JP4462020B2 - Self-scanning light emitting element array and optical writing head inspection method - Google Patents

Description

  The present invention relates to a method for inspecting a self-scanning light emitting element array chip and an optical writing head, and more particularly to a method for inspecting light emission abnormality of a light emitting unit thyristor.

  A self-scanning light-emitting element array including a transfer unit and a light-emitting unit (including a plurality of light-emitting points) using a PNPN three-terminal light-emitting thyristor creates a light-emitting pattern based on a transfer signal and an image signal. Such a self-scanning light emitting element array chip is used in combination with a drive circuit thereof as a light source for writing an optical printer, that is, an optical writing head.

As described in Patent Document 1, detection of abnormal light emission in a chip of such a self-scanning light emitting element array is provided with an end terminal bonding pad on each chip, and the voltage is measured to measure the abnormal light emission of the chip. Was inspecting.
Japanese Patent Laid-Open No. 9-99581

  Since the drive circuit that supplies the transfer signal (transfer clock) and the image signal (write signal) to the self-scanning light emitting element array does not transmit the transfer clock, a light emission error occurs due to some transfer error, and the image position is It may shift or the image may fall out.

Luminous abnormalities can be roughly classified into the following modes.
(1) Only the xth light emission point is lit (2) No light is emitted after the xth light emission point (2-1) The light emission point between the first to x light emission points is lit only once (2-2) First to xth The light emitting points between the light emitting points are repeatedly turned on (2-3) The light emitting points between the first to (x-1) light emitting points are turned on once, and the xth light emitting point is turned on multiple times (3) the xth light emitting point And the yth light emitting point do not light (x <y)
(3-1) The light emission points of the first to xth and yth to final light emission points are turned on only once. (3-2) After the light emission points of the first to xth and yth to final light emission points are turned on once, Repeated lighting from the first light emitting point In the above-described method of providing an end terminal on the self-scanning light emitting element array chip and confirming whether normal transfer is being performed, the bonding area for the end terminal increases and the chip area increases. , The cost goes up. Further, there is a problem that the end terminal cannot be taken out depending on the chip design. For example, when a self-scanning light emitting element array of two circuits is mounted on one chip and each light emitting point is transferred from both ends of the chip to the center, the end terminals must be taken out from the center of the chip. It is difficult to place a bonding pad on the design.

An object of the present invention is to provide a method capable of inspecting a self-scanning light emitting element array chip transfer abnormality without providing an end terminal bonding pad.
Another object of the present invention is to provide a method for detecting a light emission abnormality in an optical writing head constructed by arranging a plurality of self-scanning light emitting element array chips.

  The following three types of self-scanning light emitting element arrays according to the present invention are used.

The first type is
A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor A transfer unit that turns on a thyristor adjacent to the certain thyristor by changing a gate voltage of the thyristor by a circuit network including the diode and a gate resistor;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element A self-scanning light-emitting element array chip including a light-emitting unit provided with a line for applying an image signal for.

The second type is
A plurality of three-terminal light-emitting thyristors for transfer are arranged one-dimensionally; the gates of adjacent thyristors are connected to each other by a coupling resistor; a power supply line is connected to each gate electrode of the thyristor, and each gate resistor is connected A three-phase clock pulse line from the outside is connected in sequence to the cathode or anode of each thyristor; when a thyristor is turned on by a single-phase clock pulse, Changing the gate voltage of the thyristor by a circuit network composed of the coupling resistor and the gate resistor; a transfer unit for turning on a thyristor adjacent to the certain thyristor by a clock pulse of another phase;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element A self-scanning light-emitting element array chip including a light-emitting unit provided with a line for applying an image signal for.

The third type is
A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor The gate voltage of the thyristor is changed by a circuit network composed of the diode and the gate resistor; the thyristor adjacent to the certain thyristor is turned on by the clock pulse of the other phase; one of the clock pulses of the two phases Is connected to the gate of the first transfer thyristor to be turned on via a diode. A transfer unit,
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element A self-scanning light-emitting element array chip including a light-emitting unit provided with a line for applying an image signal for.

  The present invention is a method for inspecting light emission abnormality of such a self-scanning light emitting element array chip, wherein a current measuring circuit is inserted into the power supply line, and the last of the plurality of arranged transfer thyristors is arranged. The current flowing through the power supply line is measured by the current measurement circuit at the timing when only the thyristor is turned on, and the light emission abnormality of the self-scanning light emitting element array chip is detected from the measured value.

  An optical writing head can be constructed by arranging a plurality of self-scanning light emitting element array chips in one dimension.

  The present invention is also a method for inspecting a light emission abnormality of such an optical writing head, wherein a current measuring circuit is inserted into the power supply line for each chip, and a plurality of the arrayed elements are arranged for each chip. The current flowing through the power supply line is measured by the current measuring circuit at the timing when only the last thyristor of the transfer thyristors is turned on, and a light emission abnormality of the optical writing head is detected from the measured value. To do.

  When testing using one current measurement circuit, the power line of each chip is connected to one common power line, a current measurement circuit is inserted into the common power line, It is preferable that the current flowing through the common power supply line is measured by the current measuring circuit at the timing when only the transfer thyristor is turned on, and the light emission abnormality of the optical writing head is detected from the measured value.

  Further, in the optical writing head inspection method of the present invention, the self-scanning light emitting element array chips are blocked every predetermined number, and the power lines of the chips in each block are connected to a common power line for each block, Current measurement circuits are inserted into the respective common power supply lines, and currents flowing through the respective common power supply lines at the timing when only the last transfer thyristor is turned on through all chips in each block are referred to as the respective current measurement circuits. And detecting a light emission abnormality of the optical writing head based on the measured value.

