is a natural number) and the number m of driving devices (m is a natural number) satisfy a / c = (b × m) / n, and a1 of a light emitting elements (a1 is a1 <Natural number satisfying a) n element-side connection portions connected to each of the light emitting elements, and m1 (m1 is a natural number satisfying m1 <m) of the m driving devices, respectively. When the b drive side connections provided are individually connected, Note that a1, n, c, b, and m1 are based on b, m, and m1, where a, a1, c, and n are known numbers so as to satisfy a1 / c = (b × m1) / n. A drive device is determined.

  By determining b, m, and m1 with a, a1, c, and n as known numbers as described above, the element-side connection portion of the light-emitting element array having a light-emitting elements and the drive-side connection portion of the drive device Are connected individually, and when the element side connection part of the light emitting element array having a light emitting element is individually connected to the drive side connection part of the drive device, the drive side connection part In other words, it is possible to relatively easily determine a drive device that does not have a large number, that is, a drive device having the same number of drive side connection portions. As a result, the drive device determined as described above can be used for either driving a light emitting element array having a light emitting elements or driving a light emitting element array having a1 light emitting elements. It can be used as a possible drive device.

  When driving a light emitting device having a drive device without an excess drive side connection, the output waiting time is the same as when driving a light emission device having an excess drive side connection as in the prior art. Does not occur. Therefore, when the light emitting device of the present invention is applied to, for example, a printer, the image printing speed can be improved as compared with the case where the light emitting device of the prior art is applied to a printer.

  In addition, when the element side connection part of the light emitting element array having a light emitting element and the drive side connection part of the driving device are individually connected, and the element side connection part of the light emitting element array having a1 light emitting element, Since it is not necessary to design and manufacture an individual drive device or light emitting element array according to each case where the drive side connection portion of the drive device is individually connected, the number of manufacturing steps can be reduced, and the same number It is possible to improve the productivity of a light emitting device including a driving device having a driving side connection portion.

  According to the light emitting device of the present invention, the light emitting device includes a plurality of light emitting element arrays and m (m is a natural number) driving devices. The number c of light emitting elements in one light emitting element array (c is a natural number of 2 or more), the number n of element side connection portions connected to each light emitting element (n is a natural number), and the total number of light emitting elements in a plurality of light emitting element arrays. a (a is a natural number), a drive side connection portion provided in the drive device, the number b of drive side connection portions (b is a natural number) individually connected to the element side connection portion of the light emitting element array, and the drive device The number m satisfies a / c = (b × m) / n, and n pieces are connected to each of a1 (a1 is a natural number satisfying a1 <a) of the a light emitting elements. And the b drive side connection parts respectively provided in m1 (m1 is a natural number satisfying m1 <m) of the m drive devices are individually connected. The a1, n, c, b, and m1 are a1 / c = (b × m1) / n The drive device is determined based on b, m, and m1 when a, a1, c, and n are known numbers so as to satisfy the above.

  By determining b, m, and m1 with a, a1, c, and n as known numbers as described above, the element-side connection portion of the light-emitting element array having a light-emitting elements and the drive-side connection portion of the drive device Are connected individually, and when the element side connection part of the light emitting element array having a light emitting element is individually connected to the drive side connection part of the drive device, the drive side connection part In other words, it is possible to relatively easily determine a drive device that does not have a large number, that is, a drive device having the same number of drive side connection portions. As a result, the drive device determined as described above can be used for either driving a light emitting element array having a light emitting elements or driving a light emitting element array having a1 light emitting elements. It can be used as a possible drive device.

  When driving a light emitting device having a drive device without an excess drive side connection, the output waiting time is the same as when driving a light emission device having an excess drive side connection as in the prior art. Does not occur. Therefore, when the light emitting device of the present invention is applied to, for example, a printer, the image printing speed can be improved as compared with the case where the light emitting device of the prior art is applied to a printer.

  In addition, when the element side connection part of the light emitting element array having a light emitting element and the drive side connection part of the driving device are individually connected, and the element side connection part of the light emitting element array having a1 light emitting element, Since it is not necessary to design and manufacture an individual drive device or light emitting element array according to each case where the drive side connection portion of the drive device is individually connected, the number of manufacturing steps can be reduced, and the same number It is possible to improve the productivity of a light emitting device including a driving device including the driving side connecting portion.

  According to the image forming apparatus of the present invention, the light emitting device is driven by the driving unit based on the image information, and the light from the light emitting device is condensed on the charged photosensitive drum by the light collecting unit. The photosensitive drum is exposed to form an electrostatic latent image on the surface thereof. When the developer is supplied to the photosensitive drum on which the electrostatic latent image is formed by the developer supplying means, the developer adheres to the photosensitive drum and an image is formed. An image formed with the developer on the photosensitive drum is transferred to the recording sheet by the transfer unit, and the developer transferred to the recording sheet is fixed by the fixing unit, whereby an image is formed on the recording sheet. Since the photosensitive drum can be accurately exposed by the light emitting device, a recorded image with excellent image quality can be obtained. Further, by using the light emitting device with improved productivity for the image forming apparatus, the productivity of the image forming apparatus can be improved.

  According to the design support program of the present invention, the design support method for the light emitting device can be provided as a design support program for causing a computer to execute. Further, it is possible to cause a computer to execute the light emitting device design support method. When the element side connection part of the light emitting element array having a number of light emitting elements and the drive side connection part of the driving device are individually connected by executing the design support method of the light emitting device using a computer, And a drive device in which the drive side connection portion does not remain in any case where the element side connection portion of the light emitting element array having one light emitting element and the drive side connection portion of the drive device are individually connected. A drive device having the same number of drive side connection portions can be determined relatively easily. As a result, the drive device determined as described above can be used for either driving a light emitting element array having a light emitting elements or driving a light emitting element array having a1 light emitting elements. It can be used as a possible drive device.

  FIG. 1 is a diagram showing a light emitting device 10 according to a first embodiment of the present invention. The light emitting device 10 includes a plurality of self-scanning light emitting devices (SLED) arrays D1, D2,..., Dk-1, Dk (the symbol k is a natural number of 2 or more), m (m Is a natural number) light emitting ICs (Integrated Circuits) 15. In FIG. 1, for ease of understanding, one light emitting IC 15 is shown. Hereinafter, when the SLED arrays D1, D2,..., Dk−1, Dk are collectively referred to and when an unspecified SLED array is indicated, it may be simply referred to as “SLED array D”.

  Each SLED array D is adjacent to a plurality of switch element arrays (not shown) in which a plurality of light emitting switch elements are linearly arranged on the semiconductor substrate 11 and spaced from each other, in the width direction of the switch element arrays, A plurality of light emitting elements (c is a natural number of 2 or more) arranged in a state facing the plurality of switch elements along the switch element array are arranged in a straight line on the semiconductor substrate 11 in the present embodiment. In the embodiment, two light emitting element arrays 21 and a light emission control signal for controlling each light emitting element to each light emitting element array 21, specifically, n for inputting a control voltage or a control current for light emission (n is In this embodiment, two electrode pad portions 12 are included. In the present embodiment, the number of light emitting elements in the plurality of SLED arrays D is a (a is a natural number). The arrangement direction of the light emitting elements in the light emitting element array 21 is the same as the arrangement direction of the switch elements in the switch element array.

