I wonder if you have checked the English abstract of the docume t in Japanese in a similar context by further conducting PAJ search on IPDL, where the abstract of this document by Denso is translated as follows:

インジェクタ駆動回路
要約
マイクロコンピュータの処理負荷を軽減しつつ、コモンレール内の燃料圧力を効率良く減圧することができるインジェクタ駆動回路を提供する。
【解決手段】コモンレール式燃料噴射システムにおいて、マイコン１５１は、機関運転状態に応じてインジェクタ１０１～１０４の駆動信号を生成すると共に、コモンレール圧を減圧するかしないかを判定する。駆動回路１００は、マイコン１５１からの駆動信号に基づきトランジスタＴ１０～Ｔ４０をオンし、インジェクタ１０１～１０４を駆動する。また、駆動回路１００は、マイコン１５１からの空打ち要求に際し、インジェクタ１０１～１０４のソレノイド１０１ａ～１０４ａに流れる電流値に基づき、実際には燃料噴射を行わない程度に小さい電流域でトランジスタＴ１０～Ｔ４０をオン／オフし、インジェクタ１０１～１０４による空打ちを実施してコモンレール圧を減圧する。

INJECTOR DRIVING CIRCUIT
Abstract:
PROBLEM TO BE SOLVED: To efficiently carry out pressure reduction of fuel pressure within a common rail while reducing processing load of a microcomputer.
SOLUTION: In a common rail type fuel injection system, the microcomputer 151 generates drive signals of injectors 101 to 104 in response to an engine operation state, and determines whether pressure reduction of a common rail pressure is carried out or not. A drive circuit 100 turns ON transistors T10 to T40 and drives the injectors 101 to 104 based on the drive signals from the microcomputer 151. Upon request of cold blow from the microcomputer 151, the drive circuit 100 turns ON/OFF the transistors T10 to T40 in a small current region in which a fuel injection is not actually carried out, based on a current value flowing in a solenoids 101a to 104a of the injectors 101 to 104, and the cold blow by the injectors 101 to 104 is performed thereby reducing the common rail pressure.

As I haven't conducted any other search myself, nor have no expertise in this field, I am not so sure about my answer.