  In the optical writing head inspection method of the present invention, the power supply line of the chip in each block is connected to the common power supply line for each block, and each common power supply line is connected to one common power supply for the optical writing head. Connected to the line, one current measurement circuit is inserted into this common power supply line, and each block is operated in a time-sharing manner, and only the last transfer thyristor is turned on through all the chips in each block. The current flowing through the one common power supply line is measured by the current measuring circuit at the timing, and a light emission abnormality of the optical writing head is detected from the measured value.

  In the self-scanning light emitting element array inspection method of the present invention, when the transfer unit final thyristor is turned on, the light emitting unit final thyristor is turned on, and then all the transfer unit thyristors are turned off. Whether or not is lit is determined by measuring a current flowing through the power supply line to detect a light emission abnormality of the optical writing head.

  In the inspection method of the self-scanning light emitting element array of the present invention, when the transfer unit final thyristor is turned on, the light emitting unit final thyristor is turned on, then all transfer unit thyristors are turned off, and the transfer unit thyristor is turned on again. The optical writing head is configured to determine whether a transfer unit thyristor corresponding to the light emitting unit thyristor that is lit is on by measuring a current flowing through the power supply line when it is turned on. It is characterized by detecting an abnormal light emission.

According to the present invention, in a self-scanning light-emitting element array chip using a three-terminal light-emitting thyristor with a PNPN structure, it is determined whether or not the light-emitting point has reached the final bit by monitoring the current at the _VGA terminal. Since a light emission abnormality can be detected, various problems associated with providing an end terminal according to the prior art do not occur.

  The inspection method of the present invention can be applied to a self-check at start-up and an operation check at regular intervals in addition to a full-time monitor. In addition, determination can be performed in units of chips, and determination can be performed in units of blocks, so that a flexible inspection method can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

The current flowing from the V _GA terminal of the self-scanning light-emitting array chip monitors the current value at the timing of the last light emitting element is turned Tests for proper value.

As an example, an equivalent circuit of an 8-bit diode-coupled self-scanning light-emitting element array chip in which the gates of the transfer unit thyristors are coupled by diodes, and driving waveforms thereof are shown in FIGS. 1, S _{1 to} S ₈ are transfer unit thyristors, L _{1 to} L ₈ are light emitting unit thyristors, R _{G1 to} R _G8 are gate resistors, D _{1 to} D ₇ are coupling diodes, V _GA is a power supply terminal, Φ _S is a start pulse terminal, Φ ₁ and Φ 2 are clock pulse terminals, Φ _I is an image signal terminal, and R _S , R ₁ , R 2, and R _I are current limiting resistors.

Note that _VGA is used as a power supply voltage, and R _S , R ₁ , R 2, and R _I are also used as resistance values. The resistance values of the gate resistors R _{G1 to} R _G8 are the same and are represented by _RG .

  As is apparent from FIG. 1, the circuit is an anode common type in which the anodes of the transfer unit thyristor and the light emitting unit thyristor are grounded.

In the circuit described above, now, the clock pulse Φ1 is in the H level start pulse [Phi _S at the L level, to calculate the current flowing into the V _GA terminal when only the transfer unit thyristors S ₁ is turned on. Because thyristors _{S 1} is in the ON state, the gate voltage _{V GON} thyristor _{S 1} is substantially the substrate potential. The current I _G1 flowing through the gate resistor R _G1 is
I _G1 = (V _GON −V _GA ) / R _G (1)
It becomes. Further, the current flowing through the gate resistor _{R G2,} since potential difference across by the voltage drop _{V D} of the diode _{D 1} to the gate resistor _{R G2} decreases,
I _G2 = (V _GON −V _GA −V _D ) / R _G (2)
It becomes.

Less than,
I _G3 = (V _GON −V _GA −2V _D ) / R _G (3)
I _G4 = (V _GON −V _GA −3V _D ) / R _G (4)
・
・
However, when the numerator value of the above equation becomes negative, the diode is turned off and no current flows. For example _{V GON = -0.3V, V GA =} -5V, Considering V D = 1.2V, diode _{D 5} or less is turned _{off, I G5} following current is zero. When R _G = 30 kΩ, the current I _GA (S ₁ ) flowing through the V _GA terminal when the thyristor S ₁ is on is
I _GA (S ₁ ) = IG ₁ + IG ₂ + _{IG 3} + IG ₄ = (4V _GON −4V _GA −6V _D ) / _RG
≈390 μA.

So far, the first transfer unit thyristor _{S 1} is was when turned on, the terminal end side (8 bits in FIG. 1), constituted by a coupling diode _D 1 to D ₇ and the gate resistor _R G1 _{to R G8} The current I _GA changes because the network to be cut is cut off. For example, if the thyristor _{S 7} is turned on, since there is no gate resistor _{R G7} and _{R G8} only current flows _paths, the _{I GA (S 7) = I} G7 + I G8. In the case where the thyristor _{S 8} is on, since there is no gate resistor _{R G8} only current _path, the _{I GA (S 8) = I} G8.

An example of the drive waveform and the current value of the current I _GA is shown in FIG. When compared with a thyristor connected to the clock pulse terminal Φ2, I _GA (S ₂ ) = I _GA (S ₄ ) = 390 μA, I _GA (S ₆ ) = 350 μA, I _GA (S ₈ ) = 160 μA, and transfer When the final thyristor is turned on, the _IGA value is less than half that in other cases.

Therefore, at the timing when the transfer unit final thyristor is turned on, the current _IGA is measured by an ammeter (not shown), and the success or failure of the transfer operation is determined based on whether or not the current is within a certain range. If there is an abnormality in the transfer operation, it can be seen that there is a light emission abnormality.

  FIG. 4A shows a light emission abnormality inspection method in an optical writing head configured by arranging a plurality of self-scanning light emitting element arrays. A plurality of chips are linearly arranged to constitute a light source for an optical writing head. FIG. 4A shows a light source in which five chips CHIP 1 to 5 are arranged to simplify the drawing. The chip is assumed to be of 8 bits shown in FIG.