  The light emitting IC 15 includes b (b is a natural number) output terminal portions 16. Each output terminal portion 16 of the light emitting IC 15 and each electrode pad portion 12 of each SLED array D are individually connected. In the present embodiment, the element side connection portion corresponds to the electrode pad portion 12 of the SLED array D. The drive side connection portion corresponds to the output terminal portion 16 of the light emitting IC 15. A plurality of light emitting element arrays having a light emitting elements correspond to the SLED array D. The driving device corresponds to the light emitting IC 15.

  Hereinafter, a light emitting device design support method for determining the light emitting IC 15 provided in the light emitting device 10 applied to the optical printer head in the electrophotographic image forming apparatus will be described. In the present embodiment, a description will be given of a light emitting IC 15 used in two recording paper sizes having different total numbers of light emitting elements, specifically, A3 size and A4 size, and a processing method for determining the number.

The number of light-emitting elements of one SLED array D constituting the plurality of SLED arrays D is c, and the total number of light-emitting elements in all SLED arrays D corresponding to the A3 size is a. Each light-emitting element is connected to each of the a light-emitting elements. When n electrode pad portions 12 and b output terminal portions 16 respectively provided in m light emitting ICs 15 corresponding to A3 size are individually connected, c, n, a, b, m Is
a / c = (b × m) / n (1)
N electrodes connected to each of the total number of light emitting elements a1 (a1 is a natural number satisfying a1 <a) of all the SLED arrays D satisfying the above-described formula (1) and corresponding to the A4 size. When the pad portion 12 and b output terminal portions 16 respectively provided in m1 (m1 is a natural number satisfying m1 <m) light emitting ICs 15 corresponding to the A4 size are individually connected, a1, n, c, b, m1 are
a1 / c = (b × m1) / n (2)
The light emitting IC 15 is determined based on b, m, and m1 where a, a1, c, and n are known numbers so as to satisfy the above equation (2).

Hereinafter, the processing method for determining the light emitting ICs 15 used in the A3 size and the A4 size and the number thereof will be described in more detail. FIG. 2 is a flowchart showing a procedure related to determination of the light emitting IC 15 in the light emitting device 10. In the present embodiment, one SLED array D includes 128 light emitting elements, and the image resolution is 600 dpi (dots per pixel).
The case where the light emitting device 10 is configured according to the specification of inch) will be described.

  In step S1, the number c of light emitting elements of one SLED array D constituting the plurality of SLED arrays D is determined. In the present embodiment, the number c of light emitting elements in one SLED array D is determined to be 128. In step S2, the total number a of light emitting elements in all SLED arrays D corresponding to the A3 size is determined. In the present embodiment, the total number a of the light emitting elements is determined to be 7680. In step S3, the number n of electrode pad portions 12 of one SLED array D constituting a plurality of SLED arrays D is determined. In the present embodiment, the number n of the electrode pad portions 12 is determined to be two. In step S4, the total number a1 of light emitting elements in all SLED arrays D corresponding to the A4 size is determined. In the present embodiment, the total number a1 of the light emitting elements is determined to be 5120.

In step S5, c, a, and n determined in steps S1 to S3 are substituted into the first relational expression shown in the above equation (1), and the output terminal portion 16 of the light emitting IC 15 corresponding to the A3 size. The total number x is calculated. Substituting c = 128, a = 7680 and n = 2 into equation (1),
7680/128 = (b × m) / 2
And
b × m = 120 (3)
Is obtained. Therefore, since the total number x of the output terminal portions 16 of the light emitting IC 15 corresponding to the A3 size corresponds to “b × m” on the left side of the equation (3), the total number x of the output terminal portions 16 is 120.

In step S6, c, a1, and n determined in steps S1, S2, and S4 are substituted into the second relational expression shown in the above equation (2), and the output terminal of the light emitting IC 15 corresponding to the A4 size. The total number x1 of the part 16 is calculated. In other words, each of the n electrode pad portions 12 connected to each of the a1 light emitting elements of the a light emitting elements and the m1 light emitting ICs 15 of the m light emitting ICs 15 are provided. The total number x1 of the output terminal portions 16 of the light emitting IC 15 when the b output terminal portions 16 are individually connected is calculated. Substituting c = 128, a1 = 5120, and n = 2 into equation (3),
5120/128 = (b × m1) / 2
And
b × m1 = 80 (4)
Is obtained. Therefore, since the total number x1 of the output terminal portions 16 of the light emitting IC 15 corresponding to the A4 size corresponds to “b × m1” on the left side of the equation (4), the total number x1 of the output terminal portions 16 is 80.

  Here, the condition that the number of output terminal portions 16 of one light emitting IC 15 corresponding to the A3 size and the number of output terminal portions 16 of one light emitting IC 15 corresponding to the A4 size are the same number, and the above 1 When b, m, and m1 are determined based on the condition that the number b of the output terminal portions 16 of the two light emitting ICs 15 is a positive integer that simultaneously satisfies the expressions (3) and (4), the expression (3) and the numerical value on the right side of Expression (4), that is, the total number x of the output terminal portions 16 of the light emitting IC 15 corresponding to the A3 size and the total number x1 of the output terminal portions 16 of the light emitting IC 15 corresponding to the A4 size. Calculate the greatest common divisor. In step S7, the greatest common divisor of x and x1 is calculated. In the present embodiment, “40” is calculated as the greatest common divisor of the numerical value “120” on the right side of Equation (3) and the numerical value “80” on the right side of Equation (4).

  In step S8, based on “40” which is the greatest common divisor of x and x1, and Expressions (3) and (4) corresponding to the first and second relational expressions, the output terminal of the light emitting IC 15 The number b of the parts 16, the number m of the light emitting ICs 15 corresponding to the A3 size, and the number m1 of the light emitting ICs 15 corresponding to the A4 size are determined. The number b of the output terminal portions 16 of the light emitting IC 15 is “1”, “2”, “4”, “5”, “8” which are divisors of the calculated greatest common divisor “40” of x and x1. , “10”, “20”, or “40”, but when the number of light emitting ICs 15 corresponding to the A3 size and the A4 size is minimized as much as possible, the output terminal The number b of the parts 16 may be determined as the greatest common divisor between x and x1 calculated in step S7. For example, when the number b of the output terminal portions 16 of the light emitting IC 15 is determined to be 40, the number m of the light emitting ICs 15 corresponding to the A3 size is determined as 3 from the equation (3), and corresponds to the A4 size. The number m1 of the light emitting ICs 15 is determined to be two from the equation (4). Thereby, the number of light emitting ICs 15 corresponding to the A3 size and the A4 size can be minimized.

  In step S9, based on the number b of output terminal portions 16 of the light emitting IC 15 determined in step S8, the number m of light emitting ICs 15 corresponding to the A3 size, and the number m1 of light emitting ICs 15 corresponding to the A4 size, The light emitting IC 15 is determined. When the light emitting IC 15 is determined, the procedure for determining the light emitting IC 15 in the light emitting device 10 is completed.

  As described above, according to the present embodiment, the total number a of light emitting elements in all SLED arrays D corresponding to the A3 size, the total number a1 of light emitting elements in all SLED arrays D corresponding to the A4 size, and one SLED array. The number c of the light emitting elements D and the number n of the electrode pad portions 12 are known numbers, the number b of the output terminal portions 16 of the light emitting IC 15, the number m of the light emitting ICs 15 corresponding to the A3 size, and the A4 size. The number m1 of the light emitting ICs 15 is determined. Accordingly, when the electrode pad portion 12 of the SLED array D having a light emitting elements and the output terminal portion 16 of the light emitting IC 15 are individually connected, and the electrode pad portion of the SLED array D having a1 light emitting elements. 12 and the output terminal portion 16 of the light emitting IC 15 are connected individually, the light emitting IC 15 in which the output terminal portion 16 does not remain, in other words, the number b of the output terminal portions 16 is the same for light emission. The IC 15 can be determined relatively easily.