A self-scanning light-emitting element array chip usually includes five bonding pads. That is, the bonding pads for V _GA terminals, bonding pads for the start pulse terminal [Phi _S, bonding pads for clock pulses terminal .phi.1, a bonding pad, the bonding pad for the image signal terminals [Phi _I clock pulse terminal .phi.2, in the figure, each chip "V", "S", "1", "2", "I" are displayed.

A start pulse Φ _S , a clock pulse Φ1, and a clock pulse Φ2 are commonly supplied to the chips CHIP1 to CHIP5. Image signals Φ _I 1, Φ _I 2, Φ _I 3, Φ _I 4, and Φ _I 5 are individually supplied to each chip.

To carry out the test method of the present invention, as shown in FIG. 4A, during each _{V GA} terminal and -5V supply 10 of the chip CHIP1～CHIP5, inserting the ammeter J1~J5 respectively.

Each ammeter detects a transfer abnormality, that is, a light emission abnormality by monitoring the current _IGA . In each chip, when the current I _GA (S ₈ ) measured when only the thyristor S ₈ is on is between 100 μA and 250 μA, it is determined that the transfer operation is successful. Here, the current I _GA (S ₈ ) is 100 μA or less because no thyristor is turned on in the chip. In the case mentioned in the problem, (2-1), ( It corresponds to 3-1).

Although an ammeter is inserted here, a voltage drop may be measured by inserting a resistor. An example of a voltage drop measurement circuit is shown in FIG. 4B. Or In Figure 4A, there is shown an ammeter J1 to J5, as a means of specific current measurement, a current flows from the _{V GA} terminal of each chip, the range of (here, 100～250Myuei) defaults in A circuit for determining whether or not using a comparator was used.

In the figure, CP _{1 to} CP ₁₀ are comparators, which have + −2 input terminals, and output an H level when the voltage at the + terminal is higher than the − terminal, and output an L level when the voltage is reversed. Have a job. In FIG. 4B, Block1 corresponds to the ammeter J1 in FIG. 4A. Block 1 is composed of two comparators CP ₁ and CP ₂ , a resistor R ₁ , and an AND gate A ₁ . The comparator CP ₁ assumes that the voltage drop caused by the resistor R ₁ (1 kΩ) is determined by the resistors R ₆ and R ₇ (here, R ₆ = 1 kΩ, R ₇ = 49 kΩ, and V _GA = −5V). Te, -0.1 V) is compared to, and outputs the lower limit value (H level and the current is greater than 100 .mu.A) flows through the resistor _{R 1} in this case the current. On the other hand, the comparator CP ₂ assumes that the voltage drop caused by the resistor R ₁ is a voltage determined by the resistors R ₈ and R ₉ (here, R ₈ = 1 kΩ, R ₉ = 19 kΩ, V _GA = −5 V, − 0.25 V) is compared with the upper limit value of the current (in this case outputs the H level and current is small flowing through the resistor _{R l} than 250 .mu.A). The two comparator output results by taking the logical product of Dl is, at a timing when the transfer unit thyristor S ₈ is lit, if H level, it is apparent that a transfer CHIP1 successful. The data lines of the logical product results D1 to D5 may be taken out of the head as they are, or may be taken out after serial-parallel conversion using a shift register or the like. Further, if it is not necessary to know the position of the chip where the transfer failure has occurred, the logical product of the respective outputs may be taken.

Here, the comparator is used to determine whether or not it is within the reference, but the voltage drop due to the resistors R _{1 to} R ₅ may be measured by an AD converter while being switched by an analog switch.

  The current measuring means is provided in the head, but may be provided on the power source side.

Here, the 8-bit self-scanning light emitting element array has been described. However, any number of bits may be used, and the current _IGA may be measured at the lighting timing of the last bit. Further, although a circuit using an anode common type self-scanning light emitting element array is taken as an example, a cathode common type may be used by appropriately switching the polarity.

In the first embodiment, the diode-coupled self-scanning light-emitting element array in which the gates of the transfer unit thyristors are coupled by diodes is taken as an example. However, even in the resistance-coupled type, the timing at which the thyristor of the last bit is turned on Since the current I _GA is smaller than the other currents, a similar method can be used.

FIG. 5 shows an equivalent circuit of a resistance-coupled self-scanning light-emitting element array. R _{i (i + 1)} (i = 1 to 7) represents a coupling resistance. The resistance values of these coupling resistors are the same, and the value is represented by R _{i (i + 1)} .

  In this case, three-phase clock pulses Φ1, Φ2, and Φ3 are used as transfer clock pulses. R1, R2 and R3 are current limiting resistors inserted in each clock pulse line.

In this equivalent circuit, when the ratio of the resistance values of the gate resistance and the coupling resistance is R _G : R _{i (i + 1)} = 1: 2, a network composed of the gate resistance and the coupling resistance continues indefinitely. Then, the ratio of the current flowing through the gate resistor R _Gi to the current flowing through the gate resistor R _{G (i + 1)} is 2: 1, and the relationship between the current I _GA and the waveform of the drive pulse is as shown in FIG. Although the difference between the current I _GA (S ₇ ) and the current I _GA (S ₈ ) is smaller than that of the coupled diode method, at the timing when the thyristor S ₈ is actually turned on, the cathode of the thyristor S ₇ is connected. clock pulse Φ1 you are has become the H level, the thyristor _{S 7} can not be turned on, it may be compared current _I GA _{(S 5)} and a current _I GA _{(S 8).} Therefore, as when the thyristor _{S 8} is turned on, in the case the thyristors _{S 8} is not turned _{on, (I GA (S 5)} -I GA (S 8)) / I GA (S 8) ≒ 0 .5. Accordingly, the thyristor S ₈ measures the current I _GA at the timing of the on, if the value is less than a predetermined value, can be inspected abnormal emission.

Further, in the optical writing head in which the self-scanning light emitting element array chips of FIG. 5 are linearly arranged, as described with reference to FIG. 4A, by providing an ammeter on each _VGA line of each chip, Luminescence abnormality can be detected.

  In the first embodiment, a self-scanning light emitting element array having an independent start pulse terminal is taken as an example. However, the present invention is also applicable to a self-scanning light emitting element array of a method of synthesizing a start pulse terminal from another logic. Applicable. Such a self-scanning light emitting element array is disclosed in Japanese Patent Application Laid-Open No. 2001-68736 related to the application of the present applicant.

An example is shown in FIG. A diode 20 and one end of the clock pulse Φ2 for connected current limiting terminal resistor R2, is inserted between the gate of the transfer unit thyristors S _1. Thereby, the start pulse terminal can be omitted.

Figure 8 shows a current value of the clock pulse .phi.1, .phi.2 waveform and the current _{I GA.} Since the current at the ON timing of the last bit is smaller than the other bits, the same method as described above can be used.

Further, in the optical writing head in which the self-scanning light emitting element array chips of FIG. 7 are linearly arranged, as described with reference to FIG. 4A, by providing an ammeter on each _VGA line of each chip, Luminescence abnormality can be detected.

In the embodiment shown in FIG. 4A, the current _IGA can be measured for each chip. However, this method requires as many ammeters as the number of chips, which is expensive. Therefore, as shown in FIG. 9, the _{V GA} line of each chip is connected to a common _{V GA} line 30 of one, and inserting one ammeter J to the common _{V GA} line 30, the ammeter J It was decided to measure the current _IGA . Here, _VGA lines of 60 chips for one head are collected. Anyway, when measuring the current I _GA for all chips, even by applying a current I _GA of 390μA at most one chip with thyristor is on other than the final bit abnormal transfer of 60 chips, the current change is 2% Because it is only about this, the measurement accuracy must be high. For this reason, an abnormality was detected by examining in advance whether there was a change of 1% or more based on the initial current _IGA measured in a state where normal transfer was confirmed. In order to ensure measurement accuracy of about 1%, the ammeter J was built in the head using a 10-bit AD converter.

  It is obvious that this inspection method can be applied even if the chip in FIG. 9 is the chip shown in FIGS.

In Example 4, it is necessary to capture a 1% change in current. However, a highly accurate ammeter is expensive, and the semiconductor resistor has a large temperature coefficient, so that it may be necessary to correct the temperature coefficient. For this reason, cost may become high on the contrary. Therefore, 60 chips are divided into a plurality of blocks, and the current I _GA for each block is measured. For example, if the whole is divided into 10 blocks, the number of chips included in one block is 6 chips, and an abnormality can be detected with 10 times the sensitivity of the fourth embodiment. FIG. 10 shows a part of an equivalent circuit of this optical writing head. Only five blocks are shown to simplify the drawing. It can be seen that ammeters J1, J2, J3... Are provided for each block.

6 V _GA line of each chip within one block are connected to one common V _GA line as shown in FIG. 9, shown in Figure 10 to a common V _GA line of each block As shown, ammeters J1, J2, J3... Are inserted. Each ammeter detects a current at the ON timing of the last bit of each block.

  It is obvious that this inspection method can be applied even if the chip is the chip shown in FIGS.

In the fifth embodiment, since an ammeter is required for each block, the cost is increased. Therefore, each block is operated separately in a time division manner, and the current _IGA is measured by one ammeter for each block. In order to drive each block in a time-sharing manner, clock pulses Φ1 and Φ2 are prepared for each block as shown in FIG. In this case, the chip uses a chip without the start pulse terminal [Phi _S as chip shown in FIG.

V _GA line six of each chip within one block are connected to one common V _GA line as shown in FIG. 9, the common V _GA line of each block, in FIG. 11 As shown in the figure, the _VGA line 32 of the optical writing head is connected, and one ammeter J is inserted into the _VGA line 32.

  Clock pulses Φ1-1 and Φ2-1 are for BLOCK1, clock pulses Φ1-2 and Φ2-2 are for BLOCK2, Φ1-3 and Φ2-3 are for BLOCK3, Φ1-4 and Φ2-4 are for BLOCK4, Φ1- 5 and Φ2-5 are for BLOCK5. Each clock pulse is supplied to the respective block via a clock pulse line.

In the circuit as described above, if the clock pulses Φ1 and Φ2 are separately supplied to each block, the current _IGA can be measured by one ammeter for each block.

On the other hand, when a chip having a start pulse terminal Φ _S is used, the start pulses Φ _S 1, Φ _S 2, Φ _S 3, Φ _S 4, and Φ _S 5 are changed to BLOCK 1, 2, as shown in FIG. Prepare for each of 3, 4 and 5. Each start pulse Φ _S is supplied to each block via a start pulse line. The clock pulses Φ1 and Φ2 are supplied to each block in common.

In the circuit as described above, if the start pulse Φs is separately supplied to each block, the current I _GA can be measured by one ammeter J for each block.

In Example 6, a clock pulse .phi.1, must prepare the Φ2 line or the start pulse [Phi _S line only pair of blocks, the number of wires increases, the structure of the optical writing head is complicated. Clock pulses .phi.1, .phi.2, illustrating a method of inspecting the lighting state of each chip or each block or less configuration in which a common start pulse [Phi _S. The configuration of the head or block is the same as in FIG.