  As a result, the light emitting IC 15 determined as described above is used in either case of driving the SLED array D having a light emitting elements or driving the SLED array D having a1 light emitting elements. It can be used as a compatible light emitting IC. In other words, the light emitting IC 15 determined as described above can be used as a light emitting IC that can handle both the A3 size and the A4 size.

  Further, when the light emitting device 10 including the light emitting IC 15 without the excessive output terminal portion 16 is driven, the output as in the case of driving the light emitting device having the excessive output terminal portion 16 as in the prior art. There is no waiting time. Therefore, when the light emitting device 10 of the present invention is applied to, for example, a printer, the image printing speed can be improved as compared with the case where the light emitting device of the conventional technology is applied to a printer.

  Further, when the electrode pad portion 12 of the SLED array D having a light emitting elements and the output terminal portion 16 of the light emitting IC 15 are individually connected, and the electrode pad portion 12 of the SLED array D having a1 light emitting elements. Since it is not necessary to design and manufacture the individual light emitting IC 15 or SLED array D according to the case where the light emitting IC 15 and the output terminal portion 16 of the light emitting IC 15 are individually connected, the number of manufacturing steps can be reduced. Thus, the productivity of the light emitting device 10 including the light emitting IC 15 having the same number of output terminal portions 16 can be improved.

  Further, as described above, the light emitting IC 15 in which the output terminal portion 16 does not remain can be determined relatively easily, and the light emitting device 10 can be configured using the determined light emitting IC 15. The mounting area of the light emitting IC 15 can be reduced and the light emitting device 10 can be downsized as compared with the light emitting device of the prior art configured by the light emitting IC having a portion.

  In addition, a design support program can be used to cause a general-purpose computer to execute the design support method for the light emitting device 10 related to the determination of the light emitting IC 15. By executing the design support method for the light emitting device 10 using a general-purpose computer, as described above, the element side connection portion of the light emitting element array having a light emitting elements, and the drive side connection portion of the driving device, Are connected individually, and when the element side connection part of the light emitting element array having a light emitting element is individually connected to the drive side connection part of the drive device, the drive side connection part In other words, it is possible to relatively easily determine a drive device that does not have a large number, that is, a drive device having the same number of drive side connection portions. As a result, the drive device determined as described above can be used for either driving a light emitting element array having a light emitting elements or driving a light emitting element array having a1 light emitting elements. It can be used as a possible drive device.

  FIG. 3 is an electric circuit diagram showing a basic configuration of the light emitting device 10. In the following description, portions corresponding to the matters described in advance are denoted by the same reference numerals, and redundant description may be omitted. The light emitting device 10 includes an SLED array D, a light emission signal transmission path 22, a connection unit 24, a scanning signal transmission path 25, a start signal transmission path 26, and a drive unit 73. The SLED array D includes an electrode pad portion 12, a light emitting element array 21, and a switch element array 23.

  The driving means 73 is connected to the first scanning signal transmission path 25a, the second scanning signal transmission path 25b, the third scanning signal transmission path 25c, the light emission signal transmission path 22, and the start signal transmission path 26. The first to third scanning signal transmission paths 25a to 25c, the light emission signal transmission path 22 and the start signal transmission path 26 are realized by wiring.

  The driving means 73 provides the first scanning signal φ1 to the first scanning signal transmission path 25a, the second scanning signal φ2 to the second scanning signal transmission path 25b, and the third scanning signal φ3 to the third scanning signal transmission path 25c. give. Further, the driving means 73 gives a start signal φS to the start signal transmission path 26 and gives a light emission signal φE to the light emission signal transmission path 22. The driving means 73 supplies the start signal φS to the light emitting IC 15, the scanning IC that supplies the first to third scanning signal φ 1 to φ 3 to the first to third scanning signal transmission paths 25 a to 25 c and the start signal transmission path 26, respectively. This is realized by a scanning start IC. The output terminal portion 16 of the light emitting IC 15 is connected to the electrode pad portion 12 of the SLED array D, and the electrode pad portion 12 is connected to the light emission signal transmission path 22 via the resistance element Rφ.

  Hereinafter, when an unspecified scanning signal transmission path is indicated, the suffixes “a”, “b”, and “c” may be omitted in the reference numerals as in “scanning signal transmission path 25”. When an unspecified scanning signal is indicated, the suffixes “1”, “2”, and “3” may be omitted from the reference numerals as in “scanning signal φ”.

  In the light emitting device 10, the light emitting IC 15 included in the driving unit 73 is a light emitting IC determined by the above-described light emitting device design support method, and the electrode pad portion 12 of the SLED array D having a light emitting elements. And the output terminal part 16 of the light emitting IC, and the electrode pad part 12 of the SLED array D having a1 light emitting elements and the output terminal part 16 of the light emitting IC are individually connected. In any case, the output terminal portions 16 do not remain, in other words, the number of the output terminal portions 16 is the same number of light emitting ICs.

  More specifically, the light emitting IC 15 is capable of supporting both cases of driving the SLED array D having a light emitting elements and driving the SLED array D having a1 light emitting elements. IC, in other words, a light emitting IC that can handle both A3 size and A4 size. The light emitting device 10 is configured to drive the SLED array D by the light emitting IC 15 as described above.

  The driving means 73 receives a clock pulse signal as a reference from the outside, and outputs the first to third scanning signals φ1 to φ3 and the start signal φS in synchronization with the clock pulse signal to transmit the scanning signal. Are provided to the path 25 and the start signal transmission path 26, respectively. The clock pulse signal is supplied from the control unit 96 of the image forming apparatus 87 described later. The clock cycle of the clock pulse signal is selected to be longer than the control cycle in the control means 96 of the image forming apparatus 87 described later. The light emitting IC 15 included in the driving unit 73 outputs the light emission signals φE from the plurality of b output terminal portions 16 in the present embodiment, based on image information given from the outside together with the clock pulse signal, The output light emission signal φE is applied to the light emission signal transmission path 22 via each electrode pad portion 12.

  In the first to third scanning signal transmission lines 25a to 25c, switch elements T1, T2,..., Tj−1, Tj (symbol j is a symbol j in the switch element array 23 in which a plurality of light emitting switch elements are linearly arranged. A resistance element Rφ connected in series with a natural number of 2 or more is connected to each other, and the driving means 73 is connected to the first to third scanning signal transmission lines 25a to 25c via the resistance element Rφ. Hereinafter, when the switch elements T1, T2,..., Tj−1, Tj are collectively referred to, and when an unspecified switch element is indicated, it may be simply referred to as “switch element T”. The resistance element Rφ has a function as a voltage dividing resistor that prevents the overcurrent from flowing from the driving unit 73 to the scanning signal transmission path 25 and divides the voltage applied to each switch element T.