That is, in the self-scanning light emitting element array having the start pulse terminal of FIG. 1 or FIG. 5, after the transfer unit final thyristor is turned on, only the chip to be measured sets the image signal Φ ₁ to the L level, Turn on the light. Thereafter, the clock pulse Φ2 of all the chips is set to the H level, and the transfer unit thyristors of all the chips are turned off. At this time, in a normal chip, only one final light emitting unit thyristor is lit. On the other hand, when there is an abnormality, the light emitting thyristors other than the final light emitting unit thyristor are turned on or completely turned off. Therefore, by measuring the _VGA current at this time and measuring that it is in the normal current range, it is possible to evaluate whether or not this chip is normally lit. By repeating this operation sequentially, the operation of all the chips can be confirmed.

Examples of drive pulses in the circuit of FIG. 9 are shown in FIGS. 13A and 13B (continuation of FIG. 13A). First, the on state of the shift unit is sequentially sent, and the shift unit of the last bit is turned on (time t ₁ ). (Here, CHIP1) then wish to operation check chips phi _I terminal (here, phi _I 1) to the L level, Other phi _I terminal is kept at the H level (time _t 2). Subsequently, the clock pulse phi ₂ H level, thereby turning off all transfer unit thyristor CHIP1～CHIP5 (time _t 3). The light emitting unit thyristor that is turned on at this point becomes the last bit of CHIP1 when CHIP1 is normally transferred. On the other hand, when CHIP1 is not normally transferred, thyristors other than the last bit are turned on. Measuring the current of the _{V GA} in this state of the time _{t 3.} Next, φ _I 1 is set to H level to turn off the light emitting thyristor. Subsequently, the ON state of the transfer unit is sequentially sent again, and the transfer unit thyristor for the last bit is turned ON (time t ₄ ). (Here, CHIP2) then wish to operation check chips phi _I terminal (here, phi _I 2) as a L-level, Other phi _I terminal is kept at the H level (time _t 5). Subsequently, the clock pulse φ2 is set to the H level, and all the transfer unit thyristors CHIP1 to CHIP5 are turned off (time t ₆ ). The thyristor that is turned on at this time becomes the last bit of CHIP2 when CHIP2 is normally transferred. On the other hand, when CHIP2 is not normally transferred, thyristors other than the last bit are turned on. By measuring the current of the _{V GA} in the state of the time _{t 5,} determines whether the operation of CHIP2. Thereafter, the determination is performed by lighting the last thyristor of each chip in the same manner.

In Example 7, a self-scanning light-emitting element array having a start terminal is taken as an example, but when a self-scanning light-emitting element array of a method of synthesizing the start terminal of FIG. 7 from the logic of other terminals is used, When the clock pulse Φ2 keep the H level, since the path through which a current flows from the clock pulse Φ2 pin V _GA terminal flows out is present, even chip transfer unit thyristor is not also turned on one, in FIG. 14 As shown, currents I1 and I2 flow. Therefore, after the transfer unit final thyristor is turned on, the image signal Φ _{1 is set} to L level only for the chip to be measured, and the light emitting unit final thyristor is turned on. After that, once the clock pulse Φ2 is set to H level and all the thyristors of the transfer unit are turned off, and the clock pulse Φ2 is set to L level again, only the transfer unit thyristor corresponding to the lit light emitting unit thyristor can be turned on. Evaluation similar to Example 7 is possible.

The above operation will be described with reference to FIGS. 15 and 16A to 16D.
Figure 15 is a diagram showing a driving pulse, FIG 16A~ to 16D are views showing respectively the current flowing to the _{V GA} terminal.
16A is final thyristors _{L 8} is a state of CHIP1 at time _{t 3} in FIG. 15 is on. At this time, currents I1 and I2 flow. In this state, as shown in FIG. 16B, a current corresponding to I1 flows in CHIP2-5. Next, at time t ₄ , in CHIP 1, as shown in FIG. 16C, thyristor S ₈ is turned on, but currents of almost the same value flow through I 2. On the other hand, in CHIP2～5, as shown in FIG. 16D, in order to transfer unit thyristor also not lit one, start diode _{D S} becomes the clock pulse φ2 is at the L level will be turned _{off, V GA} no current flows .
The method of this embodiment is also applicable to the self-scanning light emitting element array chip of FIGS.
When applied to the chip of FIG. 1, the drive pulse shown in FIG. 13B can be the drive pulse shown in FIG. Because thyristors L ₈ and S ₈ are connected the gate, it is possible to obtain the same effect as the present embodiment. It should be noted that, in this case, the thyristor _{S 8} is not turned on.
In the case of application to the chip of FIG. 5, the clock pulse φ2 is set to the L level again after the transfer unit is completely turned off.

  Although Examples 1-5 can evaluate light emission abnormality in real time, since Examples 6-8 select the evaluation object by a time division, it is difficult to evaluate light emission abnormality in real time. Thus, the timing at which the sixth to eighth embodiments are performed may be, for example, at the time of executing a self-check at startup. Furthermore, if necessary, a check may also be performed between paper feeds during printing.

  FIG. 17 shows a configuration of an optical printer using such an optical printer head by arranging a plurality of self-scanning light emitting element array chips to form an optical head for an optical printer. A photoconductive material (photosensitive member) such as amorphous Si is formed on the surface of the cylindrical photosensitive drum 42. This drum rotates at the speed of printing. The surface of the photosensitive drum of the rotating drum is uniformly charged with the electric charge 44. Then, the optical printer head 40 irradiates the photoconductor with the light of the dot image to be printed, and neutralizes the charging where the light hits. Subsequently, the developing unit 48 applies toner to the photoconductor according to the charged state on the photoconductor. Then, the toner is transferred onto the paper 54 sent from the cassette 52 by the transfer device 50. The sheet is heated and fixed by the fixing device 46 and sent to the stacker 58. On the other hand, the drum after the transfer is neutralized by the erasing lamp 60 over the entire surface, and the toner remaining on the cleaner 62 is removed.

3 is an equivalent circuit of a diode-coupled self-scanning light emitting element array chip. It is a figure which shows the drive waveform of the circuit of FIG. FIG. 2 is a diagram illustrating an example of a drive waveform of the circuit of FIG. 1 and a current value of a current _IGA . It is a figure which shows the optical writing head comprised by arranging the some self-scanning light emitting element array. It is a figure which shows the example of a measurement circuit of a voltage drop. 3 is an equivalent circuit of a resistively coupled self-scanning light emitting element array chip. FIG. 6 is a diagram showing an example of a drive waveform of the circuit of FIG. 5 and a current value of a current _IGA . FIG. 6 is an equivalent circuit diagram of a self-scanning light emitting element array in which a start pulse terminal is synthesized from other logic. It is a figure which shows the drive waveform of the circuit of FIG. 7, and the electric current value example of electric current _IGA . It is an equivalent circuit diagram of an optical writing head using one ammeter. FIG. 3 is an equivalent circuit diagram of an optical writing head in which a plurality of chips are blocked. FIG. 5 is an equivalent circuit diagram of another optical writing head in which a plurality of chips are blocked. FIG. 10 is an equivalent circuit diagram of still another optical writing head in which a plurality of chips are blocked. FIG. 10 is a diagram showing drive pulses in the circuit of FIG. 9. It is a figure which shows the drive pulse which is a continuation of FIG. 13A. It is a figure which shows the path | route from which an electric current flows out toward a _VGA terminal. It is a figure which shows a drive pulse. It is a figure which shows the electric current which flows toward a _VGA terminal. It is a figure which shows the electric current which flows toward a _VGA terminal. It is a figure which shows the electric current which flows toward a _VGA terminal. It is a figure which shows the electric current which flows toward a _VGA terminal. It is a figure which shows the structure of an optical printer.

Explanation of symbols

10 _VGA power supply 30, 32 Common _VGA line 40 Optical writing head 42 Photosensitive drum 44 Band electricity 46 Fixing device 48 Developing device 50 Transfer device 52 Cassette 54 Paper 58 Stacker 60 Erase lamp 62 Cleaning device

Claims (18)