  The switch element T is realized by a light-emitting thyristor having a PNPN structure in which, for example, P-type semiconductor layers and N-type semiconductor layers are alternately stacked. The switch element T has a negative resistance characteristic similar to that of the reverse blocking three-terminal thyristor. The switch element T has a threshold voltage lower than the voltage of the scanning signal φ given through the scanning signal transmission path 25 by light reception, and is given a threshold voltage when the scanning signal φ is given or the current of the scanning signal φ. When the current decreases and the scanning signal φ is given, a trigger signal is generated at the gate, which is a predetermined portion, and light is emitted. The voltage of the scanning signal φ is a voltage applied between the anode and the cathode of the switch element T when the scanning signal φ is given, and the current of the scanning signal φ is a switch when the scanning signal φ is given. This is a current applied to the element T.

  In the light emitting signal transmission path 22, the light emitting elements L1, L2,..., Li-1, Li (symbol i is a positive integer of 2 or more) in the light emitting element array 21 in which a plurality of light emitting elements are linearly arranged. Are connected in series with each other, and the driving means 73 is connected to the light emission signal transmission line 22 via the resistance element Rφ. Hereinafter, when the light emitting elements L1, L2,..., Li-1, Li are collectively referred to and when an unspecified light emitting element is indicated, the light emitting element L may be simply referred to as “light emitting element L”. The light emitting element L is a light emitting element for exposure. The light emitting element L is formed so as to emit light having a wavelength of 600 nm or more and less than 800 nm. The resistance element Rφ has a function as a voltage dividing resistor that divides the voltage applied to each light emitting element L while preventing an overcurrent from flowing from the driving means 73 to the light emitting signal transmission path 22.

  The light emitting element L is realized by, for example, a light emitting thyristor having a PNPN structure in which P type semiconductor layers and N type semiconductor layers are alternately stacked. The light emitting element L has a negative resistance characteristic similar to that of the reverse blocking three-terminal thyristor. The light emitting element L has a threshold voltage lower than the voltage of the light emission signal φE by giving a trigger signal to a gate which is a predetermined portion, and when the light emission signal φE is given or from the current of the light emission signal φE. If the threshold current decreases and the light emission signal φE is given, light is emitted. The voltage of the light emission signal φE is a voltage applied between the anode and the cathode of the light emitting element L when the light emission signal φE is given, and the current of the light emission signal φE is light emission when the light emission signal φE is given. This is a current applied to the element L. The numbers of the switch elements T and the light emitting elements L are equal, that is, the symbols j and i are selected to be equal.

  The connection means 24 electrically connects the gate, which is the predetermined portion of each light emitting element L, and the gate, which is the predetermined portion of each switch element T corresponding to each light emitting element L. Specifically, the connecting means 24 electrically connects the gate of the light emitting element L1 and the gate of the switch element T1, electrically connects the gate of the light emitting element L2 and the gate of the switch element T2, and emits light. The gate of the element Li-1 and the gate of the switch element Tj-1 are electrically connected, and the gate of the light emitting element Li and the gate of the switch element Tj are electrically connected individually. The connecting means 24 is realized by a conductive path formed of a conductive material such as a metal material and an alloy material.

  FIG. 4 shows that the drive means 73 supplies a start signal φS to the start signal transmission path 26, a first scanning signal φ1 to be applied to the first scanning signal transmission path 25a, a second scanning signal φ2 to be applied to the second scanning signal transmission path 25b, The third scanning signal φ3 applied to the third scanning signal transmission path 25c and the light emission signal φE applied to the light emission signal transmission path 22, the light emission intensity of the light emitting element L1, and the light emission switching element for scanning start (hereinafter referred to as “scanning start switching element”). It is a waveform diagram showing the light emission intensity of T0 and switch elements T1 to T4. The light emission intensity of the light emitting element L1, the scanning start switch element T0, and the switch elements T1 to T4 indicates that light is emitted when the level is high (abbreviation: H), and light is emitted when the level is low (abbreviation: L). It means not. In FIG. 4, the horizontal axis represents time, and represents the elapsed time from the reference time.

  For the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE, the vertical axis represents the signal level. The signal level represents the magnitude of voltage or current. When the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE are at a high level (abbreviation: H), high voltage or high current is transmitted. When the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE are at a low (abbreviation: L) level, a low voltage or a low current is supplied to the signal transmission path. When the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE are at the L level, the voltage or current supplied to the signal transmission path is smaller than the threshold voltage or threshold current of each element. In the case of voltage, the high level is, for example, not less than 3 volts (V) and less than 10 volts (V). In the case of voltage, the low level is, for example, 0 (zero) volts (V).

  In the present embodiment, the voltage of the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE at the H level is, for example, 5 volts (V), and the L level start signal φS, The voltages of the third scanning signals φ1 to φ3 and the light emission signal φE are set to 0 volts (V), for example. The waveforms of the first to third scanning signals φ1 to φ3 are the same and have different phases.

  In the light emitting device 10, the light emitting state of the switch element T is transferred along the arrangement direction of the light emitting elements L in order to reduce the threshold voltage or the threshold current of the light emitting elements L to emit light.

  Next, the operation of the driving unit 73 will be described. First, at time t0, the driving unit 73 sets the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE to the L level. By setting the start signal φS to the L level, the threshold voltage or threshold current of the scanning start switch element T0 becomes smaller than the H level of the third scanning signal φ3. When the signal level of the light emission signal φE, the start signal φS, and the scanning signal φ is changed from the L level to the H level, the driving unit 73 changes the signal level to the H level until the signal level is changed from the H level to the L level next time. To maintain. Further, when the signal level of the light emission signal φE, the start signal φS, and the scanning signal φ is changed from the H level to the L level, the driving unit 73 sets the signal level to the L level until the signal level is changed from the L level to the H level. To keep.

  At time t1, the driving unit 73 changes only the third scanning signal φ3 from the L level to the H level. At time t1, start signal φS, first and second scanning signals φ1, φ2 and light emission signal φE are at L level. As a result, the scanning start switch element T0 is turned on, that is, turned on and emits light.

  The light of the scanning start switch element T0 is most strongly incident on the switch element T1 arranged at the end of the adjacent switch element array 23 in the arrangement direction. In the switch element T other than the switch element T1 in the switch element array 13, the light emitted from the scan start switch element T0 is closer to the switch element T arranged at a position separated from the scan start switch element T0 in the arrangement direction. The strength of is reduced. The switch element T has a characteristic that a drop in threshold voltage or threshold current increases as the received light intensity increases.

  Next, the transfer of the light emission state from the scanning start switch element T0 to the switch element T1 will be described. When the scanning start switch element T0 emits light, the switch element T1 receives this light, and the threshold voltage of the switch element T1 decreases.

At time t2, the threshold voltage of the switch element T1 is V _TH (T1). Switch elements T1, T4,..., Tj-2 are connected to the first scanning signal transmission path 25a, but the switch elements T4,..., Tj-2 are sufficiently separated from the scanning start switch element T0. Therefore, even if light from the scanning start switch element T0 is received, the light is weak, so that the threshold voltage hardly changes.

  At time t2, the driving unit 73 changes the first scanning signal φ1 from the L level to the H level. At time t2, the start signal φS, the second scanning signal φ2, and the light emission signal φE are at the L level, and the third scanning signal φ3 is at the H level. The H level of the first scanning signal φ1 is lower than the threshold voltage or threshold current of the other switching elements T4,..., Tj-2 except the switching element T1 connected to the first scanning signal transmission line 25a. Is also selected for high voltage or high current.