A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor A transfer unit that turns on a thyristor adjacent to the certain thyristor by changing a gate voltage of the thyristor by a circuit network including the diode and a gate resistor;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In a self-scanning light-emitting element array chip comprising a light-emitting unit provided with a line for applying an image signal for
Insert a current measurement circuit into the power line,
At the timing when only the last thyristor of the plurality of arranged transfer thyristors is turned on, the current flowing through the power supply line is measured by the current measuring circuit, and the self-scanning light emitting element array is measured based on the measured value. Inspection method for detecting light emission abnormality of chip. A plurality of three-terminal light-emitting thyristors for transfer are arranged one-dimensionally; the gates of adjacent thyristors are connected to each other by a coupling resistor; a power supply line is connected to each gate electrode of the thyristor, and each gate resistor is connected A three-phase clock pulse line from the outside is connected in sequence to the cathode or anode of each thyristor; when a thyristor is turned on by a single-phase clock pulse, Changing the gate voltage of the thyristor by a circuit network composed of the coupling resistor and the gate resistor; a transfer unit for turning on a thyristor adjacent to the certain thyristor by a clock pulse of another phase;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In a self-scanning light-emitting element array chip comprising a light-emitting unit provided with a line for applying an image signal for
Insert a current measurement circuit into the power line,
At the timing when only the last thyristor of the plurality of arranged transfer thyristors is turned on, the current flowing through the power supply line is measured by the current measuring circuit, and the self-scanning light emitting element array is measured based on the measured value. Inspection method for detecting light emission abnormality of chip. A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor The gate voltage of the thyristor is changed by a circuit network composed of the diode and the gate resistor; the thyristor adjacent to the certain thyristor is turned on by the clock pulse of the other phase; one of the clock pulses of the two phases Is connected to the gate of the first transfer thyristor to be turned on via a diode. A transfer unit,
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In a self-scanning light-emitting element array chip comprising a light-emitting unit provided with a line for applying an image signal for
Insert a current measurement circuit into the power line,
At the timing when only the last thyristor of the plurality of arranged transfer thyristors is turned on, the current flowing through the power supply line is measured by the current measuring circuit, and the self-scanning light emitting element array is measured based on the measured value. Inspection method for detecting light emission abnormality of chip. A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor A transfer unit that turns on a thyristor adjacent to the certain thyristor by changing a gate voltage of the thyristor by a circuit network including the diode and a gate resistor;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light emitting element array chips, each having a light emitting portion provided with a line for applying an image signal for, are arranged in a one-dimensional manner,
For each chip, insert a current measurement circuit into the power line,
For each chip, at the timing when only the last thyristor of the plurality of arranged transfer thyristors is turned on, the current flowing through the power supply line is measured by the current measuring circuit, and the light is measured based on the measured value. An inspection method for detecting a light emission abnormality of a writing head. A plurality of three-terminal light-emitting thyristors for transfer are arranged one-dimensionally; the gates of adjacent thyristors are connected to each other by a coupling resistor; a power supply line is connected to each gate electrode of the thyristor, and each gate resistor is connected A three-phase clock pulse line from the outside is connected in sequence to the cathode or anode of each thyristor; when a thyristor is turned on by a single-phase clock pulse, Changing the gate voltage of the thyristor by a circuit network composed of the coupling resistor and the gate resistor; a transfer unit for turning on a thyristor adjacent to the certain thyristor by a clock pulse of another phase;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light emitting element array chips, each having a light emitting portion provided with a line for applying an image signal for, are arranged in a one-dimensional manner,
For each chip, insert a current measurement circuit into the power line,
For each chip, at the timing when only the last thyristor of the plurality of arranged transfer thyristors is turned on, the current flowing through the power supply line is measured by the current measuring circuit, and the light is measured based on the measured value. An inspection method for detecting a light emission abnormality of a writing head. A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor The gate voltage of the thyristor is changed by a circuit network composed of the diode and the gate resistor; the thyristor adjacent to the certain thyristor is turned on by the clock pulse of the other phase; one of the clock pulses of the two phases Is connected to the gate of the first transfer thyristor to be turned on via a diode. A transfer unit,
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light emitting element array chips, each having a light emitting portion provided with a line for applying an image signal for, are arranged in a one-dimensional manner,
For each chip, insert a current measurement circuit into the power line,
For each chip, at the timing when only the last thyristor of the plurality of arranged transfer thyristors is turned on, the current flowing through the power supply line is measured by the current measuring circuit, and the light is measured based on the measured value. An inspection method for detecting a light emission abnormality of a writing head. A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor A transfer unit that turns on a thyristor adjacent to the certain thyristor by changing a gate voltage of the thyristor by a circuit network including the diode and a gate resistor;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light-emitting elements including a light-emitting unit provided with a line for applying an image signal for one-dimensionally arranged,
Connect the power line of each chip to one common power line,
A current measurement circuit is inserted into the common power supply line, and the current flowing through the common power supply line is measured by the current measurement circuit at the timing when only the last transfer thyristor is turned on through all the chips. An inspection method for detecting a light emission abnormality of an optical writing head. A plurality of three-terminal light-emitting thyristors for transfer are arranged one-dimensionally; the gates of adjacent thyristors are connected to each other by a coupling resistor; a power supply line is connected to each gate electrode of the thyristor, and each gate resistor is connected A three-phase clock pulse line from the outside is connected in sequence to the cathode or anode of each thyristor; when a thyristor is turned on by a single-phase clock pulse, Changing the gate voltage of the thyristor by a circuit network composed of the coupling resistor and the gate resistor; a transfer unit for turning on a thyristor adjacent to the certain thyristor by a clock pulse of another phase;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light emitting element array chips, each having a light emitting portion provided with a line for applying an image signal for, are arranged in a one-dimensional manner,
Connect the power line of each chip to one common power line,
A current measurement circuit is inserted into the common power supply line, and the current flowing through the common power supply line is measured by the current measurement circuit at the timing when only the last transfer thyristor is turned on through all the chips. An inspection method for detecting a light emission abnormality of an optical writing head. A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor The gate voltage of the thyristor is changed by a circuit network composed of the diode and the gate resistor; the thyristor adjacent to the certain thyristor is turned on by the clock pulse of the other phase; one of the clock pulses of the two phases Is connected to the gate of the first transfer thyristor to be turned on via a diode. A transfer unit,
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light emitting element array chips, each having a light emitting portion provided with a line for applying an image signal for, are arranged in a one-dimensional manner,
Connect the power line of each chip to one common power line,
A current measurement circuit is inserted into the common power supply line, and the current flowing through the common power supply line is measured by the current measurement circuit at the timing when only the last transfer thyristor is turned on through all the chips. An inspection method for detecting a light emission abnormality of an optical writing head. A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor A transfer unit that turns on a thyristor adjacent to the certain thyristor by changing a gate voltage of the thyristor by a circuit network including the diode and a gate resistor;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light emitting element array chips, each having a light emitting portion provided with a line for applying an image signal for, are arranged in a one-dimensional manner,
Blocking the self-scanning light emitting element array chip every predetermined number,
Connect the power line of the chip in each block to the common power line for each block,