  By receiving the light from the adjacent switch element T, the scan signal transmission path 25 to which the switch element T whose threshold voltage or threshold current has decreased is connected to the scan signal transmission path 25. When a scanning signal φ having a voltage or current higher than the minimum threshold voltage or threshold current of the switching element T is applied, the scanning signal φ is applied to the scanning signal transmission line 25 via the resistance element Rφ, and the switching element A voltage divided by the resistance element Rφ is applied to T. The voltage divided by the resistance element Rφ is gradually applied to each switch element T, and among the plurality of switch elements T connected to the same scanning signal transmission path 25, the adjacent switch elements The voltage or current applied to the switch element T that has received the light from T is earliest greater than the threshold voltage or threshold current of the switch element T. Accordingly, only the switch element T having the lowest threshold voltage or threshold current emits light, and the other switch elements T do not emit light.

  Accordingly, at time t2, the switch element T1 is turned on, that is, turned on and emits light. After the switch element T1 is turned on, the driving unit 73 sets the third scanning signal φ3 to the L level at time t3. As a result, the scanning start switch element T0 is turned off, that is, turned off and turned off.

  In this way, the light emission state transitions from the scanning start switch element T0 to the switch element T1. At time t3, the driving unit 73 changes the start signal φS from the L level to the H level, and thereafter maintains the H level, thereby changing the third scanning signal φ3 from the L level to the H level after the time t3. The scanning start switch element T0 maintains the off state.

  The time between the time t2 and the time t3 is selected to be about 1/10 of the time when the first scanning signal φ1 becomes the H level. Thus, the drive means 73 gives the scanning signal φ so that the time when the scanning signal φ given to the adjacent switch element T is at the H level overlaps, whereby the threshold voltage or threshold current of the adjacent switch element T is given. Is reliably lowered, the scanning signal φ can be set to the H level, and optical scanning can be performed reliably.

In the present embodiment, the time during which the first to third scanning signals φ1 to φ3 are at the H level is selected to be about 1 μsecond (μsecond). Accordingly, the time between time t2 and time t3 is selected to be about 0.1 μsecond (μsecond).

  When the switch element T1 is turned on at time t2 by light reception, the switch element T1 generates a trigger signal at the gate, and keeps the on state until the scanning signal φ set to H level becomes L level. In the on state, the gate voltage of the switch element T1 becomes approximately 0 (zero) volts (V). Here, the voltage of the gate of the switching element T1 is a potential difference between the gate and the back electrode grounded. Since the gate of the switch element T1 is connected to the gate of the light emitting element L1, the gate voltage of the switch element T1 becomes equal to the gate voltage of the light emitting element L1. Thus, the switch element T1 can change the voltage applied to the gate and back electrode of the light emitting element L1.

When the light emitting element L1 emits light, the driving unit 73 changes the light emission signal φE to be applied to the electrode pad portion 12 from the L level at time t4 after the time t3 when the third scanning signal φ3 is changed from the H level to the L level has elapsed. Set to H level. In the light emitting element L1, since the switch element T1 is in the ON state, as described above, the gate of the light emitting element L1 is approximately 0 (zero) volts (V). At this time, the switch elements T2,..., Tj are in an off state, the threshold voltage of the light emitting element L1 at time t4 is V _TH (L1), and the threshold voltages of the light emitting elements L2,. When V _TH (L2),..., V _TH (Li) is set, the high level V _H of the light emission signal φE is larger than the threshold voltage of the light emitting element L, and the threshold voltage of the light emitting elements L2,. By selecting a value smaller than the lowest value, only the light emitting element L1 can be selectively turned on to emit light.

  At time t5, when the driving unit 73 sets the light emission signal φE to the L level, the light emitting element L1 is turned off and turned off. The amount of exposure to a photosensitive drum 90 to be described later is adjusted according to the light emission time of the light emitting element L while the light emission intensity of the light emitting element L is constant. That is, the exposure amount is determined by determining the time between time t4 and time t5 when the light emission signal φE becomes H level. When changing the exposure amount according to the light emission intensity of the light emitting element L, it is difficult because the voltage or current applied to the light emitting element L1 needs to be finely controlled. However, by changing the exposure amount according to the light emission time, the light emission signal φE is changed. Since it is only necessary to adjust the time for the H level, the amount of exposure is easily controlled, and a constant voltage or constant current is applied to the light emitting element L, so that the light emitting element L1 can emit light stably. The time during which the light emitting element L emits light, in other words, the time during which the light emission signal φE is at the H level is selected to be 80% or less of the time during which the scanning signal φ is at the H level.

  After the time t5 has elapsed, when the driving unit 73 sets the second scanning signal φ2 to the H level at the time t6, the switch element T2 emits light. After the time t6 has elapsed, the driving unit 73 outputs the first scanning signal φ1 at the time t7. When the L level is set, the switch element T1 is turned off. As a result, the light emission state transitions from the switch element T1 to the switch element T2.

  Thereafter, the driving unit 73 repeatedly applies the first to third scanning signals φ1 to φ3 to the scanning signal transmission paths 25a to 25c, so that the on state is also obtained in the switching elements T3, T4,. Sequentially transferred along the L array direction. When the switch element T emits light, the light emission signal φE of the light emission signal transmission path 22 is changed from L level to H level to correspond to the light emitting switch element T, in other words, the light emitting switch element. Only the light emitting element L connected to T can selectively emit light.

  The switch elements T located on both sides in the arrangement direction of the switch elements T that are emitting light are all excited, but the first to third scanning signal transmission paths 25a to 25c cause the first as described above. By transmitting the third scanning signals φ1 to φ3 and applying the first to third scanning signals φ1 to φ3 to each switch element T, the light emission state of the switch element T is transferred from one to the other in the arrangement direction. In other words, optical scanning can be performed.

  The light-emitting device 10 is a light-emitting IC determined by the above-described light-emitting device design support method. When the SLED array D having a light-emitting elements is driven and the SLED array D having a1 light-emitting elements is driven. In any case of driving, the output terminal portion 16 does not remain, in other words, the number of output terminal portions 16 includes the same number of light emitting ICs.

  Accordingly, when the electrode pad portion 12 of the SLED array D having a light emitting elements and the output terminal portion 16 of the light emitting IC are individually connected, and the electrode pad portion of the SLED array D having a1 light emitting elements. 12 and the output terminal 16 of the light emitting IC are individually connected to each other, it is not necessary to design and manufacture an individual light emitting IC or SLED array D. Compared to the case where the SLED array D is designed and manufactured, the number of manufacturing steps can be reduced. As a result, the productivity of the light emitting device 10 including the light emitting IC 15 having the same number of output terminal portions 16 can be improved.

  FIG. 5 is a side view showing the basic configuration of the image forming apparatus 87 having the light emitting device 10. The image forming apparatus 87 is an electrophotographic image forming apparatus. In the present embodiment, the light emitting device 10 is used as an exposure device that exposes a photosensitive drum 90 that constitutes an image forming apparatus 87 described later. The light emitting device 10 is mounted on a circuit board on which the driving unit 73 is provided.

  The image forming apparatus 87 is an apparatus that employs a tandem system that forms four color images of yellow (Y), magenta (M), cyan (C), and black (K). The image forming apparatus 87 is roughly a circuit on which the four light emitting devices 10Y, 10M, 10C, and 10K, the lens arrays 88Y, 88M, 88C, and 88K that are the condensing means, the light emitting device 10, and the driving means 73 are mounted. First holders 89Y, 89M, 89C, 89K for holding the substrate and the lens array 88, four photosensitive drums 90Y, 90M, 90C, 90K, four developer supply means 91Y, 91M, 91C, 91K, transfer means. The transfer belt 92 includes four cleaners 93Y, 93M, 93C, and 93K, four chargers 94Y, 94M, 94C, and 94K, a fixing unit 95, and a control unit 96. Hereinafter, when the four light emitting devices 10Y, 10M, 10C, and 10K are collectively referred to and when an unspecified light emitting device is indicated, the light emitting device 10 may be simply referred to as “light emitting device 10”.

  The light emitting devices 10Y, 10M, 10C, and 10K are driven by the driving unit 73 based on the color image information of each color. The length dimension of the light emitting devices 10Y, 10M, 10C, and 10K in the arrangement direction is selected to be, for example, 200 mm or more and less than 400 mm.

  Light from the light emitting element L of each light emitting device 10 is condensed and applied to each of the photosensitive drums 90Y, 90M, 90C, and 90K via the lens array 88. The lens array 88 includes, for example, a plurality of lenses respectively disposed on the optical axis of the light emitting element L, and is configured by integrally forming these lenses. The circuit board on which the light emitting device 10 is mounted and the lens array 88 are held by the first holder 89. By the first holder 89, the light irradiation direction of the light emitting element L and the optical axis direction of the lens of the lens array 88 are aligned so as to be substantially aligned.

  Each of the photoconductive drums 90Y, 90M, 90C, and 90K is formed, for example, by adhering a photoconductive layer on the surface of a cylindrical substrate, and the outer peripheral surface receives light from the light emitting devices 10Y, 10M, 10C, and 10K. Then, an electrostatic latent image forming position where the electrostatic latent image is formed is set. The exposed photosensitive drums 90Y, 90M, 90C, and 90K are sequentially exposed at the periphery of the photosensitive drums 90Y, 90M, 90C, and 90K toward the downstream side in the rotational direction with respect to the electrostatic latent image forming positions. Developer supplying means 91Y, 91M, 91C, 91K for supplying developer to the transfer belt 92, cleaners 93Y, 93M, 93C, 93K, and chargers 94Y, 94M, 94C, 94K are arranged, respectively. A transfer belt 92 that transfers an image formed on the photosensitive drum 90 with a developer onto a recording sheet is provided in common to the four photosensitive drums 90Y, 90M, 90C, and 90K.

  The photosensitive drums 90Y, 90M, 90C, and 90K are held by a second holder, and the second holder and the first holder 89 are relatively fixed. The alignment is performed such that the rotation axis direction of each of the photoconductive drums 90Y, 90M, 90C, and 90K and the arrangement direction of the light emitting elements L of each light emitting device 10 are substantially coincident.

  The recording sheet is conveyed by the transfer belt 92, and the recording sheet on which an image is formed by the developer is conveyed to the fixing unit 95. The fixing unit 95 fixes the developer transferred to the recording sheet. The photosensitive drums 90Y, 90M, 90C, and 90K are rotated by a rotation driving unit.

  The control unit 96 provides a clock signal and image information to the driving unit 73 described above, and also includes a rotation driving unit that rotates the photosensitive drums 90Y, 90M, 90C, and 90K, a developer supply unit 91Y, 91M, 91C, and 91K, Each part of the transfer means 92, the charging means 94Y, 94M, 94C, 94K and the fixing means 95 is controlled.

  As described above, according to the present embodiment, the light emitting device is driven by the driving unit based on the image information, and the light from the light emitting device is collected on the charged photosensitive drum by the light collecting unit. The photosensitive drum is exposed to form an electrostatic latent image on the surface thereof. When the developer is supplied to the photosensitive drum on which the electrostatic latent image is formed by the developer supplying means, the developer adheres to the photosensitive drum and an image is formed. An image formed with the developer on the photosensitive drum is transferred to the recording sheet by the transfer unit, and the developer transferred to the recording sheet is fixed by the fixing unit, whereby an image is formed on the recording sheet. Since the photosensitive drum can be accurately exposed by the light emitting device, a recorded image with excellent image quality can be obtained. Since the light emitting device 10 in which the switch element T and the light emitting element L by the light emitting thyristor are integrated is used as the exposure device, such an exposure device can be manufactured at low cost, thereby reducing the manufacturing cost of the image forming apparatus 87. Can be reduced.

  The light emitting IC 15 is determined by the above-described light emitting device design support method, and the electrode pad portion 12 of the SLED array D having a light emitting elements and the output terminal portion 16 of the light emitting IC are individually connected. The number of output terminal portions 16 is the same in any case where the electrode pad portion 12 of the SLED array D having a1 light emitting elements and the output terminal portion 16 of the light emitting IC are individually connected. The productivity of the image forming apparatus 87 can be improved by using the light emitting device 10 whose productivity is improved by providing the light emitting IC 15 for the image forming apparatus 87.

  FIG. 6 is an electric circuit diagram showing a basic configuration of the light-emitting device 210 according to the second embodiment of the present invention. The light-emitting device 210 is similar to the light-emitting device 10 of the first embodiment shown in FIG. 3, and only the configuration of the switch element array and the number of scanning signal transmission paths 25 are different. Parts corresponding to those in FIG. 10 are given the same reference numerals, and descriptions of common parts are omitted to avoid duplication. The light emitting device 210 transmits the first scanning signal φ1 to the SLED array D, the light emitting signal transmission path 22, the connecting means 24, the scanning signal transmission path 25, the start signal transmission path 26, and the first scanning signal transmission path 25a. And driving means 73 for supplying the second scanning signal φ2 to the second scanning signal transmission line 25b. The SLED array D includes an electrode pad portion 12, a light emitting element array 21, and a switch element array 213.

  In the first embodiment described above, the light emitting device design support method related to the determination of the light emitting IC 15 provided in the light emitting device 10 has been described. However, even when the light emitting IC 15 is provided in the light emitting device 210, the above light emitting device is described. By this design support method, it is possible to determine the light emitting IC 15 in which the output terminal portion 16 is not excessively easily determined.

  In the light emitting device 210, the light emitting IC 15 included in the driving unit 73 is a light emitting IC determined by the above-described light emitting device design support method, and the electrode pad portion 12 of the SLED array D having a light emitting elements. And the output terminal part 16 of the light emitting IC, and the electrode pad part 12 of the SLED array D having a1 light emitting elements and the output terminal part 16 of the light emitting IC are individually connected. In any case, the output terminal portions 16 do not remain, in other words, the number of the output terminal portions 16 is the same number of light emitting ICs.

  More specifically, the light emitting IC 15 is capable of supporting both cases of driving the SLED array D having a light emitting elements and driving the SLED array D having a1 light emitting elements. IC, in other words, a light emitting IC that can handle both A3 size and A4 size.

  In the first and second scanning signal transmission paths 25a and 25b, switch elements T1, T2,..., Tj−1, Tj (symbol j is a symbol j in the switch element array 213 in which a plurality of light emitting switch elements are linearly arranged. A resistance element Rφ connected in series with each other is connected to the first and second scanning signal transmission lines 25a and 25b via the resistance element Rφ.