Current measurement circuits are inserted into the respective common power supply lines, and currents flowing through the respective common power supply lines at the timing when only the last transfer thyristor is turned on through all chips in each block are referred to as the respective current measurement circuits. And an inspection method for detecting a light emission abnormality of the optical writing head based on the measured value. A plurality of three-terminal light-emitting thyristors for transfer are arranged one-dimensionally; the gates of adjacent thyristors are connected to each other by a coupling resistor; a power supply line is connected to each gate electrode of the thyristor, and each gate resistor is connected A three-phase clock pulse line from the outside is connected in sequence to the cathode or anode of each thyristor; when a thyristor is turned on by a single-phase clock pulse, Changing the gate voltage of the thyristor by a circuit network composed of the coupling resistor and the gate resistor; a transfer unit for turning on a thyristor adjacent to the certain thyristor by a clock pulse of another phase;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light emitting element array chips, each having a light emitting portion provided with a line for applying an image signal for, are arranged in a one-dimensional manner,
Blocking the self-scanning light emitting element array chip every predetermined number,
Connect the power line of the chip in each block to the common power line for each block,
Current measurement circuits are inserted into the respective common power supply lines, and currents flowing through the respective common power supply lines at the timing when only the last transfer thyristor is turned on through all chips in each block are referred to as the respective current measurement circuits. And an inspection method for detecting a light emission abnormality of the optical writing head based on the measured value. A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor The gate voltage of the thyristor is changed by a circuit network composed of the diode and the gate resistor; the thyristor adjacent to the certain thyristor is turned on by the clock pulse of the other phase; one of the clock pulses of the two phases Is connected to the gate of the first transfer thyristor to be turned on via a diode. A transfer unit,
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light emitting element array chips, each having a light emitting portion provided with a line for applying an image signal for, are arranged in one dimension,
Blocking the self-scanning light emitting element array chip every predetermined number,
Connect the power line of the chip in each block to the common power line for each block,
Current measurement circuits are inserted into the respective common power supply lines, and currents flowing through the respective common power supply lines at the timing when only the last transfer thyristor is turned on through all chips in each block are referred to as the respective current measurement circuits. And an inspection method for detecting a light emission abnormality of the optical writing head from the measured value. A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor A transfer unit that turns on a thyristor adjacent to the certain thyristor by changing a gate voltage of the thyristor by a circuit network including the diode and a gate resistor;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light emitting element array chips, each having a light emitting portion provided with a line for applying an image signal for, are arranged in a one-dimensional manner,
Blocking the self-scanning light emitting element array chip every predetermined number,
Connect the power line of the chip in each block to the common power line for each block,
Each of the common power lines is connected to one common power line of the optical writing head, and one current measuring circuit is inserted into the common power line.
Each block is operated in a time-sharing manner, and the current measurement circuit measures the current flowing through the one common power supply line at the timing when only the last transfer thyristor is turned on through all the chips in each block. And an inspection method for detecting a light emission abnormality of the optical writing head based on a measured value. A plurality of three-terminal light-emitting thyristors for transfer are arranged one-dimensionally; the gates of adjacent thyristors are connected to each other by a coupling resistor; a power supply line is connected to each gate electrode of the thyristor, and each gate resistor is connected A three-phase clock pulse line from the outside is connected in sequence to the cathode or anode of each thyristor; when a thyristor is turned on by a single-phase clock pulse, Changing the gate voltage of the thyristor by a circuit network composed of the coupling resistor and the gate resistor; a transfer unit for turning on a thyristor adjacent to the certain thyristor by a clock pulse of another phase;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light emitting element array chips, each having a light emitting portion provided with a line for applying an image signal for, are arranged in a one-dimensional manner,
Blocking the self-scanning light emitting element array chip every predetermined number,
Connect the power line of the chip in each block to the common power line for each block,
Each of the common power lines is connected to one common power line of the optical writing head, and one current measuring circuit is inserted into the common power line.
Each block is operated in a time-sharing manner, and the current measurement circuit measures the current flowing through the one common power supply line at the timing when only the last transfer thyristor is turned on through all the chips in each block. And an inspection method for detecting a light emission abnormality of the optical writing head based on a measured value. A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor The gate voltage of the thyristor is changed by a circuit network composed of the diode and the gate resistor; the thyristor adjacent to the certain thyristor is turned on by the clock pulse of the other phase; one of the clock pulses of the two phases Is connected to the gate of the first transfer thyristor to be turned on via a diode. A transfer unit,
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In an optical writing head in which a plurality of self-scanning light emitting element array chips, each having a light emitting portion provided with a line for applying an image signal for, are arranged in a one-dimensional manner,
Blocking the self-scanning light emitting element array chip every predetermined number,
Each of the common power lines is connected to one common power line of the optical writing head, and one current measurement circuit is inserted into the common power line.
Each block is operated in a time-sharing manner, and the current measurement circuit measures the current flowing through the one common power supply line at the timing when only the last transfer thyristor is turned on through all the chips in each block. And an inspection method for detecting a light emission abnormality of the optical writing head based on a measured value. A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor A transfer unit that turns on a thyristor adjacent to the certain thyristor by changing a gate voltage of the thyristor by a circuit network including the diode and a gate resistor;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In a self-scanning light-emitting element array chip comprising a light-emitting unit provided with a line for applying an image signal for
When the transfer unit final thyristor is turned on, after turning on the light emitting unit final thyristor, turn off all transfer unit thyristors,
An inspection method for detecting a light emission abnormality of the optical writing head by determining whether or not the light emitting unit final thyristor is lit by measuring a current flowing through the power supply line. A plurality of three-terminal light-emitting thyristors for transfer are arranged one-dimensionally; the gates of adjacent thyristors are connected to each other by a coupling resistor; a power supply line is connected to each gate electrode of the thyristor, and each gate resistor is connected A three-phase clock pulse line from the outside is connected in sequence to the cathode or anode of each thyristor; when a thyristor is turned on by a single-phase clock pulse, Changing the gate voltage of the thyristor by a circuit network composed of the coupling resistor and the gate resistor; a transfer unit for turning on a thyristor adjacent to the certain thyristor by a clock pulse of another phase;
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In a self-scanning light-emitting element array chip comprising a light-emitting unit provided with a line for applying an image signal for
When the transfer unit final thyristor is turned on, after turning on the light emitting unit final thyristor, turn off all transfer unit thyristors,
An inspection method for detecting a light emission abnormality of the optical writing head by determining whether or not the light emitting unit final thyristor is lit by measuring a current flowing through the power supply line. A plurality of three-terminal light emitting thyristors for transfer are arranged one-dimensionally; gates of adjacent thyristors are connected to each other by a diode; a power supply line is connected to each gate electrode of the thyristor via each gate resistor Connect; externally connect two-phase clock pulse lines to the cathode or anode of each thyristor every other thyristor; when a thyristor is turned on by one phase of the clock pulse, in the vicinity of that thyristor The gate voltage of the thyristor is changed by a circuit network composed of the diode and the gate resistor; the thyristor adjacent to the certain thyristor is turned on by the clock pulse of the other phase; one of the clock pulses of the two phases Is connected to the gate of the first transfer thyristor to be turned on via a diode. A transfer unit,
A plurality of light emitting three-terminal thyristors are arranged one-dimensionally; each gate of the transfer thyristor is connected to a corresponding gate of the light emitting thyristor; light is emitted to the cathode or anode of each light emitting element In a self-scanning light-emitting element array chip comprising a light-emitting unit provided with a line for applying an image signal for
When the transfer unit final thyristor is turned on, after turning on the light emitting unit final thyristor, turn off all transfer unit thyristors,
When the transfer unit thyristor is turned on again, the transfer unit thyristor corresponding to the light emitting unit thyristor that is lit is determined by measuring the current flowing through the power supply line to determine whether the transfer unit thyristor is on. An inspection method for detecting a light emission abnormality of an optical writing head.

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