  Each switch element T includes a light emitting part and a light receiving part. When the light emitting part of each switch element T is indicated individually, the reference numeral of the switch element T is indicated with a suffix “s”, and when the light receiving part of each switch element T is indicated individually, the switch element T is referred to. A suffix “r” is added to the code. For example, the switch element T1 includes a light emitting unit Ts1 and a light receiving unit Tr1. Hereinafter, when an unspecified light emitting part is indicated, it is simply referred to as “Ts”, and when an unspecified light receiving part is indicated, it may be simply referred to as “Tr”.

  In each switch element T, the light emitting portion Ts and the light receiving portion Tr are provided adjacent to each other. The plurality of switch elements T are arranged with the light receiving part Tr facing the light emitting part Ts of the switch element T adjacent to one side and the light receiving part Ts facing the light receiving part Tr of the switch element T adjacent to the other side. . Specifically, the light emitting part Ts1 of the switch element T1 faces the light receiving part Tr2 of the switch element T2, and the light emitting part Ts2 of the switch element T2 faces the light receiving part Tr3 of the switch element T3.

  The light emitting part Ts and the light receiving part Tr of each switch element T are realized by the light emitting thyristor, for example. The light receiving portion Tr of the switch element T generates a trigger signal at the gate of the light receiving portion Tr, which is a predetermined portion by light reception. The trigger signal generated at the gate of the light receiving unit Tr is given to the gate of the light emitting unit Ts. When the trigger signal is given to the gate of the light emitting unit Ts, the threshold voltage or threshold current of the light emitting unit Ts decreases.

  The light emitting unit Ts is connected to the scanning signal transmission line 25, and when the threshold voltage is lower than the voltage of the scanning signal φ given through the scanning signal transmission line 25 and the scanning signal φ is given, or scanning When the threshold current is lower than the current of the signal φ and the scanning signal φ is given, a trigger signal is generated to emit light. The voltage of the scanning signal φ is a voltage applied between the anode and the cathode of the light emitting portion Ts of the switch element T when the scanning signal φ is given. The current of the scanning signal φ is given by the scanning signal φ. Current applied to the light emitting portion Ts of the switch element T.

  The connecting means 24 electrically connects the gate that is the predetermined portion of each light emitting element L and the gate that is the predetermined portion of the light emitting portion Ts of each switch element T corresponding to each light emitting element L. .

  FIG. 7 shows that the driving means 73 supplies a start signal φS to the start signal transmission path 26, a first scanning signal φ1 to be applied to the first scanning signal transmission path 25a, a second scanning signal φ2 to be applied to the second scanning signal transmission path 25b, and It is a wave form diagram which shows the light emission signal (phi) E given to the light emission signal transmission path 22, the light emission intensity of the light emitting element L1, and the light emission intensity of the scanning start switch element T0 and switch elements T1-T4. The light emission intensity of the light emitting element L1, the scanning start switch element T0, and the switch elements T1 to T4 indicates that light is emitted when the level is high (abbreviation: H), and light is emitted when the level is low (abbreviation: L). It means not. In FIG. 7, the horizontal axis represents time and represents the elapsed time from the reference time. For the start signal φS, the first and second scanning signals φ1 and φ2, and the light emission signal φE, the vertical axis represents the signal level.

  Next, the operation of the driving unit 73 will be described. First, at time t0, the driving means 73 sets the start signal φS, the first and second scanning signals φ1, φ2 and the light emission signal φE to the L level. By setting the start signal φS to the L level, the scanning start switch element T0 does not emit light.

  At time t1, the driving unit 73 changes only the start signal φS from the L level to the H level. At time t1, first and second scanning signals φ1, φ2 and light emission signal φE are at the L level. As a result, the scanning start switch element T0 is turned on, that is, turned on and emits light.

  The light of the scanning start switch element T0 is most strongly incident on the light receiving part Tr1 of the switch element T1 arranged at the end of the adjacent switch element array 213 in the arrangement direction. In the switch element T other than the switch element T1 in the switch element array 213, the light emitted from the scan start switch element T0 is closer to the switch element T arranged at a position separated from the scan start switch element T0 in the arrangement direction. The strength of is reduced. As the light receiving unit Tr of the switch element T receives light, the threshold voltage or threshold current of the light emitting unit Ts connected to the light receiving unit Tr decreases, and the light intensity received by the light receiving unit Tr increases. The threshold voltage or threshold current of the light emitting portion Ts has a large drop.

  Next, the transfer of the light emission state from the scanning start switch element T0 to the switch element T1 will be described. When the scanning start switch element T0 emits light, this light is received by the light receiving portion Tr1 of the switch element T1, and the threshold voltage of the light emitting portion Ts1 of the switch element T1 is lowered as described above.

After time t1 has elapsed, at time t2, the threshold voltage of the light emitting unit Ts1 of the switch element T1 is V _TH (T1). The switch elements T1, T3,..., Tj-1 are connected to the first scanning signal transmission line 25a. However, the switch elements T3,..., Tj-1 are sufficiently separated from the scanning start switch element T0. Therefore, even if light from the scanning start switch element T0 is received, the light is weak, so that the threshold voltage of the light emitting portion Ts hardly changes.

  At time t2, the driving unit 73 changes the first scanning signal φ1 from the L level to the H level. At time t2, the start signal φS is at the H level, and the second scanning signal φ2 and the light emission signal φE are at the L level. The H level of the first scanning signal φ1 is the threshold voltage of the light emitting portion Ts of the other switch elements T3,..., Tj−1 except the light emitting portion Ts1 of the switch element T1 connected to the first scanning signal transmission path 25a. A voltage higher or higher than the lowest threshold current is selected.

  Thereby, at time t2, the light emitting portion Ts1 of the switch element T1 is turned on, that is, turned on and emits light. After the light emitting unit Ts1 of the switch element T1 is turned on, the drive unit 73 sets the start signal φS to the L level at time t3. As a result, the scanning start switch element T0 is turned off, that is, turned off and turned off.

  In this way, the light emission state transitions from the scanning start switch element T0 to the switch element T1. At time t3, the drive unit 73 changes the start signal φS from the H level to the L level, and thereafter maintains the L level until the light emission of the switch element Tj is completed. When the start switch element T0 is not caused to emit light, the start signal φS can be kept at the L level, and the L level voltage is set to 0 (zero) volts (V), so that power is not consumed in the non-light emitting state. The time for setting the start signal φS to the H level is shorter than the time for setting the first and second scanning signals φ1 and φ2 to the H level. Since the scan start switch element T0 is used only for lowering the threshold voltage or threshold current of the light emitting portion Ts1 of the switch element T1, the time for the start signal φS to be at the H level is shortened and power consumption is reduced. Can be suppressed.

  The time between the time t2 and the time t3 is selected to be about 1/10 of the time when the first scanning signal φ1 becomes the H level. Thus, the drive means 73 gives the scanning signal φ so that the time when the scanning signal φ given to the adjacent switch element T is at the H level overlaps, whereby the threshold voltage or threshold current of the adjacent switch element T is given. Is reliably lowered, the scanning signal φ can be set to the H level, and optical scanning can be performed reliably.

  In the present embodiment, the time during which the first and second scanning signals φ1 and φ2 are at the H level is selected to be about 1 μsec. Accordingly, the time between time t2 and time t3 is selected to be about 0.1 μsecond (μsecond).

  The light receiving unit Tr1 of the switch element T1 generates a trigger signal at the gate of the light receiving unit Tr by light reception, and when the light emitting unit Ts1 of the switch element T1 is turned on at time t2, the first scanning signal φ1 set to H level is The on state is maintained until the L level is reached. When turned on, the voltage of the gate of the switch element T1 becomes approximately 0 (zero) volts (V). Here, the voltage of the gate of the switching element T1 is a potential difference between the gate and the back electrode grounded. Since the gate of the switch element T1 is connected to the gate of the light emitting element L1, the gate voltage of the switch element T1 becomes equal to the voltage of the gate of the light emitting element L1. Thus, the switch element T1 can change the voltage applied to the gate and back electrode of the light emitting element L1.

  When the light emitting element L1 emits light, the driving unit 73 changes the light emission signal φE from the L level to the H level at time t4 after the time t3 has elapsed. At time t5, when the driving unit 73 sets the light emission signal φE to the L level, the light emitting element L1 is turned off and turned off. After the time t5 has elapsed, when the driving unit 73 sets the second scanning signal φ2 to the H level at the time t6, the light emitting unit Ts2 of the switch element T2 emits light, and after the time t6 has elapsed, the first tessellation at the time t7. When the scanning signal φ1 is set to the L level, the light emitting portion Ts1 of the switch element T1 is turned off. As a result, the light emission state transitions from the switch element T1 to the switch element T2.

  Thereafter, the driving means 73 repeatedly applies the first and second scanning signals φ1, φ2 to the scanning signal transmission lines 25a, 25b, so that the on state of the switching elements T3,. It is sequentially transferred along the arrangement direction. When the light emitting portion Ts of the switch element T emits light, the light emission signal φE of the light emission signal transmission path 22 is changed from L level to H level, so that it emits light corresponding to this light emitting switch element T. Only the light emitting element L connected to the switch element T having the light emitting portion Ts can be selectively made to emit light.

  The light-emitting device 210 is a light-emitting IC determined by the above-described light-emitting device design support method. When the SLED array D having a light-emitting elements is driven and the SLED array D having a1 light-emitting elements is driven. In any case of driving, the output terminal portion 16 does not remain, in other words, the number of output terminal portions 16 includes the same number of light emitting ICs.

  Accordingly, when the electrode pad portion 12 of the SLED array D having a light emitting elements and the output terminal portion 16 of the light emitting IC are individually connected, and the electrode pad portion of the SLED array D having a1 light emitting elements. 12 and the light emitting IC output terminal section 16 are individually connected to each other, it is not necessary to design and manufacture a separate light emitting IC or SLED array D. Compared to the case where the SLED array D is designed and manufactured, the number of manufacturing steps can be reduced. As a result, the productivity of the light emitting device 210 including the light emitting IC 15 having the same number of output terminal portions 16 can be improved.

  The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the gist of the present invention. For example, in each of the above-described embodiments, the configuration in which the light-emitting element L is realized by a light-emitting thyristor has been described. However, in another embodiment of the present invention, the light-emitting element L is a light-emitting diode (abbreviation: LED). In this case, the anode of each LED is connected to the light emission signal transmission path 22, and the cathode of each LED is connected to the gate of each switch element T.

It is a figure which shows the light-emitting device 10 of the 1st Embodiment of this invention. 3 is a flowchart showing a procedure related to determination of a light emitting IC 15 in the light emitting device 10. 1 is an electric circuit diagram showing a basic configuration of a light emitting device 10. FIG. The driving means 73 supplies a start signal φS to the start signal transmission path 26, a first scanning signal φ1 to be applied to the first scanning signal transmission path 25a, a second scanning signal φ2 to be applied to the second scanning signal transmission path 25b, and a third scanning signal. The third scanning signal φ3 applied to the transmission line 25c and the light emission signal φE applied to the light emission signal transmission line 22, the light emission intensity of the light emitting element L1, and the light emission intensity of the light emission switch element T0 for scanning start and the switch elements T1 to T4 are shown. It is a waveform diagram. 2 is a side view showing a basic configuration of an image forming apparatus 87 having a light emitting device 10. FIG. It is an electric circuit diagram which shows the basic composition of the light-emitting device 210 of the 2nd Embodiment of this invention. The drive means 73 supplies the start signal φS to the start signal transmission path 26, the first scanning signal φ1 to be applied to the first scanning signal transmission path 25a, the second scanning signal φ2 to be applied to the second scanning signal transmission path 25b, and the light emission signal transmission path. 22 is a waveform diagram showing a light emission signal φE given to the light source 22, the light emission intensity of the light emitting element L1, and the light emission intensity of the scanning start switch element T0 and the switch elements T1 to T4. It is an electric circuit diagram which shows the schematic structure of the basic structure of the light-emitting device 1 of a prior art. It is a figure which simplifies and shows the prior art light-emitting device 1 shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,210 Light-emitting device 11 Semiconductor substrate 12 Electrode pad part 15 Light emitting IC
16 Output terminal portion 21 Light emitting element array 73 Driving means 87 Image forming apparatus 88Y, 88M, 88C, 88K Lens array 91Y, 91M, 91C, 91K Developer supply means 92 Transfer belt 95 Fixing means D Self-scanning light emitting element (SLED) Array L Light emitting device

Claims (4)

c (c is a natural number of 2 or more) light emitting elements and n (n is a natural number) element-side connection portions connected to the respective light emitting elements, and a (a is a natural number) light emission as a whole A plurality of light emitting element arrays having elements;
A light-emitting device design support method including b (b is a natural number) drive-side connection portions and m (m is a natural number) drive devices individually connected to the element-side connection portions of the light-emitting element array. There,
C, n, a, b, m are
a / c = (b × m) / n
And n element-side connection portions respectively connected to each of a1 (a1 is a natural number satisfying a1 <a) of the a light-emitting elements, and m of the driving devices When m1 (m1 is a natural number satisfying m1 <m) and b drive side connection units respectively provided in the drive devices are individually connected,
A1, n, c, b, m1 are:
a1 / c = (b × m1) / n
A design support method for a light-emitting device, wherein a drive device is determined based on b, m, and m1 when a, a1, c, and n are known numbers so as to satisfy the above. c (c is a natural number of 2 or more) light emitting elements and n (n is a natural number) element-side connection portions connected to the respective light emitting elements, and a (a is a natural number) light emission as a whole A plurality of light emitting element arrays having elements;
b (b is a natural number) driving side connection portions, and a light emitting device including m (m is a natural number) driving devices individually connected to the element side connection portions of the light emitting element array,
The driving device includes:
C, n, a, b, m are
a / c = (b × m) / n
And n element-side connection portions respectively connected to each of a1 (a1 is a natural number satisfying a1 <a) of the a light-emitting elements, and m of the driving devices When m1 (m1 is a natural number satisfying m1 <m) and b drive side connection units respectively provided in the drive devices are individually connected,
A1, n, c, b, m1 are
a1 / c = (b × m1) / n
The light-emitting device is determined based on b, m, and m1, where a, a1, c, and n are known numbers so as to satisfy the above. A light emitting device according to claim 2;
Driving means for driving the light emitting device based on image information;
Condensing means for condensing light from the light emitting element of the light emitting device on the photosensitive drum;
Developer supplying means for supplying the developer to the exposed photosensitive drum by which light from the light emitting device is condensed on the photosensitive drum by the condensing means;
Transfer means for transferring an image formed by a developer on the photosensitive drum to a recording sheet;
An image forming apparatus comprising: fixing means for fixing the developer transferred to the recording sheet.   A design support program for causing a computer to execute the design support method for a light emitting device according to claim 1.

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